Classification of X-ray solar flares regarding their effects on the lower ionosphere electron density profile

NASA Astrophysics Data System (ADS)

Grubor, D. P.; Ulić, D. M. Å.; Žigman, V.

2008-06-01

The classification of X-ray solar flares is performed regarding their effects on the Very Low Frequency (VLF) wave propagation along the Earth-ionosphere waveguide. The changes in propagation are detected from an observed VLF signal phase and amplitude perturbations, taking place during X-ray solar flares. All flare effects chosen for the analysis are recorded by the Absolute Phase and Amplitude Logger (AbsPal), during the summer months of 2004-2007, on the single trace, Skelton (54.72 N, 2.88 W) to Belgrade (44.85 N, 20.38 E) with a distance along the Great Circle Path (GCP) D≍2000 km in length. The observed VLF amplitude and phase perturbations are simulated by the computer program Long-Wavelength Propagation Capability (LWPC), using Wait's model of the lower ionosphere, as determined by two parameters: the sharpness (β in 1/km) and reflection height (H' in km). By varying the values of β and H' so as to match the observed amplitude and phase perturbations, the variation of the D-region electron density height profile Ne(z) was reconstructed, throughout flare duration. The procedure is illustrated as applied to a series of flares, from class C to M5 (5×10-5 W/m2 at 0.1-0.8 nm), each giving rise to a different time development of signal perturbation. The corresponding change in electron density from the unperturbed value at the unperturbed reflection height, i.e. Ne(74 km)=2.16×108 m-3 to the value induced by an M5 class flare, up to Ne(74 km)=4×1010 m-3 is obtained. The β parameter is found to range from 0.30-0.49 1/km and the reflection height H' to vary from 74-63 km. The changes in Ne(z) during the flares, within height range z=60 to 90 km are determined, as well.

Hot Alps (Invited)

NASA Astrophysics Data System (ADS)

Speranza, F.; Minelli, L.; Pignatelli, A.; Gilardi, M.

2013-12-01

Although it is frequently assumed that crust of Alpine orogens is hot due to the occurrence of thick and young (hence radiogenic) crust, evidence on the thermal ranking of orogens is contradictory. Heat flow measurements from shallow wells (depth ≤ 1 km) in the Alps yield a relatively cold thermal regime of 50-80 mW/m2, but data are likely biased by meteoric cold-water circulation. Here we report on the spectral analysis of the aeromagnetic residuals of northern Italy to derive the Curie point depth (CPD), assumed to represent the 600°C isotherm depth. Airborne magnetics were acquired on whole Italy during the 1970s by the national oil company AGIP (now Eni). Data were gathered by several surveys carried out at 1000-13,300 feet (300-4000 m) altitude, with flight line spacing of 2-10 km. Surveys of the Alps and Po Plain (northern Italy) were obtained both with a line spacing of 5 km (and 5 km tie lines), at an altitude of 4000-5000 and 13,300 feet, respectively. To evaluate CPDs we used the centroid method (routinely adopted in recent CPD studies on East Asia and central-southern Europe) on 72 square windows of 100-110 km edge, with a 50% degree of superposition. CPDs vary between 16 and 38 km (22 km on average) in the Po Plain, located south of the Alps and representing the Adriatic-African foreland area. Conversely, the Alps yield very shallow CPDs, ranging between 6 and 15 km (10 km on average). CPDs fall systematically above local Moho depths, implying that magnetic source bottoms documented in this study do not represent a lithological boundary over non-magnetic peridotitic mantle, but can be safely associated with CPDs and the 600°C isotherm. CPDs from the Po Plain are in rough agreement with reported heat flow values of 25-60 mW/m2, and imply and average thermal conductivity (k) of the Po Plain crust of 1.5 W/m°K, at the lower bound of k values measured and inferred for the crust. Conversely, the average 10 km CPD documented in the Alps translates into heat flow values ranging from 90 to 150 mW/m2, if k values of 1.5 to 2.5 W/m°K (respectively) are assumed (the latter is average k value of the crust assumed for other world provinces, such as California). A ~150 mW/m2 heat flow value turns out to be similar to that observed in Tuscany and the Tyrrhenian Sea back-arc basin, as well as to values documented for active rifts and young oceans. Di Stefano et al. (2009) documented P wave velocities around 8 km/sec in the upper mantle of the Alps, suggesting the lack of shallow asthenosphere. Thus high heat flow of the Alps must be produced by radiogenic crust, instead of asthenospheric upwelling. A 600°C isotherm at ~10 km depth implies widespread melting at mid-lower crustal depths, considering the 60 km crustal thickness of the Alps. This is consistent with the very low P-wave velocities observed at 20-40 km depth beneath the chain by Di Stefano et al. (2009). When extrapolated to other orogens of the geological past, the thermal regime of the Alps may explain the extensive occurrence of intrusives exposed in eroded pre-Alpine orogens and cratons. Reference: Di Stefano, R., et al. (2009), J. Geophys. Res., 114, doi:10.1029/2008JB005641.

Anomalies of rupture velocity in deep earthquakes

NASA Astrophysics Data System (ADS)

Suzuki, M.; Yagi, Y.

2010-12-01

Explaining deep seismicity is a long-standing challenge in earth science. Deeper than 300 km, the occurrence rate of earthquakes with depth remains at a low level until ~530 km depth, then rises until ~600 km, finally terminate near 700 km. Given the difficulty of estimating fracture properties and observing the stress field in the mantle transition zone (410-660 km), the seismic source processes of deep earthquakes are the most important information for understanding the distribution of deep seismicity. However, in a compilation of seismic source models of deep earthquakes, the source parameters for individual deep earthquakes are quite varied [Frohlich, 2006]. Rupture velocities for deep earthquakes estimated using seismic waveforms range from 0.3 to 0.9Vs, where Vs is the shear wave velocity, a considerably wider range than the velocities for shallow earthquakes. The uncertainty of seismic source models prevents us from determining the main characteristics of the rupture process and understanding the physical mechanisms of deep earthquakes. Recently, the back projection method has been used to derive a detailed and stable seismic source image from dense seismic network observations [e.g., Ishii et al., 2005; Walker et al., 2005]. Using this method, we can obtain an image of the seismic source process from the observed data without a priori constraints or discarding parameters. We applied the back projection method to teleseismic P-waveforms of 24 large, deep earthquakes (moment magnitude Mw ≥ 7.0, depth ≥ 300 km) recorded since 1994 by the Data Management Center of the Incorporated Research Institutions for Seismology (IRIS-DMC) and reported in the U.S. Geological Survey (USGS) catalog, and constructed seismic source models of deep earthquakes. By imaging the seismic rupture process for a set of recent deep earthquakes, we found that the rupture velocities are less than about 0.6Vs except in the depth range of 530 to 600 km. This is consistent with the depth variation of deep seismicity: it peaks between about 530 and 600 km, where the fast rupture earthquakes (greater than 0.7Vs) are observed. Similarly, aftershock productivity is particularly low from 300 to 550 km depth and increases markedly at depth greater than 550 km [e.g., Persh and Houston, 2004]. We propose that large fracture surface energy (Gc) value for deep earthquakes generally prevent the acceleration of dynamic rupture propagation and generation of earthquakes between 300 and 700 km depth, whereas small Gc value in the exceptional depth range promote dynamic rupture propagation and explain the seismicity peak near 600 km.

Earth's gravity field mapping requirements and concept. [using a supercooled gravity gradiometer

NASA Technical Reports Server (NTRS)

Vonbun, F. O.; Kahn, W. D.

1981-01-01

A future sensor is considered for mapping the Earth's gravity field to meet future scientific and practical requirements for earth and oceanic dynamics. These are approximately + or - 0.1 to 10 mgal over a block size of about 50 km and over land and an ocean geoid to 1 to 2 cm over a distance of about 50 km. To achieve these values requires a gravity gradiometer with a sensitivity of approximately 10 to the -4 power EU in a circular polar orbiting spacecraft with an orbital altitude ranging 160 km to 180 km.

Undergraduate Research Program in Atmospheric Science: Houston Ozone Studies

NASA Astrophysics Data System (ADS)

Morris, P. A.; Balimuttajjo, M.; Damon, D.; Herridge, A.; Hromis, A. G.; Litwin, D.; Wright, J. M.

2011-12-01

The Minority University Consortium for Earth and Space Sciences (MUCESS) composed of the University of Houston-Downtown (UHD), Medgar Evers College (City University of New York), South Carolina State University, is an undergraduate atmospheric science program funded by NSF. The program's goal is to increase the participation of minority universities in STEM activities and careers by providing students with the knowledge and skills needed to perform weather balloon launches, interpret ozone and temperature variations in the troposphere and stratosphere. Ozone profiles up to 30 km altitude are obtained via an instrument payload attached to a weather balloon. The payload instrumentation consists of an EN-SCI ECC ozonesonde and an iMET radiosonde. The data is transmitted to a base station in real time and includes pressure, temperature, humidity, and GPS coordinates This presentation is directed towards comparing our 2011 Houston data to data that either UHD or the University of Houston (UH) has collected. Our launches are primarily on Sunday, and UH's on Friday. Our primary objective is to identify ground level ozone variations on Sunday and compare with weekday levels as tropospheric ozone is largely controlled by anthropogenic activities. Ozone levels vary depending on the time of year, temperature, rain, wind direction, chemical plant activities, private and commercial traffic patterns.etc. Our limited Friday launches, supported by UH data, indicate that ground level ozone is generally elevated in contrast to Sunday data, For example, our Friday July 2011 launch detected elevated low-altitude ozone levels with ground level ozone levels of 42 nb that increased to 46 nb from 500 m to 1 km. Other peaks are at 2.7 km (44 nb) and 6km (41 nb), decreasing to 17 nb at the tropopause (12 km). Overall, Sunday low altitude ozone levels are generally lower. Our Sunday ground level ozone data ranges from a low of 25 nb on July 11 to a high of 50 nb on August 1. A combination of wind direction and industrial output variations are likely responsible for the these differences. On July 11, ozone levels decrease slightly from the ground-level values up to 2 km. Above this altitude, significant fluctuations in ozone values ranging from 20 to 40nb occur from 2 to 7 km. These fluctuations inversely correlate with humidity. Relative humidity of 20% corresponding to high ozone and 60% humidity values for low ozone. This probably reflects dilution of ozone with water vapor. In contrast, on August 1 ozone values decrease abruptly at 800 meters to 35 nb with only minor fluctuations with increasing altitude to the tropopause. For both days, the change from ground-level ozone values to the higher altitude patterns correlates with a slight temperature inversion. The Stratospheric ozone also shows a significant contrast on the two days. At 22 km altitude an ozone value of 150 nb is seen on August 1 cf the more typical 110 nb on July 11. The high value seen on August 1 is coincident with a major solar flare. These variations are typical of the range of stratospheric ozone levels seen throughout the year and may be attributable to short-term fluctuations in solar activity.

Retrieval of O2(1Σ) and O2(1Δ) volume emission rates in the mesosphere and lower thermosphere using SCIAMACHY MLT limb scans

NASA Astrophysics Data System (ADS)

Zarboo, Amirmahdi; Bender, Stefan; Burrows, John P.; Orphal, Johannes; Sinnhuber, Miriam

2018-01-01

We present the retrieved volume emission rates (VERs) from the airglow of both the daytime and twilight O2(1Σ) band and O2(1Δ) band emissions in the mesosphere and lower thermosphere (MLT). The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard the European Space Agency Envisat satellite observes upwelling radiances in limb-viewing geometry during its special MLT mode over the range 50-150 km. In this study we use the limb observations in the visible (595-811 nm) and near-infrared (1200-1360 nm) bands. We have investigated the daily mean latitudinal distributions and the time series of the retrieved VER in the altitude range from 53 to 149 km. The maximal observed VERs of O2(1Δ) during daytime are typically 1 to 2 orders of magnitude larger than those of O2(1Σ). The latter peaks at around 90 km, whereas the O2(1Δ) emissivity decreases with altitude, with the largest values at the lower edge of the observations (about 53 km). The VER values in the upper mesosphere (above 80 km) are found to depend on the position of the sun, with pronounced high values occurring during summer for O2(1Δ). O2(1Σ) emissions show additional high values at polar latitudes during winter and spring. These additional high values are presumably related to the downwelling of atomic oxygen after large sudden stratospheric warmings (SSWs). Accurate measurements of the O2(1Σ) and O2(1Δ) airglow, provided that the mechanism of their production is understood, yield valuable information about both the chemistry and dynamics in the MLT. For example, they can be used to infer the amounts and distribution of ozone, solar heating rates, and temperature in the MLT.

Backscatter-to-Extinction Ratios in the Top Layers of Tropical Mesoscale Convective Systems and in Isolated Cirrus from LITE Observations

NASA Technical Reports Server (NTRS)

Platt, C. M. R.; Winker, D. M.; Vaughan, M. A.; Miller, S. D.

1999-01-01

Cloud-integrated attenuated backscatter from observations with the Lidar In-Space Technology Experiment (LITE) was studied over a range of cirrus clouds capping some extensive mesoscale convective systems (MCSS) in the Tropical West Pacific. The integrated backscatter when the cloud is completely attenuating, and when corrected for multiple scattering, is a measure of the cloud particle backscatter phase function. Four different cases of MCS were studied. The first was very large, very intense, and fully attenuating, with cloud tops extending to 17 km and a maximum lidar pulse penetration of about 3 km. It also exhibited the highest integrated attenuated isotropic backscatter, with values in the 532-nm channel of up to 2.5 near the center of the system, falling to 0.6 near the edges. The second MCS had cloud tops that extended to 14.8 km. Although MCS2 was almost fully attenuating, the pulse penetration into the cloud was up to 7 km and the MCS2 had a more diffuse appearance than MCS1. The integrated backscatter values were much lower in this system but with some systematic variations between 0.44 and 0.75. The third MCS was Typhoon Melissa. Values of integrated backscatter in tt-ds case varied from 1.64 near the eye of the typhoon to between 0.44 and 1.0 in the areas of typhoon outflow and in the 532-nm channel. Mean pulse penetration through the cloud top was 2-3 km, the lowest penetration of any of the systems. The fourth MCS consisted of a region of outflow from Typhoon Melissa. The cloud was semitransparent for more than half of the image time. During that time, maximum cloud depth was about 7 km. The integrated backscatter varied from about 0.38 to 0.63 in the 532-nm channel when the cloud was fully attenuating. In some isolated cirrus between the main systems, a plot of integrated backscatter against one minus the two-way transmittance gave a linear dependence with a maximum value of 0.35 when the clouds were fully attenuating. The effective backscatter-to-extinction ratios, when allowing for different multiple-scattering factors from space, were often within the range of those observed with ground-based lidar. Exceptions occurred near the centers of the most intense convection, where values were measured that were considerably higher than those in cirrus observed from the surface. In this case, the values were more compatible with theoretical values for perfectly formed hexagonal columns or plates. The large range in theoretically calculated back- scatter-to-extinction ratio and integrated multiple-scattering factor precluded a closer interpretation in terms of cloud microphysics.

Inhibition of thiopurine S-methyltransferase activity by impurities in commercially available substrates: a factor for differing results of TPMT measurements.

PubMed

Kröplin, T; Fischer, C; Iven, H

1999-06-01

Thiopurine S-methyltransferase (TPMT) activity, when measured in red blood cells (RBC) with a recently published TPMT activity assay using 6-thioguanine (6-TG) as substrate, could not be reproduced in another laboratory. We investigated factors which could influence the results of the TPMT activity measurement. We tested twelve 6-TG and four 6-mercaptopurine (6-MP) compounds from different suppliers as substrates and determined the enzyme kinetic parameters Km and Vmax. Furthermore, we studied the influence of different 6-TG compounds on the affinity of the methyl donor S-adenosyl-L-methionine (SAM) to the TPMT enzyme. All 6-TG products were of equal purity (declared >98% by the supplier): this was ascertained by HPLC. However, the rate of methylation obtained following incubation with 6-TG from different suppliers ranged from 10% to 100% when incubated with the same RBC lysate. The lowest apparent Km value for a 6-TG was 22.3 micromol x l(-1), while the product with the highest methylation rate showed a Km of 156 micromol x l(-1). From these results we assume that there is a contaminant in some 6-TG products, which acts as a strong inhibitor of TPMT activity. Compounds possibly used for the synthesis of 6-TG (guanine, pyridine, 6-chloroguanine) did not affect the methylation rate. Thioxanthine, which is known to be a strong inhibitor of TPMT when added to the assay system to give a 2% contamination, reduced TPMT activity from 100% to 72%. Using 6-MP from different suppliers as substrate resulted in Km values ranging from 110 to 162 micromol x l(-1) and Vmox values ranging from 54 to 68 nmol 6-MMP x g(-1)Hb x h(-1). The Km value for the methyl donor SAM was similar to and independent from the thiopurine substrates tested (range 4.9-11 micromol-l(-1) SAM). In contrast to other investigators, we found non-enzymatic S-methylation, which was negligible under our assay conditions (3% with 128 micromol x l(-1) SAM), but could become relevant in experiments using higher SAM concentrations. TPMT enzyme activity determined with 6-TG as substrate may be strongly inhibited by a contaminant in some of the 6-TG lots distributed.

Modelling CO emission - II. The physical characteristics that determine the X factor in Galactic molecular clouds

NASA Astrophysics Data System (ADS)

Shetty, Rahul; Glover, Simon C.; Dullemond, Cornelis P.; Ostriker, Eve C.; Harris, Andrew I.; Klessen, Ralf S.

2011-08-01

We investigate how the X factor, the ratio of the molecular hydrogen column density (?) to velocity-integrated CO intensity (W), is determined by the physical properties of gas in model molecular clouds (MCs). The synthetic MCs are results of magnetohydrodynamic simulations, including a treatment of chemistry. We perform radiative transfer calculations to determine the emergent CO intensity, using the large velocity gradient approximation for estimating the CO population levels. In order to understand why observations generally find cloud-averaged values of X = XGal˜ 2 × 1020 cm-2 K-1 km-1 s, we focus on a model representing a typical Milky Way MC. Using globally integrated ? and W reproduces the limited range in X found in observations and a mean value X = XGal= 2.2 × 1020 cm-2 K-1 km-1 s. However, we show that when considering limited velocity intervals, X can take on a much larger range of values due to CO line saturation. Thus, the X factor strongly depends on both the range in gas velocities and the volume densities. The temperature variations within individual MCs do not strongly affect X, as dense gas contributes most to setting the X factor. For fixed velocity and density structure, gas with higher temperatures T has higher W, yielding X ∝ T-1/2 for T ˜ 20-100 K. We demonstrate that the linewidth-size scaling relationship does not influence the X factor - only the range in velocities is important. Clouds with larger linewidths σ, regardless of the linewidth-size relationship, have a higher W, corresponding to a lower value of X, scaling roughly as X ∝σ-1/2. The 'mist' model, often invoked to explain a constant XGal consisting of optically thick cloudlets with well-separated velocities, does not accurately reflect the conditions in a turbulent MC. We propose that the observed cloud-averaged values of X ˜ XGal are simply a result of the limited range in ?, temperatures and velocities found in Galactic MCs - a nearly constant value of X therefore does not require any linewidth-size relationship, or that MCs are virialized objects. Since gas properties likely differ (albeit even slightly) from cloud to cloud, masses derived through a standard value of the X factor should only be considered as a rough first estimate. For temperatures T ˜ 10-20 K, velocity dispersions σ˜ 1-6 km s-1and ? cm-2, we find cloud-averaged values X ˜ 2-4 × 1020 cm-2 K-1 km-1 s for solar-metallicity models.

Illitization and paleothermal regimes in the Middle Ordovician St. Peter Sandstone, Central Michigan Basin: K-Ar, Oxygen Isotope, and fluid inclusion data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Girard, J.P.; Barnes, D.A.

1995-01-01

Hydrocarbon reservoirs occur in the Middle Ordovician St. Peter Sandstone in the central Michigan basin at depths of 1.5-3.5 km and are diagenetically altered. Latest diagenetic cements include saddle dolomite, pervasive microcrystalline illite and chlorite, and quartz. A K-Ar and {sup 18}O/{sup 16}O study of the fine-grained authigenic illite in 25 samples from 16 wells covering a large area within the basin yields K-Ar ages ranging from 367 to 322 Ma and {delta}{sup 18}O values between 12.7 and 16.9% SMOW. The {delta}{sup 18}O values of diagenetic quartz overgrowths range from 15.2 to 18.9%. Fluid inclusion temperatures in the quartz cementmore » range from 70 to 170{degrees}C, reflecting multiple generations of diagenetic quartz and/or precipitation over most of the diagenetic history. Reequilibrated fluid inclusions in the saddle dolomite cement yield temperatures ranging from 90 to 150{degrees}C. A regionally significant episode of illitization occurred during the Late Devonian-Mississipian. Temperatures of illite formation are indirectly estimated to be in the range of 125-170{degrees}C and most paleodepths of illitization are between 2.8 and 3.2 km. These results imply that (1) illite formed from {sup 18}O-rich fluids, and (2) elevated geothermal gradients, i.e., greater than 34% C/km, existed in the Michigan basin in the late Paleozoic. The K-Ar ages and the {delta}{sup 18}O values are not correlated to present depths of the samples or paleodepths of illitization. Illites with young ages and low {delta}{sup 18}O values tend to be geographically distributed along the north-south branch of the buried Precambrian rift. The {delta}{sup 18}O values of the diagenetic quartz follow a similar trend. The spread of illite K-Ar ages and {delta}{sup 19}O values, and their geographic distribution, are best explained as reflecting abnormally high thermal regimes in the part of the basin located above the presumably highly fractured basement along the rift.« less

Pedestrian crossing situations: quantification of comfort boundaries to guide intervention timing.

PubMed

Lubbe, Nils; Rosén, Erik

2014-10-01

Technical systems that warn or brake for vehicle-pedestrian encounters reduce injuries more effectively the earlier an intervention is initiated. However, premature intervention can irritate drivers, leading to system deactivation and, consequently, no injury reduction whatsoever. It has been proposed that no intervention should be initiated as long as attentive drivers are within their comfort zones. This study aims at quantifying driver comfort boundaries for pedestrian crossing situations to offer guidance for the appropriate timing of interventions. Sixty two volunteers drove through an intersection on a test track at 30 and 50km/h. A pedestrian dummy was launched from behind an obstruction towards the driving path of the approaching car. Brake onset indicated discomfort. Time to collision (TTC), longitudinal and lateral distance were measured at brake onset. TTC was independent of driving speed ranging from 2.1 to 4.3s with a median of 3.2s. Longitudinal distance ranged from 19 to 48 meters with an apparent difference between driving speeds. Lateral distances differed slightly, but significantly between driving speeds. The median was 3.1m (3.2m for 30km/h and 2.9m for 50km/h) and values ranged from 1.9 to 4.1m. Lateral distance in seconds ranged from 1.9 to 4.3s with a median value of 3.1s (3.2s for 30km/h and 3.0s for 50km/h). TTC was independent of driving speed, trial order and volunteer age. It might be considered suitable to intervene in situations where, for example, 90% of drivers have exceeded their comfort boundary, i.e. when drivers have already initiated braking. This percentile value translates to intervention at a TTC of 2.5s (95% confidence 2.4-2.7s). The study was limited to Swedish nationals, fully aware drivers, and two driving speeds, but did not investigate behavioural changes due to system interaction. This study showed that TTC at brake onset was a suitable measure for the quantification of driver comfort boundaries in pedestrian crossing situations. All drivers applied their brakes prior to 2.1s TTC. Copyright © 2014 Elsevier Ltd. All rights reserved.

Tectonic history of the Syria Planum province of Mars

USGS Publications Warehouse

Tanaka, K.L.; Davis, P.A.

1988-01-01

We attribute most of the development of extensive fractures in the Tharsis region to discrete tectonic provinces within the region, rather than to Tharsis as a single entity. One of these provinces is in Syria Planum. Faults and collapse structures in the Syria Planum tectonic province on Mars are grouped into 13 sets based on relative age, areal distribution, and morphology. According to superposition and fault crosscutting relations and crater counts we designate six distinct episodes of tectonic activity. Photoclinometric topographic profiles across 132 grabens and fault scarps show that Syria Planum grabens have widths (average of 2.5 km, and most range from 1 to 6 km) similar to lunar grabens, but the Martian grabens have slightly higher side walls (average abour 132 m) and gentler wall slopes (average of 9?? and range of 2??-25??) than lunar grabens (93 m high and 18?? slopes). Estimates of the amount of extension for individual grabens range from 20 to 350 m; most estimates of the thickness of the faulted layer range from 0.5 to 4.5 km (average is 1.5 km). This thickness range corresponds closely to the 0.8- to 3.6-km range in depth for pits, troughs, and canyons in Noctis Labyrinthus and along the walls of Valles Marineris. We propose that the predominant 1- to 1.5-km values obtained for both the thickness of the faulted layer and the depths of the pits, troughs, and theater heads of the canyons reflect the initial depth to the water table in this region, as governed by the depth to the base of ground ice. Maximum depths for these features may indicate lowered groundwater table depths and the base of ejecta material. -from Authors

Earth GRAM-99 and Trace Constituents

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2004-01-01

Global Reference Atmospheric Model (GRAM-99) is an engineering-level model of Earth's atmosphere. It provides both mean values and perturbations for density, temperature, pressure, and winds, as well as monthly- and geographically-varying trace constituent concentrations. From 0-27 km, GRAM thermodynamics and winds are based on National Oceanic and Atmospheric Administration Global Upper Air Climatic Atlas (GUACA) climatology. Above 120 km, GRAM is based on the NASA Marshall Engineering Thermosphere (MET) model. In the intervening altitude region, GRAM is based on Middle Atmosphere Program (MAP) climatology that also forms the basis of the 1986 COSPAR International Reference Atmosphere (CIRA). Atmospheric composition is represented in GRAM by concentrations of both major and minor species. Above 120 km, MET provides concentration values for N2, O2, Ar, O, He, and H. Below 120 km, species represented also include H2O, O3, N2O, CO, CH4, and CO2. At COSPAR 2002 a comparison was made between GRAM constituents below 120 km and those provided by Naval Research Laboratory (NRL) climatology. No current need to update GRAM constituent climatology in that height range was identified. This report examines GRAM (MET) constituents between 100 and 1000 km altitudes. Discrepancies are noted between GRAM (MET) constituent number densities and mass density or molecular weight. Near 110 km altitude, there is up to about 25% discrepancy between MET number density and mass density (with mass density being valid and number densities requiring adjustment). Near 700 km altitude there is also up to about 25% discrepancy between MET number density and mean molecular weight (with molecular weight requiring adjustment). In neither case are MET mass density estimates invalidated. These discrepancies have been traced to MET subroutines SLV (which affects 90-170 km height range) and SLVH (which affects helium above 440 km altitude). With these discrepancies corrected, results are presented to illustrate GRAM (MET) constituent mole fractions in terms of height-latitude cross sections from 100 to 1000 km altitude, and latitude-longitude 'maps' at 450 km (approximate height of International Space Station). Plans are discussed for an update of MET (and GRAM) to correct these constituent inconsistencies and to incorporate several new thermospheric model features.

Progress in the determination of the gravitational coefficient of the earth

NASA Technical Reports Server (NTRS)

Ries, J. C.; Eanes, R. J.; Shum, C. K.; Watkins, M. M.

1992-01-01

In most of the recent determinations of the geocentric gravitational coefficient (GM) of the earth, the laser ranging data to the Lageos satellite have had the greatest influence on the solution. These data, however, have generally been processed with a small but significant error in one of the range corrections. In a new determination of GM using the corrected center-of-mass offset, a value of 398600.4415 cu km/sq sec (including the mass of the atmosphere) has been obtained, with an estimated uncertainty (1 sigma of 0.0008 cu km/sq sec.

Seismic Shaking Removal of Craters 0.2-0.5 km in Diameter on Asteroid 433 Eros

NASA Technical Reports Server (NTRS)

Thomas, P. C.; Robinson, M. S.

2005-01-01

Impact cratering acts in a variety of ways to create a surprising range of scenery on small satellites and asteroids. The visible crater population is a self-modifying characteristic of these airless objects, and determining the various ways younger craters can add or subtract from the population is an important aspect of small body "geology." Asteroid 433 Eros, the most closely studied of any small body, has two aspects of its crater population that have attracted attention: a fall-off of crater densities below approx.100 m diameter relative to an expected equilibrium population [1] and regions of substantially lower large crater densities [2, 3, 4]. In this work we examine the global variation of the density of craters on Eros larger than 0.177 km, a size range above that involved in small crater depletion hypotheses [1, 5]. We counted all craters on Eros to a size range somewhat below 0.177 km diameter (and different from data used in [3]). The primary metric for this study is the number of craters between 0.177 and 1.0 km within a set radius of each grid point on the 2deg x 2deg shape model of Eros. This number can be expressed as an R-value [6], provided that it is remembered that the large bin size makes individual R values slightly different from those obtained in the usual root-2 bins.

Effect of racing on the serum concentrations of cardiac troponin I and creatine kinase myocardial band in racing camels (Camelus dromedarius).

PubMed

Tharwat, Mohamed; Al-Sobayil, Fahd; Buczinski, Sébastien

2013-06-01

This study was designed to investigate the effect of racing on the serum concentrations of cardiac troponin I (cTnI) and creatine kinase myocardial (CK-MB) in healthy racing camels (Camelus dromedarius). Twenty-three racing camels scheduled for a 5 km race were investigated in this study. From each camel, 3 blood samples were collected: 24 h before racing (T0), within 2 h after the race (T1) and 24 h post-race (T2). Following the 5 km race, 91.3 % of the racing camels had increases in serum cTnI concentrations, while concentrations remained unchanged in 8.7 %. The cTnI concentration (median 0.06 ng/mL; range, 0.03-0.15 ng/mL) was significantly higher (P < 0.001) than the pre-race values (median 0.04 ng/mL; range, 0.01-0.07 ng/mL). Twenty-four hours post-race, the cTnI concentrations had returned very nearly to their pre-race values (median 0.04 ng/mL; range, 0.00-0.09 ng/mL) and were not significantly different (P = 0.35) from the pre-race values. Following the 5 km race, increases in CK-MB mass were seen in 17.4 % of the camels, with no changes in 4.3 % and decreases in 78.3 %. The CK-MB mass (median 0.41 ng/mL; range, 0.19-0.60 ng/mL) did not differ significantly (P = 0.84) when compared to the pre-race values (median 0.42 ng/mL; range, 0.32-0.55 ng/mL). Twenty-four hours post-race, the CK-MB mass concentrations (median 0.41 ng/mL; range, 0.15-0.55 ng/mL) did not differ significantly (P > 0.05) compared to pre-race or immediate post-race values. Resting cTnI concentrations in the racing camels were initially low, but increased above the baseline level in most of the camels immediately after racing, and returned to pre-race values within the 24-h post-race period. CK-MB is a less sensitive biomarker for myocardial activity as compared with cTnI. These findings could be of importance when evaluating racing camels with suspected cardiac disease after recent hard exercise.

Impact Craters: Size-Dependent Degration Rates

NASA Astrophysics Data System (ADS)

Ravi, S.; Mahanti, P.; Meyer, H. M.; Robinson, M. S.

2017-12-01

From superposition relations, Shoemaker and Hackman (1) devised the lunar geologic timescale with Copernican and Eratosthenian as the most recent periods. Classifying craters into the two periods is key to understanding impactor flux and regolith maturation rates over the last 3 Ga. Both Copernican and Eratosthenian craters exhibit crisp morphologies (sharp rims, steep slopes), however, only the former exhibit high reflectance rays and ejecta (1). Based on the Optical Maturity Parameter (OMAT; 2), Grier et al. (3) classified 50 fresh craters (D >20 km) into 3 categories - young (OMAT >0.22), intermediate, and old (OMAT <0.16). In our previous work, Copernican craters (D > 10) were identified (4) from a catalogue of 11,875 craters (5). In this work; we compare two size ranges (D: 5 km - 10 km and 10 km to 15 km) of 177 Copernican craters based on the average OMAT, measured near the crater rim (3). OMAT is measured at the crater rim (as opposed to further away from the crater) to minimize the influence of spatial variation of OMAT (6) in our investigation. We found that OMAT values are typically lower for smaller craters (5km < D < 10km) in comparison to larger craters (10km < D < 15km). However, when compared against morphological freshness (as determined by d/D for simpler craters), the smaller craters were fresher (higher d/D value). Since the OMAT value decreases with age, craters with higher d/D value (morphologically fresher) should have higher OMAT, but this is not the case. We propose that quicker loss of OMAT (over time) for smaller craters compared to decrease in d/D with crater ageing, is responsible for the observed decreased OMAT for smaller craters. (1) Shoemaker and Hackman, 1962 (2) Lucey et al., 2000 (3) Grier et al., 2001 (4) Ravi et al., 2016 (5) Reinhold et al., 2015 (6) Mahanti et al., 2016

Low latitude middle atmosphere ionization studies

NASA Technical Reports Server (NTRS)

Bassi, J. P.

1976-01-01

Low latitude middle atmosphere ionization was studied with data obtained from three blunt conductivity probes and one Gerdien condenser. An investigation was conducted into the effects of various ionization sources in the 40 to 65 Km altitude range. An observed enhancement of positive ion conductivity taking place during the night can be explained by an atmsopheric effect, with cosmic rays being the only source of ionization only if the ion-ion recombination coefficient (alpha sub i) is small(10 to the -7 power cu cm/s) and varies greatly with altitude. More generally accepted values of alpha sub i ( approximately equal to 3x10 to the -7 power cu cm/s) require an additional source of ionization peaking at about 65 Km, and corresponding approximately to the integrated effect of an X-ray flux measured on a rocket flown in conjunction with the ionization measurements. The reasonable assumption of an alpha sub i which does not vary with altitude in the 50-70 Km range implies an even greater value alpha sub i and a more intense and harder X-ray spectrum.

Aids for the Study of Electromagnetic Blackout

DTIC Science & Technology

1975-02-25

to gamma rays, 1-MT burst at 20 km 5-32 5-23B One-way absorption due to gamma rays. o-MT hurst at ’O km 5-32 5-23C One-way absorption due to ga’ma...0 2- F ( n)z I I L -I 0. 0.2L.~ INTEGRAL VALUES OF EXPONENT n Figure 6-13. Multiplying factors for refraction and range errors in a spherically

Identifying Intraplate Mechanism by B-Value Calculations in the South of Java Island

NASA Astrophysics Data System (ADS)

Bagus Suananda Y., Ida; Aufa, Irfan; Harlianti, Ulvienin

2018-03-01

Java is the most populous island in Indonesia with 50 million people live there. This island geologically formed at the Eurasia plate margin by the subduction of the Australian oceanic crust. At the south part of Java, beside the occurrence of 2-plate convergence earthquake (interplate), there are also the activities of the intraplate earthquake. Research for distinguish this 2 different earthquake type is necessary for estimating the behavior of the earthquake that may occur. The aim of this research is to map the b-value in the south of Java using earthquake data from 1963 until 2008. The research area are divided into clusters based on the epicenter mapping results with magnitude more than 4 and three different depth (0-30 km, 30-60 km, 60-100 km). This location clustering indicate group of earthquakes occurred by the same structure or mechanism. On some cluster in the south of Java, b-value obtained are between 0.8 and 1.25. This range of b-value indicates the region was intraplate earthquake zone, with 0.72-1.2 b-value range is the indication of intraplate earthquake zone. The final validation is to determine the mechanism of a segment done by correlating the epicenter and b-value plot with the available structural geology data. Based on this research, we discover that the earthquakes occur in Java not only the interplate earthquake, the intraplate earthquake also occurred here. By identifying the mechanism of a segment in the south of Java, earthquake characterization that may occur can be done for developing the accurate earthquake disaster mitigation system.

The Advective Flux and Temporal Evolution of Aerosols from the Western Pacific Rim as Observed during TRACE-P

NASA Astrophysics Data System (ADS)

Anderson, B. E.; Jordan, C. E.; Grant, W. B.; Browell, E. V.; Hudgins, C. H.; Winstead, E. L.; Thornhill, K. L.

2002-12-01

The 2001, NASA Transport and Chemical Evolution over the Pacific (TRACE-P) experiment was conducted during late winter and early spring, the time of year when eastward transport of dust and pollution from southern and central Asia reaches a maximum. From bases of operation in Hong Kong, Japan, and Hawaii, extensive measurements of trace species concentrations and characteristics were made from aboard a P-3B and DC-8 aircraft as they flew coordinated sampling missions within air masses at varying distances from the Asian coast and at altitudes ranging from near surface to over 12 km. Data recorded aboard the DC-8 included total condensation nuclei (CN) number densities and fractional volatility; aerosol size distributions, composition and optical properties; and multi-wavelength profiles of polarized, aerosol backscatter. Examining these data in light of simultaneous meteorological and chemical species measurements, we have calculated the advective flux and mean values of aerosol mass and physical properties at various locations within the Western Pacific Basin. At distances >100 km offshore, we find that the highest fluxes of sub-micron particles occurred below 2 km in the region downwind of Shanghai. These air masses exhibited CN concentrations approaching 50,000 cm-3 and visible scattering coefficients in excess of 200 Mm-1. For near-shore sampling between 26° and 36°N within this height range, these parameters averaged ~8,000 cm-3 and 130 Mm-, respectively, . As a result of dilution, surface deposition, and precipitation scavenging, these values rapidly diminished during eastward transport so that parcels sampled at low altitudes >1500 km from land typically contained ~1000 cm-3 CN and exhibited scattering coefficients <30 Mm-1. Because of the decreased strength of loss processes and greater atmospheric stability, parcels sampled in the 2- to 7-km height range were more apt to maintain their initial aerosol signatures during long-range transport.

Kelvin-Helmholtz waves in extratropical cyclones passing over mountain ranges: KH Waves in Extratropical Cyclones over Mountain Ranges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medina, Socorro; Houze, Robert A.

2016-02-19

Kelvin–Helmholtz billows with horizontal scales of 3–4 km have been observed in midlatitude cyclones moving over the Italian Alps and the Oregon Cascades when the atmosphere was mostly statically stable with high amounts of shear and Ri < 0.25. In one case, data from a mobile radar located within a windward facing valley documented a layer in which the shear between down-valley flow below 1.2 km and strong upslope cross-barrier flow above was large. Several episodes of Kelvin–Helmholtz waves were observed within the shear layer. The occurrence of the waves appears to be related to the strength of the shear:more » when the shear attained large values, an episode of billows occurred, followed by a sharp decrease in the shear. The occurrence of large values of shear and Kelvin–Helmholtz billows over two different mountain ranges suggests that they may be important features occurring when extratropical cyclones with statically stable flow pass over mountain ranges.« less

Seismicity associated with magmatism, faulting and hydrothermal circulation at Aluto Volcano, Main Ethiopian Rift

NASA Astrophysics Data System (ADS)

Wilks, Matthew; Kendall, J.-Michael; Nowacki, Andy; Biggs, Juliet; Wookey, James; Birhanu, Yelebe; Ayele, Atalay; Bedada, Tulu

2017-06-01

The silicic volcanic centres of the Main Ethiopian Rift (MER) play a central role in facilitating continental rifting. Many of these volcanoes host geothermal resources and are located in heavily populated regions. InSAR studies have shown several are deforming, but regional seismic networks have detected little seismicity. A local network of 12 seismometers was deployed at Aluto Volcano from 2012 to 2014, and detected 2142 earthquakes within a 24-month period. We locate the events using a 1D velocity model that exploits a regional model and information from geothermal boreholes and calculate local magnitudes, b-values and focal mechanisms. Event depths generally range from the near surface to 15 km with most of the seismicity clustering in the upper 2 km. A significant amount of seismicity follows the Artu Jawa Fault Zone, which trends in alignment with the Wonji Fault Belt, NNE-SSW and is consistent with previous studies of strain localisation in the MER. Focal mechanisms are mostly normal in style, with the mean T-axes congruent to the orientation of extension in the rift at this latitude. Some show relatively small left-lateral strike-slip components and are likely associated with the reactivation of NE-ENE structures at the southern tip of the Aluto-Gedemsa segment. Events range from - 0.40 to 2.98 in magnitude and we calculate an overall b-value of 1.40 ± 0.14. This relatively elevated value suggests fluid-induced seismicity that is particularly evident in the shallow hydrothermal reservoir and above it. Subdividing our observations according to depth identifies distinct regions beneath the volcanic edifice: a shallow zone (- 2-0 km) of high seismicity and high b-values that corresponds to the hydrothermal system and is influenced by a high fluid saturation and circulation; a relatively aseismic zone (0-2 km) with low b-values that is impermeable to ascending volatiles; a region of increased fluid-induced seismicity (2-9 km) that is driven by magmatic intrusion from below and a deeper zone (below 9 km) that is interpreted as a partially crystalline, magmatic mush. These observations indicate that both the magmatic and hydrothermal systems of Aluto volcano are seismically active and highlight the need for dedicated seismic monitoring at volcanoes in the MER.

Characteristic length scales and time-averaged transport velocities of suspended sediment in the mid-Atlantic Region, USA

USGS Publications Warehouse

Pizzuto, James; Schenk, Edward R.; Hupp, Cliff R.; Gellis, Allen; Noe, Greg; Williamson, Elyse; Karwan, Diana L.; O'Neal, Michael; Marquard, Julia; Aalto, Rolf E.; Newbold, Denis

2014-01-01

Watershed Best Management Practices (BMPs) are often designed to reduce loading from particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles are only moved downstream episodically, resting for long periods in storage between transport events. A theory is developed that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage given sediment budget data (by grain size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended sediment transport length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At 5 upland watersheds of the mid-Atlantic region, transport length scales for silt-clay range from 4 to 60 km, while those for sand range from 0.4 to 113 km. Mean sediment velocities for silt-clay range from 0.0072 km/yr to 0.12 km/yr, while those for sand range from 0.0008 km/yr to 0.20 km/yr, 4–6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100–1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to determine the complete distribution of suspended sediment velocities in real watersheds.

Spring geochemistry in an active volcanic environment (São Miguel, Azores): source and fluxes of inorganic solutes.

PubMed

Freire, P; Andrade, C; Coutinho, R; Cruz, J V

2014-01-01

Mineral waters were monthly sampled in selected springs from Furnas and Fogo trachytic central volcanoes (São Miguel, Azores, Portugal). Water temperatures between 15.1 °C and 90.2 °C, characterize poorly mineralized waters of Na-HCO₃ and Na-HCO₃-Cl types. According to the spring location, two watersheds were selected in each volcano to evaluate solute fluxes and chemical weathering rates (Fogo volcano: Ribeira Grande river - RRG; Furnas volcano: Ribeira Quente river - RRQ). Na, Mg, K and Ca fluxes in groundwater represented 43%, 60%, 46% and 57% of the total (subsurface plus surface fluxes) in RRG, and respectively 43%, 53%, 46% and 49% in RRQ. Average HCO₃ flux is ten times higher in RRQ (130.1 × 10(6) mol/yr) compared to RRG (13.8 × 10(6) mol/yr), reflecting the volcano degassing and the lower ratio between groundwater and river water fluxes. Based on these values, total CO₂-consumption by weathering ranged from 1.5 × 10(6)mol/km(2)/yr (RRG) to 4 × 10(6)mol/km(2)/yr (RRQ). TDS load varied between 3772 t/yr (RRG) and 15388 t/yr (RRQ), and the ratio between values in groundwater and in surface water is respectively equal to 0.72 and 2.04. The associated chemical weathering rates in groundwater were 206 t/km(2)/yr (RRG) and 399 t/km(2)/yr (RRQ). Coupled to river water, these values indicate that total chemical weathering rates are respectively equal to 493 t/km(2)/yr and 594 t/km(2)/yr. A similar approach developed for the entire archipelago showed that the chemical weathering rates due to groundwater are in the range from 33 to 321 t/km(2)/yr, being partially controlled by the age of the islands. Results of the present study point out to the need to consider groundwater solute fluxes due to weathering when establishing geochemical budgets. Copyright © 2013 Elsevier B.V. All rights reserved.

Shock melting and vaporization of lunar rocks and minerals.

NASA Technical Reports Server (NTRS)

Ahrens, T. J.; O'Keefe, J. D.

1972-01-01

The entropy associated with the thermodynamic states produced by hypervelocity meteoroid impacts at various velocities are calculated for a series of lunar rocks and minerals and compared with the entropy values required for melting and vaporization. Taking into account shock-induced phase changes in the silicates, we calculate that iron meteorites impacting at speeds varying from 4 to 6 km/sec will produce shock melting in quartz, plagioclase, olivine, and pyroxene. Although calculated with less certainty, impact speeds required for incipient vaporization vary from 7 to 11 km/sec for the range of minerals going from quartz to periclase for aluminum (silicate-like) projectiles. The impact velocities, which are required to induce melting in a soil, are calculated to be in the range of 3 to 4 km/sec, provided thermal equilibrium is achieved in the shock state.

Magnitude of crustal shortening and structural framework of the easternmost Himalayan orogen, northern Indo-Burma Ranges of northeastern India

NASA Astrophysics Data System (ADS)

Haproff, P. J.; Yin, A.

2016-12-01

Along-strike variation in crustal shortening throughout the Himalayan orogen has been attributed to (1) diachronous, eastward-increasing convergence, or (2) localized controls including pre-collisional stratigraphic configuration and climate. In this study, we present new geologic maps and balanced cross-sections across the easternmost segment of the Himalayan orogen, the N-S-trending N. Indo-Burma Ranges of northeastern India. First order structures are NE-dipping, km-wide ductile thrust shear zones with mylonitic fabrics indicating top-to-the SW motion. Major structures include the Mayodia klippe and Hunli window, generated during folding of the SW-directed Tidding thrust and duplexing of Lesser Himalayan rocks (LHS) at depth. Reconstruction of two balanced cross-sections yields minimum shortening estimates of 70% (48 km) and 71% (133 km), respectively. The widths of the orogen for each transect are 21 km and 54 km, respectively. Our percent strain values are comparable to that of western Arunachal Himalaya, reflecting eastward-increasing strain due to counterclockwise rotation of India during convergence or along-strike variation in India's subduction angle. However, shortening magnitudes much less than that of the Sikkim (641 km), Bhutan (414-615 km), and western Arunachal Himalaya (515-775 km) could signal eastward increasing shortening of a unique Himalayan stratigraphic framework, evidenced by few GHC rocks, absence of Tethyan strata, and an extensive subduction mélange and forearc complex.

The Puzzlingly Small Ca II Triplet Absorption in Elliptical Galaxies

NASA Astrophysics Data System (ADS)

Saglia, R. P.; Maraston, Claudia; Thomas, Daniel; Bender, Ralf; Colless, Matthew

2002-11-01

We measure the central values (within Re/8) of the Ca II triplet line indices CaT* and CaT and the Paschen index PaT at 8600 Å for a 93% complete sample of 75 nearby early-type galaxies with BT<12 mag and Vgal<2490 km s-1. We find that the values of CaT* are constant to within 5% over the range of central velocity dispersions 100 km s-1<=σ<=340 km s-1, while the PaT (and CaT) values are mildly anticorrelated with σ. Using simple and composite stellar population models, we show the following: (1) The measured CaT* and CaT are lower than expected from simple stellar population (SSP) models with Salpeter initial mass functions (IMFs) and with metallicities and ages derived from optical Lick (Fe, Mg, and Hβ) indices. Uncertainties in the calibration, the fitting functions, and the SSP modeling taken separately cannot explain the discrepancy. On average, the observed PaT values are within the range allowed by the models and the large uncertainties in the fitting functions. (2) The steepening of the IMF at low masses required to lower the CaT* and CaT indices to the observed values is incompatible with the measured FeH index at 9916 Å and the dynamical mass-to-light ratios of elliptical galaxies. (3) Composite stellar populations with a low-metallicity component reduce the disagreement, but rather artificial metallicity distributions are needed. Another explanation may be that calcium is indeed underabundant in elliptical galaxies.

From points to forecasts: Predicting invasive species habitat suitability in the near term

USGS Publications Warehouse

Holcombe, Tracy R.; Stohlgren, Thomas J.; Jarnevich, Catherine S.

2010-01-01

We used near-term climate scenarios for the continental United States, to model 12 invasive plants species. We created three potential habitat suitability models for each species using maximum entropy modeling: (1) current; (2) 2020; and (3) 2035. Area under the curve values for the models ranged from 0.92 to 0.70, with 10 of the 12 being above 0.83 suggesting strong and predictable species-environment matching. Change in area between the current potential habitat and 2035 ranged from a potential habitat loss of about 217,000 km2, to a potential habitat gain of about 133,000 km2.

Vertical structure of Venus polar thermosphere from in-situ data of the Venus Express Atmospheric Drag Experiment (VExADE)

NASA Astrophysics Data System (ADS)

Mueller-Wodarg, Ingo; Svedhem, Håkan; Bruinsma, Sean; Gurvits, Leonid; Cimo, Giuseppe; Molera Calves, Guifre; Bocanegra Bahamon, Tatiana; Rosenblatt, Pascal; Duev, Dmitry; Marty, Jean-Charles; Progebenko, Sergei

The Venus Express Atmospheric Drag Experiment (VExADE) has enabled first ever in-situ measurements of the density of the near-polar thermosphere of Venus above an altitude of 165 km. The measured values have been compared with existing models such as VTS3, which has been built mainly with the Pioneer Venus Orbiter Mass Spectrometer (PV-ONMS) data taken near 16˚ latitude, but extrapolated globally. The VExADE density values have been derived from the Precise Orbit Determination (POD) of the VEx spacecraft using both navigation and dedicated tracking data around pericenter passes during several VExADE campaigns. The last campaign has also benefited from the Planetary Radio Interferometry and Doppler Experiment (PRIDE) tracking. The combination of POD techniques has provided 46 reliable estimates of the polar thermosphere density. An independent set of density measurements was also taken by inferring the torque of the VEx spacecraft exerted by Venus’ upper atmosphere on the spacecraft during pericenter passes. This method has provided more than 120 density values in remarkably good agreement with the density values provided by the POD method. To date, the VExADE data have probed a range of 160 to 185 km in altitude, 80 to 90 degrees North in latitude and 5 to 20 hours in local time. While sampling in these ranges is insufficient to establish detailed horizontal density structures of the polar thermosphere a set of important properties can be inferred. First, the densities are lower by a factor of around 1.5 than the densities predicted by VTS3. At the same time, we find the density scale heights of VExADE and VTS3 to be consistent. Second, the density values exhibit strong variability, which is not taken into account in the VTS3 model. In order to investigate this dynamical behavior of the polar thermosphere, the ratio between the VExADE and VTS3 density has been analyzed. The latitude, altitude and local time trends are tentatively identified, but the sparse sampling provided by the VExADE data prevents us from drawing any definitive conclusions. We tentatively interpret the measured densities by a vertical wave-like pattern in the thermosphere with the amplitude of about 40% of the mean density value and a vertical wavelength of about 15 km. The causes of this vertical structure are as yet unknown. In order to improve sampling in this altitude range and thereby advance our understanding of the behavior of the polar thermosphere, further measurements are needed. An opportunity will be offered by the forthcoming aerobraking campaign scheduled for June-July 2014. The altitude of the spacecraft will decrease down to 130 km where the sensitivity of the accelerometer will enable density measurements. Tracking data and torque data may still be used to provide reliable density measurements at higher altitudes (150 to 185 km range).

Water miscible mono alcohols' effect on the proteolytic performance of Bacillus clausii serine alkaline protease.

PubMed

Duman, Yonca Avci; Kazan, Dilek; Denizci, Aziz Akin; Erarslan, Altan

2014-01-01

In this study, our investigations showed that the increasing concentrations of all examined mono alcohols caused a decrease in the Vm, kcat and kcat/Km values of Bacillus clausii GMBE 42 serine alkaline protease for casein hydrolysis. However, the Km value of the enzyme remained almost the same, which was an indicator of non-competitive inhibition. Whereas inhibition by methanol was partial non-competitive, inhibition by the rest of the alcohols tested was simple non-competitive. The inhibition constants (KI) were in the range of 1.32-3.10 M, and the order of the inhibitory effect was 1-propanol>2-propanol>methanol>ethanol. The ΔG(≠) and ΔG(≠)E-T values of the enzyme increased at increasing concentrations of all alcohols examined, but the ΔG(≠)ES value of the enzyme remained almost the same. The constant Km and ΔG(≠)ES values in the presence and absence of mono alcohols indicated the existence of different binding sites for mono alcohols and casein on enzyme the molecule. The kcat of the enzyme decreased linearly by increasing log P and decreasing dielectric constant (D) values, but the ΔG(≠) and ΔG(≠)E-T values of the enzyme increased by increasing log P and decreasing D values of the reaction medium containing mono alcohols.

Kicks of magnetized strange quark stars induced by anisotropic emission of neutrinos

NASA Astrophysics Data System (ADS)

Ayala, Alejandro; Manreza Paret, D.; Pérez Martínez, A.; Piccinelli, Gabriella; Sánchez, Angel; Ruíz Montaño, Jorge S.

2018-05-01

We study the anisotropic neutrino emission from the core of neutron stars induced by the star's magnetic field. We model the core as made out of a magnetized ideal gas of strange quark matter and implement the conditions for stellar equilibrium in this environment. The calculation is performed without resorting to analytical simplifications and for temperature, density, and magnetic field values corresponding to typical conditions for a neutron star's evolution. The anisotropic neutrino emission produces a rocket effect that contributes to the star's kick velocity. We find that the computed values for the kick velocity lie within the range of the observed values, reaching velocities of the order of ˜1000 km s-1 for magnetic fields between 1015-1018 G and radii of 20 to 5 km, respectively.

Electron content of the ionosphere and the plasma sphere on the basis of ATS-6-Data, NNSS-data, and ionograms. [Navy Navigation Satellite System

NASA Technical Reports Server (NTRS)

Leitinger, R.; Hartmann, G. K.; Davies, K.

1976-01-01

The reported investigation takes into account data obtained with the aid of the geostationary satellite ATS-6, the satellites of the U.S. navy navigation system (NNSS) at an altitude between 900 and 1200 km, and the satellites ISIS 1 and ISIS 2. The altitude range between ground and ATS-6 is divided into two regions, including the 'ionosphere', involving the region with an upper limit of 2000 km, and the 'plasma sphere', involving the region above an altitude of 2000 km. Data concerning the electron content obtained from different sources are compared, taking into account discrepancies between ionogram-derived values and values computed on the basis of satellite measurements. Attention is also given to the vertical electron content of the ionosphere on the basis of a combination of data obtained with the aid of the ATS-6 and the NNSS.

Version 1.3 AIM SOFIE measured methane (CH4): Validation and seasonal climatology

NASA Astrophysics Data System (ADS)

Rong, P. P.; Russell, J. M.; Marshall, B. T.; Siskind, D. E.; Hervig, M. E.; Gordley, L. L.; Bernath, P. F.; Walker, K. A.

2016-11-01

The V1.3 methane (CH4) measured by the Aeronomy of Ice in the Mesosphere (AIM) Solar Occultation for Ice Experiment (SOFIE) instrument is validated in the vertical range of 25-70 km. The random error for SOFIE CH4 is 0.1-1% up to 50 km and degrades to 9% at ˜ 70 km. The systematic error remains at 4% throughout the stratosphere and lower mesosphere. Comparisons with CH4 data taken by the SCISAT Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) and the Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) show an agreement within 15% in the altitude range 30-60 km. Below 25 km SOFIE CH4 is systematically higher (≥20%), while above 65 km it is lower by a similar percentage. The sign change from the positive to negative bias occurs between 55 km and 60 km (or 40 km and 45 km) in the Northern (or Southern) Hemisphere. Methane, H2O, and 2CH4 + H2O yearly differences from their values in 2009 are examined using SOFIE and MIPAS CH4 and the Aura Microwave Limb Sounder (MLS) measured H2O. It is concluded that 2CH4 + H2O is conserved with altitude up to an upper limit between 35 km and 50 km depending on the season. In summer this altitude is higher. In the Northern Hemisphere the difference relative to 2009 is the largest in late spring and the established difference prevails throughout summer and fall, suggesting that summer and fall are dynamically quiet. In both hemispheres during winter there are disturbances (with a period of 1 month) that travel downward throughout the stratosphere with a speed similar to the winter descent.

Thermal and unroofing history of a thick, tilted Basin-and-Range crustal section in the Tortilla Mountains, Arizona

USGS Publications Warehouse

Howard, K.A.; Foster, D.A.

1996-01-01

We estimate here a geothermal gradient of only 17 ?? 5??C km-1 for the tilted Grayback fault block in southeastern Arizona when extension began ???25 Ma. This gradient is lower than preextension gradients estimated elsewhere in the Basin and Range, is only about 50% of typical gradients in the Basin and Range today, and needs to be accounted for in models of continental extension. The Grayback block exposes a 12-km-thick crustal section of Proterozoic and Cretaceous granitoids, which was tilted 90?? during extension between 25 and 15 Ma. Zircon fission-track ages decrease structurally downward (westward) across the block and were all within a zone of partial track annealing prior to tilting and quenching. The zircon age gradient suggests that the 220??-240??C isotherm migrated downward 5-6 km during Paleogene erosion and regional cooling. Apatite fission-track ages decrease westward from ???83 Ma in the structurally highest crystalline rocks to ???24 Ma at ???6-km paleodepth and then to ???15 Ma another 6 km farther west. Track-length analysis confirms that apatites above the break in slope in age at ???5.7-km paleodepth resided in a zone of partial annealing prior to tilting, and deeper apatites record rapid cooling upon tilting and unroofing beginning ???25 Ma. At that time the 110 ?? 10??C isotherm determined by the depth at which tracks in apatite were fully erased was at a basement paleodepth of ???5.7 km, and the 220 ?? 30??C isotherm as estimated from zircon data resided at a pretilting basement depth of ???12.15 km. From consistent values of paleogeothermal gradient for two depth intervals we estimate the pretilt gradient was 17 ?? 5??C km-1. From 25 to 15 Ma the rotating Grayback block cooled rapidly as higher, westward moving blocks unroofed it tectonically at a rate of ???1 km m.y.-1.

Evaluating the Sensitivity of Glacial Isostatic Adjustment to a Hydrous Melt at 410 km Depth

NASA Astrophysics Data System (ADS)

Hill, A. M.; Milne, G. A.; Ranalli, G.

2017-12-01

We present a sensitivity analysis aimed at testing whether observables related to GIA can support or refute the existence of a low viscosity partial melt layer located above the mantle transition zone, as required by the so-called "Transition Zone Water Filter" model (Bercovici and Karato 2003). In total, 400 model runs were performed sampling a range of melt layer thicknesses (1, 10 & 20 km) and viscosities (1015 - 1019 Pas) as well as plausible viscosity values in the upper and lower mantle. Comparing model output of postglacial decay times and j2, 18 of the considered viscosity models were found to be compatible with all of the observational constraints. Amongst these, only three `background' upper and lower mantle viscosities are permitted regardless of the properties of the melt layer: an upper mantle value of 3×1020 Pas and lower mantle values of 1022, 3×1022 and 5×1022 Pas. Concerning the properties of the melt layer itself, a thin (1 km) layer may have any of the investigated viscosities (1015 to 1019 Pas). For thicker melt layers, the viscosity must be ≥1018 Pas (20 km) or ≥1017 Pas (10 km). Our results indicate clear parameter trade-offs between the properties of the melt layer and the background viscosity structure. Given that the observations permit several values of lower mantle viscosity, we conclude that tightening constraints on this parameter would be valuable for future investigation of the type presented here. Furthermore, while decay times from both locations considered in this investigation (Ångerman River, Sweden; Richmond Gulf, Canada) offer meaningful constraints on viscosity structure, the value for Richmond Gulf is significantly more uncertain and so increasing its precision would likely result in improved viscosity constraints.

The Hack's law applied to young volcanic basin: the Tahiti case

NASA Astrophysics Data System (ADS)

Ye, F.; Sichoix, L.; Barriot, J.; Serafini, J.

2010-12-01

We study the channel morphology over the Tahiti island from the Hack’s law perspective. The Hack’s law is an empirical power relationship between basin drainage area and the length of its main channel. It had also been shown that drainage area becomes more elongate with increasing basin size. For typical continental basins, the exponent value lies between 0.47 for basins larger than 260,000 km2 and 0.7 for those spanning less than 20,720 km2 (Muller, 1973). In Tahiti, we extracted 27 principal basins ranging from 7 km2 to 90 km2 from a Digital Terrain Model of the island with a 5 m-resolution. We demonstrate that the Hack’s law still apply for such small basins (correlation coefficient R2=0.7) with an exponent value being approximately 0.5. It appears that the exponent value is influenced by the local geomorphic condition, and does not follow the previous study results (the exponent value decreases with increasing drainage area.) Our exponent value matches the result found w.r.t. debris-flow basins of China for drainage areas less than 100 km2 (Li et al., 2008). Otherwise, the young volcanic basins of Tahiti do not become longer and narrower with increasing basin size (R2=0.1). Besides, there is no correlation between the basin area and the basin convexity (R2=0). This means that there is no statistical change in basin shape with basin size. We present also the drainage area-slope relationship with respect to sediment or transport-limited processes. Key words: Hack’s law, channel morphology, DTM

A spectral analysis of Deneb (A2 Iae)

NASA Astrophysics Data System (ADS)

Albayrak, B.

2000-12-01

This study presents a detailed model atmosphere abundance analysis of Deneb which was performed using Kurucz LTE ATLAS9 model atmospheres. The atmospheric parameters were determined from Mg I/II and Fe I/II equilibrium, and by fitting the Hgamma profile and optical region spectrophotometry. The compromise values which best satisfy these criteria are T_eff = 9000 K and log g = 1.45. The Mg I, Mg II, Si II, Ti II, Cr II, Fe I, and Fe II lines yield microturbulences of 3.60, 6.50, 8.50, 8.00, 11.90, 3.60, and 10.40 km s-1, respectively. An average microturbulence of 7 km s-1 was used for the other atomic species. From a comparision of the synthetic spectrum with the observations, the best value for the rotational velocity is v sin i = 25 km s-1, and for the macroturbulent velocity is zeta = 14 km s-1, which are similar to those of some earlier derived values. Also, the individual spectrograms have a range of radial velocity variation of ~ 15 km s-1 which is approximately equal to macroturbulent velocity. These values of the macroturbulence and the range of radial velocity variation are close to the sum of the amplitudes (10.44 km s-1) of all the pulsation periods found by Lucy (\\cite{lucy}), who also suggested that the surface motions of the atmosphere of Deneb can be identified with macroturbulence. Deneb showed a definite helium underabundance with a well determined He/H value = 0.071. The CNO values (C being mildly deficient, N being in moderate excess, and an O being slightly deficient) are consistent with the mixing of the CNO-cycled products into the surface layers from the processed materials presumably dredged-up from the interior. Aluminium is mildly deficient by ~ 0.24 dex with respect to solar value, while sulfur is moderately underabundant by ~ 0.43 dex in Deneb. Mg and Si have the solar abundances. The metal abundances (Ca to Ni) tend to be greater than solar except for Sc which is slightly deficient. The heavy elements abundances (Sr, Y, and Zr) are all greater than solar. These abundance patterns conform to the common tendency seen with other normal Population I A supergiants found by Venn (\\cite{venna}). The rare-earth elements (Ba, La, and Eu) which have been unexplored in other Galactic early A-type supergiants are significantly overabundant relative the Sun. Based on data obtained at the Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada. Table A.1 is only available electronically with the On-Line publication at http://link.springer.de/link/service/00230/

Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro.

PubMed

Gonzalez, R J; Wilson, R W; Wood, C M; Patrick, M L; Val, A L

2002-01-01

We measured unidirectional ion fluxes of fish collected directly from the Rio Negro, an extremely dilute, acidic blackwater tributary of the Amazon. Kinetic analysis of Na(+) uptake revealed that most species had fairly similar J(max) values, ranging from 1,150 to 1,750 nmol g(-1) h(-1), while K(m) values varied to a greater extent. Three species had K(m) values <33 micromol L(-1), while the rest had K(m) values >or=110 micromol L(-1). Because of the extremely low Na(+) concentration of Rio Negro water, the differences in K(m) values yield very different rates of Na(+) uptake. However, regardless of the rate of Na(+) uptake, measurements of Na(+) efflux show that Na(+) balance was maintained at very low Na(+) levels (<50 micromol L(-1)) by most species. Unlike other species with high K(m) values, the catfish Corydoras julii maintained high rates of Na(+) uptake in dilute waters by having a J(max) value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L(-1) NaCl, J(max) fell >50%, and K(m) dropped about 70%. The unusual acclimatory drop in K(m) may represent a mechanism to ensure high rates of Na(+) uptake on return to dilute water. As well as being tolerant of extremely dilute waters, Rio Negro fish generally were fairly tolerant of low pH. Still, there were significant differences in sensitivity to pH among the species on the basis of degree of stimulation of Na(+) efflux at low pH. There were also differences in sensitivity to low pH of Na(+) uptake, and two species maintained significant rates of uptake even at pH 3.5. When fish were exposed to low pH in Rio Negro water instead of deionized water (with the same concentrations of major ions), the effects of low pH were reduced. This suggests that high concentrations of dissolved organic molecules in the water, which give it its dark tea color, may interact with the branchial epithelium in some protective manner.

Evaluation of 2 possible further developments of the UK in-flight radiation warning meter for SSTS

NASA Technical Reports Server (NTRS)

Wilson, I. J.; Eustace, R. C.

1972-01-01

A mass reduction of the moderator and the response to the nucleon flux, responsible for the tissue-star component of the total-dose equivalent rate using a high atomic number material, are discussed. Radiation situations at SST cruising altitudes (approximately 20 km) due to solar proton flares were simulated in the stratosphere and on the ground. Actual stratospheric situations due to galactic cosmic radiation with a limited range of quality factor values (2-4) were encountered during slow ascents by balloons to 36 km. Synthetic situations obtained from high and low energy acclerator radiations were used to obtain radiation distributions having a larger range of quality factor values (11/2-9) than experienced in the stratosphere. The measurements made in these simulations related to the directly ionizing, neutron and tissue-star components of dose-equivalent rate. Due to the restricted range of neutron spectra encountered in the stratosphere, a significant mass reduction of the moderator by 4 kg was made, with the moderator clad with cadmium or some other slow neutron absorber.

Lithospheric flexural strength and effective elastic thicknesses of the Eastern Anatolia (Turkey) and surrounding region

NASA Astrophysics Data System (ADS)

Oruç, Bülent; Gomez-Ortiz, David; Petit, Carole

2017-12-01

The Lithospheric structure of Eastern Anatolia and the surrounding region, including the northern part of the Arabian platform is investigated via the analysis and modeling of Bouguer anomalies from the Earth Gravitational Model EGM08. The effective elastic thickness of the lithosphere (EET) that corresponds to the mechanical cores of the crust and lithospheric mantle is determined from the spectral coherence between Bouguer anomalies and surface elevation data. Its average value is 18.7 km. From the logarithmic amplitude spectra of Bouguer anomalies, average depths of the lithosphere-asthenosphere boundary (LAB), Moho, Conrad and basement in the study area are constrained at 84 km, 39 km, 16 km and 7 km, respectively. The geometries of the LAB and Moho are then estimated using the Parker-Oldenburg inversion algorithm. We also present a lithospheric strength map obtained from the spatial variations of EET determined by Yield Stress Envelopes (YSE). The EET varies in the range of 12-23 km, which is in good agreement with the average value obtained from spectral analysis. Low EET values are interpreted as resulting from thermal and flexural lithospheric weakening. According to the lithospheric strength of the Eastern Anatolian region, the rheology model consists of a strong but brittle upper crust, a weak and ductile lower crust, and a weak lower part of the lithosphere. On the other hand, lithosphere strength corresponds to weak and ductile lower crust, a strong upper crust and a strong uppermost lithospheric mantle for the northern part of the Arabian platform.

Seismic structure of the Slave craton crust

NASA Astrophysics Data System (ADS)

Barantseva, O.; Vinnik, L. P.; Farra, V.; van der Hilst, R. D.; Artemieva, I. M.; Montagner, J. P.

2017-12-01

We present P- and S-receiver functions for 20 stations along a 200-km-long NNW-SSE seismological profile across the Slave craton, and estimate the average crustal Vp/Vs ratio which is indicative of rock composition. We observe high Vp/Vs ratio ( 1.85-2.00) for the bulk crust and elevated Vp values at a depth range from 20-30 km to 40 km. High Vp values (>7.0 km/s) suggest mafic composition of the lower crust. In case of dry lower crustal rocks, the Vp/Vs ratio is expected to range from 1.6 to 1.8, which is lower than the observed values of 1.9-2.0. Laboratory studies show that Vp/Vs 1.9-2.0 can be explained by the presence of numerous cracks saturated with an incompressible fluid. Our results are at odds with the structure of the cratonic crust in many regions worldwide, and may suggest a unique geodynamic evolution of the Slave crust. Possible explanations for the observed crustal structure include the presence of an underplated mafic material, possibly related to intraplate magmatism or paleosubduction. Receiver functions are highly sensitive to the change of acoustic impedance and S-wave velocities, but do not resolve the internal seismic structure with a high precision. We extend our study of the crustal structure by using ambient noise tomography (ANT). We measure Rayleigh wave dispersion from Green's functions that are estimated from one-year noise cross-correlation (NCF). The phase velocity maps are inverted for 1D wave speed profiles which are then combined to form 2D and 3D models of the crust of the Slave Province. The combined results of RF analyses and ANT are interpreted in terms of crustal structure, composition, and evolution.

Detection of Acoustic/Infrasonic/Seismic Waves Generated by Hypersonic Re-Entry of the HAYABUSA Capsule and Fragmented Parts of the Spacecraft

NASA Astrophysics Data System (ADS)

Yamamoto, Masa-Yuki; Ishihara, Yoshiaki; Hiramatsu, Yoshihiro; Kitamura, Kazuki; Ueda, Masayoshi; Shiba, Yasuo; Furumoto, Muneyoshi; Fujita, Kazuhisa

2011-10-01

Acoustic/infrasonic/seismic waves were observed during the re-entry of the Japanese asteroid explorer ``HAYABUSA'' at 6 ground sites in Woomera, Australia, on 2010 June 13. Overpressure values of infrasound waves were detected at 3 ground sites in a range from 1.3 Pa, 1.0 Pa, and 0.7 Pa with each distance of 36.9 km, 54.9 km, and 67.8 km, respectively, apart from the SRC trajectory. Seismic waveforms through air-to-ground coupling processes were also detected at 6 sites, showing a one-to-one correspondence to infrasound waves at all simultaneous observation sites. Audible sound up to 1 kHz was recorded at one site with a distance of 67.8 km. The mother spacecraft was fragmented from 75 km down to 38 km with a few explosive enhancements of emissions. A persistent train of HAYABUSA re-entry was confirmed at an altitude range of between 92 km down to 82 km for about 3 minutes. Light curves of 136 fragmented parts of the spacecraft were analyzed in detail based on video observations taken at multiple ground sites, being classified into three types of fragmentations, i.e., melting, explosive, and re-fragmented types. In a comparison between infrasonic waves and video-image analyses, regarding the generation of sonic-boom type shock waves by hypersonically moving artificial meteors, both the sample return capsule and fragmented parts of the mother spacecraft, at an altitude of 40 ± 1 km were confirmed with a one-to-one correspondence with each other.

Thermal Dependence of the Apparent Km of Glutathione Reductases from Three Plant Species

PubMed Central

Mahan, James R.; Burke, John J.; Orzech, Karen A.

1990-01-01

The thermal dependencies of the apparent Km of the glutathione reductases from spinach (Spinacia oleracea L.) corn (Zea mays L.), and cucumber (Cucumis sativus L.) were determined. The apparent Km of the enzymes were found to vary up to 9-fold between 12.5 and 45°C. Values of the apparent Km in excess of 200% of the observed minimum are suggested to be detrimental to the normal function of the enzyme. We propose the term “thermal kinetic window” to describe to the range of temperatures over which the apparent Km of the glutathione reductase is within 200% of its minimum and suggest that it may be a useful indicator of the limits of thermal stress for a given species. The thermal kinetic windows determined in this study are: <16°C for spinach, 23 to 32°C for corn, and 35 to 41°C for cucumber. PMID:16667543

Short and long periodic atmospheric variations between 25 and 200 km

NASA Technical Reports Server (NTRS)

Justus, C. G.; Woodrum, A.

1973-01-01

Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of gravity wave and planetary wave atmospheric variations are presented. Time structure of the gravity wave variations were determined by the analysis of residuals from harmonic analysis of time series data. Planetary wave contributions in the 25-85 km range were discovered and found to have significant height and latitudinal variation. Long period planetary waves, and seasonal variations were also computed by harmonic analysis. Revised height variations of the gravity wave contributions in the 25 to 85 km height range were computed. An engineering method and design values for gravity wave magnitudes and wave lengths are given to be used for such tasks as evaluating the effects on the dynamical heating, stability and control of spacecraft such as the space shuttle vehicle in launch or reentry trajectories.

Spatial variations in isostatic compensation mechanisms of the Ninetyeast Ridge and their tectonic significance

NASA Astrophysics Data System (ADS)

Sreejith, K. M.; Krishna, K. S.

2013-10-01

Ninetyeast Ridge (NER), one of the longest linear volcanic features on the Earth, offers an excellent opportunity of understanding the isostatic response to the interactions of mantle plume with the migrating mid-ocean ridge. Bathymetry, geoid, and gravity (shipborne and satellite) data along 72 closely spaced transects and 17 overlapping grids on the NER are analyzed and modeled to determine the effective elastic thickness (Te) beneath the entire ridge. The results of 2-D and 3-D flexural modeling of the NER show large spatial variations in Te values ranging from 4 to 35 km, suggesting that the ridge was compensated along its length by different isostatic mechanisms. The southern (south of 22°S latitude) and northern (north of 2°N latitude) parts of the NER have Te values of >10 and >23 km, respectively, revealing that the southern part was emplaced on a lithosphere of intermediate strength possibly on flank of the Indian plate, whereas the northern part was emplaced in an intraplate setting. In contrast, in the central part of the NER (between latitudes 22°S and 2°N), highly variable Te values (4-22 km) are estimated. The scattered Te values in the central NER suggest that this part may have evolved due to the occurrence of frequent ridge jumps caused by the interaction of Kerguelen hot spot with rapid northward migration of the Wharton spreading ridge. Residual Mantle Bouguer Anomaly (RMBA) map of the NER and adjacent basins reveals that the entire length of the NER is associated with a significant negative anomaly up to 200 mGal, indicating the presence of thickened crust or less dense mantle beneath the ridge. 3-D crustal thickness map of the NER, generated by inversion of the RMBA data, shows a thick crust ranging from 15 to 19 km. The present study clearly shows that NER possesses a highly segmented isostatic pattern with the occurrence of subcrustal underplating or subsurface loading.

Crustal Structure beneath Alaska from Receiver Functions

NASA Astrophysics Data System (ADS)

Zhang, Y.; Li, A.

2017-12-01

The crustal structure in Alaska has not been well resolved due to the remote nature of much of the state. The USArray Transportable Array (TA), which is operating in Alaska and northwestern Canada, significantly increases the coverage of broadband seismic stations in the region and allows for a more comprehensive study of the crust. We have analyzed P-receiver functions from earthquake data recorded by 76 stations of the TA and AK networks. Both common conversion point (CCP) and H-K methods are used to estimate the mean crustal thickness. The results from the CCP stacking method show that the Denali fault marks a sharp transition from thick crust in the south to thin crust in the north. The thickest crust up to 52 km is located in the St. Elias Range, which has been formed by oblique collision between the Yakutat microplate and North America. A thick crust of 48 km is also observed beneath the eastern Alaska Range. These observations suggest that high topography in Alaska is largely compensated by the thick crust root. The Moho depth ranges from 28 km to 35 km beneath the northern lowlands and increases to 40-45 km under the Books Range. The preliminary crustal thickness from the H-K method generally agrees with that from the CCP stacking with thicker crust beneath high mountain ranges and thinner crust beneath lowlands and basins. However, the offshore part is not well constrained due to the limited coverage of stations. The mean Vp/Vs ratio is around 1.7 in the Yukon-Tanana terrane and central-northern Alaska. The ratio is about 1.9 in central and southern Alaska with higher values at the Alaska Range, Wrangell Mountains, and St. Elias Range. Further data analyses are needed for obtaining more details of the crustal structure in Alaska to decipher the origin and development of different tectonic terranes.

Ultrasonic P- and S-Wave Attenuation and Petrophysical Properties of Deccan Flood Basalts, India, as Revealed by Borehole Studies

NASA Astrophysics Data System (ADS)

Vedanti, Nimisha; Malkoti, Ajay; Pandey, O. P.; Shrivastava, J. P.

2018-03-01

Petrophysical properties and ultrasonic P- and S-wave attenuation measurements on 35 Deccan basalt core specimens, recovered from Killari borehole site in western India, provide unique reference data-sets for a lesser studied Deccan Volcanic Province. These samples represent 338-m-thick basaltic column, consisting four lava flows each of Ambenali and Poladpur Formations, belonging to Wai Subgroup of the Deccan volcanic sequence. These basalt samples are found to be iron-rich (average FeOT: 13.4 wt%), but relatively poor in silica content (average SiO2: 47.8 wt%). The saturated massive basalt cores are characterized by a mean density of 2.91 g/cm3 (range 2.80-3.01 g/cm3) and mean P- and S-wave velocities of 5.89 km/s (range 5.01-6.50 km/s) and 3.43 km/s (range 2.84-3.69 km/s), respectively. In comparison, saturated vesicular basalt cores show a wide range in density (2.40-2.79 g/cm3) as well as P-wave (3.28-4.78 km/s) and S-wave (1.70-2.95 km/s) velocities. Based on the present study, the Deccan volcanic sequence can be assigned a weighted mean density of 2.74 g/cm3 and a low V p and V s of 5.00 and 3.00 km/s, respectively. Such low velocities in Deccan basalts can be attributed mainly to the presence of fine-grained glassy material, high iron contents, and hydrothermally altered secondary mineral products, besides higher porosity in vesicular samples. The measured Q values in saturated massive basalt cores vary enormously (Q p: 33-1960 and Q s: 35-506), while saturated vesicular basalt samples exhibit somewhat lesser variation in Q p (6-46) as well as Q s (5-49). In general, high-porosity rocks exhibit high attenuation, but we observed the high value of attenuation in some of the massive basalt core samples also. In such cases, energy loss is mainly due to the presence of fine-grained glassy material as well as secondary alteration products like chlorophaeite, that could contribute to intrinsic attenuation. Dominance of weekly bound secondary minerals might also be responsible for the generation of microcracks, which may generate squirt flow in saturated samples. Hence, we argue that the Deccan basalts attenuate seismic energy significantly, where its composition plays a major role.

Seismic velocity and attenuation structures in the Earth's inner core

NASA Astrophysics Data System (ADS)

Yu, Wen-Che

2007-12-01

I study seismic velocity and attenuation structures in the top 400 km of the Earth's inner core along equatorial paths, velocity-attenuation relationship, and seismic anisotropy in the top of the inner core beneath Africa. Seismic observations exhibit "east-west" hemispheric differences in seismic velocity, attenuation, and anisotropy. Joint modeling of the PKiKP-PKIKP and PKPbc-PKIKP phases is used to constrain seismic velocity and attenuation structures in the top 400 km of the inner core for the eastern and western hemispheres. The velocity and attenuation models for the western hemisphere are simple, having a constant velocity gradient and a Q value of 600 in the top 400 km of the inner core. The velocity and attenuation models for the eastern hemisphere appear complex. The velocity model for the eastern hemisphere has a small velocity gradient in the top 235 km, a steeper velocity gradient at the depth range of 235 - 375 km, and a gradient similar to PREM in the deeper portion of the inner core. The attenuation model for the eastern hemisphere has a Q value of 300 in the top 300 km and a Q value of 600 in the deeper portion of the inner core. The study of velocity-attenuation relationship reveals that inner core is anisotropic in both velocity and attenuation, and the direction of high attenuation corresponding to that of high velocity. I hypothesize that the hexagonal close packed (hcp) iron crystal is anisotropic in attenuation, with the axis of high attenuation corresponding to that of high velocity. Anisotropy in the top of the inner core beneath Africa is complex. Beneath eastern Africa, the thickness of the isotropic upper inner core is about 0 km. Beneath central and western Africa, the thickness of the isotropic upper inner core increases from 20 to 50 km. The velocity increase across the isotropic upper inner core and anisotropic lower inner core boundary is sharp, laterally varying from 1.6% - 2.2%. The attenuation model has a Q value of 600 for the isotropic upper inner core and 150 to 400 for the anisotropic lower inner core.

Catchment-scale denudation and chemical erosion rates determined from 10Be and mass balance geochemistry (Mt. Lofty Ranges of South Australia)

NASA Astrophysics Data System (ADS)

Bestland, Erick A.; Liccioli, Caterina; Soloninka, Lesja; Chittleborough, David J.; Fink, David

2016-10-01

Global biogeochemical cycles have, as a central component, estimates of physical and chemical erosion rates. These erosion rates are becoming better quantified by the development of a global database of cosmogenic radionuclide 10Be (CRN) analyses of soil, sediment, and outcrops. Here we report the denudation rates for two small catchments (~ 0.9 km2) in the Mt. Lofty Ranges of South Australia as determined from 10Be concentrations from quartz sand from the following landscape elements: 1) dissected plateaux, or summit surfaces (14.10 ± 1.61 t km- 2 y- 1), 2) sandstone outcrops (15.37 ± 1.32 t km- 2 y- 1), 3) zero-order drainages (27.70 ± 1.42 t km- 2 y- 1), and 4) stream sediment which reflect a mix of landscape elements (19.80 ± 1.01 t km- 2 y- 1). Thus, the more slowly eroding plateaux and ridges, when juxtaposed with the more rapidly eroding side-slopes, are leading to increased relief in this landscape. Chemical erosion rates for this landscape are determined by combining cosmogenic denudation rates with the geochemical mass balance of parent rock, soil and saprolite utilizing zirconium immobility and existing mass balance methods. Two different methods were used to correct for chemical weathering and erosion in the saprolite zone that is shielded at depth from CRN production. The corrected values are higher than uncorrected values: total denudation of 33.24 or 29.11 t km- 2 y- 1, and total chemical erosion of 15.64 or 13.68 t km- 2 y- 1. Thus, according to these methods, 32-40% of the denudation is taking place by chemical weathering and erosion in the saprolite below CRN production depth. Compared with other similar areas, the overall denudation and chemical erosion rates are low. In most areas with sub-humid climates and tectonic uplift, physical erosion is much greater than chemical erosion. The low physical erosion rates in these Mt. Lofty Range catchments, in what is a relatively active tectonic setting, are thought to be due to low rainfall intensity during the winter wet season, which inhibits physical erosion such as land-sliding and debris flows.

Alum Innovative Exploration Project (Ram Power Inc.)

DOE Data Explorer

Miller, Clay

2010-01-01

Data generated from the Alum Innovative Exploration Project, one of several promising geothermal properties located in the middle to upper Miocene (~11-5 Ma, or million years BP) Silver Peak-Lone Mountain metamorphic core complex (SPCC) of the Walker Lane structural belt in Esmeralda County, west-central Nevada. The geothermal system at Alum is wholly concealed; its upper reaches discovered in the late 1970s during a regional thermal-gradient drilling campaign. The prospect boasts several shallow thermal-gradient (TG) boreholes with TG >75oC/km (and as high as 440oC/km) over 200-m intervals in the depth range 0-600 m. Possibly boiling water encountered at 239 m depth in one of these boreholes returned chemical- geothermometry values in the range 150-230oC. GeothermEx (2008) has estimated the electrical- generation capacity of the current Alum leasehold at 33 megawatts for 20 years; and the corresponding value for the broader thermal anomaly extending beyond the property at 73 megawatts for the same duration.

Observations of temporal change of nighttime cloud cover from Himawari 8 and ground-based sky camera over Chiba, Japan

NASA Astrophysics Data System (ADS)

Lagrosas, N.; Gacal, G. F. B.; Kuze, H.

2017-12-01

Detection of nighttime cloud from Himawari 8 is implemented using the difference of digital numbers from bands 13 (10.4µm) and 7 (3.9µm). The digital number difference of -1.39x104 can be used as a threshold to separate clouds from clear sky conditions. To look at observations from the ground over Chiba, a digital camera (Canon Powershot A2300) is used to take images of the sky every 5 minutes at an exposure time of 5s at the Center for Environmental Remote Sensing, Chiba University. From these images, cloud cover values are obtained using threshold algorithm (Gacal, et al, 2016). Ten minute nighttime cloud cover values from these two datasets are compared and analyzed from 29 May to 05 June 2017 (20:00-03:00 JST). When compared with lidar data, the camera can detect thick high level clouds up to 10km. The results show that during clear sky conditions (02-03 June), both camera and satellite cloud cover values show 0% cloud cover. During cloudy conditions (05-06 June), the camera shows almost 100% cloud cover while satellite cloud cover values range from 60 to 100%. These low values can be attributed to the presence of low-level thin clouds ( 2km above the ground) as observed from National Institute for Environmental Studies lidar located inside Chiba University. This difference of cloud cover values shows that the camera can produce accurate cloud cover values of low level clouds that are sometimes not detected by satellites. The opposite occurs when high level clouds are present (01-02 June). Derived satellite cloud cover shows almost 100% during the whole night while ground-based camera shows cloud cover values that range from 10 to 100% during the same time interval. The fluctuating values can be attributed to the presence of thin clouds located at around 6km from the ground and the presence of low level clouds ( 1km). Since the camera relies on the reflected city lights, it is possible that the high level thin clouds are not observed by the camera but is observed by the satellite. Also, this condition constitutes layers of clouds that are not observed by each camera. The results of this study show that one instrument can be used to correct each other to provide better cloud cover values. These corrections is dependent on the height and thickness of the clouds. No correction is necessary when the sky is clear.

Quantifying the source regions of observed pore water B and δ^{11}B signatures at shallow depths in forearcs

NASA Astrophysics Data System (ADS)

Saffer, D. M.; Kopf, A. J.

2006-12-01

At many subduction zones, geochemistry of pore waters taken from boreholes and mud volcanoes indicates a contribution from deep, high-temperature sources. These observations include pore water freshening, elevated K, thermogenic hydrocarbons, enrichment in volatiles such as B and Li, and decreased δ11B, δ6Li, and δ37Cl. As tracers of subduction zone devolatilization, geochemical signatures provide constraints on fluid flow pathways and rates within the forearc; in addition, the return flux of volatiles to the oceans through forearcs may constitute a significant component of the global cycles for B and Li. Identifying the location and distribution of source regions for these tracers is one critical step toward characterizing subduction zone fluid transport systems. To date, this problem is relatively well studied for pore water freshening signals and thermogenic hydrocarbons. In contrast, there has been little work to rigorously constrain the locations of source regions for other tracers, or to quantify the expected source concentrations. Here, we focus on numerous observations of high [B] and low δ11B in fluids sampled at shallow depths, which have been interpreted to reflect desorption of isotopically light B from clays with increased temperature, and subsequent advection of the altered fluids to the seafloor either near the trench or on the continental slope. At the Costa Rican, Nankai, and N. Japan margins, observed values of [B] range from ~2000 to 4000 μM (typical seawater concentration is ~42 μM), and δ11B values are as low as ~25 ‰ (average seawater value is ~39.5 ‰). We use a simple model to combine (1) heating and compaction that accompany progressive burial of sediment with (2) previously published laboratory experimental data that constrain the distribution coefficient (Kd) for B in marine sediments as a function of temperature, to quantify the expected distribution of B concentrations and isotopic ratios within bulk mudstones in subduction zones. We track packages of sediment as they are heated and compacted, and calculate resulting [B] and δ11B step-wise from conservation of mass and applying a temperature-dependent Kd. The resulting distribution of [B] and δ11B depend primarily upon the rates of heating and porosity loss with burial. In our preliminary analysis, we consider a generic subduction zone with a total taper angle of 8°, and evaluate two end- member cases: cold and warm scenarios, in which heat flow on the incoming plate is set at 60 mW m-2, and 120 mW m-2, respectively. For the cold end-member scenario, simulated values of [B] within the subducted sedment at 30 km from the trench range from 650 to 1200 μM and values of δ11B range from 23.4 to 30.6 ‰. At 60 km from the trench, [B] ranges from 1010 to 3340 μM and δ11B from 18.0 to 25.0 ‰. For the warm scenario, simulated [B] ranges from 970 to 2400 μM at 30 km and 2250 to 11480 μM at 60 km; δ11B ranges from 19.2 to 25.2 ‰ at 30 km and 15.9 to 19.5 ‰ at 60 km. These signatures are generally stronger than those observed in pore fluids at shallow depths, consistent with the probable re-adsorption of some B during updip or vertical advection. Ultimately, the results of these calculations can be used as input for hydrologic models that include re-adsorption, to quantitatively investigate the fluid flow rates and permeabilities required to transport B at rates required to produce the observed signatures.

Short-range solar radiation forecasts over Sweden

NASA Astrophysics Data System (ADS)

Landelius, Tomas; Lindskog, Magnus; Körnich, Heiner; Andersson, Sandra

2018-04-01

In this article the performance for short-range solar radiation forecasts by the global deterministic and ensemble models from the European Centre for Medium-Range Weather Forecasts (ECMWF) is compared with an ensemble of the regional mesoscale model HARMONIE-AROME used by the national meteorological services in Sweden, Norway and Finland. Note however that only the control members and the ensemble means are included in the comparison. The models resolution differs considerably with 18 km for the ECMWF ensemble, 9 km for the ECMWF deterministic model, and 2.5 km for the HARMONIE-AROME ensemble. The models share the same radiation code. It turns out that they all underestimate systematically the Direct Normal Irradiance (DNI) for clear-sky conditions. Except for this shortcoming, the HARMONIE-AROME ensemble model shows the best agreement with the distribution of observed Global Horizontal Irradiance (GHI) and DNI values. During mid-day the HARMONIE-AROME ensemble mean performs best. The control member of the HARMONIE-AROME ensemble also scores better than the global deterministic ECMWF model. This is an interesting result since mesoscale models have so far not shown good results when compared to the ECMWF models. Three days with clear, mixed and cloudy skies are used to illustrate the possible added value of a probabilistic forecast. It is shown that in these cases the mesoscale ensemble could provide decision support to a grid operator in terms of forecasts of both the amount of solar power and its probabilities.

Validation of Temperature Measurements from the Airborne Raman Ozone Temperature and Aerosol Lidar During SOLVE

NASA Technical Reports Server (NTRS)

Burris, John; McGee, Thomas; Hoegy, Walter; Lait, Leslie; Twigg, Laurence; Sumnicht, Grant; Heaps, William; Hostetler, Chris; Bui, T. Paul; Neuber, Roland;

Altitude profiles of temperature from 4 to 80 km over the tropics from MST radar and lidar

NASA Astrophysics Data System (ADS)

Parameswaran, K.; Sasi, M. N.; Ramkumar, G.; Nair, P. R.; Deepa, V.; Murthy, B. V. K.; Nayar, S. R. P.; Revathy, K.; Mrudula, G.; Satheesan, K.; Bhavanikumar, Y.; Sivakumar, V.; Raghunath, K.; Rajendraprasad, T.; Krishnaiah, M.

2000-10-01

Using ground-based techniques of MST radar and Lidar, temperature profiles in the entire height range of 4 to 75km are obtained for the first time at a tropical location. The temporal resolution of the profiles is ~1h in the lower altitudes and 12.5min in the higher altitudes and altitude resolution is ~300m. The errors involved in the derived values are presented. Preliminary analysis of temperature variations in a night revealed fluctuations with characteristics resembling those of large-scale gravity waves.

Equation of state fits to the lower mantle and outer core

NASA Technical Reports Server (NTRS)

Butler, R.; Anderson, D. L.

1978-01-01

The lower mantle and outer core are subjected to tests for homogeneity and adiabaticity. An earth model is used which is based on the inversion of body waves and Q-corrected normal-mode data. Homogeneous regions are found at radii between 5125 and 4825 km, 4600 and 3850 km, and 3200 and 2200 km. The lower mantle and outer core are inhomogeneous on the whole and are only homogeneous in the above local regions. Finite-strain and atomistic equations of state are fit to the homogeneous regions. The apparent convergence of the finite-strain relations is examined to judge their applicability to a given region. In some cases the observed pressure derivatives of the elastic moduli are used as additional constraints. The effect of minor deviations from adiabaticity on the extrapolations is also considered. An ensemble of zero-pressure values of the density and seismic velocities are found for these regions. The range of extrapolated values from these several approaches provides a measure of uncertainties involved.

Global Reference Atmospheric Model and Trace Constituents

NASA Technical Reports Server (NTRS)

Justus, C.; Johnson, D.; Parker, Nelson C. (Technical Monitor)

2002-01-01

Global Reference Atmospheric Model (GRAM-99) is an engineering-level model of the Earth's atmosphere. It provides both mean values and perturbations for density, temperature, pressure, and winds, as well as monthly- and geographically-varying trace constituent concentrations. From 0-27 km, thermodynamics and winds are based on National Oceanic and Atmospheric Administration Global Upper Air Climatic Atlas (GUACA) climatology. Above 120 km, GRAM is based on the NASA Marshall Engineering Thermosphere (MET) model. In the intervening altitude region, GRAM is based on Middle Atmosphere Program (MAP) climatology that also forms the basis of the 1986 COSPAR Intemationa1 Reference Atmosphere (CIRA). MAP data in GRAM are augmented by a specially-derived longitude variation climatology. Atmospheric composition is represented in GRAM by concentrations of both major and minor species. Above 120 km, MET provides concentration values for N2, O2, Ar, O, He, and H. Below 120 km, species represented also include H2O, O3, N2O, CO, CH, and CO2. Water vapor in GRAM is based on a combination of GUACA, Air Force Geophysics Laboratory (AFGL), and NASA Langley Research Center climatologies. Other constituents below 120 km are based on a combination of AFGL and h4AP/CIRA climatologies. This report presents results of comparisons between GRAM Constituent concentrations and those provided by the Naval Research Laboratory (NRL) climatology of Summers (NRL,/MR/7641-93-7416, 1993). GRAM and NRL concentrations were compared for seven species (CH4, CO, CO2, H2O, N2O, O2, and O3) for months January, April, July, and October, over height range 0-115 km, and latitudes -90deg to + 90deg at 10deg increments. Average GRAM-NRL correlations range from 0.878 (for CO) to 0.975 (for O3), with an average over all seven species of 0.936 (standard deviation 0.049).

Runoff and soil erosion of field plots in a subtropical mountainous region of China

NASA Astrophysics Data System (ADS)

Fang, N. F.; Wang, L.; Shi, Z. H.

2017-09-01

Anthropogenic pressure coupled with strong precipitation events and a mountainous landscape have led to serious soil erosion and associated problems in the subtropical climate zone of China. This study analyzes 1576 rainfall-runoff-soil loss events at 36 experimental plots (a total of 148 plot-years of data) under a wide range of conditions in subtropical mountainous areas of China where slope farming is commonly practiced. The plots, which have standardized dimensions, represent five common types of land use and have four different slopes. Event-based analyses show that almost half of the total rainfall caused soil erosion in the study area. The dominant factor controlling the runoff coefficient is the slope gradient rather than the land use type. The maximum soil lossfor crop plots under steep tillage (35°) is 5004 t km-2 for a single event. Among the common local crops, the average soil loss values increase in the following order: buckwheat < mung bean < sesame. Among the most widespread grasses, orchards and crops, the soil loss increase in the following order: red clover < nectarine < orange < maize. A large proportion of the soil loss is caused by a small number of extreme events. The annual average soil loss of the 44 plots ranges from 19 to 4090 t km-2 year-1. The annual soil loss of plots of different land use types decrease in the following order: bare land (1533 t km-2 year-1) > cropland (1179 t km-2 year-1) > terraced cropland (1083 t km-2 year-1) > orchard land (1020 t km-2 year-1) > grassland (762 t km-2 year-1) > terraced orchard land (297 t km-2 year-1) > forest and grassland (281 t km-2 year-1).

The O(3P) and N(4S) density measurement at 225 km by ultraviolet absorption and fluorescence in the Apollo-Soyuz test project

NASA Technical Reports Server (NTRS)

Kaufman, F.; Rawling, W. T.; Donahue, T. M.; Anderson, J. G.; Hudson, R. D.

1976-01-01

The densities of O(3P) and N(4S) at 225 km were determined during the Apollo Soyuz Test Project by a resonance absorption/fluorescence technique in which OI and NI line radiation produced and collimated on board the Apollo was reflected from the Soyuz back to the Apollo for spectral analysis. The two spacecraft maneuvered so that a range of observation angles of plus or minus 15 deg with respect to the normal to the orbital velocity vector was scanned. The measurements were made at night on two consecutive orbits at spacecraft separations of 150 and 500 m. The resulting relative counting rates as function of observation angle were compared to calculated values to determine the oxygen value. This value agrees with mass spectrometric measurements made under similar conditions. The nitrogen value is in good agreement with other measurements and suggests a smaller diurnal variation than is predicted by present models.

GRAM 88 - 4D GLOBAL REFERENCE ATMOSPHERE MODEL-1988

NASA Technical Reports Server (NTRS)

Johnson, D. L.

1994-01-01

The Four-D Global Reference Atmosphere program was developed from an empirical atmospheric model which generates values for pressure, density, temperature, and winds from surface level to orbital altitudes. This program can generate altitude profiles of atmospheric parameters along any simulated trajectory through the atmosphere. The program was developed for design applications in the Space Shuttle program, such as the simulation of external tank re-entry trajectories. Other potential applications are global circulation and diffusion studies; also the generation of profiles for comparison with other atmospheric measurement techniques such as satellite measured temperature profiles and infrasonic measurement of wind profiles. GRAM-88 is the latest version of the software GRAM. The software GRAM-88 contains a number of changes that have improved the model statistics, in particular, the small scale density perturbation statistics. It also corrected a low latitude grid problem as well as the SCIDAT data base. Furthermore, GRAM-88 now uses the U.S. Standard Atmosphere 1976 as a comparison standard rather than the US62 used in other versions. The program is an amalgamation of two empirical atmospheric models for the low (25km) and the high (90km) atmosphere, with a newly developed latitude-longitude dependent model for the middle atmosphere. The Jacchia (1970) model simulates the high atmospheric region above 115km. The Jacchia program sections are in separate subroutines so that other thermosphericexospheric models could easily be adapted if required for special applications. The improved code eliminated the calculation of geostrophic winds above 125 km altitude from the model. The atmospheric region between 30km and 90km is simulated by a latitude-longitude dependent empirical model modification of the latitude dependent empirical model of Groves (1971). A fairing technique between 90km and 115km accomplished a smooth transition between the modified Groves values and the Jacchia values. Below 25km the atmospheric parameters are computed by the 4-D worldwide atmospheric model of Spiegler and Fowler (1972). This data set is not included. GRAM-88 incorporates a hydrostatic/gas law check in the 0-30 km altitude range to flag and change any bad data points. Between 5km and 30km, an interpolation scheme is used between the 4-D results and the modified Groves values. The output parameters consist of components for: (1) latitude, longitude, and altitude dependent monthly and annual means, (2) quasi-biennial oscillations (QBO), and (3) random perturbations to partially simulate the variability due to synoptic, diurnal, planetary wave, and gravity wave variations. Quasi-biennial and random variation perturbations are computed from parameters determined by various empirical studies and are added to the monthly mean values. The GRAM-88 program is for batch execution on the IBM 3084. It is written in STANDARD FORTRAN 77 under the MVS/XA operating system. The IBM DISPLA graphics routines are necessary for graphical output. The program was developed in 1988.

An experimental investigation of mesospheric ionization

NASA Technical Reports Server (NTRS)

Mitchell, J. D.

1973-01-01

Mesospheric ionization and its variability are examined. Data were obtained primarily by the parachute-borne blunt probe technique conducted in coordinated rocket experiments at White Sands Missile Range, New Mexico and Wallops Island, Virginia. Electrical conductivity measurements and deduced charge density values from ten rocket launches are presented and discussed. Positive ion conductivity and electron density were found to be relatively invariant with height between 45 and 60 km. Variations in positive conductivity of a factor of two and enhancements in negative conductivity by as much as a factor of four were measured by the blunt probe. A simple lumped parameter ion chemistry model is shown to satisfactorily explain the charge density values for the undisturbed lower D-region. Implications of the data in terms of this model are considered. The principal loss mechanism for positive ions in the 45 to 60 km. region is concluded to be dissociative recombination. Electron densities deduced from the conductivity data are explained by detachment involving a minor neutral constituent which is mixed between 65 and 45 km. and then cuts off sharply below 45 km. A correlation study involving blunt probe measurements shows relatively good agreement between variations in positive conductivity and temperature.

Molecular and biochemical characterization of natural and recombinant phosphoglycerate kinase B from Trypanosoma rangeli.

PubMed

Villafraz, O; Rondón-Mercado, R; Cáceres, A J; Concepción, J L; Quiñones, W

2018-04-01

T. rangeli epimastigotes contain only a single detectable phosphoglycerate kinase (PGK) enzyme in their cytosol. Analysis of this parasite's recently sequenced genome showed a gene predicted to code for a PGK with the same molecular mass as the natural enzyme, and with a cytosolic localization as well. In this work, we have partially purified the natural PGK from T. rangeli epimastigotes. Furthermore, we cloned the predicted PGK gene and expressed it as a recombinant active enzyme. Both purified enzymes were kinetically characterized and displayed similar substrate affinities, with Km ATP values of 0.13 mM and 0.5 mM, and Km 3PGA values of 0.28 mM and 0.71 mM, for the natural and recombinant enzyme, respectively. The optimal pH for activity of both enzymes was in the range of 8-10. Like other PGKs, TrPGK is monomeric with a molecular mass of approximately 44 kDa. The enzyme's kinetic characteristics are comparable with those of cytosolic PGK isoforms from related trypanosomatid species, indicating that, most likely, this enzyme is equivalent with the PGKB that is responsible for generating ATP in the cytosol of other trypanosomatids. This is the first report of a glycolytic enzyme characterization from T. rangeli. Copyright © 2018 Elsevier Inc. All rights reserved.

The NASA/MSFC Global Reference Atmospheric Model-1995 version (GRAM-95)

NASA Technical Reports Server (NTRS)

Justus, C. G.; Jeffries, W. R., III; Yung, S. P.; Johnson, D. L.

1995-01-01

The latest version of the Global Reference Atmospheric Model (GRAM-95) is presented and discussed. GRAM-95 uses the new Global Upper Air Climatic Atlas (GUACA) CD-ROM data set, for 0- to 27-km altitudes. As with earlier versions, GRAM-95 provides complete geographical and altitude coverage for each month of the year. Individual years 1985 to 1991 and a period-of-record (1980 to 1991) can be simulated for the GUACA height range. GRAM-95 uses a specially developed data set, based on Middle Atmosphere Program (MAP) data, for the 20- to 120-km height range, and the NASA Marshall Engineering Thermosphere (MET) model for heights above 90 km. Fairing techniques assure a smooth transition in the overlap height ranges (20 to 27 km and 90 to 120 km). In addition to the traditional GRAM variables of pressure, density, temperature and wind components, GRAM-95 now includes water vapor and 11 other atmospheric constituents (O3, N2O, CO, CH4, CO2, N2, O2, O, A, He, and H). A new, variable-scale perturbation model provides both large-scale and small-scale deviations from mean values for the thermodynamic variables and horizontal and vertical wind components. The perturbation model includes new features that simulate intermittency (patchiness) in turbulence and small-scale perturbation fields. The density perturbations and density gradients (density shears) computed by the new model compare favorably in their statistical characteristics with observed density perturbations and density shears from 32 space shuttle reentry profiles. GRAM-95 provides considerable improvement in wind estimates from the new GUACA data set, compared to winds calculated from the geostrophic wind relations previously used in the 0- to 25-km height range. The GRAM-95 code has been put into a more modular form, easier to incorporate as subroutines in other programs (e.g., trajectory codes). A complete user's guide for running the program, plus sample input and output, is provided.

High resolution mesospheric sodium properties for adaptive optics applications

NASA Astrophysics Data System (ADS)

Pfrommer, T.; Hickson, P.

2014-05-01

Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims: It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods: We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results: The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a specified fraction of the returned sodium light. We find a mean value of 13.1 ± 0.3 km for the range containing 95% of the photons, with a maximum width of 21 km. The temporal power spectral density of fluctuations of the centroid altitude is well described by a power law having an index that ranges from -1.6 to -2.3 with a mean value of -1.87 ± 0.02. This is significantly steeper than the value of -5/3 that would be expected if the dynamics were dominated by Kolmogorov turbulence, indicating that other factors such as gravity waves play an important role. The amplitude of the power spectrum has a mean value of 34+6-5~m2 Hz-1 at a frequency of 1 Hz, but ranges over two orders of magnitude. The annual means of the index and amplitude show a variation that is well beyond the calculated error range. Long-term global weather patterns may be responsible for this effect. The database is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A102

Rayleigh lidar observations of gravity wave activity in the stratosphere and lower mesosphere

NASA Technical Reports Server (NTRS)

Miller, M. S.; Gardner, C. S.; Liu, C. H.

1987-01-01

Forty-two monochromatic gravity wave events were observed in the 25 to 55 km altitude region during 16 nights of Rayleigh lidar measurements at Poker Flat, Alaska and Urbana, Illinois. The measured wave parameters were compared to previous radar and lidar measurements of gravity wave activity. Vertical wavelengths, lambda(z), between 2 and 11.5 km with vertical phase velocities, c(z), between 0.1 and 1 m/s were observed. Measured values of lambda(z) and c(z) were used to infer observed wave periods, T(ob), between 50 and 1000 minutes and horizontal wavelengths, lambda(x), from 25 to 2000 km. Dominant wave activity was found at vertical wavelengths between 2 to 4 km and 7 to 10 km. No seasonal variations were evident in the observed wave parameters. Vertical and horizontal wavelengths showed a clear tendency to increase with T(ob), which is consistent with recent sodium lidar studies of monochromatic wave events near the mesopause. Measured power law relationships between the wave parameters were lambda(z) varies as T(ob) sup 0.96, lambda(x) varies as T(ob) sup 1.8, and c(z) varies as T(ob) sup -0.85. The kinetic energy calculated for the monochromatic wave events varied as k(z) sup -2, k(x) sup -1, and f(ob) sup -1.7. The atmospheric scale heights calculated for each observation date range from 6.5 to 7.6 km with a mean value of 7 km. The increase of rms wind perturbations with altitude indicated an amplitude growth length of 20.9 km. The altitude profile of kinetic energy density decreased with height, suggesting that waves in this altitude region were subject to dissipation or saturation effects.

Estimates of velocity structure and source depth using multiple P waves from aftershocks of the 1987 Elmore Ranch and Superstition Hills, California, earthquakes

USGS Publications Warehouse

Mori, J.

1991-01-01

Event record sections, which are constructed by plotting seismograms from many closely spaced earthquakes recorded on a few stations, show multiple free-surface reflections (PP, PPP, PPPP) of the P wave in the Imperial Valley. The relative timing of these arrivals is used to estimate the strength of the P-wave velocity gradient within the upper 5 km of the sediment layer. Consistent with previous studies, a velocity model with a value of 1.8 km/sec at the surface increasing linearly to 5.8 km/sec at a depth of 5.5 km fits the data well. The relative amplitudes of the P and PP arrivals are used to estimate the source depth for the aftershock distributions of the Elmore Ranch and Superstition Hills main shocks. Although the depth determination has large uncertainties, both the Elmore Ranch and Superstition Hills aftershock sequencs appear to have similar depth distribution in the range of 4 to 10 km. -Author

Cyanide removal by Chinese vegetation--quantification of the Michaelis-Menten kinetics.

PubMed

Yu, Xiaozhang; Zhou, Puhua; Zhou, Xishi; Liu, Yunda

2005-07-01

Little is known about metabolism rates of environmental chemicals by vegetation. A good model compound to study the variation of rates among plant species is cyanide. Vascular plants possess an enzyme system that detoxifies cyanide by converting it to the amino acid asparagine. Knowledge of the kinetic parameters, the half-saturation constant (Km) and the maximum metabolic capacity (vmax), is very useful for enzyme characterization and biochemical purposes. The goal of this study is to find the enzyme kinetics (K(M) and vmax) during cyanide metabolism in the presence of Chinese vegetation, to provide quantitative data for engineered phytoremediation, and to investigate the variation of metabolic rates of plants. Detached leaves (1.0 g fresh weight) from 12 species out of 9 families were kept in glass vessels with 100 mL of aqueous solution spiked with potassium cyanide at 23 degrees C for 28 h. Four different treatment concentrations of cyanide were used, ranging from 0.44 to 7.69 mg CN/L. The disappearance of cyanide from the aqueous solution was analyzed spectrophotometrically. Realistic values of the half-saturation constant (KM) and the maximum metabolic capacity (vmax) were estimated by a computer program using non-linear regression treatments. As a comparison, Lineweaver-Burk plots were also used to estimate the kinetic parameters. The values obtained for K(M) and vmax varied with plant species. Using non-linear regression treatments, values of vmax and K(M) were found in a range between 6.68 and 21.91 mg CN/kg/h and 0.90 to 3.15 mg CN/L, respectively. The highest vmax was by Chinese elder (Sambucus chinensis), followed by upright hedge-parsley (Torilis japonica). The lowest Vmax was demonstrated by the hybrid willow (Salix matssudana x alba). However, the highest K(M) was found in the water lily (Nymphea teragona), followed by the poplar (Populus deltoides Marsh). The lowest K(M) was demonstrated by corn (Zea mays L.). The values of vmax were normally distributed with a mean of 13 mg CN/kg/h. Significant removal of cyanide from aqueous solution was observed in the presence of plant materials without phytotoxicity, even at high doses of cyanide. This gives rise to the conclusion that the Chinese plant species used in this study are all able to efficiently metabolize cyanide, although with different maximum metabolic capacities. A second conclusion is that the variation of metabolism rates between species is small. All these plants had a similar K(M), indicating the same enzyme is active in all plants. Detoxification of cyanide with trees seems to be a feasible option for cleaning soils and water contaminated with cyanide. For phytoremediation projects, screening appropriate plant species adapted to local conditions should be seriously considered. More chemicals should be investigated to find common principles of the metabolism of environmental chemicals by plants.

Home-range and activity pattern of rehabilitated malayan sun bears (Helarctos malayanus) in the Tembat Forest Reserve, Terengganu

NASA Astrophysics Data System (ADS)

Abidin, Mohammad Kamaruddin Zainal; Mohammed, Ahmad Azhar; Nor, Shukor Md

2018-04-01

Re-introduction programme has been adopted in solving the conflict issues related with the Malayan sun bears in Peninsular Malaysia. Two rehabilitated sun bears (#1533 and #1532) were collared and released in Tembat Forest Reserve, Hulu Terengganu to study the home-range and activity pattern. Tracking of sun bear in wild have be conducted manually by using telemetry devices namely radio frequency systems and GPS-UHF download system. A total of 912 locations were recorded. The home range size (indicate by the size of convex polygon) of bear #1533 is larger than bear #1532, with value of 95% minimum convex polygon was 130 km2 compared to its counterpart was 33.28 km2. Bears moved to forest (primary and secondary) and oil palm area. Bear #1533 and #1532 were more active in daytime (diurnal) especially from sunrise to midday. Activity pattern of both rehabilitated bears suggested influence by their daily activity in captivity. This study has proposed two guidelines in re-introduction, 1) minimum distance between release site and possible conflict area is 10-13 km and 2) release during the bear's active time.

Shock-induced microstructural response of mono- and nanocrystalline SiC ceramics

NASA Astrophysics Data System (ADS)

Branicio, Paulo S.; Zhang, Jingyun; Rino, José P.; Nakano, Aiichiro; Kalia, Rajiv K.; Vashishta, Priya

2018-04-01

The dynamic behavior of mono- and nanocrystalline SiC ceramics under plane shock loading is revealed using molecular-dynamics simulations. The generation of shock-induced elastic compression, plastic deformation, and structural phase transformation is characterized at different crystallographic directions as well as on a 5-nm grain size nanostructure at 10 K and 300 K. Shock profiles are calculated in a wide range of particle velocities 0.1-6.0 km/s. The predicted Hugoniot agree well with experimental data. Results indicate the generation of elastic waves for particle velocities below 0.8-1.9 km/s, depending on the crystallographic direction. In the intermediate range of particle velocities between 2 and 5 km/s, the shock wave splits into an elastic precursor and a zinc blende-to-rock salt structural transformation wave, which is triggered by shock pressure over the ˜90 GPa threshold value. A plastic wave, with a strong deformation twinning component, is generated ahead of the transformation wave for shocks in the velocity range between 1.5 and 3 km/s. For particle velocities greater than 5-6 km/s, a single overdriven transformation wave is generated. Surprisingly, shocks on the nanocrystalline sample reveal the absence of wave splitting, and elastic, plastic, and transformation wave components are seamlessly connected as the shock strength is continuously increased. The calculated strengths 15.2, 31.4, and 30.9 GPa for ⟨001⟩, ⟨111⟩, and ⟨110⟩ directions and 12.3 GPa for the nanocrystalline sample at the Hugoniot elastic limit are in excellent agreement with experimental data.

A quantitative analysis of global intermediate and deep seismicity

NASA Astrophysics Data System (ADS)

Ruscic, Marija; Becker, Dirk; Le Pourhiet, Laetitita; Agard, Philippe; Meier, Thomas

2017-04-01

The seismic activity in subduction zones around the world shows a large spatial variabilty with some regions exhibiting strong seismic activity down to depths of almost 700km while in other places seismicity terminates at depths of about 200 or 300 km. Also the decay of the number of seismic events or of the seismic moment with depth is more pronounced in some regions than in others. The same is true for the variability of the ratio of large to small events (the b-value of the Gutenberg-Richter relation) that is varying with depth. These observations are often linked to parameters of the downgoing plate like age or subduction velocity. In this study we investigate a subset of subduction zones utilizing the revised ISC catalogue of intermediate and deep seismicity to determine statistical parameters well suited to describe properties of intermediate deep and deep events. The seismicity is separated into three depth intervals from 50-175km, 175-400km and >400km based on the depth at which the plate contact decouples, the observed nearly exponential decay of the event rate with depth and the supposed depth of phase transition at 410 km depth where also an increase of the event number with depth is observed. For estimation of the b-value and the exponential decay with depth, a restriction of the investigated time interval to the period after 1997 produced significantly better results indicating a globally homogeneous magnitude scale with the magnitude of completeness of about Mw 5. On a global scale the b-value decreases with depth from values of about 1 at 50-175km to values of slightly below 0.8 for events below 400km. Also, there is a slight increase of the b-value with the age of the subducting plate. These changes in the b-value with depth and with age may indicate a varying fragmentation of the slab. With respect to the ratio of the seismic moment between deeper and shallower parts of the subduction zones a dependence on the age is apparent with older slabs exhibiting higher ratios indicating stronger hydration of older slabs and consequently stronger seismic activity at depth in older and thicker slabs. Furthermore, older slabs show the tendency to larger b-values. This indicates stronger fragmentation of older slabs favoring smaller events. Between 50 km and 300 km depth, seismicity in subduction zones decays nearly exponentially with depth. However, the majority of subduction zones show between about 60 km and 100 km lower seismic activity than expected by an exponential decay. This observation correlates well with findings from petrological studies that rocks are rarely scraped off from the downgoing plate at these depths indicating low seismic coupling and low stresses at the plate interface in a depth range below the seismogenic zone and above 100 km depth were dehydration reactions become virulent. Interestingly, the percentage of this deficit becomes larger with plate age for event frequency (reduced number of events), but decreases for moment release (events have larger magnitudes). It is observed that the forearc high is located above the plate interface with reduced seismic coupling. The forearc high is thus an indication of upward directed return flow along the seismically decoupled plate interface. In addition, it is found that the topography of the forearc high is larger above shallow dipping slabs. A correlation of the depth dependent seismic behavior with the subduction or trench velocity is not observed for the investigated subduction zones. Plate age seems to be the dominating factor for properties of intermediate deep and deep seismicity.

Impact of Coupled Radiation and Ablation on the Aerothermodynamics of Meteor Entries

NASA Technical Reports Server (NTRS)

Johnston, Christopher O.; Stern, Eric C.

2017-01-01

A high-fidelity approach for simulating the aerothermodynamic environments of meteor entries is developed. Two primary components of this model are coupled radiation and coupled ablation. Coupled radiation accounts for the impact of radiation on the flow field energy equations, while coupled ablation explicitly models the injection of ablation products within the flow field and radiation simulations. For a meteoroid with a velocity of 20 km/s, coupled radiation reduces the stagnation point radiative heating by over 60%. For altitudes below 40 km, the impact of coupled radiation on the flow field structure is shown to be fundamentally different, as a result of the large optical thicknesses, than that seen for reentry vehicles, which do not reach such altitudes at velocities greater than 10 km/s. The impact of coupled ablation (with coupled radiation) is shown to provide at least a 70% reduction in the radiative heating relative to the coupled-radiation-only cases. This large reduction is partially the result of the low ionization energies, relative to air species, of ablation products. The low ionization energies of ablation products, such as Mg and Ca, provide strong photoionization and atomic line absorption in regions of the spectrum that air species do not. MgO and CaO are also shown to provide significant absorption. Turbulence is shown to impact the distribution of ablation products through the shock- layer, which results in up to a 100% increase in the radiative heating downstream of the stagnation point. To create a database of heat transfer coefficients the developed model was applied to a range of cases. This database considered velocities ranging from 14 to 20 km/s, altitudes ranging from 20 to 50 km, and nose radii ranging from 1 to 100 m. The heat transfer coefficients from these simulations are below 0.045 for the range of cases (with turbulence), which is significantly lower than the canonical value of 0.1.

Application analysis of Monte Carlo to estimate the capacity of geothermal resources in Lawu Mount

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supriyadi, E-mail: supriyadi-uno@yahoo.co.nz; Srigutomo, Wahyu; Munandar, Arif

2014-03-24

Monte Carlo analysis has been applied in calculation of geothermal resource capacity based on volumetric method issued by Standar Nasional Indonesia (SNI). A deterministic formula is converted into a stochastic formula to take into account the nature of uncertainties in input parameters. The method yields a range of potential power probability stored beneath Lawu Mount geothermal area. For 10,000 iterations, the capacity of geothermal resources is in the range of 139.30-218.24 MWe with the most likely value is 177.77 MWe. The risk of resource capacity above 196.19 MWe is less than 10%. The power density of the prospect area coveringmore » 17 km{sup 2} is 9.41 MWe/km{sup 2} with probability 80%.« less

Strato-mesospheric carbon monoxide profiles above Kiruna, Sweden (67.8 ° N, 20.4 ° E), since 2008

NASA Astrophysics Data System (ADS)

Ryan, Niall J.; Palm, Mathias; Raffalski, Uwe; Larsson, Richard; Manney, Gloria; Millán, Luis; Notholt, Justus

2017-02-01

This paper presents the retrieval and validation of a self-consistent time series of carbon monoxide (CO) above Kiruna using measurements from the Kiruna Microwave Radiometer (KIMRA). The data set currently spans the years 2008-2015, and measurements are ongoing at Kiruna. The spectra are inverted using an optimal estimation method to retrieve altitude profiles of CO concentrations in the atmosphere within an average altitude range of 48-84 km. Atmospheric temperature data from the Special Sensor Microwave Imager/Sounder aboard the US Air Force meteorological satellite DMSP-F18, are used in the inversion of KIMRA spectra between January 2011 and May 2014. This KIMRA CO data set is compared with CO data from the Microwave Limb Sounder aboard the Aura satellite: there is a maximum bias for KIMRA of ˜ 0.65 ppmv at 68 km (corresponding to 14.7 % of the mean CO value at 68 km) and a maximum relative bias of 22 % (0.44 ppmv) at 60 km. Standard deviations of the differences between profiles are similar in magnitude to the estimated uncertainties in the profiles. Correlations between the instruments are within 0.87 and 0.94. These numbers indicate agreement between the instruments. To expand the CO data set outside of the lifetime of DMSP-F18, another inversion setup was used that incorporates modelled temperatures from the European Centre for Medium-Range Weather Forecasts. The effect on the retrieved CO profiles when using a different temperature data set in the inversion was assessed. A comparison of the two overlapping KIMRA CO data sets shows a positive bias of < 5 % in the extended data set and a correlation > 0.98 between the lower retrievable altitude limit and 82.5 km. The extended data set shows a larger range ( ≤ 6 %) of CO concentrations that is not explained by random error estimates. Measurements are continuing and the extended KIMRA CO time series currently spans 2008-2015, with gaps corresponding to non-operation and summer periods when CO concentrations below ˜ 90 km drop to very low values. The data can be accessed at doi:10.1594/PANGAEA.861730.

New methods of data calibration for high power-aperture lidar.

PubMed

Guan, Sai; Yang, Guotao; Chang, Qihai; Cheng, Xuewu; Yang, Yong; Gong, Shaohua; Wang, Jihong

2013-03-25

For high power-aperture lidar sounding of wide atmospheric dynamic ranges, as in middle-upper atmospheric probing, photomultiplier tubes' (PMT) pulse pile-up effects and signal-induced noise (SIN) complicates the extraction of information from lidar return signal, especially from metal layers' fluorescence signal. Pursuit for sophisticated description of metal layers' characteristics at far range (80~130km) with one PMT of high quantum efficiency (QE) and good SNR, contradicts the requirements for signals of wide linear dynamic range (i.e. from approximate 10(2) to 10(8) counts/s). In this article, Substantial improvements on experimental simulation of Lidar signals affected by PMT are reported to evaluate the PMTs' distortions in our High Power-Aperture Sodium LIDAR system. A new method for pile-up calibration is proposed by taking into account PMT and High Speed Data Acquisition Card as an Integrated Black-Box, as well as a new experimental method for identifying and removing SIN from the raw Lidar signals. Contradiction between the limited linear dynamic range of raw signal (55~80km) and requirements for wider acceptable linearity has been effectively solved, without complicating the current lidar system. Validity of these methods was demonstrated by applying calibrated data to retrieve atmospheric parameters (i.e. atmospheric density, temperature and sodium absolutely number density), in comparison with measurements of TIMED satellite and atmosphere model. Good agreements are obtained between results derived from calibrated signal and reference measurements where differences of atmosphere density, temperature are less than 5% in the stratosphere and less than 10K from 30km to mesosphere, respectively. Additionally, approximate 30% changes are shown in sodium concentration at its peak value. By means of the proposed methods to revert the true signal independent of detectors, authors approach a new balance between maintaining the linearity of adequate signal (20-110km) and guaranteeing good SNR (i.e. 10(4):1 around 90km) without debasing QE, in one single detecting channel. For the first time, PMT in photon-counting mode is independently applied to subtract reliable information of atmospheric parameters with wide acceptable linearity over an altitude range from stratosphere up to lower thermosphere (20-110km).

Boundary-Layer Edge Conditions and Transition Reynolds Number Data for a Flight Test at Mach 20 (Reentry F)

NASA Technical Reports Server (NTRS)

Johnson, Charles B.; Stainback, P. Calvin; Wicker, Kathleen C.; Boney, Lillian R.

1972-01-01

A flight experiment, designated Reentry F, was conducted to measure heat-transfer rates for laminar, transitional, and turbulent boundary layers on a 5 deg half-angle cone 3.962 m (13 ft) long with a preflight nose radius of 2.54 mm (0.10 in.). Data were obtained over an altitude range from 36.58 to 18.29 km (120 000 to 60 000 ft) at a flight velocity of about 6.096 km/sec (20 000 ft/sec). The nominal values of the free-stream total enthalpy, sharp-cone Mach number, and the wall-to-total enthalpy ratio were 18 MJ/kg (8000 Btu/lb), 15, and 0.03, respectively. Calculated boundary-layer edge conditions that account for effects of the entropy layer and corresponding local transition Reynolds numbers are reported in the present paper. Fully developed turbulent flow occurred with essentially constant boundary-layer edge conditions near the sharp-cone values. Transition data were obtained with local edge Mach numbers ranging from about 5.55 to 15. Transition Reynolds numbers, based on local condition, were as high as 6.6 x 10(exp 7) with an edge Mach number of about 14.4 at an altitude of 24.38 km (80 000 ft). The transition could be correlated with previous flight data taken over a Mach number range from 3 to 12 in terms of parameters including the effects of local unit Reynolds number, boundary-layer wall-to-edge enthalpy ratio, and local Mach number.

An assessment of elephant home ranges and movement patterns during construction of Hulu Terengganu hydroelectric dam, Terengganu using GPS satellite collars

NASA Astrophysics Data System (ADS)

Magintan, D.; Shukorb, M. N.; Lihan, Tukimat; Campos, Ahimza-arceiz; Saaban, Salman; Husin, Shahril Mohd; Ahmad, Mohd Noh

2016-11-01

Home ranges and movement patterns of elephants during construction of hydroelectric dams were carried out in Hulu Terengganu, Terengganu, Peninsular Malaysia. Two elephants from two herds were captured, collared and released in the catchment area four to five months before inundation started in early October 2014. The two elephants were identified as Puah (female) and Sireh (male). The home range size of each individual during the construction of dams was estimated at 96.53 km2 for Puah and 367.99 km2 for Sireh. The monthly estimates of ranging for Puah was between 5.1 km2 and 38.4 km2 with average monthly ranging of 19.2 ± 4.7, while for Sireh, the monthly ranging estimates were between 20.6 km2 and 184.7 km2 with average monthly ranging at 79.9 ± 34.7. The movement mean rate (based on distance per day) for Puah and Sireh per day were 1.3 ± 0.1 km and 1.9 ± 0.1 km, respectively. Puah movement estimates for the first day after putting the collar was 0.88 km, whereas, the distance movement for Sireh on the first day after the collar was 0.02 km. The total distance travelled for Puah before inundation was 226.18 km, while Sireh covered 267.38 km.

Spatial Patterns in Water Quality Changes during Dredging in Tropical Environments

PubMed Central

Fisher, Rebecca; Stark, Clair; Ridd, Peter; Jones, Ross

2015-01-01

Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. It is also important for public perception of risks associated with dredging. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics. Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80th percentile of the baseline value for turbidity-based metrics or the 20th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. This upper (~20 km) limit was unusual and caused by a local oceanographic feature of consistent unidirectional flow during the project. Water quality loggers were located along the principal axis of this flow (from 200 m to 30 km) and provided the opportunity to develop a matrix of exposure based on running means calculated across multiple time periods (from hours to one month) and distance from the dredging, and summarized across a broad range of percentile values. This information can be used to more formally develop water quality thresholds for benthic organisms, such as corals, filter-feeders (e.g. sponges) and seagrasses in future laboratory- and field-based studies using environmentally realistic and relevant exposure scenarios, that may be used to further refine distance based analyses of impact, potentially further reducing the size of the dredging footprint. PMID:26630575

Lightning climatology in the Congo Basin: detailed analysis

NASA Astrophysics Data System (ADS)

Soula, Serge; Kigotsi, Jean; Georgis, Jean-François; Barthe, Christelle

2016-04-01

The lightning climatology of the Congo Basin including several countries of Central Africa is analyzed in detail for the first time. It is based on World Wide Lightning Location Network (WWLLN) data for the period from 2005 to 2013. A comparison of these data with the Lightning Imaging Sensor (LIS) data for the same period shows the WWLLN detection efficiency (DE) in the region increases from about 1.70 % in the beginning of the period to 5.90 % in 2013, relative to LIS data, but not uniformly over the whole 2750 km × 2750 km area. Both the annual flash density and the number of stormy days show sharp maximum values localized in eastern of Democratic Republic of Congo (DRC) and west of Kivu Lake, regardless of the reference year and the period of the year. These maxima reach 12.86 fl km-2 and 189 days, respectively, in 2013, and correspond with a very active region located at the rear of the Virunga mountain range characterised with summits that can reach 3000 m. The presence of this range plays a role in the thunderstorm development along the year. The estimation of this local maximum of the lightning density by taking into account the DE, leads to a value consistent with that of the global climatology by Christian et al. (2003) and other authors. Thus, a mean maximum value of about 157 fl km-2 y-1 is found for the annual lightning density. The zonal distribution of the lightning flashes exhibits a maximum between 1°S and 2°S and about 56 % of the flashes located below the equator in the 10°S - 10°N interval. The diurnal evolution of the flash rate has a maximum between 1400 and 1700 UTC, according to the reference year, in agreement with previous works in other regions of the world.

Spatial Patterns in Water Quality Changes during Dredging in Tropical Environments.

PubMed

Fisher, Rebecca; Stark, Clair; Ridd, Peter; Jones, Ross

2015-01-01

Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. It is also important for public perception of risks associated with dredging. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics. Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80th percentile of the baseline value for turbidity-based metrics or the 20th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. This upper (~20 km) limit was unusual and caused by a local oceanographic feature of consistent unidirectional flow during the project. Water quality loggers were located along the principal axis of this flow (from 200 m to 30 km) and provided the opportunity to develop a matrix of exposure based on running means calculated across multiple time periods (from hours to one month) and distance from the dredging, and summarized across a broad range of percentile values. This information can be used to more formally develop water quality thresholds for benthic organisms, such as corals, filter-feeders (e.g. sponges) and seagrasses in future laboratory- and field-based studies using environmentally realistic and relevant exposure scenarios, that may be used to further refine distance based analyses of impact, potentially further reducing the size of the dredging footprint.

A record of more than 500,000 years of large-volume travertine formation in the southwestern United States and links between paleohydrology, paleoclimate, and landscape evolution

NASA Astrophysics Data System (ADS)

Priewisch, A.; Crossey, L. J.; Embid, E.; Karlstrom, K. E.; Polyak, V.; Asmerom, Y.; Ricketts, J. W.

2011-12-01

CO2 springs and associated travertine deposits offer a unique tool to better understand Cenozoic paleohydrology and paleoclimate in the context of geomorphic and neotectonic evolution of the southwestern United States. Travertine accumulations represent places of persistent and significant mantle CO2 degassing in high discharge spring systems that are found along faults and above magmatic systems. They complement speleothem records from the same regions in that they can provide better links to the surface geomorphic and neotectonic systems. New Mexico and Arizona host several exceptionally well-preserved, large-volume travertine deposits that extend from 10 - 60 km2, with thicknesses ranging from 15 to more than 60 m. Precise U-series and stable isotope analyses are underway for large travertine platforms at Mesa del Oro, NM (~27 km2), Riley North and South Mesa, NM (~60 km2), Mesa Aparejo/Belen Quarries, NM (~13 km2), and Springerville, AZ (~30 km2). New ages for the travertine deposits at Mesa del Oro are 56 ka, 253 ka, 361 ka, and more than 500 ka. The travertine deposits at Riley North and South Mesa are older than 500 ka and 207/287 ka, respectively. At Mesa Aparejo, travertine ages are 312 ka and more than 500 ka. U/Th dates from Springerville, AZ show that major travertine accumulations occurred over several time intervals: 36-100 ka, 200-280 ka and 300-350 ka. Stable isotope analyses overlap substantially, exhibiting high δ13C values, +2.0% to +8.3%, and δ18O values that range from -13.5% to -4%. High δ13C values are interpreted to be caused by rapid CO2 degassing while the range of δ18O values is interpreted to represent changing water temperatures and mixing trends of groundwater. U-series data show that travertine deposition at all of these localities overlapped temporally and that major aggradation and high volume deposition was not steady, but occurred episodically at 36-100, 200-280, and 300-380 ka. Times of high accumulation rates are interpreted as times of high groundwater flow and hence as a proxy for regional paleohydrology/paleoclimate controls while the locations of the travertine occurrences (along faults of the Jemez lineament and Rio Grande rift) reflect more local CO2-discharge (tectonic) controls. These travertine occurrences are important indicators of the extent of past natural CO2 leakage that can inform carbon sequestration models both in areas of modern CO2 gas fields (Springerville) and at sites of potential paleo-gas fields. The travertine platforms now occupy positions high in the landscape (inverted topography) and also provide data on the scales and timing of regional landscape denudation.

Mars Global Reference Atmospheric Model (Mars-GRAM) and Database for Mission Design

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Johnson, D. L.

2003-01-01

Mars Global Reference Atmospheric Model (Mars-GRAM 2001) is an engineering-level Mars atmosphere model widely used for many Mars mission applications. From 0-80 km, it is based on NASA Ames Mars General Circulation Model, while above 80 km it is based on Mars Thermospheric General Circulation Model. Mars-GRAM 2001 and MGCM use surface topography from Mars Global Surveyor Mars Orbiting Laser Altimeter. Validation studies are described comparing Mars-GRAM with Mars Global Surveyor Radio Science and Thermal Emission Spectrometer data. RS data from 2480 profiles were used, covering latitudes 75 deg S to 72 deg N, surface to approximately 40 km, for seasons ranging from areocentric longitude of Sun (Ls) = 70-160 deg and 265-310 deg. RS data spanned a range of local times, mostly 0-9 hours and 18-24 hours. For interests in aerocapture and precision landing, comparisons concentrated on atmospheric density. At a fixed height of 20 km, RS density varied by about a factor of 2.5 over ranges of latitudes and Ls values observed. Evaluated at matching positions and times, these figures show average RSMars-GRAM density ratios were generally 1+/-)0.05, except at heights above approximately 25 km and latitudes above approximately 50 deg N. Average standard deviation of RSMars-GRAM density ratio was 6%. TES data were used covering surface to approximately 40 km, over more than a full Mars year (February, 1999 - June, 2001, just before start of a Mars global dust storm). Depending on season, TES data covered latitudes 85 deg S to 85 deg N. Most TES data were concentrated near local times 2 hours and 14 hours. Observed average TES/Mars-GRAM density ratios were generally 1+/-0.05, except at high altitudes (15-30 km, depending on season) and high latitudes (greater than 45 deg N), or at most altitudes in the southern hemisphere at Ls approximately 90 and 180 deg. Compared to TES averages for a given latitude and season, TES data had average density standard deviation about the mean of approximately 2.5% for all data, or approximately 1-4%, depending on time of day and dust optical depth. Average standard deviation of TES/Mars-GRAM density ratio was 8.9% for local time 2 hours and 7.1% for local time 14 hours. Thus standard deviation of observed TES/Mars-GRAM density ratio, evaluated at matching positions and times, is about three times the standard deviation of TES data about the TES mean value at a given position and season.

Chemical composition and distribution of lithium-rich brines in salar de Uyuni and nearby salars in southwestern Bolivia

USGS Publications Warehouse

Ericksen, G.E.; Vine, J.D.; Raul, Ballon A.

1978-01-01

Preliminary investigations at Salar de Uyuni and the nearby salars (salt pans) of Coipasa and Empexa in the southern part of the Bolivian Altiplano show the presence of widespread lithium-rich brines. Widely scattered brine samples from Salar de Uyuni, which has an area of about 9000 km2 and is the largest salt pan on earth, show lithium values ranging from 80 to 1500 ppm. High values of 300-700 ppm are most prevalent in an area of about 2500 km2 in the east-central and southeastern part of the salar. A few brine samples in small areas in Coipasa and Empexa Salars have values ranging from 170 to 580 ppm Li. All the brines are essentially saturated with halite and are moderately high in sulfate (5000-15,000 ppm SO4) but low in carbonate (<500 ppm HCO3). Potassium and magnesium values are relatively high, chiefly in the range of 2000-20,000 ppm, and the K Mg ratio is about 1:1. The Li K and Li Mg ratios are relatively constant at about 1:20. The crystalline saline material and brines in these salars are residual from a former large lake, Lago Minchin, that occupied much of the southern Bolivian Altiplano during late Pleistocene time, augmented by saline material carried to the salars by streams since final drying of this lake. Thermal springs associated with rhyolitic volcanic rocks of Quaternary age may have been a major source of the lithium. ?? 1978.

Multiresolution analysis of the spatiotemporal variability in global radiation observed by a dense network of 99 pyranometers

NASA Astrophysics Data System (ADS)

Lakshmi Madhavan, Bomidi; Deneke, Hartwig; Witthuhn, Jonas; Macke, Andreas

2017-03-01

The time series of global radiation observed by a dense network of 99 autonomous pyranometers during the HOPE campaign around Jülich, Germany, are investigated with a multiresolution analysis based on the maximum overlap discrete wavelet transform and the Haar wavelet. For different sky conditions, typical wavelet power spectra are calculated to quantify the timescale dependence of variability in global transmittance. Distinctly higher variability is observed at all frequencies in the power spectra of global transmittance under broken-cloud conditions compared to clear, cirrus, or overcast skies. The spatial autocorrelation function including its frequency dependence is determined to quantify the degree of similarity of two time series measurements as a function of their spatial separation. Distances ranging from 100 m to 10 km are considered, and a rapid decrease of the autocorrelation function is found with increasing frequency and distance. For frequencies above 1/3 min-1 and points separated by more than 1 km, variations in transmittance become completely uncorrelated. A method is introduced to estimate the deviation between a point measurement and a spatially averaged value for a surrounding domain, which takes into account domain size and averaging period, and is used to explore the representativeness of a single pyranometer observation for its surrounding region. Two distinct mechanisms are identified, which limit the representativeness; on the one hand, spatial averaging reduces variability and thus modifies the shape of the power spectrum. On the other hand, the correlation of variations of the spatially averaged field and a point measurement decreases rapidly with increasing temporal frequency. For a grid box of 10 km × 10 km and averaging periods of 1.5-3 h, the deviation of global transmittance between a point measurement and an area-averaged value depends on the prevailing sky conditions: 2.8 (clear), 1.8 (cirrus), 1.5 (overcast), and 4.2 % (broken clouds). The solar global radiation observed at a single station is found to deviate from the spatial average by as much as 14-23 (clear), 8-26 (cirrus), 4-23 (overcast), and 31-79 W m-2 (broken clouds) from domain averages ranging from 1 km × 1 km to 10 km × 10 km in area.

Variability and trend in ozone over the southern tropics and subtropics

NASA Astrophysics Data System (ADS)

Toihir, Abdoulwahab Mohamed; Portafaix, Thierry; Sivakumar, Venkataraman; Bencherif, Hassan; Pazmiño, Andréa; Bègue, Nelson

2018-03-01

Long-term variability in ozone trends was assessed over eight Southern Hemisphere tropical and subtropical sites (Natal, Nairobi, Ascension Island, Java, Samoa, Fiji, Reunion and Irene), using total column ozone data (TCO) and vertical ozone profiles (altitude range 15-30 km) recorded during the period January 1998-December 2012. The TCO datasets were constructed by combination of satellite data (OMI and TOMS) and ground-based observations recorded using Dobson and SAOZ spectrometers. Vertical ozone profiles were obtained from balloon-sonde experiments which were operated within the framework of the SHADOZ network. The analysis in this study was performed using the Trend-Run model. This is a multivariate regression model based on the principle of separating the variations of ozone time series into a sum of several forcings (annual and semi-annual oscillations, QBO (Quasi-Biennial Oscillation), ENSO, 11-year solar cycle) that account for most of its variability. The trend value is calculated based on the slope of a normalized linear function which is one of the forcing parameters included in the model. Three regions were defined as follows: equatorial (0-10° S), tropical (10-20° S) and subtropical (20-30° S). Results obtained indicate that ozone variability is dominated by seasonal and quasi-biennial oscillations. The ENSO contribution is observed to be significant in the tropical lower stratosphere and especially over the Pacific sites (Samoa and Java). The annual cycle of ozone is observed to be the most dominant mode of variability for all the sites and presents a meridional signature with a maximum over the subtropics, while semi-annual and quasi-biannual ozone modes are more apparent over the equatorial region, and their magnitude decreases southward. The ozone variation mode linked to the QBO signal is observed between altitudes of 20 and 28 km. Over the equatorial zone there is a strong signal at ˜ 26 km, where 58 % ±2 % of total ozone variability is explained by the effect of QBO. Annual ozone oscillations are more apparent at two different altitude ranges (below 24 km and in the 27-30 km altitude band) over the tropical and subtropical regions, while the semi-annual oscillations are more significant over the 27-30 km altitude range in the tropical and equatorial regions. The estimated trend in TCO is positive and not significant and corresponds to a variation of ˜ 1.34±0.50 % decade-1 (averaged over the three regions). The trend estimated within the equatorial region (0-15° S) is less than 1 % per decade, while it is assessed at more than 1.5 % decade-1 for all the sites located southward of 17° S. With regard to the vertical distribution of trend estimates, a positive trend in ozone concentration is obtained in the 22-30 km altitude range, while a delay in ozone improvement is apparent in the UT-LS (upper troposphere-lower stratosphere) below 22 km. This is especially noticeable at approximately 19 km, where a negative value is observed in the tropical regions.

A distance scale from the infrared magnitude/H I velocity-width relation. III - The expansion rate outside the local supercluster

NASA Astrophysics Data System (ADS)

Aaronson, M.; Mould, J.; Huchra, J.; Sullivan, W. T., III; Schommer, R. A.; Bothun, G. D.

1980-07-01

Infrared magnitudes and 21 cm H I velocity widths are presented for galaxies in the Pegasus I cluster (V ≍ 4000 km s-1), the Cancer cluster (V ≍ 4500 km s-1), cluster Zwicky 1400.4 ± 0949 (Z74-23) (V ≍ 6000 km s-1), and the Perseus supercluster (V ≍ 5500 km s-1). The data are used to determine redshift-independent distances from which values of the Hubble ratio can be derived. With a zero point based solely on the Sandage-Tammann distances to M3 1 and M33, the following results are obtained (zero-point error excluded): Pegasus I.--r = 42 ± 4 Mpc, V/r = 91 ± 8 km s-1 Mpc-1; Cancer.--r = = 49 ± 6 Mpc, V/r = 89 ± 11 km s-1 Mpc-1; Z74-23.--r = 6l ± 4 Mpc, V/r = 96 ± 7 km s-1 Mpc-1; Perseus supercluster.--r = 53 ± 2 Mpc, V/r = 104 ± 6 km s-1 Mpc-1; The closely similar value of the Hubble ratio found in the four independent samples suggests that the zero-point calibration in the IR/H I technique does not depend on environment. The difference between the mean of these Hubble ratios, V/r = 95 ± 4 km s-1 Mpc -1, and that measured for Virgo in Paper II, V/r = 65 ±4 km s-1 Mpc-1, is significant at a formal level of 5 σ. The simplest explanation of the discrepancy is to postulate a Local Group component of motion in the direction of Virgo. The resulting velocity perturbation is ΔV = 480 ± 75 km s-1. This value agrees well with recent observations of a dipole term in the 3 K microwave background, the only other anisotropy test for which a detection significance of 5 σ or more is claimed. We are thus led to a preliminary estimate for the value of the Hubble constant of H0 = 95 ± 4 km s-1 Mpc-1. If a zero point based on de Vaucouleurs's distances to M31 and M33 is adopted instead, all distances decrease by , and the Hubble constant increases by a similar amount. A variety of possible systematic errors which might affect the present conclusions are investigated, but we can find none that are relevant. In particular, because the galaxy samples are chosen from a cluster population which is generally all at the same distance, Malmquist bias does not occur. In fact, two of the clusters (Pegasus I and Z74-23) are sampled in both magnitude and velocity width to a level as deep as Virgo itself. Other observational data related to the value of H0 are examined, as are a number of previously used anisotropy tests, including color-luminosity relations, brightest cluster member(s), central surface brightnesses, and supernovae. We find that some of these tests support the present results, while contrary evidence is currently weak. A model in which Virgo gravitationally retards the Hubble flow of galaxies within the Local Supercluster provides a natural interpretation of our findings. A range of 1.5-3 in local density contrast then leads to a value of the density parameter Ω ≍ 0.7-0.2. The deceleration parameter q0 is then 0.35-0.1 for a simple Friedmann-type expanding universe.

Impact of topography, climate and moisture sources on isotopic composition (δ18O &δD) of rivers in the Pyrenees: Implications for topographic reconstructions in small orogens

NASA Astrophysics Data System (ADS)

Huyghe, Damien; Mouthereau, Frédéric; Sébilo, Mathieu; Vacherat, Arnaud; Ségalen, Loïc; Richard, Patricia; Biron, Philippe; Bariac, Thierry

2018-02-01

Understanding how orogenic topography controls the spatial distribution and isotopic composition of precipitation is critical for paleoaltitudinal reconstructions. Here, we determine the isotopic composition (δ18O and δD) of 82 small rivers and springs from small catchments in the Pyrenees. Calculation of the deuterium excess (d-excess) parameter allows the distinction of four distinct isotopic provinces with d-excess values of between 15 and 22‰ in the northwest, between 7 and 14‰ in the central northern Pyrenees and between 3 and 11‰ in the northeast. The southern Pyrenees have a homogenous d-excess signature ranging from 7 to 14‰. Our results show significant local moisture recycling and/or rain amount effect in the northwestern Pyrenees, and control by evaporation processes during rainfall events in the southern Pyrenees and for low elevated samples of the northeast of the range. Based on the distribution of d-excess values, we estimate contrasting isotope lapse rates of -2.9/-21.4‰/km (δ18O/δD) in the northwest, -2.7/-21.4‰/km (δ18O/δD) in the north central and -3.7/-31.7‰/km (δ18O/δD) in the northeastern Pyrenees. The southern Pyrenees show distinctly higher lapse rates of -9.5/-77.5‰/km (δ18O/δD), indicating that in this area the altitudinal effect in not the only parameter driving isotopic composition of rivers. Despite their relatively low topographic gradient, the Pyrenees exert a direct control on the isotopic composition of river waters, especially on their northern side. The variations in isotopic composition-elevation relationships documented along the strike of the range are interpreted to reflect an increasing continentality effect driven by wind trajectories parallel to the range, and mixing with Mediterranean air masses. Despite these effects, the measurable orographic effect on precipitation in the Pyrenees proves that the isotopic composition approach for reconstructing past topography is applicable to low-elevation orogens.

The NASA/MSFC global reference atmospheric model: MOD 3 (with spherical harmonic wind model)

NASA Technical Reports Server (NTRS)

Justus, C. G.; Fletcher, G. R.; Gramling, F. E.; Pace, W. B.

1980-01-01

Improvements to the global reference atmospheric model are described. The basic model includes monthly mean values of pressure, density, temperature, and geostrophic winds, as well as quasi-biennial and small and large scale random perturbations. A spherical harmonic wind model for the 25 to 90 km height range is included. Below 25 km and above 90 km, the GRAM program uses the geostrophic wind equations and pressure data to compute the mean wind. In the altitudes where the geostrophic wind relations are used, an interpolation scheme is employed for estimating winds at low latitudes where the geostrophic wind relations being to mesh down. Several sample wind profiles are given, as computed by the spherical harmonic model. User and programmer manuals are presented.

The density of cometary protons upstream of Comet Halley's bow shock

NASA Astrophysics Data System (ADS)

Neugebauer, M.; Goldstein, B. E.; Balsiger, H.; Neubauer, F. M.; Schwenn, R.; Shelley, E. G.

1989-02-01

Cometary protons picked up by the solar wind were detected by the high energy range spectrometer of the Giotto ion mass spectrometer starting at a cometocentric distance of about 12 million km. On the average, the density of cometary protons varied approximately as the inverse square of the cometocentric distance, reaching a value of 0.11/cu cm just outside the bow shock. The data can be successfully fit to models that include substantial amounts of both slow (1 km/s) and fast (8 km/s or greater) H atoms beyond the bow shock. Large local variations in the density of picked-up protons can be explained on the basis of variations in the direction of the interplanetary magnetic field in upstream regions where pitch angle scattering was weak.

Deriving and Constraining 3D CME Kinematic Parameters from Multi-Viewpoint Coronagraph Images

NASA Astrophysics Data System (ADS)

Thompson, B. J.; Mei, H. F.; Barnes, D.; Colaninno, R. C.; Kwon, R.; Mays, M. L.; Mierla, M.; Moestl, C.; Richardson, I. G.; Verbeke, C.

2017-12-01

Determining the 3D properties of a coronal mass ejection using multi-viewpoint coronagraph observations can be a tremendously complicated process. There are many factors that inhibit the ability to unambiguously identify the speed, direction and shape of a CME. These factors include the need to separate the "true" CME mass from shock-associated brightenings, distinguish between non-radial or deflected trajectories, and identify asymmetric CME structures. Additionally, different measurement methods can produce different results, sometimes with great variations. Part of the reason for the wide range of values that can be reported for a single CME is due to the difficulty in determining the CME's longitude since uncertainty in the angle of the CME relative to the observing image planes results in errors in the speed and topology of the CME. Often the errors quoted in an individual study are remarkably small when compared to the range of values that are reported by different authors for the same CME. For example, two authors may report speeds of 700 +- 50 km/sec and 500+-50 km/sec for the same CME. Clearly a better understanding of the accuracy of CME measurements, and an improved assessment of the limitations of the different methods, would be of benefit. We report on a survey of CME measurements, wherein we compare the values reported by different authors and catalogs. The survey will allow us to establish typical errors for the parameters that are commonly used as inputs for CME propagation models such as ENLIL and EUHFORIA. One way modelers handle inaccuracies in CME parameters is to use an ensemble of CMEs, sampled across ranges of latitude, longitude, speed and width. The CMEs simulated in order to determine the probability of a "direct hit" and, for the cases with a "hit," derive a range of possible arrival times. Our study will provide improved guidelines for generating CME ensembles that more accurately sample across the range of plausible values.

Receiver Function Study of the Crustal Structure Beneath the Northern Andes (colombia)

NASA Astrophysics Data System (ADS)

Poveda, E.; Monsalve, G.; Vargas-Jimenez, C. A.

2013-05-01

We have investigated crustal thickness beneath the Northern Andes with the teleseismic receiver function technique. We used teleseismic data recorded by an array of 18 broadband stations deployed by the Colombian Seismological Network, and operated by the Colombian Geological Survey. We used the primary P-to-S conversion and crustal reverberations to estimate crustal thickness and average Vp/Vs ratio; using Wadati diagrams, we also calculated the mean crustal Vp/Vs ratio around stations to further constrain the crustal thickness estimation. In northern Colombia, near the Caribbean coast, the estimated crustal thickness ranges from 25 to 30 km; in the Middle Magdalena Valley, crustal thickness is around 40 km; beneath the northern Central Cordillera, the Moho depth is nearly 40 km; at the Ecuador-Colombia border, beneath the western flank of the Andes, the estimated thickness is about 46 km. Receiver functions at a station at the craton in South East Colombia, near the foothills of the Eastern Cordillera, clearly indicate the presence of the Moho discontinuity at a depth near 36 km. The greatest values of crustal thickness occur beneath a plateau (Altiplano Cundiboyacense) on the Eastern Cordillera, near the location of Bogota, with values around 58 km. Receiver functions in the volcanic areas of the south-western Colombian Andes do not show a systematic signal from the Moho, indicating abrupt changes in Moho geometry. Signals at stations on the Eastern Cordillera near Bogota reveal a highly complex crustal structure, with a combination of sedimentary layers up to 9 km thick, dipping interfaces, low velocity layers, anisotropy and/or lateral heterogeneity that still remain to be evaluated. This complexity obeys to the location of these stations at a region of a highly deformed fold and thrust belt.

The Eighty Six Hα Spectra from the Orion Nebula (M42, Sh2-281) with DEFPOS

NASA Astrophysics Data System (ADS)

Sahan, M.; Yegingil, I.

2017-12-01

In this study, eighty six Hα (6563 Å) emission line spectra from the central region (˜ 40^' }× 40^' }) of the Orion Nebula (NGC1976, M42, Sh2-281) have been obtained using DEFPOS spectrometer with a circular field of view of 4^' } at TUBITAK National Observatory (TUG, Antalya, Turkey). Measurements provide information about the intensities, line widths, and radial velocities of the gas surrounding the Sh2-281 HII-region. The intensities, the radial velocities and the line widths of the Hα emission line were found in the range of from 319.85 R to 6009.08 R (mean 2006 ± 400 R), from -14.91 km s^{-1} to + 5.40 km s^{-1} (mean -4.51± 3.80 km s^{-1}), and from 27.83 km s^{-1} to 49.60 km s^{-1} (mean 41.09± 7.74 km s^{-1}), respectively. Moreover, the mean emission measure (EM) calculated from {I_{H{α }}} values was obtained as 4513.02 cm^{-6} pc. The mean LSR velocity of the nebula was found to be -4.51 km s^{-1} and was compared with some previous works. The intensity values of DEFPOS data were also compared with the data obtained from VTSS, SkyView, and SHASSA maps using APER and SKY codes. We found that our results were approximately the similar variation with VTSS (mean 2002.04 R), SkyView (mean 2680.05 R), and SHASSA (mean 2400.06 R) maps. We believe that DEFPOS spectrometer with a 4' diameter field of view is able to provide a powerful tool for the study of diffuse ionized gas and this new results may have significant contribution to the literature.

Cloud Top Scanning radiometer (CTS): User's guide

NASA Technical Reports Server (NTRS)

Brown, K. S.

1981-01-01

The CTS maps the Earth's surface with a resolution of 0.1 km from an altitude of 18km with 60km side-to-side coverage of the field. It has three spectral channels. The 0.625 micrometer centered visual channel detects reflectance to within 1 percent. The 6.75 micrometer centered water vapor channel detects changes in temperature of less than one degree Kelvin at 175 K. The 11.5 micrometer centered infrared window channel detects changes of less one half degree Kelvin at 175 K. The data can be converted graphically into three display images of the scene. Values for scene temperature and albedo are calculated from calibration equations. The equations were derived from in-situ and laboratory measurements. Intercomparisons of the flight data temperatures with ground based and other remote sensor results established the certainty of the derived temperature values to within 3 K over a wide temperature range (180 to 320 K). The system performance, calibration, and operation is successful and the engineering information describing this system should prove useful to scientists and potential users of the data.

Pattern recognition of the targets with help of polarization properties of the signal

NASA Astrophysics Data System (ADS)

Ponomaryov, Volodymyr I.; de Rivera, Luis N.; Castellanos, Aldo B.; Popov, Anatoly V.

1999-10-01

We proposed to use the possibility of recognition of the targets on background of the scattering from the surface, weather objects with the help of polarimetric 3-cm radar. It has been investigated such polarization characteristics: the amplitudes of the polarization matrix elements; an anisotropy coefficient; depolarization coefficient; asymmetry coefficient; the energy section was less than 1 dB at ranges up to 15 km and less than 1.5 dB at ranges up to 100 km. During the experiments urban objects and 6 various ships of small displacement having the closest values of the backscattering cross-section were used. The analysis has shown: the factor of the polarization selection for anisotropy objects and weather objects had the values about 0.02-0.08 Isotropy had the values of polarimetric correlation factor for hydrometers about 0.7-0.8, for earth surface about 0.8-0.9, for sea surface - from 0.33 to 0.7. The results of the work of recognition algorithm of a class 'concrete objects', and 'metal objects' are submitted as example in the paper. The result of experiments have shown that the probability of correct recognition of the identified objects was in the limits from 0.93 to 0.97.

Spatial variations in effective elastic thickness in the Western Pacific Ocean and their implications for Mesozoic volcanism

NASA Astrophysics Data System (ADS)

Kalnins, L. M.; Watts, A. B.

2009-08-01

We have used free-air gravity anomaly and bathymetric data, together with a moving window admittance technique, to determine the spatial variation in oceanic elastic thickness, Te, in the Western Pacific ocean. Synthetic tests using representative seamounts show that Te can be recovered to an accuracy of ± 5 km for plates up to 30 km thick, with increased accuracy of ± 3 km for Te ≤ 20 km. The Western Pacific has a T e range of 0-50 km, with a mean of 9.4 km and a standard deviation of 6.8 km. The T e structure of the region is dominated by relatively high Te over the Hawaiian-Emperor Seamount Chain, intermediate values over the Marshall Islands, Gilbert Ridge, and Marcus-Wake Guyots, and low values over the Line Islands, Mid-Pacific Mountains, Caroline Islands, Shatsky Rise, Hess Rise, and Musician Seamounts. Plots of Te at sites with radiometric ages suggest that Te is to first order controlled by the age of the lithosphere at the time of loading. In areas that backtrack into the South Pacific Isotopic and Thermal Anomaly (SOPITA), Te may be as low as the depth to the 180 ± 120 °C isotherm at least locally. In the northern part of the study area including the Hawaiian-Emperor Seamount Chain, Te correlates with the depth to 310 ± 120 °C. These best-fitting isotherms imply peak rates of volcanism during 100-120 Ma (Early Cretaceous) and 140-150 Ma (Late Jurassic). The corresponding addition of 8 × 10 6 km 3 and 4 × 10 6 km 3 of volcanic material to the surface of the oceanic crust would result in long-term sea-level rises of 20 m and 10 m respectively. The Late Jurassic volcanic event, like the later Early Cretaceous event, appears to have influenced the tectonic evolution of the Pacific plate convergent boundaries, resulting in increased volcanism and orogenesis.

The Compatibility of Friedmann Cosmological Models with Observed Properties of Gamma-Ray Bursts and a Large Hubble Constant

NASA Technical Reports Server (NTRS)

Horack, John M.; Koshut, Thomas M.; Mallozzi, Robert S.; Emslie, A. Gordon; Meegan, Charles A.

1996-01-01

The distance scale to cosmic gamma-ray bursts (GRB's) is still uncertain by many orders of magnitude; however, one viable scenario places GRB's at cosmological distances, thereby permitting them to be used as tracers of the cosmological expansion over a significant range of redshifts zeta. Also, several recent measurements of the Hubble constant H(sub 0) appearing in the referred literature report values of 70-80 km/s /Mpc. Although there is significant debate regarding these measurements, we proceed here under the assumption that they are evidence of a large value for H(sub 0). This is done in order to investigate the additional constraints on cosmological models that can be obtained under this hypothesis when combined with the age of the universe and the brightness distribution of cosmological gamma-ray bursts. We show that the range of cosmological models that can be consistent with the GRB brightness distribution, a Hubble constant of 70-80 km/s/Mpc, and a minimum age of the universe of 13-15 Gyr is constrained significantly, largely independent of a wide range of assumptions regarding the evolutionary nature of the burst population. Low-density, Lambda greater than 0 cosmological models with deceleration parameter in the range -1 less than q(sub 0) less than 0 and density parameter sigma(sub 0) in the range approximately equals 0.10-0.25(Omega(sub 0) approximately equals 0.2-0.5) are strongly favored.

Comparative kinetics and reciprocal inhibition of nitrate and nitrite uptake in roots of uninduced and induced barley (Hordeum vulgare L.) seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Travis, R. L.; Huffaker, R. C.

1992-01-01

Nitrate and NO2- transport by roots of 8-day-old uninduced and induced intact barley (Hordeum vulgare L. var CM 72) seedlings were compared to kinetic patterns, reciprocal inhibition of the transport systems, and the effect of the inhibitor, p-hydroxymercuribenzoate. Net uptake of NO3- and NO2- was measured by following the depletion of the ions from the uptake solutions. The roots of uninduced seedlings possessed a low concentration, saturable, low Km, possibly a constitutive uptake system, and a linear system for both NO3- and NO2-. The low Km system followed Michaelis-Menten kinetics and approached saturation between 40 and 100 micromolar, whereas the linear system was detected between 100 and 500 micromolar. In roots of induced seedlings, rates for both NO3- and NO2- uptake followed Michaelis-Menten kinetics and approached saturation at about 200 micromolar. In induced roots, two kinetically identifiable transport systems were resolved for each anion. At the lower substrate concentrations, less than 10 micromolar, the apparent low Kms of NO3- and NO2- uptake were 7 and 9 micromolar, respectively, and were similar to those of the low Km system in uninduced roots. At substrate concentrations between 10 and 200 micromolar, the apparent high Km values of NO3- uptake ranged from 34 to 36 micromolar and of NO2- uptake ranged from 41 to 49 micromolar. A linear system was also found in induced seedlings at concentrations above 500 micromolar. Double reciprocal plots indicated that NO3- and NO2- inhibited the uptake of each other competitively in both uninduced and induced seedlings; however, Ki values showed that NO3- was a more effective inhibitor than NO2-. Nitrate and NO2- transport by both the low and high Km systems were greatly inhibited by p-hydroxymercuribenzoate, whereas the linear system was only slightly inhibited.

Flood frequency analysis for nonstationary annual peak records in an urban drainage basin

USGS Publications Warehouse

Villarini, G.; Smith, J.A.; Serinaldi, F.; Bales, J.; Bates, P.D.; Krajewski, W.F.

2009-01-01

Flood frequency analysis in urban watersheds is complicated by nonstationarities of annual peak records associated with land use change and evolving urban stormwater infrastructure. In this study, a framework for flood frequency analysis is developed based on the Generalized Additive Models for Location, Scale and Shape parameters (GAMLSS), a tool for modeling time series under nonstationary conditions. GAMLSS is applied to annual maximum peak discharge records for Little Sugar Creek, a highly urbanized watershed which drains the urban core of Charlotte, North Carolina. It is shown that GAMLSS is able to describe the variability in the mean and variance of the annual maximum peak discharge by modeling the parameters of the selected parametric distribution as a smooth function of time via cubic splines. Flood frequency analyses for Little Sugar Creek (at a drainage area of 110 km2) show that the maximum flow with a 0.01-annual probability (corresponding to 100-year flood peak under stationary conditions) over the 83-year record has ranged from a minimum unit discharge of 2.1 m3 s- 1 km- 2 to a maximum of 5.1 m3 s- 1 km- 2. An alternative characterization can be made by examining the estimated return interval of the peak discharge that would have an annual exceedance probability of 0.01 under the assumption of stationarity (3.2 m3 s- 1 km- 2). Under nonstationary conditions, alternative definitions of return period should be adapted. Under the GAMLSS model, the return interval of an annual peak discharge of 3.2 m3 s- 1 km- 2 ranges from a maximum value of more than 5000 years in 1957 to a minimum value of almost 8 years for the present time (2007). The GAMLSS framework is also used to examine the links between population trends and flood frequency, as well as trends in annual maximum rainfall. These analyses are used to examine evolving flood frequency over future decades. ?? 2009 Elsevier Ltd.

Global Distribution and Variations of NO Infrared Radiative Flux and Its Responses to Solar Activity and Geomagnetic Activity in the Thermosphere

NASA Astrophysics Data System (ADS)

Tang, Chaoli; Wei, Yuanyuan; Liu, Dong; Luo, Tao; Dai, Congming; Wei, Heli

2017-12-01

The global distribution and variations of NO infrared radiative flux (NO-IRF) are presented during 2002-2016 in the thermosphere covering 100-280 km altitude based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) data set. For investigating the spatial variations of the mutual relationship between NO-IRF and solar activity, the altitude ranges from 100 km to 280 km are divided into 90 altitude bins, and the latitude regions of 83°S-83°N are divided into 16 latitude bins. By processing about 1.8E9 NO-IRF observation values from about 5E6 vertical nighttime profiles recorded in SABER data set, we obtained more than 4.1E8 samples of NO-IRF. The annual-mean values of NO-IRF are then calculated by all available NO-IRF samples within each latitude and altitude bin. Local latitudinal maxima in NO-IRF are found between 120 and 145 km altitude, and the maximum NO-IRF located at polar regions are 3 times more than that of the minimum at equatorial region. The influences of solar and geomagnetic activity on the spatial variations of NO-IRF are investigated. Both the NO-IRF and its response to solar and geomagnetic activity show nearly symmetric distribution between the two hemispheres. It is demonstrated that the observed changes in NO-IRF at altitudes between 100 and 225 km correlate well with the changes in solar activity. The NO-IRF at solar maximum is about 4 times than that at solar minimum, and the current maximum of NO-IRF in 2014 is less than 70% of the prior maximum in 2001. For the first time, the response ranges of the NO-IRF to solar and geomagnetic activity at different altitudes and latitudes are reported.

Inorganic and organic carbon spatial variability in the Congo River during high waters (December 2013)

NASA Astrophysics Data System (ADS)

Borges, Alberto V.; Bouillon, Steven; Teodoru, Cristian; Leporcq, Bruno; Descy, Jean-Pïerre; Darchambeau, François

2014-05-01

Rivers are important components of the global carbon cycle, as they transport terrestrial organic matter from the land to the sea, and emit CO2 to the atmosphere. In particular, tropical systems that account for 60% of global freshwater discharge to the oceans. In contrast with south American rivers, very little information is available for African rivers on their carbon flows and stocks, in particular the Congo river, the second largest river in the World in terms of freshwater discharge (1457 km3 yr-1) and in terms of drainage basin (3.75 106 km2) located the second largest tropical forest in the World. Here, we report a data-set of continuous (every minute) records of the partial pressure of CO2 (pCO2) (total of 10,000 records), and discrete samples of particulate (POC) and dissolved (DOC) organic carbon (total of 75 samples) in the mainstem and major tributaries of the Congo river, along the 1700 km stretch from Kisangani to Kinshasa (total river length = 4374 km), during the high water period (December 2013). The pCO2 dynamic range was high ranging from minimum values of 2000 ppm in white waters tributaries (higher turbidity, conductivity and O2, lower DOC), up to maximal values of 18,000 ppm in blackwaters tributaries (lower turbidity, conductivity and O2, higher DOC). In the mainstem, very strong horizontal (cross-section) gradients were imposed by the presence of blackwaters close to the riverbanks and the presence of whitewaters in the middle of the river. In the mainstem, a distinct horizontal (longitudinal) pattern was observed with pCO2 increasing, and conductivity and turbidity decreasing downstream.

Study of atmospheric aerosols over the central Himalayan region using a newly developed Mie light detection and ranging system: preliminary results

NASA Astrophysics Data System (ADS)

Bangia, Tarun; Omar, Amitesh; Sagar, Ram; Kumar, Ashish; Bhattacharjee, Samaresh; Reddy, Arjun; Agarwal, Prem Kumar; Phanikumar

2011-01-01

A LIDAR system to receive Mie backscattered photons has been developed at the Manora peak, Nainital, India and it is the first of its kind in the central Himalayan region. The system is sensitive to receive backscattered photons from heights up to ~20 km (above ground level). The atmospheric extinction profiles using Mie LIDAR have been estimated for the first time at this site in January (winter) and March (spring) seasons in three campaigns and maximum values are found to be ~0.01, 0.03, and 0.08 km-1, respectively. The aerosol optical depth (AOD) values are found to be ~0.051, 0.098, and 0.233 in three campaigns, respectively, showing enhancement from January (winter) to March (spring) indicating a seasonal variation. AOD values of LIDAR, aerosol robotic network, and moderate resolution imaging spectroradiometer were found within the standard deviations. The aerosol loading at the site has increased during the last decade as evident from previous studies.

Q-values and Attenuation of the Shallow Crust Under Uturuncu Volcano, Bolivia

NASA Astrophysics Data System (ADS)

Mcfarlin, H. L.; McNutt, S. R.; Thompson, G.

2017-12-01

Uturuncu Volcano, located in the Altiplano-Puna region of the central Andes, near the border of Bolivia and Chile, has been shown to be inflating at a rate of 1-2 cm/yr over an area that is about 70 km wide. The PLUTONS project deployed 28 broadband seismometers around Uturuncu from April 2009 to October 2012. Several thousand shallow (depth < 20 km) local earthquakes were recorded. Attenuation of seismic waves along travel paths for these local crustal earthquakes can be measured by calculating Q-values, which we have performed using the method of single station spectral ratios by Frankel (1982). Large scatter in the Q-values for various distances and travel times appear to be a function of variations in source depth, focal mechanism, and back azimuth. Preliminary Q-values were calculated for azimuths in 30° increments in sectors around each station. Estimates for Q range from about 60 to 700, with many showing a low Q in the direction of the summit from each station. This suggests that the volcanic pile is more highly attenuating than the surrounding crust.

Curie point depth in the SW Caribbean using the radially averaged spectra of magnetic anomalies

NASA Astrophysics Data System (ADS)

Salazar, Juan M.; Vargas, Carlos A.; Leon, Hermann

2017-01-01

We have estimated the Curie Point Depth (CPD) using the average radial power spectrum in a tectonically complex area located in the SW Caribbean basin. Data analyzed came from the World Digital Magnetic Anomaly Map, and three methods have been used to compare results and evaluate uncertainties: Centroid, Spectral Peak, and Forward Modeling. Results show a match along the three methods, suggesting that the CPD values in the area ranging between 6 km and 50 km. The results share the following characteristics: A) High values (> 30 km) are in continental regions; B) There is a trend of maximum CPD values along the SW-NE direction, starting from the Central Cordillera in Colombia to the Maracaibo Lake in Venezuela; C) There is a maximum CPD at the Sierra Nevada de Santa Marta (Colombia) as well as between Costa Rica - Nicaragua and Nicaragua - Honduras borders. The lowest CPD values (< 20 km) are associated with the coastal regions and offshore. We also tested results by estimating the geothermal gradient and comparing measured observations of the study area. Our results suggest at least five thermal terrains in the SW Caribbean Basin: A) The area that is comprising the Venezuela Basin, the Beata Ridge and the Colombia Basin up to longitude parallel to the Providencia Throat. B) The area that includes zones to the north of the Cocos Ridge and Panam Basin up to the trench. C) The orogenic region of the northern Andes and including areas of the Santa Marta Massif. D) The continental sector that encompasses Nicaragua, northern Costa Rica and eastern of Honduras. E) Corresponds to areas of the northern Venezuela and Colombia, NW of Colombia, the Panamanian territory and the transition zones between the Upper and Lower Nicaragua Rise.

Spatial multi-scale variability of soil nutrients in relation to environmental factors in a typical agricultural region, eastern China.

PubMed

Liu, Yang; Lv, Jianshu; Zhang, Bing; Bi, Jun

2013-04-15

Identifying the sources of spatial variability and deficiency risk of soil nutrients is a crucial issue for soil and agriculture management. A total of 1247 topsoil samples (0-20 cm) were collected at the nodes of a 2×2 km grid in Rizhao City and the contents of soil organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) were determined. Factorial kriging analysis (FKA), stepwise multiple regression, and indicator kriging (IK) were appled to investigate the scale dependent correlations among soil nutrients, identify the sources of spatial variability at each spatial scale, and delineate the potential risk of soil nutrient deficiency. Linear model of co-regionalization (LMC) fitting indicated that the presence of multi-scale variation was comprised of nugget effect, an exponential structure with a range of 12 km (local scale), and a spherical structure with a range of 84 km (regional scale). The short-range variation of OC and TN was mainly dominated by land use types, and TP was controlled by terrain. At long-range scale, spatial variation of OC, TN, and TP was dominated by parent material. Indicator kriging maps depicted the probability of soil nutrient deficiency compared with the background values in eastern Shandong province. The high deficiency risk area of all nutrient integration was mainly located in eastern and northwestern parts. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of Preionization in Radiative Shocks. II. Application to the Herbig–Haro Objects

NASA Astrophysics Data System (ADS)

Dopita, Michael A.; Sutherland, Ralph S.

2017-04-01

In an earlier paper we treated the preionization problem in shocks over the velocity range 20 km s‑1 < {v}{{s}}< 1000 km s‑1 in a fully self-consistent manner. Here we investigate in detail the effect of the upstream UV photon field generated in the radiative zone of shocks in the range in which hydrogen is only partly ionized 20 km s‑1 (< {v}{{s}}< 150 km s‑1). We show that, as a result of superheating in the nonequilibrium preshock plasma, both the magnetic parameter and the Mach number of the shock are strongly affected by the preionization state of the gas, which controls to a large extent the radiative spectrum of the shock. We use these models to provide specific line diagnostics for Herbig–Haro objects, which allow us to solve for both the preshock density and shock velocity, and we present detailed models of the HH 34 jet, which allows us to derive the shock conditions, mass-loss rate, momentum flux, and chemical abundances in the jet. We show that the refractory elements Mg, Ca, Fe, and Ni are enhanced by 0.22 dex over the solar values, which provides interesting clues about the jet-launching mechanism in pre-main-sequence evolution.

Geochemical water signature in the Bahariya Depression, Western Desert, Egypt

NASA Astrophysics Data System (ADS)

Sciarra, Alessandra; Mazzini, Adriano; Lupi, Matteo; Hammed, Mohammed S.

2017-04-01

The Bahariya Oasis is located about 200 km SW of Cairo in the central part of the Western Desert of Egypt. It occupies a sub-elliptic 40 km wide depression stretching NE-SW for approximately 90 km. The Bahariya Oasis has been targeted for numerous geological studies on structural geology, stratigraphy, and iron ore deposits. The oasis was characterized since the Roman times by the presence of natural hydrothermal springs venting water from the relatively shallow Nubia Sandstone formation. Inside the depression are visible numerous circular concentric features that morphologically resemble the hydrothermal vent complexes observed at igneous provinces in other localities of the planet. In order to investigate the origin and the mechanisms of formation of these features, we conducted a fieldwork survey as well as fluids sampling from the available well sites. The aim was to constrain the origin of the fluids that potentially triggered or facilitated the formation of the concentric structures observed on the field. This study presents the geochemical results of groundwaters and soil gas samples. Ten samples were collected from deep wells present in the area. In particular, 8 warm waters were collected by wells between 800 m and 1200 m deep. The measured temperatures at these sites range from 36.5 °C to 52.3°C, while the coldest wells have temperatures ranging from 27.9 °C to 36.5°C. For each sample collected from the wells we analyzed the major, minor and trace elements, dissolved gases (He, Ne, H2, O2, N2, CH4, CO2, Rn), and relative isotopic values. In the areas around the wells we measured CO2 and CH4 fluxes as well as radon activity. Overall, the water showed a high value of dissolved Rn, ranging from 9 to 43 Bq/l, and dissolved CO2 ranging from 5.9 to 17.4 cc/l. The waters show a radiogenic signature of isotopic helium, highlighting very prolonged interaction with local crust enriched in radiogenic elements. The isotopic values of δ18O and δD show a clear meteoric component but do not reflect a local type of recharge since they do not lie on the current Egyptian meteoric water line. Indeed, δD ‰ values range from -83.2 ‰ a -76.3 ‰, and δ18O varies from a -11.3 ‰ -10.8 ‰. Accordingly, we can infer that the water currently flushed by the wells originates from reservoirs of palaeo-meteoric fluids trapped during colder conditions. The measured temperature range is relatively low suggesting low-enthalpy geothermal system. The estimated geothermal gradients in the Bahariya oasis is 37°C/km. The exhalation flux values show the presence of low levels of carbon dioxide and methane that are within the normal respiration of the soil indicating no significant emission of deep gas around the artificial wells. In a parallel study we identify Ba-rich feldspar from breccia samples collected from the paleo-venting sites. This is in agreement with the geochemical signature of the waters enriched in Ba, Fe, and partially in Sr. This could indicate a correlation between the paleowaters and the igneous intrusion , and therefore with the genesis of the circular features probably interpreted as paleo-piercements.

Investigation of tropical cirrus cloud properties using ground based lidar measurements

NASA Astrophysics Data System (ADS)

Dhaman, Reji K.; Satyanarayana, Malladi; Krishnakumar, V.; Mahadevan Pillai, V. P.; Jayeshlal, G. S.; Raghunath, K.; Venkat Ratnam, M.

2016-05-01

Cirrus clouds play a significant role in the Earths radiation budget. Therefore, knowledge of geometrical and optical properties of cirrus cloud is essential for the climate modeling. In this paper, the cirrus clouds microphysical and optical properties are made by using a ground based lidar measurements over an inland tropical station Gadanki (13.5°N, 79.2°E), Andhra Pradesh, India. The variation of cirrus microphysical and optical properties with mid cloud temperature is also studied. The cirrus clouds mean height is generally observed in the range of 9-17km with a peak occurrence at 13- 14km. The cirrus mid cloud temperature ranges from -81°C to -46°C. The cirrus geometrical thickness ranges from 0.9- 4.5km. During the cirrus occurrence days sub-visual, thin and dense cirrus were at 37.5%, 50% and 12.5% respectively. The monthly cirrus optical depth ranges from 0.01-0.47, but most (<80%) of the cirrus have values less than 0.1. Optical depth shows a strong dependence with cirrus geometrical thickness and mid-cloud height. The monthly mean cirrus extinction ranges from 2.8E-06 to 8E-05 and depolarization ratio and lidar ratio varies from 0.13 to 0.77 and 2 to 52 sr respectively. A positive correlation exists for both optical depth and extinction with the mid-cloud temperature. The lidar ratio shows a scattered behavior with mid-cloud temperature.

Vertical Distribution of NO, NO(2), and HNO(3) as Derived from Stratospheric Absorption Infrared Spectra.

PubMed

Fontanella, J C; Girard, A; Gramont, L; Louisnard, N

1975-04-01

This paper is devoted to the results concerning NO, NO(2), and HNO(3) obtained during airborne experiments performed in June-July 1973 on Concorde 001. The altitude of flight was about 16 km. Results concerning NO are, within the accuracy of measurement, in agreement with results of a previousspectrometric balloonborne experiment conducted jointly by IASB and ONERA (14 May 1973). Nitric oxide is concentrated in stratospheric layers clearly above the flight altitude. Integrated amount of NO along the optical path is (4 +/- 1.5) x 10(16) mol cm(-2) for a solar elevation varying from +2 degrees above the horizontal plane to -1 degrees . A value of 6 x 10(8) mol cm(-3) may be given as an upper limit for the local concentration at the flight altitude. Thereis no significant difference in the integrated amount observed at sunset and sunrise. Measured value of NO(2) local concentration at 15.5 km is (1.1 +/- 0.2) x 10(9) mol cm(-3), in sunset conditions. This value is not greatly modified between 15 km and 30 km. Measured value of HNO(3). This value increases with altitude between 15 km and 20 km. The local concentration is maximum at 20 km. The measured value is (2 +/- 1) x 10(10) mol cm(-3) at 20 km. It seems that local concentration decreases rapidly above 20 km.

Curie point depth from spectral analysis of aeromagnetic data for geothermal reconnaissance in Afghanistan

NASA Astrophysics Data System (ADS)

Saibi, H.; Aboud, E.; Gottsmann, J.

2015-11-01

The geologic setting of Afghanistan has the potential to contain significant mineral, petroleum and geothermal resources. However, much of the country's potential remains unknown due to limited exploration surveys. Here, we present countrywide aeromagnetic data to estimate the Curie point depth (CPD) and to evaluate the geothermal exploration potential. CPD is an isothermal surface at which magnetic minerals lose their magnetization and as such outlines an isotherm of about 580 °C. We use spectral analysis on the aeromagnetic data to estimate the CPD spatial distribution and compare our findings with known geothermal fields in the western part of Afghanistan. The results outline four regions with geothermal potential: 1) regions of shallow Curie point depths (∼16-21 km) are located in the Helmand basin. 2) regions of intermediate depths (∼21-27 km) are located in the southern Helmand basin and the Baluchistan area. 3) Regions of great depths (∼25-35 km) are located in the Farad block. 4) Regions of greatest depths (∼35-40 km) are located in the western part of the northern Afghanistan platform. The deduced thermal structure in western Afghanistan relates to the collision of the Eurasian and Indian plates, while the shallow CPDs are related to crustal thinning. This study also shows that the geothermal systems are associated with complex magmatic and tectonic association of major intrusions and fault systems. Our results imply geothermal gradients ranging from 14 °C/km to 36 °C/km and heat-flow values ranging from 36 to 90 mW/m2 for the study area.

Stratospheric aerosols from the Sarychev volcano eruption in the 2009 Arctic summer

NASA Astrophysics Data System (ADS)

Jégou, F.; Berthet, G.; Brogniez, C.; Renard, J.-B.; François, P.; Haywood, J. M.; Jones, A.; Bourgeois, Q.; Lurton, T.; Auriol, F.; Godin-Beekmann, S.; Guimbaud, C.; Krysztofiak, G.; Gaubicher, B.; Chartier, M.; Clarisse, L.; Clerbaux, C.; Balois, J. Y.; Verwaerde, C.

2013-02-01

Aerosols from the Sarychev volcano eruption (Kuril Islands, northeast of Japan) were observed in the Arctic lower stratosphere a few days after the strongest SO2 injection which occurred on 15 and 16 June 2009. From the observations provided by the Infrared Atmospheric Sounding Interferometer (IASI) an estimated 0.9 Tg of sulphur dioxide was injected into the Upper Troposphere and Lower Stratosphere (UTLS). The resultant stratospheric sulphate aerosols were detected by the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb sounder and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite instruments. By the first week of July the aerosol plume had spread out over the entire Arctic region. The Sarychev-induced stratospheric aerosol over the Kiruna region (north of Sweden) was measured by the Stratospheric and Tropospheric Aerosol Counter (STAC) during eight balloon flights planned in August and September 2009. During this balloon campaign the Micro RADIomètre BALlon (MicroRADIBAL) and the Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON) remote-sensing instruments also observed these aerosols. Aerosol concentrations returned to near-background levels by spring 2010. The effective radius, the Surface Area Density (SAD), the aerosol extinction, and the total sulphur mass from STAC in situ measurements are enhanced with mean values in the range 0.15-0.21 μm, 5.5-14.7 μm2 cm-3, 5.5-29.5×10-4 km-1, and 4.9-12.6×10-10 kg [S] kg-1 [air], respectively, between 14 km and 18 km. The observed and modelled e-folding time of sulphate aerosols from the Sarychev eruption is around 70-80 days, a value much shorter than the 12-14 months calculated for aerosols from the 1991 eruption of Mt. Pinatubo. The OSIRIS stratospheric Aerosol Optical Depth (AOD) at 750 nm is enhanced by a factor of 6 with a value of 0.02 in late July compared to 0.0035 before the eruption. The HadGEM2 and MIMOSA model outputs indicate that aerosol layers in polar region up to 14-15 km are largely modulated by stratosphere-troposphere exchange processes. The spatial extension of the Sarychev plume is well represented in the HadGEM2 model with lower altitudes of the plume being controlled by upper tropospheric troughs which displace the plume downward and upper altitudes around 18-20 km in agreement with lidar observations. A good consistency is found between the HadGEM2 sulphur mass density and the value inferred from the STAC observations with a maximum located about 1 km above the tropopause ranging from 1 to 2×10-9 kg [S] kg-1 [air], which is one order of magnitude higher than the background level.

Cultural Diffusion Was the Main Driving Mechanism of the Neolithic Transition in Southern Africa

PubMed Central

Jerardino, Antonieta; Fort, Joaquim; Isern, Neus; Rondelli, Bernardo

2014-01-01

It is well known that the Neolithic transition spread across Europe at a speed of about 1 km/yr. This result has been previously interpreted as a range expansion of the Neolithic driven mainly by demic diffusion (whereas cultural diffusion played a secondary role). However, a long-standing problem is whether this value (1 km/yr) and its interpretation (mainly demic diffusion) are characteristic only of Europe or universal (i.e. intrinsic features of Neolithic transitions all over the world). So far Neolithic spread rates outside Europe have been barely measured, and Neolithic spread rates substantially faster than 1 km/yr have not been previously reported. Here we show that the transition from hunting and gathering into herding in southern Africa spread at a rate of about 2.4 km/yr, i.e. about twice faster than the European Neolithic transition. Thus the value 1 km/yr is not a universal feature of Neolithic transitions in the world. Resorting to a recent demic-cultural wave-of-advance model, we also find that the main mechanism at work in the southern African Neolithic spread was cultural diffusion (whereas demic diffusion played a secondary role). This is in sharp contrast to the European Neolithic. Our results further suggest that Neolithic spread rates could be mainly driven by cultural diffusion in cases where the final state of this transition is herding/pastoralism (such as in southern Africa) rather than farming and stockbreeding (as in Europe). PMID:25517968

Cloud overlapping parameter obtained from CloudSat/CALIPSO dataset and its application in AGCM with McICA scheme

NASA Astrophysics Data System (ADS)

Jing, Xianwen; Zhang, Hua; Peng, Jie; Li, Jiangnan; Barker, Howard W.

2016-03-01

Vertical decorrelation length (Lcf) as used to determine overlap of cloudy layers in GCMs was obtained from CloudSat/CALIPSO measurements, made between 2007 and 2010, and analyzed in terms of monthly means. Global distributions of Lcf were produced for several cross-sectional lengths. Results show that: Lcf over the tropical convective regions typically exceeds 2 km and shift meridionally with season; the smallest Lcf (< 1 km) tends to occur in regions dominated by marine stratiform clouds; Lcf for mid-to-high latitude continents of the Northern Hemisphere (NH) ranges from 5-6 km during winter to 2-3 km during summer; and there are marked differences between continental and oceanic values of Lcf in the mid-latitudes of the NH. These monthly-gridded, observationally-based values of Lcf data were then used by the Monte Carlo Independent Column Approximation (McICA) radiation routines within the Beijing Climate Center's GCM (BCC_AGCM2.0.1). Additionally, the GCM was run with two other descriptions of Lcf: one varied with latitude only, and the other was simply 2 km everywhere all the time. It is shown that using the observationally-based Lcf in the GCM led to local and seasonal changes in total cloud fraction and shortwave (longwave) cloud radiative effects that serve mostly to reduce model biases. This indicates that usage of Lcf that vary according to location and time has the potential to improve climate simulations.

Three-dimensional thermal structure of the South Polar Vortex of Venus

NASA Astrophysics Data System (ADS)

Hueso, Ricardo; Garate-Lopez, Itziar; Garcia-Muñoz, Antonio; Sánchez-Lavega, Agustín

2014-11-01

We have analyzed thermal infrared images provided by the VIRTIS-M instrument aboard Venus Express (VEX) to obtain high resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes. The maps investigate three different dynamical configurations of the polar vortex including its classical dipolar shape, a regularly oval shape and a transition shape between the different configurations of the vortex. We apply the atmospheric model described by García Muñoz et al. (2013) and a variant of the retrieval algorithm detailed in Grassi et al. (2008) to obtain maps of temperature over the Venus south polar region in the quoted altitude range. These maps are discussed in terms of cloud motions and relative vorticity distribution obtained previously (Garate-Lopez et al. 2013). Temperature maps retrieved at 55 - 63 km show the same structures that are observed in the ~5 µm radiance images. This altitude range coincides with the optimal expected values of the cloud top altitude at polar latitudes and magnitudes derived from the analysis of ~5 µm images are measured at this altitude range. We also study the imprint of the vortex on the thermal field above the cloud level which extends up to 80 km. From the temperature maps, we also study the vertical stability of different atmospheric layers. The cold collar is clearly the most statically stable structure at polar latitudes, while the vortex and subpolar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex at 55-63 km exhibit lower values of static stability than their immediate surroundings.ReferencesGarate-Lopez et al. Nat. Geosci. 6, 254-257 (2013).García Muñoz et al. Planet. Space Sci. 81, 65-73 (2013).Grassi, D. et al. J. Geophys. Res. 113, 1-12 (2008).AcknowledgementsWe thank ESA for supporting Venus Express, ASI, CNES and the other national space agencies supporting VIRTIS on VEX and their principal investigators G. Piccioni and P. Drossart. This work was supported by projects AYA2012-36666 with FEDER support, PRICI-S2009/ESP-1496, Grupos Gobierno Vasco IT-765-13 and by UPV/EHU through program UFI11/55. IGL and AGM acknowledge ESA/RSSD for hospitality and access to ‘The Grid’ computing resources.

Regional geologic framework off northeastern United States

USGS Publications Warehouse

Schlee, J.; Behrendt, John C.; Grow, J.A.; Robb, James M.; Mattick, R.; Taylor, P.T.; Lawson, B.J.

1976-01-01

Six multichannel seismic-reflection profiles taken across the Atlantic continental margin Previous HitoffTop the northeastern United States show an excess of 14 km of presumed Mesozoic and younger sedimentary rocks in the Baltimore Canyon trough and 8 km in the Georges Bank basin. Beneath the continental rise, the sedimentary prism thickness exceeds 7 km south of New Jersey and Maryland, and it is 4.5 km thick south of Georges Bank. Stratigraphically, the continental slope--outer edge of the continental shelf is a transition zone of high-velocity sedimentary rock, probably carbonate, that covers deeply subsided basement. Acoustically, the sedimentary sequence beneath the shelf is divided into three units which are correlated speculatively with the Cenozoic, the Cretaceous, and the Jurassic-Triassic sections. These units thicken offshore, and some have increased seismic velocities farther offshore. The uppermost unit thickens from a fraction of a kilometer to slightly more than a kilometer in a seaward direction, and velocity values range from 1.7 to 2.2 km/sec. The middle unit thickens from a fraction of a kilometer to as much as 5 km (northern Baltimore Canyon trough), and seismic velocity ranges from 2.2 to 5.4 km/sec. The lowest unit thickens to a maximum of 9 km (northern Baltimore Canyon), and velocities span the 3.9 to 5.9-km/sec interval. The spatial separation of magnetic and gravity anomalies on line 2 (New Jersey) suggests that in the Baltimore Canyon region the magnetic-slope anomaly is due to edge effects and that the previously reported free-air and isostatic gravity anomalies over the outer shelf may be due in part to a lateral increase in sediment density (velocity) near the shelf edge. The East Coast magnetic anomaly and the free-air gravity high both coincide over the outer shelf edge on line 1 (Georges Bank) but are offset by 20 km from the ridge on the reflection profile. Because the magnetic-slope-anomaly wavelength is nearly 50 km across, a deep source is likely. In part, the positive free-air gravity anomaly likewise may represent the significant lateral density increase within the sedimentary section to ard the outer edge of the shelf.

Functional traits help to explain half-century long shifts in pollinator distributions.

PubMed

Aguirre-Gutiérrez, Jesús; Kissling, W Daniel; Carvalheiro, Luísa G; WallisDeVries, Michiel F; Franzén, Markus; Biesmeijer, Jacobus C

2016-04-15

Changes in climate and land use can have important impacts on biodiversity. Species respond to such environmental modifications by adapting to new conditions or by shifting their geographic distributions towards more suitable areas. The latter might be constrained by species' functional traits that influence their ability to move, reproduce or establish. Here, we show that functional traits related to dispersal, reproduction, habitat use and diet have influenced how three pollinator groups (bees, butterflies and hoverflies) responded to changes in climate and land-use in the Netherlands since 1950. Across the three pollinator groups, we found pronounced areal range expansions (>53%) and modelled range shifts towards the north (all taxa: 17-22 km), west (bees: 14 km) and east (butterflies: 11 km). The importance of specific functional traits for explaining distributional changes varied among pollinator groups. Larval diet preferences (i.e. carnivorous vs. herbivorous/detritivorous and nitrogen values of host plants, respectively) were important for hoverflies and butterflies, adult body size for hoverflies, and flight period length for all groups. Moreover, interactions among multiple traits were important to explain species' geographic range shifts, suggesting that taxon-specific multi-trait analyses are needed to predict how global change will affect biodiversity and ecosystem services.

Retrieval of temperature profiles from CHAMP for climate monitoring: intercomparison with Envisat MIPAS and GOMOS and different atmospheric analyses

NASA Astrophysics Data System (ADS)

Gobiet, A.; Kirchengast, G.; Manney, G. L.; Borsche, M.; Retscher, C.; Stiller, G.

2007-02-01

This study describes and evaluates a Global Navigation Satellite System (GNSS) radio occultation (RO) retrieval scheme particularly aimed at delivering bias-free atmospheric parameters for climate monitoring and research. The focus of the retrieval is on the sensible use of a priori information for careful high-altitude initialisation in order to maximise the usable altitude range. The RO retrieval scheme has been meanwhile applied to more than five years of data (September 2001 to November 2006) from the German CHAllenging Minisatellite Payload for geoscientific research (CHAMP) satellite. In this study it was validated against various correlative datasets including the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Global Ozone Monitoring for Occultation of Stars (GOMOS) sensors on Envisat, five different atmospheric analyses, and the operational CHAMP retrieval product from GeoForschungsZentrum (GFZ) Potsdam. In the global mean within 10 to 30 km altitude we find that the present validation observationally constrains the potential RO temperature bias to be <0.2 K. Latitudinally resolved analyses show biases to be observationally constrained to <0.2-0.5 K up to 35 km in most cases, and up to 30 km in any case, even if severely biased (about 10 K or more) a priori information is used in the high altitude initialisation of the retrieval. No evidence is found for the 10-35 km altitude range of RO bias sources other than those potentially propagated downward from initialisation, indicating that the widely quoted RO promise of "unbiasedness and long-term stability due to intrinsic self-calibration" can indeed be realized given care in the data processing to strictly limit structural uncertainty. The results demonstrate that an adequate high-altitude initialisation technique is crucial for accurate stratospheric RO retrievals and that still common methods of initialising the involved hydrostatic integral with an upper boundary temperature or pressure value derived from meteorological analyses is prone to introduce biases from the initialisation data to the retrieved temperatures down to below 25 km. Above 30 to 35 km, GNSS RO delivers a considerable amount of observed information up to around 40 km, which is particularly interesting for numerical weather prediction (NWP) systems, where direct assimilation of non-initialized (a priori-free) observed RO bending angles is thus the method of choice. The results underline the value of RO for climate applications.

Retrieval of temperature profiles from CHAMP for climate monitoring: intercomparison with Envisat MIPAS and GOMOS and different atmospheric analyses

NASA Astrophysics Data System (ADS)

Gobiet, A.; Kirchengast, G.; Manney, G. L.; Borsche, M.; Retscher, C.; Stiller, G.

2007-07-01

This study describes and evaluates a Global Navigation Satellite System (GNSS) radio occultation (RO) retrieval scheme particularly aimed at delivering bias-free atmospheric parameters for climate monitoring and research. The focus of the retrieval is on the sensible use of a priori information for careful high-altitude initialisation in order to maximise the usable altitude range. The RO retrieval scheme has been meanwhile applied to more than five years of data (September 2001 to present) from the German CHAllenging Minisatellite Payload for geoscientific research (CHAMP) satellite. In this study it was validated against various correlative datasets including the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Global Ozone Monitoring for Occultation of Stars (GOMOS) sensors on Envisat, five different atmospheric analyses, and the operational CHAMP retrieval product from GeoForschungsZentrum (GFZ) Potsdam. In the global mean within 10 to 30 km altitude we find that the present validation observationally constrains the potential RO temperature bias to be <0.2 K. Latitudinally resolved analyses show biases to be observationally constrained to <0.2-0.5 K up to 35 km in most cases, and up to 30 km in any case, even if severely biased (about 10 K or more) a priori information is used in the high altitude initialisation of the retrieval. No evidence is found for the 10-35 km altitude range of residual RO bias sources other than those potentially propagated downward from initialisation, indicating that the widely quoted RO promise of "unbiasedness and long-term stability due to intrinsic self-calibration" can indeed be realised given care in the data processing to strictly limit structural uncertainty. The results thus reinforce that adequate high-altitude initialisation is crucial for accurate stratospheric RO retrievals. The common method of initialising, at some altitude in the upper stratosphere, the hydrostatic integral with an upper boundary temperature or pressure value derived from meteorological analyses is prone to introduce biases from the upper boundary down to below 25 km. Also above 30 to 35 km, GNSS RO delivers a considerable amount of observed information up to around 40 km, which is particularly interesting for numerical weather prediction (NWP) systems, where direct assimilation of non-initialised observed RO bending angles (free of a priori) is thus the method of choice. The results underline the value of RO for climate applications.

First detection of HDO in the atmosphere of Venus at radio wavelengths - An estimate of the H2O vertical distribution

NASA Technical Reports Server (NTRS)

Encrenaz, T.; Lellouch, E.; Paubert, G.; Gulkis, S.

1991-01-01

The 225.9 GHz line of HDO has been detected in absorption in the atmosphere of Venus, with the 30-m IRAM antenna. This measurement gives information regarding the vertical distributions of HDO, and thus H2O, in this planet. The observations are consistent with an H2O vertical distribution strongly depleted by saturation at an altitude of 95 km, and, assuming a D/H enrichment of 120 with respect to the terrestrial value, with a mixing ratio of 3.5 (+ or - 2.0) ppm in the range 65-95 km.

Missile sizing for ascent-phase intercept

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hull, D.G.; Salguero, D.E.

1994-11-01

A computer code has been developed to determine the size of a ground-launched, multistage missile which can intercept a theater ballistic missile before it leaves the atmosphere. Typical final conditions for the inteceptor are 450 km range, 60 km altitude, and 80 sec flight time. Given the payload mass (35 kg), which includes a kinetic kill vehicle, and achievable values for the stage mass fractions (0.85), the stage specific impulses (290 sec), and the vehicle density (60 lb/ft{sup 3}), the launch mass is minimized with respect to the stage payload mass ratios, the stage burn times, and the missile anglemore » of attack history subject to limits on the angle of attack (10 deg), the dynamic pressure (60,000 psf), and the maneuver load (200,000 psf deg). For a conical body, the minimum launch mass is approximately 1900 kg. The missile has three stages, and the payload coasts for 57 sec. A trade study has been performed by varying the flight time, the range, and the dynamic pressure Emits. With the results of a sizing study for a 70 lb payload and q{sub max} = 35,000 psf, a more detailed design has been carried out to determine heat shield mass, tabular aerodynamics, and altitude dependent thrust. The resulting missile has approximately 100 km less range than the sizing program predicted primarily because of the additional mass required for heat protection. On the other hand, launching the same missile from an aircraft increases its range by approximately 100 km. Sizing the interceptor for air launch with the same final conditions as the ground-launched missile reduces its launch mass to approximately 1000 kg.« less

The NASA/MSFC Global Reference Atmospheric Model: 1999 Version (GRAM-99)

NASA Technical Reports Server (NTRS)

Justus, C. G.; Johnson, D. L.

1999-01-01

The latest version of Global Reference Atmospheric Model (GRAM-99) is presented and discussed. GRAM-99 uses either (binary) Global Upper Air Climatic Atlas (GUACA) or (ASCII) Global Gridded Upper Air Statistics (GGUAS) CD-ROM data sets, for 0-27 km altitudes. As with earlier versions, GRAM-99 provides complete geographical and altitude coverage for each month of the year. GRAM-99 uses a specially-developed data set, based on Middle Atmosphere Program (MAP) data, for 20-120 km altitudes, and NASA's 1999 version Marshall Engineering Thermosphere (MET-99) model for heights above 90 km. Fairing techniques assure smooth transition in overlap height ranges (20-27 km and 90-120 km). GRAM-99 includes water vapor and 11 other atmospheric constituents (O3, N2O, CO, CH4, CO2, N2, O2, O, A, He and H). A variable-scale perturbation model provides both large-scale (wave) and small-scale (stochastic) deviations from mean values for thermodynamic variables and horizontal and vertical wind components. The small-scale perturbation model includes improvements in representing intermittency ("patchiness"). A major new feature is an option to substitute Range Reference Atmosphere (RRA) data for conventional GRAM climatology when a trajectory passes sufficiently near any RRA site. A complete user's guide for running the program, plus sample input and output, is provided. An example is provided for how to incorporate GRAM-99 as subroutines in other programs (e.g., trajectory codes).

Nearly constant ratio between the proton inertial scale and the spectrum break length scale in the plasma beta range from 0.2 to 1.4 in the solar wind turbulence

NASA Astrophysics Data System (ADS)

Wang, X.; Tu, C. Y.; He, J.; Wang, L.

2017-12-01

The spectrum break at the ion scale of the solar wind magnetic fluctuations are considered to give important clue on the turbulence dissipation mechanism. Among several possible mechanisms, the most notable ones are the two mechanisms that related respectively with proton thermal gyro-radius and proton inertial length. However, no definite conclusion has been given for which one is more reasonable because the two parameters have similar values in the normal plasma beta range. Here we do a statistical study for the first time to see if the two mechanism predictions have different dependence on the solar wind velocity and on the plasma beta in the normal plasma beta range in the solar wind at 1 AU. From magnetic measurements by Wind, Ulysses and Messenger, we select 60 data sets with duration longer than 8 hours. We found that the ratio between the proton inertial scale and the spectrum break scale do not change considerably with both varying the solar wind speed from 300km/s to 800km/s and varying the plasma beta from 0.2 to 1.4. The average value of the ratio times 2pi is 0.46 ± 0.08. However, the ratio between the proton gyro-radius and the break scale changes clearly. This new result shows that the proton inertial scale could be a single factor that determines the break length scale and hence gives a strong evidence to support the dissipation mechanism related to it in the normal plasma beta range. The value of the constant ratio may relate with the dissipation mechanism, but it needs further theoretical study to give detailed explanation.

Seismic images of the Brooks Range fold and thrust belt, Arctic Alaska, from an integrated seismic reflection/refraction experiment

USGS Publications Warehouse

Levander, A.; Fuis, G.S.; Wissinger, E.S.; Lutter, W.J.; Oldow, J.S.; Moore, Thomas E.

1994-01-01

We describe results of an integrated seismic reflection/refraction experiment across the Brooks Range and flanking geologic provinces in Arctic Alaska. The seismic acquisition was unusual in that reflection and refraction data were collected simultaneously with a 700 channel seismograph system deployed numerous times along a 315 km profile. Shot records show continuous Moho reflections from 0-180 km offset, as well as numerous upper- and mid-crustal wide-angle events. Single and low-fold near-vertical incidence common midpoint (CMP) reflection images show complex upper- and middle-crustal structure across the range from the unmetamorphosed Endicott Mountains allochthon (EMA) in the north, to the metamorphic belts in the south. Lower-crustal and Moho reflections are visible across the entire reflection profile. Travel-time inversion of PmP arrivals shows that the Moho, at 33 km depth beneath the North Slope foothills, deepens abruptly beneath the EMA to a maximum of 46 km, and then shallows southward to 35 km at the southern edge of the range. Two zones of upper- and middle-crustal reflections underlie the northern Brooks Range above ~ 12-15 km depth. The upper zone, interpreted as the base of the EMA, lies at a maximum depth of 6 km and extends over 50 km from the range front to the north central Brooks Range where the base of the EMA outcrops above the metasedimentary rocks exposed in the Doonerak window. We interpret the base of the lower zone, at ~ 12 km depth, to be from carbonate rocks above the master detachment upon which the Brooks Range formed. The seismic data suggest that the master detachment is connected to the faults in the EMA by several ramps. In the highly metamorphosed terranes south of the Doonerak window, the CMP section shows numerous south-dipping events which we interpret as a crustal scale duplex involving the Doonerak window rocks. The basal detachment reflections can be traced approximately 100 km, and dip southward from about 10-12 km near the range front, to 14-18 km beneath the Doonerak window, to 26-28 km beneath the metamorphic belts in the central Brooks Range. The section documents middle- and lower-crustal involvement in the formation of the Brooks Range. ?? 1994.

Magmatic Flow Record From AMS Data La Gloria Pluton, Central Chile

NASA Astrophysics Data System (ADS)

Gutierrez, F.; Payacan, I. J.; Calderon, S.

2011-12-01

La Gloria Pluton (LGP) is a 10 Ma epizonal intrusion in the Southern Andes, located 40 km east of Santiago, in central Chile. 20 km long and 5 km wide LPG has a thickness of 2.5 km, in the form of a NW elongating inverted canoe. LGP intrudes Miocene volcanics as NS extending cluster of Miocene granitoids. LGP was emplaced at the west of an inverse fault system without exhibiting significant post-intrusion deformation. The fault system includes the Laguna Negra Fault and the El Coironal Fault, at its southern and northern ends respectively. LGP has been interpreted to have had a short cooling time, where subsolidus reequilibration was not pervasive, allowing identification of early and late magmatic conditions and suggesting it to be a single closed chamber. LGP is zoned vertically from granodiorite/quartz monzodiorite to quartz monzonite towards the roof, where hornblende and biotite and minor magnetite-ilmenite are omnipresent. AMS samples were collected at 39 sites to determine of the magnetic anisotropy susceptibility tensor. Magnetic fabric is generally oblate and anisotropy values range from 1.3 to 13.9%, consistent with the prescience magnetite and ilmenite. Magnetic lineation (ML) has a NNW trend, a subhorizontal dip and values between 0.4 and 5.3%. Magnetic foliation (MF) has a NW trend and dip varying from vertical at the walls of the intrusive to subhorizontal inside and under the roof. MF values ranges between 0.8 and 13.3%. Since linear trend of MF is restricted to the LGP interior only and can not be caused by a simple inverse fault system, we interpret the AMS results as a consequence of magmatic flow. ML represents the main flow direction, where several shallow plutons intrude at 10Ma in NW direction. MF is consequence of convection, related to cooling and differentiation, and is comparable to numerical simulations of magma fluid-dynamics during differentiation (R4). Two profiles (EW and NS) indicate that MF linear trend is from 29°/km to 50°/km, where the width of the pluton is 6 and 3.5 km respectively. Vertical MF represents vertical magma flows at the walls, whereas horizontal MF represents horizontal magma flow at the interior and under the roof the chamber. This suggests that a generalization of the MF trend allows determining the subsurface width of a pluton. Acknowledgments This research has been developed by the PBCT-PDA07 project and the FONDECYT (National Fund for Scientific & Technological Development) 11100241 project, both granted by CONICYT (Chilean National Commission for Science and Technology). We thank 4ea for logistic support in field activities in an area difficult to access.

In-situ measurements of nitric oxide in the high latitude upper stratosphere

NASA Technical Reports Server (NTRS)

Horvath, J. J.; Frederick, J. E.

1985-01-01

The vertical profiles of nitric acid were measured over Poker Flat, Alaska, in August 1984 and January and February 1985 using a rocket-launched parachute-deployed chemiluminescence sensor. Results for the altitude range 35-45 km indicate a large seasonal variation, with wintertime mixing ratios being a factor of two above summer values. The winter profiles contain sharp positive vertical gradients persisting through the highest altitudes observed. Above the stratopause, the mixing ratio observed in February increases rapidly and between 52 and 53 km reaches 148.9 ppbv, an order of magnitude greater than typical mid-latitude values measured with this instrument. Such behavior is consistent with the idea that nitric oxide produced at greater altitudes reaches the high-latitude upper stratosphere or lower mesosphere in winter. The results support the existence of a vertical coupling between diverse regions of the atmosphere in the high-latitude winter.

Triggered surface slips in the Salton Trough associated with the 1999 Hector Mine, California, earthquake

USGS Publications Warehouse

Rymer, M.J.; Boatwright, J.; Seekins, L.C.; Yule, J.D.; Liu, J.

2002-01-01

Surface fracturing occurred along the southern San Andreas, Superstition Hills, and Imperial faults in association with the 16 October 1999 (Mw 7.1) Hector Mine earthquake, making this at least the eighth time in the past 31 years that a regional earthquake has triggered slip along faults in the Salton Trough. Fractures associated with the event formed discontinuous breaks over a 39-km-long stretch of the San Andreas fault, from the Mecca Hills southeastward to Salt Creek and Durmid Hill, a distance from the epicenter of 107 to 139 km. Sense of slip was right lateral; only locally was there a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 13 mm. Maximum slip values in 1999 and earlier triggered slips are most common in the central Mecca Hills. Field evidence indicates a transient opening as the Hector Mine seismic waves passed the southern San Andreas fault. Comparison of nearby strong-motion records indicates several periods of relative opening with passage of the Hector Mine seismic wave-a similar process may have contributed to the field evidence of a transient opening. Slip on the Superstition Hills fault extended at least 9 km, at a distance from the Hector Mine epicenter of about 188 to 196 km. This length of slip is a minimum value, because we saw fresh surface breakage extending farther northwest than our measurement sites. Sense of slip was right lateral; locally there was a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 18 mm, with the largest amounts found distributed (or skewed) away from the Hector Mine earthquake source. Slip triggered on the Superstition Hills fault commonly is skewed away from the earthquake source, most notably in 1968, 1979, and 1999. Surface slip on the Imperial fault and within the Imperial Valley extended about 22 km, representing a distance from the Hector Mine epicenter of about 204 to 226 km. Sense of slip dominantly was right lateral; the right-lateral component of slip ranged from 1 to 19 mm. Locally there was a minor (~1-2 mm) vertical component of slip; larger proportions of vertical slip (up to 10 mm) occurred in Mesquite basin, where scarps indicate long-term oblique-slip motion for this part of the Imperial fault. Slip triggered on the Imperial fault appears randomly distributed relative to location along the fault and source direction. Multiple surface slips, both primary and triggered slip, indicate that slip repeatedly is small at locations of structural complexity.

Brachiopod δ18O values do reflect ambient oceanography: Lacepede Shelf, southern Australia

NASA Astrophysics Data System (ADS)

James, Noel P.; Bone, Yvonne; Kurtis Kyser, T.

1997-06-01

Although commonly used as proxies for attributes of ancient ocean waters, the δ18O values of brachiopods from modern seas are little studied. To evaluate the utility of brachiopods as recorders of regional oceanography, modern shells from the Lacepede Shelf (25 000 km2) of southern Australia were analyzed for δ18O, and the results were compared to the values of ambient seawater. Southern Ocean waters cover this area of extensive cool-water carbonate deposition, but there are distinct sectors of seasonal upwelling and lesser fluvial outflow. δ18O values of brachiopods across the environmental spectrum from 40 to 300 m water depth are in general isotopic equilibrium with surrounding seawater. Nevertheless, δ18O values from individual sample sites vary as much as 0.60‰. The area of cold-water upwelling in particular is clearly delimited by a group of high δ18O values. The range of values across this one shelf, on the order of 2.5‰, is similar to the range of values postulated on the basis of similar results for secular changes in many ancient oceans.

Mars-Gram Validation with Mars Global Surveyor Data

NASA Technical Reports Server (NTRS)

Justus, C. G.; Johnson, D.; Parker, Nelson C. (Technical Monitor)

2002-01-01

Mars Global Reference Atmospheric Model (Mars-GRAM 2001) is an engineering-level Mars atmosphere model widely used for many b4ars mission applications. From 0-80 km, it is based on NASA Ames Mars General Circulation Model (MGCM), while above 80 km it is based on University of Arizona Mars Thermospheric General Circulation Model. Mars-GRAM 2001 and MGCM use surface topography from Mars Global Surveyor Mars Orbiting Laser Altimeter (MOLA). Validation studies are described comparing Mars-GRAM with Mars Global Surveyor Radio Science (RS) and Thermal Emission Spectrometer (TES) data. RS data from 2480 profiles were used, covering latitudes 75deg S to 72deg N, surface to approx. 40 km, for seasons ranging from areocentric longitude of Sun (Ls) = 70-160deg and 265-310deg. RS data spanned a range of local times, mostly 0-9 hours and 18-24 hours. For interests in aerocapture and precision landing, comparisons concentrated on atmospheric density. At a fixed height of 20 km, measured RS density varied by about a factor of 2.5 over the range of latitudes and Ls values observed. Evaluated at matching positions and times, average RS/Mars-GRAM density ratios were generally lf0.05, except at heights above approx. 25 km and latitudes above approx.50deg N. Average standard deviation of RS/Mars-GRAM density ratio was 6%. TES data were used covering surface to approx. 40 km, over more than a full Mars year (February, 1999 - June, 2001, just before start of Mars global dust storm). Depending on season, TES data covered latitudes 85deg S to 85deg N. Most TES data were concentrated near local times 2 hours and 14 hours. Observed average TES/Mars-GRAM density ratios were generally 1+/-0.05, except at high altitudes (15-30 km, depending on season) and high latitudes (> 45deg N), or at most altitudes in the southern hemisphere at Ls approx. 90 and 180deg). Compared to TES averages for a given latitude and season, TES data had average density standard deviation about the mean of approx. 6.5-10.5% (varying with height) for all data, or approx. 5- 12%, depending on time of day and dust optical depth. Average standard deviation of TES/Mars-GRAM density ratio was 8.9% for local time 2 hours and 7.1% for 1o:al time 14 hours. Thus standard deviation of observed TES/Mars-GRAM density ratio, evaluated at matching positions and times, is about the same as the standard deviation of TES data about the TES mean value at a given position and season.

Petrologic Constraints on Magma Plumbing Systems Beneath Hawaiian Volcanoes

NASA Astrophysics Data System (ADS)

Li, Y.; Peterman, K. J.; Scott, J. L.; Barton, M.

2016-12-01

We have calculated the pressures of partial crystalliztion of basaltic magmas from Hawaii using a petrological method. A total of 1576 major oxide analyses of glasses from four volcanoes (Kilauea and the Puna Ridge, Loihi, Mauna Loa, and Mauna Kea, on the Big Island) were compiled and used as input data. Glasses represent quenched liquid compositions and are ideal for calculation of pressures of partial crystallization. The results were filtered to exclude samples that yielded unrealistic high errors associated with the calculated pressure or negative value of pressure, and to exclude samples with non-basaltic compositions. Calculated pressures were converted to depths of partial crystallization. The majority (68.2%) of pressures for the shield-stage subaerial volcanoes Kilauea, Mauna Loa, and Mauna Kea, fall in the range 0-140 MPa, corresponding to depths of 0-5 km. Glasses from the Puna Ridge yield pressures ranging from 18 to 126 MPa and are virtually identical to pressures determined from glasses from Kilauea (0 to 129 MPa). These results are consistent with the presence of magma reservoirs at depths of 0-5 km beneath the large shield volcanoes. The inferred depth of the magma reservoir beneath the summit of Kilauea (average = 1.8 km, maximum = 5 km) agrees extremely well with depths ( 2-6 km) estimated from seismic studies. The results for Kilauea and Mauna Kea indicate that significant partial crystallization also occurs beneath the summit reservoirs at depths up to 11 km. These results are consistent with seismic evidence for the presence of a magma reservoir at 8-11 km beneath Kilauea at the base of the volcanic pile. The results for Loihi indicate crystallization at higher average pressures (100-400 MPa) and depths (3-14 km) than the large shield volcanoes, suggesting that the plumbing system is not yet fully developed, and that the Hawaiian volcanic plumbing systems evolve over time.

Comparison of alternative spatial resolutions in the application of a spatially distributed biogeochemical model over complex terrain

USGS Publications Warehouse

Turner, D.P.; Dodson, R.; Marks, D.

1996-01-01

Spatially distributed biogeochemical models may be applied over grids at a range of spatial resolutions, however, evaluation of potential errors and loss of information at relatively coarse resolutions is rare. In this study, a georeferenced database at the 1-km spatial resolution was developed to initialize and drive a process-based model (Forest-BGC) of water and carbon balance over a gridded 54976 km2 area covering two river basins in mountainous western Oregon. Corresponding data sets were also prepared at 10-km and 50-km spatial resolutions using commonly employed aggregation schemes. Estimates were made at each grid cell for climate variables including daily solar radiation, air temperature, humidity, and precipitation. The topographic structure, water holding capacity, vegetation type and leaf area index were likewise estimated for initial conditions. The daily time series for the climatic drivers was developed from interpolations of meteorological station data for the water year 1990 (1 October 1989-30 September 1990). Model outputs at the 1-km resolution showed good agreement with observed patterns in runoff and productivity. The ranges for model inputs at the 10-km and 50-km resolutions tended to contract because of the smoothed topography. Estimates for mean evapotranspiration and runoff were relatively insensitive to changing the spatial resolution of the grid whereas estimates of mean annual net primary production varied by 11%. The designation of a vegetation type and leaf area at the 50-km resolution often subsumed significant heterogeneity in vegetation, and this factor accounted for much of the difference in the mean values for the carbon flux variables. Although area wide means for model outputs were generally similar across resolutions, difference maps often revealed large areas of disagreement. Relatively high spatial resolution analyses of biogeochemical cycling are desirable from several perspectives and may be particularly important in the study of the potential impacts of climate change.

Evaluation of acoustic telemetry grids for determining aquatic animal movement and survival

USGS Publications Warehouse

Kraus, Richard T.; Holbrook, Christopher; Vandergoot, Christopher; Stewart, Taylor R.; Faust, Matthew D.; Watkinson, Douglas A.; Charles, Colin; Pegg, Mark; Enders, Eva C.; Krueger, Charles C.

2018-01-01

Acoustic telemetry studies have frequently prioritized linear configurations of hydrophone receivers, such as perpendicular from shorelines or across rivers, to detect the presence of tagged aquatic animals. This approach introduces unknown bias when receivers are stationed for convenience at geographic bottlenecks (e.g., at the mouth of an embayment or between islands) as opposed to deployments following a statistical sampling design.We evaluated two-dimensional acoustic receiver arrays (grids: receivers spread uniformly across space) as an alternative approach to provide estimates of survival, movement, and habitat use. Performance of variably-spaced receiver grids (5–25 km spacing) was evaluated by simulating (1) animal tracks as correlated random walks (speed: 0.1–0.9 m/s; turning angle standard deviation: 5–30 degrees); (2) variable tag transmission intervals along each track (nominal delay: 15–300 seconds); and (3) probability of detection of each transmission based on logistic detection range curves (midpoint: 200–1500 m). From simulations, we quantified i) time between successive detections on any receiver (detection time), ii) time between successive detections on different receivers (transit time), and iii) distance between successive detections on different receivers (transit distance).In the most restrictive detection range scenario (200 m), the 95th percentile of transit time was 3.2 days at 5 km grid spacing, 5.7 days at 7 km, and 15.2 days at 25 km; for the 1500 m detection range scenario, it was 0.1 days at 5 km, 0.5 days at 7 km, and 10.8 days at 25 km. These values represented upper bounds on the expected maximum time that an animal could go undetected. Comparison of the simulations with pilot studies on three fishes (walleye Sander vitreus, common carp Cyprinus carpio, and channel catfish Ictalurus punctatus) from two independent large lake ecosystems (lakes Erie and Winnipeg) revealed shorter detection and transit times than what simulations predicted.By spreading effort uniformly across space, grids can improve understanding of fish migration over the commonly employed receiver line approach, but at increased time cost for maintaining grids.

Density-lag anomaly patterns in backshore sands along a paraglacial barrier spit

NASA Astrophysics Data System (ADS)

Pupienis, Donatas; Buynevich, Ilya; Jarmalavičius, Darius; Fedorovič, Julija; Žilinskas, Gintautas; Ryabchuk, Daria; Kovaleva, Olga; Sergeev, Alexander; Cichon-Pupienis, Anna

2016-04-01

The Curonian Spit, located along the southeast Baltic Sea coast, is one of the longest paraglacial mega-barriers in the world (~100 km) and is characteried by microtidal sandy beaches and unbroken foredune ridge emplaced by human activities in historical times. Both are dominated by quartzo-feldpathic sand, with various fractions of heavy minerals that may be concentrated as density lag. Such heavy-mineral concentrations (HMCs) may be distributed weither randomly or regularly along the coast, depending on the geological framework, hydro-aeolian processes, and human activities (e.g., steel elements of coastal engineering structures, military installations, etc.). In this study, we focus on the longshore patterns in HMC distribution and relative magnitude (mainly the concentration of ferrimagnetic components). Along the entire Curonian Spit coast (Russia-Lithuania), a total of 184 surface sand samples were collected at 1 km interval from the berm and foredune toe (seaward base). HMCs were characterized in the laboratory using bulk low-field magnetic susceptibility (MS). The Wavelength and Lomb spectral analysis were used to assess the spatial rhythmicity of their longshore distribution. Generally, quartz sand is characterised by low MS values of ĸ<50 μSI, whereas higher values ĸ>150 μSI are typical for heavy mineral-rich sand. MS values on the berm and foredune toe range from 11.2-4977.9 μSI and from 9.2-3153.0 μSI, respectively. Density lag anomalies had MS values exceeding an average value by ≥3 times. Wavelength and Lomb spectral analysis allowed to identify several clusters of periodicities with wavelength varying from 2-12 km, with power spectra having statistically significant values (>95 % CI). Along the modern Curonian Spit coast, two scales of rhythmic pattern variation are evident: macroscale (≤12 km) and mesoscale (2-3 km). The former can be attributed to localized expressions of geological framework (iron-rich components) and engineering structures (especially within the southern part of the spit), whereas the mesoscale patterns reflect spatial distribution of short-term hydro-aeolian forcing (erosional-accretionary cells) that may shift temporally. This research was supported by Lithuanian Science Council (Grant No. MIP-039/2014), the Internationalization Program Award, Temple University and Russian Scientific Fund (Grant No. 14-37-00047).

Atomic charge transfer-counter polarization effects determine infrared CH intensities of hydrocarbons: a quantum theory of atoms in molecules model.

PubMed

Silva, Arnaldo F; Richter, Wagner E; Meneses, Helen G C; Bruns, Roy E

2014-11-14

Atomic charge transfer-counter polarization effects determine most of the infrared fundamental CH intensities of simple hydrocarbons, methane, ethylene, ethane, propyne, cyclopropane and allene. The quantum theory of atoms in molecules/charge-charge flux-dipole flux model predicted the values of 30 CH intensities ranging from 0 to 123 km mol(-1) with a root mean square (rms) error of only 4.2 km mol(-1) without including a specific equilibrium atomic charge term. Sums of the contributions from terms involving charge flux and/or dipole flux averaged 20.3 km mol(-1), about ten times larger than the average charge contribution of 2.0 km mol(-1). The only notable exceptions are the CH stretching and bending intensities of acetylene and two of the propyne vibrations for hydrogens bound to sp hybridized carbon atoms. Calculations were carried out at four quantum levels, MP2/6-311++G(3d,3p), MP2/cc-pVTZ, QCISD/6-311++G(3d,3p) and QCISD/cc-pVTZ. The results calculated at the QCISD level are the most accurate among the four with root mean square errors of 4.7 and 5.0 km mol(-1) for the 6-311++G(3d,3p) and cc-pVTZ basis sets. These values are close to the estimated aggregate experimental error of the hydrocarbon intensities, 4.0 km mol(-1). The atomic charge transfer-counter polarization effect is much larger than the charge effect for the results of all four quantum levels. Charge transfer-counter polarization effects are expected to also be important in vibrations of more polar molecules for which equilibrium charge contributions can be large.

Isotopic and chemical evidence concerning the genesis and contamination of basaltic and rhyolitic magma beneath the Yellowstone Plateau Volcanic Field

USGS Publications Warehouse

Hildreth, W.; Halliday, A.N.; Christiansen, R.L.

1991-01-01

Since 2.2 Ma, the Yellowstone Plateau Volcanic Field has produced ~6000 km3 of rhyolite tuffs and lavas in >60 separate eruptions, as well as ~100 km3 of tholeiitic basalt from >50 vents peripheral to the silicic focus. Intermediate eruptive products are absent. Early postcollapse rhyolites show large shifts in Nd, Sr, Pb, and O isotopic composition caused by assimilation of roof rocks and hydrothermal brines during collapse and resurgence. Younger intracaldera rhyolite lavas record partial isotopic recovery toward precaldera ratios. Thirteen extracaldera rhyolites show none of these effects and have sources independent of the subcaldera magma system. Contributions from the Archaean crust have extreme values and wide ranges of Nd-, Sr, and Pb-isotope ratios, but Yellowstone rhyolites have moderate values and limited ranges. This requires their deep-crustal sources to have been pervasively hybridized by distributed intrusion of Cenozoic basalt, most of which was probably contemporaneous with the Pliocene and Quaternary volcanism. Most Yellowstone basalts had undergone cryptic clinopyroxene fractionation in the lower crust or crust-mantle transition zone and, having also ascended through or adjacent to crustal zones of silicic-magma generation, most underwent some crustal contamination. -from Authors

Preliminary study of crust-upper mantle structure of the Tibetan Plateau by using broadband teleseismic body waveforms

NASA Astrophysics Data System (ADS)

Zhu, Lu-Pei; Zeng, Rong-Sheng; Wu, Francis T.; Owens, Thomas J.; Randall, George E.

1993-05-01

As part of a joint Sino-U.S. research project to study the deep structure of the Tibetan Plateau, 11 broadband digital seismic recorders were deployed on the Plateau for one year of passive seismic recording. In this report we use teleseimic P waveforms to study the seismic velocity structure of crust and upper mantle under three stations by receiver function inversion. The receiver function is obtained by first rotating two horizontal components of seismic records into radial and tangential components and then deconvolving the vertical component from them. The receiver function depends only on the structure near the station because the source and path effects have been removed by the deconvolution. To suppress noise, receiver functions calculated from events clustered in a small range of back-azimuths and epicentral distances are stacked. Using a matrix formalism describing the propagation of elastic waves in laterally homogeneous stratified medium, a synthetic receiver function and differential receiver functions for the parameters in each layer can be calculated to establish a linearized inversion for one-dimensional velocity structure. Preliminary results of three stations, Wen-quan, Golmud and Xigatze (Coded as WNDO, TUNL and XIGA), located in central, northern and southern Plateau are given in this paper. The receiver functions of all three stations show clear P-S converted phases. The time delays of these converted phases relative to direct P arrivals are: WNDO 7.9s (for NE direction) and 8.3s (for SE direction), TUNL 8.2s, XIGA 9.0s. Such long time delays indicate the great thickness of crust under the Plateau. The differences between receiver function of these three station shows the tectonic difference between southern and north-central Plateau. The waveforms of the receiver functions for WNDO and TUNL are very simple, while the receiver function of XIGA has an additional midcrustal converted phase. The S wave velocity structures at these three stations are estimated from inversions of the receiver function. The crustal shear wave velocities at WNDO and TUNL are vertically homogeneous, with value between 3.5 3.6 km/s down to Moho. This value in the lower crust is lower than the normal value for the lower crust of continents, which is consistent with the observed strong Sn attenuation in this region. The velocity structure at XIGA shows a velocity discontinuity at depth of 20 km and high velocity value of 4.0 km/s in the midcrust between 20 30 km depth. Similar results are obtained from a DSS profile in southern Tibet. The velocity under XIGA decreases below a depth of 30 km, reaching the lowest value of 3.2 km/s between 50 55 km. depth. This may imply that the Indian crust underthrusts the low part of Tibetan crust in the southern Plateau, forming a “double crust”. The crustal thickness at each of these sites is: WNDO, 68 km; TUNL, 70 km; XI-GA, 80 km.

Probing ionospheric structures using the LOFAR radio telescope

NASA Astrophysics Data System (ADS)

Mevius, M.; van der Tol, S.; Pandey, V. N.; Vedantham, H. K.; Brentjens, M. A.; de Bruyn, A. G.; Abdalla, F. B.; Asad, K. M. B.; Bregman, J. D.; Brouw, W. N.; Bus, S.; Chapman, E.; Ciardi, B.; Fernandez, E. R.; Ghosh, A.; Harker, G.; Iliev, I. T.; Jelić, V.; Kazemi, S.; Koopmans, L. V. E.; Noordam, J. E.; Offringa, A. R.; Patil, A. H.; van Weeren, R. J.; Wijnholds, S.; Yatawatta, S.; Zaroubi, S.

2016-07-01

LOFAR is the LOw-Frequency Radio interferometer ARray located at midlatitude (52°53'N). Here we present results on ionospheric structures derived from 29 LOFAR nighttime observations during the winters of 2012/2013 and 2013/2014. We show that LOFAR is able to determine differential ionospheric total electron content values with an accuracy better than 0.001 total electron content unit = 1016m-2 over distances ranging between 1 and 100 km. For all observations the power law behavior of the phase structure function is confirmed over a long range of baseline lengths, between 1 and 80 km, with a slope that is, in general, larger than the 5/3 expected for pure Kolmogorov turbulence. The measured average slope is 1.89 with a one standard deviation spread of 0.1. The diffractive scale, i.e., the length scale where the phase variance is 1rad2, is shown to be an easily obtained single number that represents the ionospheric quality of a radio interferometric observation. A small diffractive scale is equivalent to high phase variability over the field of view as well as a short time coherence of the signal, which limits calibration and imaging quality. For the studied observations the diffractive scales at 150 MHz vary between 3.5 and 30 km. A diffractive scale above 5 km, pertinent to about 90% of the observations, is considered sufficient for the high dynamic range imaging needed for the LOFAR epoch of reionization project. For most nights the ionospheric irregularities were anisotropic, with the structures being aligned with the Earth magnetic field in about 60% of the observations.

Vertical profile of polarization over Vladivostok using horizon shadowing: Clues to understanding the altitude variation of reflectance of aerosol particles

NASA Astrophysics Data System (ADS)

Pavlov, Andrey N.; Zubko, Evgenij; Konstantinov, Oleg G.; Shmirko, Konstantin; Mayor, Alexander Yu.; Videen, Gorden

2018-01-01

We report polarimetric measurements of atmospheric aerosol in evening and morning twilight over Vladivostok (Russia) in late winter-early spring of 2017 using a horizon-shadowing technique. Motion of the Sun beneath the horizon changes the altitude of the boundary of the shadowed atmosphere h, making it possible to constrain the altitude of aerosol particles contributing to the polarimetric response. We investigate the degree of linear polarization P in aerosol particles at different altitudes, ranging from 0 km up to 17 km. In two out of four experiments we found significant variations of the polarimetric response (ΔP ∼ 10%) with altitude; whereas, in the other measurements, the polarization appeared nearly the same (ΔP ∼ 2-3%) throughout the entire range of the studied altitude. Polarization P was measured in the zenith direction with the scattering angle being θ ∼ 90° At such a scattering angle, the polarization is near its maximum value Pmax. We analyze our measurements using the Umov effect that describes an inverse correlation between Pmax and the geometric albedo A. On 2017-02-21, we estimate A ≈ 0.0120 ± 0.0004 at h = 0 km and A ≈ 0.0154 ± 0.0026 at h = 10 km. On 2017-02-27, we find the opposite trend, A ≈ 0.0108 ± 0.0003 (h = 0 km) and A ≈ 0.0084 ± 0.0006 (h = 10 km). On 2017-03-02 and 2017-03-03 we find A ≈ 0.0084 ± 0.0009 and A ≈ 0.0090 ± 0.0010, respectively. Conclusions drawn from polarimetric measurements appear in qualitative accordance with results of remote sensing with a three-wavelength lidar.

Magnetotelluric Investigations in Tuwa-Godhra Region, Gujarat (India)

NASA Astrophysics Data System (ADS)

Mohan, Kapil; Chaudhary, Peush; Kumar, G. Pavan; Kothyari, Girish Ch.; Choudhary, Virender; Nagar, Mehul; Patel, Pruthul; Gandhi, Drasti; Kushwaha, Dilip; Rastogi, B. K.

2018-05-01

Magnetotelluric (MT) data have been acquired at 40 locations in Tuwa and its surrounding region (200 km east of Ahmedabad and 15 km north-northwest of Godhra) in the Mainland Gujarat with an average station spacing of 1.5 km. MT impedance tensors have been estimated in the period range of 0.001-100 s. The data have been modeled using non-linear conjugate gradient scheme taking both apparent resistivity and phase into account. From the 2D models of the MT data, the weathered granite with Quaternary sediments (with resistivity of < 700 Ω m) have been inferred up to a depth of 500 m followed by Godhra granite (having resistivity up to 105 Ω m) with a thickness 6.5 km. The Aravalli supergroup has been inferred below Godhra granite. The Lunavada group of rocks have been inferred in the eastern part of the study area (having resistivity value ranging from 103 to 104 Ω m) separated from the Godhra granite by a contact zone. The comparatively very low-resistivity rocks (< 400 Ω m) of Udaipur formation followed by Paleoproterozoic carbonate rocks with fluid have been inferred below 8-10 km depth. The percolation of water from the surface through the contact zone of Lunavada and Champaner groups has been suggested. The presence of hot water springs in 10 km SW from the center of the study area (at the contact zone of Godhra granite and basalt) might be due to the western trending lithostratigraphic slope, hydrostatic pressure generated due to heat produced from interaction of water with the carbonate rocks at deeper depth and high subsurface temperature due to high geothermal gradient. The segmented nature of Himmatnagar Fault (HnF) is identified in the central portion of the study area.

Range Reference Atmosphere 0-70 Km Altitude. Kwajalein Missile Range, Kwajalein, Marshall Islands

DTIC Science & Technology

1982-01-01

DOCUMENT 360-82 KWAJALEIN MISSILE RANGE KWAJALEIN, MARSHALL ISLANDS RANGE REFERENCE ATMOSPHERE 0-70 KM ALTITUDE, C00 L’’I METEOROLOGY GROUP .RANGE...34Reference Atmosphere (Part 1), Kwajale 4n Missile Range, Kwajalein, Marshall Islands ," ADA002664. * 19. KEY WORDS (Continue on revorsae d. If necoeewy...CLASSIFICATION OF TIlS PAGE (Whe~n Data EnterecD -v DOCUMENT 360-82 Vo- KWAJALEIN MISSILE RANGE KWAJALEIN, MARSHALL ISLANDS RANGE REFERENCE ATMOSPHERE 0-70 km

Comparisons of the NGA ground-motion relations

USGS Publications Warehouse

Abrahamson, N.; Atkinson, G.; Boore, D.; Bozorgnia, Y.; Campbell, K.; Chiou, B.; Idriss, I.M.; Silva, W.; Young, S.R.

2008-01-01

The data sets, model parameterizations, and results from the five NGA models for shallow crustal earthquakes in active tectonic regions are compared. A key difference in the data sets is the inclusion or exclusion of aftershocks. A comparison of the median spectral values for strike-slip earthquakes shows that they are within a factor of 1.5 for magnitudes between 6.0 and 7.0 for distances less than 100 km. The differences increase to a factor of 2 for M5 and M8 earthquakes, for buried ruptures, and for distances greater than 100 km. For soil sites, the differences in the modeling of soil/sediment depth effects increase the range in the median long-period spectral values for M7 strike-slip earthquakes to a factor of 3. The five models have similar standard deviations for M6.5-M7.5 earthquakes for rock sites and for soil sites at distances greater than 50 km. Differences in the standard deviations of up to 0.2 natural log units for moderate magnitudes at all distances and for large magnitudes at short distances result from the treatment of the magnitude dependence and the effects of nonlinear site response on the standard deviation. ?? 2008, Earthquake Engineering Research Institute.

A multiscale analysis of coral reef topographic complexity using lidar-derived bathymetry

USGS Publications Warehouse

Zawada, D.G.; Brock, J.C.

2009-01-01

Coral reefs represent one of the most irregular substrates in the marine environment. This roughness or topographic complexity is an important structural characteristic of reef habitats that affects a number of ecological and environmental attributes, including species diversity and water circulation. Little is known about the range of topographic complexity exhibited within a reef or between different reef systems. The objective of this study was to quantify topographic complexity for a 5-km x 5-km reefscape along the northern Florida Keys reef tract, over spatial scales ranging from meters to hundreds of meters. The underlying dataset was a 1-m spatial resolution, digital elevation model constructed from lidar measurements. Topographic complexity was quantified using a fractal algorithm, which provided a multi-scale characterization of reef roughness. The computed fractal dimensions (D) are a measure of substrate irregularity and are bounded between values of 2 and 3. Spatial patterns in D were positively correlated with known reef zonation in the area. Landward regions of the study site contain relatively smooth (D ??? 2.35) flat-topped patch reefs, which give way to rougher (D ??? 2.5), deep, knoll-shaped patch reefs. The seaward boundary contains a mixture of substrate features, including discontinuous shelf-edge reefs, and exhibits a corresponding range of roughness values (2.28 ??? D ??? 2.61). ?? 2009 Coastal Education and Research Foundation.

Structure and rheology of the lithosphere below southeastern margin of India and Sri Lanka, and its conjugate segment of the east Antarctica: Implications on early breakup history and margin formation

NASA Astrophysics Data System (ADS)

Rao Gangumalla, Srinivasa; Radhakrishna, Munukutla

2014-05-01

The eastern continental margin of India has evolved as a consequence of rifting and breakup between India and east Antarctica during the early Cretaceous. Plate reconstruction models for the breakup of eastern Gondwanaland by many earlier workers have unambiguously placed the southeast margin of Sri Lanka and India together as a conjugate segment with the east Antarctica margin that extends from Gunnerus Ridge in the west to western Enderby basin in the east. In this study, we present results of integrated analysis of gravity, geoid, magnetic and seismic data from these two conjugate portions in order to examine the lithosphere structure and early seafloor spreading, style of breakup, continent-ocean boundary (COB) and rheological characteristics at these margins. The interpreted COB lies at a distance of 55-140 km on the side of southeast margin of Sri Lanka and India, whereas, it lies at a distance of 190-550 km on the side of east Antarctica margin. The seismic profiles and the constrained potential field models across these two segments do not show the existence of seaward dipping reflector sequences or magmatic underplating suggesting that these segments have not encountered major magmatic activity. While, significant crustal thinning/stretching is observed at the east Antarctic margin, the Cauvery offshore had experienced limited stretching with faulted Moho interface. Further, the conspicuous residual geoid low in the Cauvery offshore basin is inferred to be due to a continental crustal block. The modelled Lithosphere-Astenosphere Boundary (LAB) in these two margins is located around 110-120 km depth with slightly thicker lithosphere at the east Antarctica margin. In addition, the interpretation of magnetic anomalies provided structure of the oceanic crust generated through seafloor spreading processes with age and magnetization data constrained from the identified magnetic anomalies in the respective margins. Using the Bouguer coherence method, we computed spatial variations in effective elastic thickness (Te) at these margin segments. The estimated Te values at the Indian margin ranges between 5-8 km in the southeast of Sri Lanka to around 10-12 km in the Cauvery offshore which decrease further north to < 5 km in the Cauvery-Palar basin. Along the east Antarctic margin, the Te values ranges between 5-10 km in the Gunnerus ridge region, 35-40 km in the western Enderby basin which decrease further towards the central Enderby basin up to 20 km. In this study, the above results have been analyzed in terms of early breakup mechanism and subsequent evolution of these two conjugate segments.

Regional-Scale High-Latitude Extreme Geoelectric Fields Pertaining to Geomagnetically Induced Currents

NASA Technical Reports Server (NTRS)

Pulkkinen, Antti; Bernabeu, Emanuel; Eichner, Jan; Viljanen, Ari; Ngwira, Chigomezyo

2015-01-01

Motivated by the needs of the high-voltage power transmission industry, we use data from the high-latitude IMAGE magnetometer array to study characteristics of extreme geoelectric fields at regional scales. We use 10-s resolution data for years 1993-2013, and the fields are characterized using average horizontal geoelectric field amplitudes taken over station groups that span about 500-km distance. We show that geoelectric field structures associated with localized extremes at single stations can be greatly different from structures associated with regionally uniform geoelectric fields, which are well represented by spatial averages over single stations. Visual extrapolation and rigorous extreme value analysis of spatially averaged fields indicate that the expected range for 1-in-100-year extreme events are 3-8 V/km and 3.4-7.1 V/km, respectively. The Quebec reference ground model is used in the calculations.

Fractionation of Cu and Mo isotopes caused by vapor-liquid partitioning, evidence from the Dahutang W-Cu-Mo ore field

NASA Astrophysics Data System (ADS)

Yao, Junming; Mathur, Ryan; Sun, Weidong; Song, Weile; Chen, Huayong; Mutti, Laurence; Xiang, Xinkui; Luo, Xiaohong

2016-05-01

The study presents δ65Cu and δ97Mo isotope values from cogenetic chalcopyrite and molybdenite found in veins and breccias of the Dahutang W-Cu-Mo ore field in China. The samples span a 3-4 km range. Both isotopes show a significant degree of fractionation. Cu isotope values in the chalcopyrite range from -0.31‰ to +1.48‰, and Mo isotope values in the molybdenite range from -0.03‰ to +1.06‰. For the cogenetic sulfide veined samples, a negative slope relationship exists between δ65Cu and δ97Mo values, which suggest a similar fluid history. Rayleigh distillation models the vein samples' change in isotope values. The breccia samples do not fall on the trend, thus indicating a different source mineralization event. Measured fluid inclusion and δD and δ18O data from cogenetic quartz indicate changes in temperature, and mixing of fluids do not appear to cause the isotopic shifts measure. Related equilibrium processes associated with the partitioning of metal between the vapor-fluid in the hydrothermal system could be the probable cause for the relationship seen between the two isotope systems.

Bounds on strain in large Tertiary shear zones of SE Asia from boudinage restoration

NASA Astrophysics Data System (ADS)

Lacassin, R.; Leloup, P. H.; Tapponnier, P.

1993-06-01

We have used surface-balanced restoration of stretched, boudinaged layers to estimate minimum amounts of finite strain in the mylonitic gneisses of the Oligo-Miocene Red River-Ailao Shan shear zone (Yunnan, China) and of the Wang Chao shear zone (Thailand). The layer-parallel extension values thus obtained range between 250 and 870%. We discuss how to use such extension values to place bounds on amounts of finite shear strain in these large crustal shear zones. Assuming simple shear, these values imply minimum total and late shear strains of, respectively, 33 ± 6 and 7 ± 3 at several sites along the Red River-Ailao Shan shear zone. For the Wang Chao shear zone a minimum shear strain of 7 ± 4 is deduced. Assuming homogeneous shear would imply that minimum strike-slip displacements along these two left-lateral shear zones, which have been interpreted to result from the India-Asia collision, have been of the order of 330 ± 60 km (Red River-Ailao Shan) and 35 ± 20 km (Wang Chao).

In situ stratospheric measurements of CH4, (C-13)H4, N2O, and OC(O-18) using the BLISS tunable diode laser spectrometer

NASA Technical Reports Server (NTRS)

Webster, Christopher R.; May, Randy D.

1992-01-01

Simultaneous in situ measurements of stratospheric CH4, (C-13)H4, N2O, OC(O-18), pressure, and temperature have been made from Palestine, Texas (32 deg N) in September 1988 with the JPL Balloon-borne Laser In Situ Sensor. Measurements of CH4 and N2O in the altitude range 30-35 km agree well with other measurements, except for an anomalously high value for the N2O at 31 km. Measurements of CH4 support earlier observations of fold in the vertical profile. A ratio for stratospheric (C-13)H4/CH4 of 0.0105 +/- 0.0010 implies an enrichment of delta(C-13) = -45 +/- 92 parts per thousand over the PDB value, in agreement with previous measurements in the troposphere. A large mixing ratio of 1.9 +/- 0.2 ppmv for OC(O-18) is measured, corresponding to an enrichment of delta(O-18) = 280 +/- 50 parts per thousand for the (O-18) isotopic species over the SMOW value.

An Acousto-Optical Sensor with High Angular Resolution

PubMed Central

Kaloshin, Gennady; Lukin, Igor

2012-01-01

The paper introduces a new laser interferometry-based sensor for diagnosis of random media by means of high accuracy angle measurements and describes the results of its development and testing. Theoretical calculations of the dependence of the range of the laser interferometer on laser beam parameters, device geometry, and atmospheric turbulence characteristics are reported. It is demonstrated that at moderate turbulence intensities corresponding to those observed most frequently in turbulent atmosphere at moderate latitudes and with low interference contrast values, the performance range of the laser interferometer-based device exceeds 5 km. PMID:22737034

Bulk Properties of Isentropic Mixing into the Tropics in the Lower Stratosphere

NASA Technical Reports Server (NTRS)

Minschwaner, K.; Dessler, A. E.; Elkins, J. W.; Volk, C. M.; Fahey, D. W.; Loewenstein, M.; Podolske, J. R.; Chan, K. R.; Roche, A. E.

1996-01-01

Timescales for mixing of midlatitude air into the tropical lower stratosphere are deduced from observations of long-lived tracers N2O and CCl3F. Bulk mixing between tropical and midlatitude regions is assumed to be isentropic and relatively slow compared with local mixing within each region. The mean value of the mixing timescale ranges from 12 to 18 months near 20 km. There is a tendency for shorter mixing times at higher and lower altitudes, although vertical profiles of mixing cannot be definitively established by the data. A more robust quantity is given by the fraction of midlatitude air entrained into the tropical upwelling region. Implied mixing fractions exceed 50% above 22 km.

Crater dimensions from apollo data and supplemental sources

USGS Publications Warehouse

Pike, R.J.

1976-01-01

A catalog of crater dimensions that were compiled mostly from the new Apollo-based Lunar Topographic Orthophotomaps is presented in its entirety. Values of crater diameter, depth, rim height, flank width, circularity, and floor diameter (where applicable) are tabulated for a sample of 484 craters on the Moon and 22 craters on Earth. Systematic techniques of mensuration are detailed. The lunar craters range in size from 400 m to 300 km across and include primary impact craters of the main sequence, secondary impact craters, craterlets atop domes and cones, and dark-halo craters. The terrestrial craters are between 10 m and 22.5 km in diameter and were formed by meteorite impact. ?? 1976 D. Reidel Publishing Company.

Soil erosion rates (particulate and dissolved fluxes) variations in a temperate river basin

NASA Astrophysics Data System (ADS)

Cerdan, Olivier; Gay, Aurore; Négrel, Philippe; Pételet-Giraud, Emmanuelle; Salvador Blanes, Sébastien; Degan, Francesca

2015-04-01

Soil erosion is one of the major drivers of landscape evolution in Western Europe. However, depending on the land use characteristics and on the geological and topographical settings, miscellaneous forms of erosion may lead to a very diverse morphological evolution. To understand these landscape evolutions different scientific questions remain to be answered or quantified. The main difficulty arises from the nonlinear interactions between different erosional processes that act at different temporal and spatial scales. This study proposes to investigate different datasets describing particulate and dissolved sediment fluxes within a French River basin (The Loire River) at different spatial scales and at temporal scales ranging from the flood event to several decades. The particulate sediment load values at the outlet of the catchments range from 2.5 102 to 8.6 105 t yr-1, and the sediment yield values range from 2.9 to 32.4 t km 2 yr-1. Sediment exports from the Loire and Brittany river basins are low compared with mountainous regions and European exports. However, a strong spatial variability within this territory exists. The expected results on the sediment yield spatial pattern distribution and the correlation between SY values and basin sizes are not observed. An analysis of the sediment yield values at different time steps shows a strong effect of the seasonal availability of detached particles to be transported. High concentrations of suspended sediments during the winter and lower values during the summer and autumn are observed. Inter-annual variations are also observed, with export values varying by a factor 2 to 10 between years for one catchment. The influence of rainfall on the sediment exports is predominant, but investigations on physical characteristics of each catchment (e.g., lithology, slope, land use) are required to better understand the production and transfer processes within a drainage basin. These inter-annual variations imply that long-term data are required to provide mean SY values representative of the catchment functioning. From our calculations, 18 complete years of data are required to obtain a mean sediment yield value with less than 10% of variation on average around the mean. The specific dissolved fluxes vary from 13.7 to 199.9 t.km-2. t yr-1. Contrary to particulate matters, the impact of the lithology is illustrated by higher total dissolved solid fluxes on limestone catchments compared with graniteous or schisteous catchments. Nitrates and ammonium are indicators of anthropogenic perturbation and their fluxes vary respectively from 0.4 to 31.4 t.km-2. yr-1 and from 7.8*10-3 to 7.7 t.km-2. yr-1 and evolve differently according to land uses: nitrates fluxes are lower in the upstream Loire and higher downstream in the region where agricultural pressure is higher. The analysis of these datasets at different spatial and temporal scales permits to identify some of the dominant processes, and also to distinguish natural from anthropogenic influences. Concerning upland physical soil surface erosion rates, we find that the average travel distance of eroded particles may be limited, implying a strong decrease in physical erosion rates when moving from the local scale (m²) to the river basin scale (> 103 km²). Chemical erosion rates are less sensitive to scale and can either decrease or increase with increasing area in function of lithology, land management and topography. The results also highlight the predominant role of surface connectivity to characterize the fraction of sediment exported out of river drainage areas by physical soil surface erosion. For the export of dissolved sediment originating from weathering processes, the catchment physiography and connectivity does no longer play the dominant role. A direct link between soil production rates and exported dissolved fluxes tends to show that, contrary to the suspended particles, which are transport-limited, the dissolved matter seems to be supply-limited.

Stratospheric aerosols from the Sarychev volcano eruption in the 2009 Arctic summer

NASA Astrophysics Data System (ADS)

Jégou, F.; Berthet, G.; Brogniez, C.; Renard, J.-B.; François, P.; Haywood, J. M.; Jones, A.; Bourgeois, Q.; Lurton, T.; Auriol, F.; Godin-Beekmann, S.; Guimbaud, C.; Krysztofiak, G.; Gaubicher, B.; Chartier, M.; Clarisse, L.; Clerbaux, C.; Balois, J. Y.; Verwaerde, C.; Daugeron, D.

2013-07-01

Aerosols from the Sarychev volcano eruption (Kuril Islands, northeast of Japan) were observed in the Arctic lower stratosphere a few days after the strongest SO2 injection which occurred on 15 and 16 June 2009. From the observations provided by the Infrared Atmospheric Sounding Interferometer (IASI) an estimated 0.9 Tg of sulphur dioxide was injected into the upper troposphere and lower stratosphere (UTLS). The resultant stratospheric sulphate aerosols were detected from satellites by the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb sounder and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and from the surface by the Network for the Detection of Atmospheric Composition Changes (NDACC) lidar deployed at OHP (Observatoire de Haute-Provence, France). By the first week of July the aerosol plume had spread out over the entire Arctic region. The Sarychev-induced stratospheric aerosol over the Kiruna region (north of Sweden) was measured by the Stratospheric and Tropospheric Aerosol Counter (STAC) during eight balloon flights planned in August and September 2009. During this balloon campaign the Micro Radiomètre Ballon (MicroRADIBAL) and the Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON) remote-sensing instruments also observed these aerosols. Aerosol concentrations returned to near-background levels by spring 2010. The effective radius, the surface area density (SAD), the aerosol extinction, and the total sulphur mass from STAC in situ measurements are enhanced with mean values in the range 0.15-0.21 μm, 5.5-14.7 μm2 cm-3, 5.5-29.5 × 10-4 km-1, and 4.9-12.6 × 10-10 kg[S] kg-1[air], respectively, between 14 km and 18 km. The observed and modelled e-folding time of sulphate aerosols from the Sarychev eruption is around 70-80 days, a value much shorter than the 12-14 months calculated for aerosols from the 1991 eruption of Mt Pinatubo. The OSIRIS stratospheric aerosol optical depth (AOD) at 750 nm is enhanced by a factor of 6, with a value of 0.02 in late July compared to 0.0035 before the eruption. The HadGEM2 and MIMOSA model outputs indicate that aerosol layers in polar region up to 14-15 km are largely modulated by stratosphere-troposphere exchange processes. The spatial extent of the Sarychev plume is well represented in the HadGEM2 model with lower altitudes of the plume being controlled by upper tropospheric troughs which displace the plume downward and upper altitudes around 18-20 km, in agreement with lidar observations. Good consistency is found between the HadGEM2 sulphur mass density and the value inferred from the STAC observations, with a maximum located about 1 km above the tropopause ranging from 1 to 2 × 10-9 kg[S] kg-1[air], which is one order of magnitude higher than the background level.

THE MILKY WAY'S CIRCULAR-VELOCITY CURVE BETWEEN 4 AND 14 kpc FROM APOGEE DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bovy, Jo; Allende Prieto, Carlos; Meszaros, Szabolcs

2012-11-10

We measure the Milky Way's rotation curve over the Galactocentric range 4 kpc {approx}< R {approx}< 14 kpc from the first year of data from the Apache Point Observatory Galactic Evolution Experiment. We model the line-of-sight velocities of 3365 stars in 14 fields with b = 0 Degree-Sign between 30 Degree-Sign {<=} l {<=} 210 Degree-Sign out to distances of 10 kpc using an axisymmetric kinematical model that includes a correction for the asymmetric drift of the warm tracer population ({sigma} {sub R} Almost-Equal-To 35 km s{sup -1}). We determine the local value of the circular velocity to be V{submore » c} (R {sub 0}) = 218 {+-} 6 km s{sup -1} and find that the rotation curve is approximately flat with a local derivative between -3.0 km s{sup -1} kpc{sup -1} and 0.4 km s{sup -1} kpc{sup -1}. We also measure the Sun's position and velocity in the Galactocentric rest frame, finding the distance to the Galactic center to be 8 kpc < R {sub 0} < 9 kpc, radial velocity V {sub R, Sun} = -10 {+-} 1 km s{sup -1}, and rotational velocity V {sub {phi}, Sun} = 242{sup +10} {sub -3} km s{sup -1}, in good agreement with local measurements of the Sun's radial velocity and with the observed proper motion of Sgr A*. We investigate various systematic uncertainties and find that these are limited to offsets at the percent level, {approx}2 km s{sup -1} in V{sub c} . Marginalizing over all the systematics that we consider, we find that V{sub c} (R {sub 0}) < 235 km s{sup -1} at >99 % confidence. We find an offset between the Sun's rotational velocity and the local circular velocity of 26 {+-} 3 km s{sup -1}, which is larger than the locally measured solar motion of 12 km s{sup -1}. This larger offset reconciles our value for V{sub c} with recent claims that V{sub c} {approx}> 240 km s{sup -1}. Combining our results with other data, we find that the Milky Way's dark-halo mass within the virial radius is {approx}8 Multiplication-Sign 10{sup 11} M {sub Sun }.« less

Influence of air quality model resolution on uncertainty associated with health impacts

NASA Astrophysics Data System (ADS)

Thompson, T. M.; Selin, N. E.

2012-06-01

We use regional air quality modeling to evaluate the impact of model resolution on uncertainty associated with the human health benefits resulting from proposed air quality regulations. Using a regional photochemical model (CAMx), we ran a modeling episode with meteorological inputs representing conditions as they occurred during August through September 2006, and two emissions inventories (a 2006 base case and a 2018 proposed control scenario, both for Houston, Texas) at 36, 12, 4 and 2 km resolution. The base case model performance was evaluated for each resolution against daily maximum 8-h averaged ozone measured at monitoring stations. Results from each resolution were more similar to each other than they were to measured values. Population-weighted ozone concentrations were calculated for each resolution and applied to concentration response functions (with 95% confidence intervals) to estimate the health impacts of modeled ozone reduction from the base case to the control scenario. We found that estimated avoided mortalities were not significantly different between 2, 4 and 12 km resolution runs, but 36 km resolution may over-predict some potential health impacts. Given the cost/benefit analysis requirements of the Clean Air Act, the uncertainty associated with human health impacts and therefore the results reported in this study, we conclude that health impacts calculated from population weighted ozone concentrations obtained using regional photochemical models at 36 km resolution fall within the range of values obtained using fine (12 km or finer) resolution modeling. However, in some cases, 36 km resolution may not be fine enough to statistically replicate the results achieved using 2 and 4 km resolution. On average, when modeling at 36 km resolution, 7 deaths per ozone month were avoided because of ozone reductions resulting from the proposed emissions reductions (95% confidence interval was 2-9). When modeling at 2, 4 or 12 km finer scale resolution, on average 5 deaths were avoided due to the same reductions (95% confidence interval was 2-7). Initial results for this specific region show that modeling at a resolution finer than 12 km is unlikely to improve uncertainty in benefits analysis. We suggest that 12 km resolution may be appropriate for uncertainty analyses in areas with similar chemistry, but that resolution requirements should be assessed on a case-by-case basis and revised as confidence intervals for concentration-response functions are updated.

The Associated Absorption Features in Quasar Spectra of the Sloan Digital Sky Survey. I. Mg II Absorption Doublets

NASA Astrophysics Data System (ADS)

Chen, Zhi-Fu; Huang, Wei-Rong; Pang, Ting-Ting; Huang, Hong-Yan; Pan, Da-Sheng; Yao, Min; Nong, Wei-Jing; Lu, Mei-Mei

2018-03-01

Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II λλ2796, 2803 narrow absorption doublets in the spectra data around Mg II λ2798 emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299 ≤ z abs ≤ 2.5663. We find that a velocity offset of υ r < 6000 km s‑1 is a safe boundary to constrain the vast majority of associated Mg II systems, although we find some doublets at υ r > 6000 km s‑1. If associated Mg II absorbers are defined by υ r < 6000 km s‑1, ∼33.3% of the absorbers are supposed to be contaminants of intervening systems. Removing the 33.3% contaminants, ∼4.5% of the quasars present at least one associated Mg II system with {W}{{r}}λ 2796≥slant 0.2 \\mathringA . The fraction of associated Mg II systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The υ r distribution of the outflow Mg II absorbers is peaked at 1023 km s‑1, which is smaller than the corresponding value of the outflow C IV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by υ r > ‑3000 km s‑1 differs from that of absorbers constrained by υ r > 2000 km s‑1. Absorbers limited by υ r > 2000 km s‑1 and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger υ r . The distributions of equivalent widths, and the ratio of {W}rλ 2796/{W}rλ 2803, are the same for associated and intervening systems, and independent of quasar luminosity.

Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

NASA Technical Reports Server (NTRS)

Rall, Jonathan A. R.

1994-01-01

Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

AN INTRIGUING CHROMOSPHERIC JET OBSERVED BY HINODE: FINE STRUCTURE KINEMATICS AND EVIDENCE OF UNWINDING TWISTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Wei; Berger, Thomas E.; Title, Alan M.

2009-12-10

We report a chromospheric jet lasting for more than 1 hr observed by the Hinode Solar Optical Telescope in unprecedented detail. The ejection occurred in three episodes separated by 12-14 minutes, with the amount and velocity of material decreasing with time. The upward velocities range from 438 to 33 km s{sup -1}, while the downward velocities of the material falling back have smaller values (mean: -56km s{sup -1}) and a narrower distribution (standard deviation: 14km s{sup -1}). The average acceleration inferred from parabolic spacetime tracks is 141 m s{sup -2}, a fraction of the solar gravitational acceleration. The jet consistsmore » of fine threads (0.''5-2'' wide), which exhibit coherent, oscillatory transverse motions perpendicular to the jet axis and about a common equilibrium position. These motions propagate upward along the jet, with the maximum phase speed of 744+-11 km s{sup -1}at the leading front of the jet. The transverse oscillation velocities range from 151 to 26 km s{sup -1}, amplitudes from 6.0 to 1.9 Mm, and periods from 250 to 536 s. The oscillations slow down with time and cease when the material starts to fall back. The falling material travels along almost straight lines in the original direction of ascent, showing no transverse motions. These observations are consistent with the scenario that the jet involves untwisting helical threads, which rotate about the axis of a single large cylinder and shed magnetic helicity into the upper atmosphere.« less

Modelling the Crust beneath the Kashmir valley in Northwestern Himalaya

NASA Astrophysics Data System (ADS)

Mir, R. R.; Parvez, I. A.; Gaur, V. K.; A.; Chandra, R.; Romshoo, S. A.

2015-12-01

We investigate the crustal structure beneath five broadband seismic stations in the NW-SE trendingoval shaped Kashmir valley sandwiched between the Zanskar and the Pir Panjal ranges of thenorthwestern Himalaya. Three of these sites were located along the southwestern edge of the valley andthe other two adjoined the southeastern. Receiver Functions (RFs) at these sites were calculated usingthe iterative time domain deconvolution method and jointly inverted with surface wave dispersiondata to estimate the shear wave velocity structure beneath each station. To further test the results ofinversion, we applied forward modelling by dividing the crust beneath each station into 4-6homogeneous, isotropic layers. Moho depths were separately calculated at different piercing pointsfrom the inversion of only a few stacked receiver functions of high quality around each piercing point.These uncertainties were further reduced to ±2 km by trial forward modelling as Moho depths werevaried over a range of ±6 km in steps of 2 km and the synthetic receiver functions matched with theinverted ones. The final values were also found to be close to those independently estimated using theH-K stacks. The Moho depths on the eastern edge of the valley and at piercing points in itssouthwestern half are close to 55 km, but increase to about 58 km on the eastern edge, suggesting thathere, as in the central and Nepal Himalaya, the Indian plate dips northeastwards beneath the Himalaya.We also calculated the Vp/Vs ratio beneath these 5 stations which were found to lie between 1.7 and1.76, yielding a Poisson's ratio of ~0.25 which is characteristic of a felsic composition.

Comparison of midlatitude ionospheric F region peak parameters and topside Ne profiles from IRI2012 model prediction with ground-based ionosonde and Alouette II observations

NASA Astrophysics Data System (ADS)

Gordiyenko, G. I.; Yakovets, A. F.

2017-07-01

The ionospheric F2 peak parameters recorded by a ground-based ionosonde at the midlatitude station Alma-Ata [43.25N, 76.92E] were compared with those obtained using the latest version of the IRI model (http://omniweb.gsfc.nasa.gov/vitmo/iri2012_vitmo.html). It was found that for the Alma-Ata (Kazakhstan) location, the IRI2012 model describes well the morphology of seasonal and diurnal variations of the ionospheric critical frequency (foF2) and peak density height (hmF2) monthly medians. The model errors in the median foF2 prediction (percentage deviations between the median foF2 values and their model predictions) were found to vary approximately in the range from about -20% to 34% and showed a stable overestimation in the median foF2 values for daytime in January and July and underestimation for day- and nighttime hours in the equinoctial months. The comparison between the ionosonde hmF2 and IRI results clearly showed that the IRI overestimates the nighttime hmF2 values for March and September months, and the difference is up to 30 km. The daytime Alma-Ata hmF2 data were found to be close to the IRI predictions (deviations are approximately ±10-15 km) in winter and equinoctial months, except in July when the observed hmF2 values were much more (from approximately 50-200 km). The comparison between the Alouette foF2 data and IRI predictions showed mixed results. In particular, the Alouette foF2 data showed a tendency to be overestimated for daytime in winter months similar to the ionosonde data; however, the overestimated foF2 values for nighttime in the autumn equinox were in disagreement with the ionosonde observations. There were large deviations between the observed hmF2 values and their model predictions. The largest deviations were found during winter and summer (up to -90 km). The comparison of the Alouette II electron density profiles with those predicted by the adapted IRI2012 model in the altitude range hmF2 of the satellite position showed a great difference in the shape of the Alouette-, NeQuick-, IRI02-coorr, and IRI2001-derived Ne profiles, with overestimated Ne values at some altitudes and underestimated Ne values at others. The results obtained in the study showed that the observation-model differences were significant especially for the real observed (not median) data. For practical application, it is clearly important for the IRI2012 model to be adapted to the observed F2-layer peak parameters. However, the model does not offer a simple solution to predict the shape of the vertical electron density profile in the topside ionosphere, because of the problem with the topside shape parameters.

Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

NASA Astrophysics Data System (ADS)

Chen, J. M.; Chen, X.; Ju, W.

2013-03-01

Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs) for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP) estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shaanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI) is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE) in NPP modeled at the 1 km resolution is reduced from 14.8 g C m-2 yr-1 to 4.8 g C m-2 yr-1 in comparison with NPP modeled at 30 m resolution, where the mean NPP is 668 g C m-2 yr-1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI), elevation and aspect have small and additive effects on improving the spatial scaling between these two resolutions.

Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

NASA Astrophysics Data System (ADS)

Chen, J. M.; Chen, X.; Ju, W.

2013-07-01

Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs) for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP) estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI) is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE) in NPP modelled at the 1 km resolution is reduced from 14.8 g C m-2 yr-1 to 4.8 g C m-2 yr-1 in comparison with NPP modelled at 30 m resolution, where the mean NPP is 668 g C m-2 yr-1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI) and elevation have small and additive effects on improving the spatial scaling between these two resolutions.

Assessing soil erosion risk using RUSLE through a GIS open source desktop and web application.

PubMed

Duarte, L; Teodoro, A C; Gonçalves, J A; Soares, D; Cunha, M

2016-06-01

Soil erosion is a serious environmental problem. An estimation of the expected soil loss by water-caused erosion can be calculated considering the Revised Universal Soil Loss Equation (RUSLE). Geographical Information Systems (GIS) provide different tools to create categorical maps of soil erosion risk which help to study the risk assessment of soil loss. The objective of this study was to develop a GIS open source application (in QGIS), using the RUSLE methodology for estimating erosion rate at the watershed scale (desktop application) and provide the same application via web access (web application). The applications developed allow one to generate all the maps necessary to evaluate the soil erosion risk. Several libraries and algorithms from SEXTANTE were used to develop these applications. These applications were tested in Montalegre municipality (Portugal). The maps involved in RUSLE method-soil erosivity factor, soil erodibility factor, topographic factor, cover management factor, and support practices-were created. The estimated mean value of the soil loss obtained was 220 ton km(-2) year(-1) ranged from 0.27 to 1283 ton km(-2) year(-1). The results indicated that most of the study area (80 %) is characterized by very low soil erosion level (<321 ton km(-2) year(-1)) and in 4 % of the studied area the soil erosion was higher than 962 ton km(-2) year(-1). It was also concluded that areas with high slope values and bare soil are related with high level of erosion and the higher the P and C values, the higher the soil erosion percentage. The RUSLE web and the desktop application are freely available.

Variation of coda wave attenuation in the Alborz region and central Iran

NASA Astrophysics Data System (ADS)

Rahimi, H.; Motaghi, K.; Mukhopadhyay, S.; Hamzehloo, H.

2010-06-01

More than 340 earthquakes recorded by the Institute of Geophysics, University of Tehran (IGUT) short period stations from 1996 to 2004 were analysed to estimate the S-coda attenuation in the Alborz region, the northern part of the Alpine-Himalayan orogen in western Asia, and in central Iran, which is the foreland of this orogen. The coda quality factor, Qc, was estimated using the single backscattering model in frequency bands of 1-25 Hz. In this research, lateral and depth variation of Qc in the Alborz region and central Iran are studied. It is observed that in the Alborz region there is absence of significant lateral variation in Qc. The average frequency relation for this region is Qc = 79 +/- 2f1.07+/-0.08. Two anomalous high-attenuation areas in central Iran are recognized around the stations LAS and RAZ. The average frequency relation for central Iran excluding the values of these two stations is Qc = 94 +/- 2f0.97+/-0.12. To investigate the attenuation variation with depth, Qc value was calculated for 14 lapse times (25, 30, 35,... 90s) for two data sets having epicentral distance range R < 100 km (data set 1) and 100 < R < 200 km (data set 2) in each area. It is observed that Qc increases with depth. However, the rate of increase of Qc with depth is not uniform in our study area. Beneath central Iran the rate of increase of Qc is greater at depths less than 100 km compared to that at larger depths indicating the existence of a high attenuation anomalous structure under the lithosphere of central Iran. In addition, below ~180 km, the Qc value does not vary much with depth under both study areas, indicating the presence of a transparent mantle under them.

b-value distribution in and around Mt. Tarumae, Japan

NASA Astrophysics Data System (ADS)

Chiba, K.

2017-12-01

Mt. Tarumae is an active volcano located in southeastern Shikotsu caldera, Hokkaido, Japan. Recently, crustal expansion occurred in 1999-2000 and 2013 near the summit of Mt. Tarumae, with a M5.6 earthquake recorded west of the summit on 8 July 2014. In this study, I determined hypocenter distributions and then performed b-value analysis for the period between 1 August 2014 and 12 August 2016 to improve our understanding of the magma system geometry beneath the summit of Mt. Tarumae. Hypocenters are mainly distributed in two regions: 3 - 5 km west of Mt. Tarumae, and beneath the volcano. I then determined b-value distributions. Regions with relatively high b-values ( 1.3) are located at depths of -0.5 to 2.0 km beneath the summit and at depths greater than 6.0 km in the northwestern part at about 1.5 - 3.0 km from the summit, while a region with relatively low b-values ( 0.6) is located at depths of 2.0 - 6.0 km beneath the summit. Compared the b-value distributions with other geophysical observations, it was found that the high b-value region from -0.5 to 2.0 km depth corresponds to regions of lower resistivity, positive self-potential anomaly, and an inflation source observed in 1999-2000. It is thus inferred that this region is generated by crustal heterogeneity, a decrease in effective normal stress, and change of a frictional property due to the development of faults and fissures, and the circulation of hydrothermal fluids. On the other hand, the inflation source observed in 2013 was located near the boundary between the low b-value region beneath the summit and the deeper high b-value region in the northwestern part at about 1.5 - 3.0 km from the summit. Studies of other volcanoes suggest that such a high-b-value region likely corresponds to a magma chamber. From the deeper high b-value region estimated in this study, I am able to point out that the magma chamber is located to depths greater than 6.0 km in the northwestern part at about 1.5 - 3.0 km from the summit. Thus, these findings contribute to our understanding of the magma plumbing system beneath the summit of Mt. Tarumae.

Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements

NASA Astrophysics Data System (ADS)

Noël, Stefan; Bramstedt, Klaus; Hilker, Michael; Liebing, Patricia; Plieninger, Johannes; Reuter, Max; Rozanov, Alexei; Sioris, Christopher E.; Bovensmann, Heinrich; Burrows, John P.

2016-04-01

Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called onion peeling DOAS (ONPD), which combines an onion peeling approach with a weighting function DOAS (differential optical absorption spectroscopy) fit in the spectral region between 1559 and 1671 nm. By use of updated pointing information and optimisation of the data selection as well as of the retrieval approach, the altitude range for reasonable CH4 could be broadened from 20 to 40 km to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles (17-45 km) of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10 % for CH4 and 2-3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated. CH4 trends above about 20 km are not significantly different from zero and the trend at 17 km is about 3 ppbv year-1. The derived CO2 trends show a general decrease with altitude with values of about 1.9 ppmv year-1 at 21 km and about 1.3 ppmv year-1 at 39 km. These results are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

Aerosol optical properties variability during biomass burning events observed by the eole-aias depolarization lidars over Athens, Greece (2007-2016)

NASA Astrophysics Data System (ADS)

Mylonaki, Maria; Papayannis, Alexandros; Mamouri, Rodanthi; Argyrouli, Athina; Kokkalis, Panagiotis; Tsaknakis, Georgios; Soupiona, Ourania

2018-04-01

The EOLE multi-wavelength aerosol Ramandepolarization lidar, and the AIAS depolarization lidar, in synergy with a sun photometer (CIMEL), were used, in the period 2007-2016, to provide the vertical profiles of the aerosol optical properties over Athens, Greece. More than 30 biomass burning events (fresh and aged smoke particles) were observed, with smoke layers between 1.5 up to 4-5 km height, while their duration ranged from 1-3 days. Lidar ratio (LR) values ranged from 40-105 sr (at 355 nm) and from 40-100 sr (at 532 nm), while the linear particle depolarization ratio (LPDR) at both 355 and 532 nm, remained <7%. The extinction-related Ångström exponent (AEa) at 355 nm/532 nm) ranged from 0.3 to 2.1. Additionally, a case of a near-range transport of biomass burning aerosols arriving over Athens up to 4 km height, between 27 and 28 June 2016, was studied. For this case, we found LRs of the order of 70±5 sr (355 nm) and 65±15 sr (532 nm) and AEa(355 nm/532 nm) around 1.

Baseline climatology of extremely high vertical wind shears' values over Europe based on ERA-Interim reanalysis

NASA Astrophysics Data System (ADS)

Palarz, Angelika; Celiński-Mysław, Daniel

2017-04-01

The dominant role in the development of deep convection is played by kinematic and thermodynamic conditions, as well as atmospheric circulation, land cover and local relief. Severe thunderstorms are considerably more likely to form in environments with large values of convective available potential energy (CAPE) and significant magnitude of vertical wind shears (VWSs). According to the most recent research, the tropospheric wind shears have an important influence on intensity, longevity and organisation of the primary convective systems - bow echoes, squall lines and supercell thunderstorms. This study, in turn, examines the role of wind structure in controlling the spatial and temporal variability of VWSs over Europe. Considering the importance of the kinematic conditions for the convective systems formation, research is limited exclusively to 0-1 km, 0-3 km and 0-6 km wind shears. In order to compute the VWS' values, the data derived from ERA-Interim reanalysis for the period 1981-2015 was applied. It consisted of U and V wind components with 12-hourly sampling and horizontal resolution of 0.75×0.75°. The VWS' values were calculated as wind difference between two levels - this entails that the hodograph's shape was not considered (e.g. Clark 2013, Pucik et. al 2015). We have analysed both VWS' mean values (MN) and frequency of VWSs exceeding assumed thresholds (FQ). Taking into account previous studies (e.g. Rasmussen & Blanchard 1998, Schneider et al. 2006, Schaumann & Przybylinski 2012), the thresholds for extremely high values of vertical wind shears were set at 10 m/s for 0-1 km shear, 15 m/s for 0-3 km shear and 18 m/s for 0-6 km shear. Both MN and FQ values were characterised by strong temporal variability, as well as significant spatial differentiation over the research area. A clear diurnal cycle was identified in the case of 0-1 km shear, while seasonal variability was typical for 0-3 km and 0-6 km shears. Regardless of the season, 0-1 km shear reached higher MN and FQ values at 00 UTC than at 12 UTC. Moreover, its spatial distribution showed distinct differences linked to the underlying surface type. Surface energy budget seems to be an important factor contributing to the diurnal and spatial variability of VWSs - it generates the formation of local air circulation leading to modification of the wind direction and speed in the boundary layer. For 0-3 km and 0-6 km shears, a noticeable spatial differentiation between land and sea areas was not recognised. The significantly higher MN and FQ values over the land were found exclusively in the case of 0-3 km shear during the winter, particularly over the Mediterranean region. In the middle troposphere, the VWS' fluctuations (0-3 and 0-6 km shears) are primarily determined by the seasonal changes in atmospheric circulation patterns over the research area.

Modeling englacial radar attenuation at Siple Dome, West Antarctica, using ice chemistry and temperature data

USGS Publications Warehouse

MacGregor, J.A.; Winebrenner, D.P.; Conway, H.; Matsuoka, K.; Mayewski, P.A.; Clow, G.D.

2007-01-01

The radar reflectivity of an ice-sheet bed is a primary measurement for discriminating between thawed and frozen beds. Uncertainty in englacial radar attenuation and its spatial variation introduces corresponding uncertainty in estimates of basal reflectivity. Radar attenuation is proportional to ice conductivity, which depends on the concentrations of acid and sea-salt chloride and the temperature of the ice. We synthesize published conductivity measurements to specify an ice-conductivity model and find that some of the dielectric properties of ice at radar frequencies are not yet well constrained. Using depth profiles of ice-core chemistry and borehole temperature and an average of the experimental values for the dielectric properties, we calculate an attenuation rate profile for Siple Dome, West Antarctica. The depth-averaged modeled attenuation rate at Siple Dome (20.0 ?? 5.7 dB km-1) is somewhat lower than the value derived from radar profiles (25.3 ?? 1.1 dB km-1). Pending more experimental data on the dielectric properties of ice, we can match the modeled and radar-derived attenuation rates by an adjustment to the value for the pure ice conductivity that is within the range of reported values. Alternatively, using the pure ice dielectric properties derived from the most extensive single data set, the modeled depth-averaged attenuation rate is 24.0 ?? 2.2 dB km-1. This work shows how to calculate englacial radar attenuation using ice chemistry and temperature data and establishes a basis for mapping spatial variations in radar attenuation across an ice sheet. Copyright 2007 by the American Geophysical Union.

Predicted Spatial Spread of Canine Rabies in Australia

PubMed Central

Fleming, Peter J. S.; Ward, Michael P.; Davis, Stephen A.

2017-01-01

Modelling disease dynamics is most useful when data are limited. We present a spatial transmission model for the spread of canine rabies in the currently rabies-free wild dog population of Australia. The introduction of a sub-clinically infected dog from Indonesia is a distinct possibility, as is the spillover infection of wild dogs. Ranges for parameters were estimated from the literature and expert opinion, or set to span an order of magnitude. Rabies was judged to have spread spatially if a new infectious case appeared 120 km from the index case. We found 21% of initial value settings resulted in canine rabies spreading 120km, and on doing so at a median speed of 67 km/year. Parameters governing dog movements and behaviour, around which there is a paucity of knowledge, explained most of the variance in model outcomes. Dog density, especially when interactions with other parameters were included, explained some of the variance in whether rabies spread 120km, but dog demography (mean lifespan and mean replacement period) had minimal impact. These results provide a clear research direction if Australia is to improve its preparedness for rabies. PMID:28114327

Optical frequency transfer via a 660 km underground fiber link using a remote Brillouin amplifier.

PubMed

Raupach, S M F; Koczwara, A; Grosche, G

2014-11-03

In long-distance, optical continuous-wave frequency transfer via fiber, remote bidirectional Er³ ⁺ -doped fiber amplifiers are commonly used to mitigate signal attenuation. We demonstrate for the first time the ultrastable transfer of an optical frequency using a remote fiber Brillouin amplifier, placed in a server room along the link. Using it as the only means of remote amplification, on a 660 km loop of installed underground fiber we bridge distances of 250 km and 160 km between amplifications. Over several days of uninterrupted measurement, we find an instability of the frequency transfer (Allan deviation of Λ-weighted data with 1 s gate time) of around 1 × 10(-19) and less for averaging times longer than 3000 s. The modified Allan deviation reaches 3 × 10(-19) at an averaging time of 100 s. Beyond 100 s it follows the interferometer noise floor, and for averaging times longer than 1000 s the modified Allan deviation is in the 10(-20) range. A conservative value of the overall accuracy is 1 × 10(-19)

Assessment of Data Assimilation with the Prototype High Resolution Rapid Refresh for Alaska (HRRRAK)

NASA Technical Reports Server (NTRS)

Harrison, Kayla; Morton, Don; Zavodsky, Brad; Chou, Shih

2012-01-01

The Arctic Region Supercomputing Center has been running a quasi-operational prototype of a High Resolution Rapid Refresh for Alaska (HRRRAK) at 3km resolution, initialized by the 13km Rapid Refresh (RR). Although the RR assimilates a broad range of observations into its analyses, experiments with the HRRRAK suggest that there may be added value in assimilating observations into the 3km initial conditions, downscaled from the 13km RR analyses. The NASA Short-term Prediction Research and Transition (SPoRT) group has been using assimilated data from the Atmospheric Infrared Sounder (AIRS) in WRF and WRF-Var simulations since 2004 with promising results. The sounder is aboard NASA s Aqua satellite, and provides vertical profiles of temperature and humidity. The Gridpoint Statistical Interpolation (GSI) system is then used to assimilate these vertical profiles into WRF forecasts. In this work, we assess the use of AIRS data in combination with other global data assimilation products on non-assimilated HRRRAK case studies. Two separate weather events will be assessed to qualitatively and quantitatively assess the impacts of AIRS data on HRRRAK forecasts.

Volcán Quizapu, Chilean Andes

USGS Publications Warehouse

Hildreth, Wes; Drake, Robert E.

1992-01-01

Quizapu is a flank vent of the basalt-to-rhyodacite Holocene stratocone, Cerro Azul, and lies at the focus of a complex Quaternary volcanic field on the Andean volcanic front. The Quizapu vent originated in 1846 when 5 km3 of hornblende-dacite magma erupted effusively with little accompanying tephra. Between ∼ 1907 and 1932, phreatic and strombolian activity reamed out a deep crater, from which 4 km3 of dacite magma identical to that of 1846 fed the great plinian event of 10–11 April 1932. Although a total of >9 km3 of magma was thus released in 86 years, there is no discernible subsidence. As the pre-plinian crater was lined by massive lavas, 1932 enlargement was limited and the total plinian deposit contains only ∼ 0.4 wt % lithics. Areas of 5-cm and 1-cm isopachs for compacted 1932 fallout are about half of those estimated in the 1930's, yielding a revised ejecta volume of ∼9.5 km3. A strong inflection near the 10-cm isopach (downwind ∼110 km) on a plot of log Thickness vs Area1/2 reflects slow settling of fine plinian ash — not of coignimbrite ash, as the volume of pyroclastic flows was trivial (<0.01 km3). About 17 vol.% of the fallout lies beyond the 1-cm isopach, and ∼ 82 wt% of the ejecta are finer than 1 mm. A least 18 hours of steady plinian activity produced an exceptionally uniform fall deposit. Observed column height (27–30 km) and average mass eruption rate (1.5x108 kg/s) compare well with values for height and peak intensity calculated from published eruption models. The progressive “aeolian fractionation” of downwind ash (for which Quizapu is widely cited) is complicated by the large compositional range of 1932 juvenile pumice (52–70% SiO2). The eruption began with andesitic scoria and ended with basaltic scoria, but >95% of the ejecta are dacitic pumice (67–68% SiO2); minor andesitic scoria and frothier rhyodacite pumice (70% SiO2) accompanied the dominant dacite. Phenocrysts (pl>hb∼opx>mt>ilm∼cpx) are similar in both abundance and composition in the 1846 (effusive) and 1932 (plinian) dacites. Despite the contrast in mode of eruption, bulk compositions are also indistinguishable. The only difference so far identified is a lower range of δ D values for 1846 hornblende, consistent with pre-eruptive degassing of the effusive batch.

Three-dimensional imaging of the S-velocity structure for the crust and the upper mantle beneath the Arabian Sea from Rayleigh wave analysis

NASA Astrophysics Data System (ADS)

Corchete, V.

2017-04-01

A 3D imaging of S-velocity for the Arabian Sea crust and upper mantle structure is presented in this paper, determined by means of Rayleigh wave analysis, for depths ranging from zero to 300 km. The crust and upper mantle structure of this region of the earth never has been the subject of a surface wave tomography survey. The Moho map performed in the present study is a new result, in which a crustal thickening beneath the Arabian Fan sediments can be observed. This crustal thickening can be interpreted as a quasi-continental oceanic transitional structure. A crustal thickness of up to 20 km also can be observed for the Murray Ridge system in this Moho map. This crustal thickening can be due to that the Murray Ridge System consists of Indian continental crust. This continental crust is extremely thinned to the southwest of this region, as shown in this Moho map. This area can be interpreted as oceanic in origin. In the depth range from 30 to 60 km, the S-velocity presents its lower values at the Carlsberg Ridge region, because it is the younger region of the study area. In the depth range from 60 to 105 km of depth, the S-velocity pattern is very similar to that shown for the previous depth range, except for the regions in which the asthenosphere is reached, for these regions appear a low S-velocity pattern. The lithosphere-asthenosphere boundary (LAB), or equivalently the lithosphere thickness, determined in the present study is also a new result, in which the lithosphere thickness for the Arabian Fan can be estimated in 60-70 km. The lower lithospheric thickness observed in the LAB map, for the Arabian Fan, shows that this region may be in the transition zone between continental and oceanic structure. Finally, a low-velocity zone (LVZ) has been determined, for the whole study area, located between the LAB and the boundary of the asthenosphere base (or equivalently the lithosphere-asthenosphere system thickness). The asthenosphere-base map calculated in the present study is also a new result.

Agricultural drought assessment using remotely sensed data in Central America

NASA Astrophysics Data System (ADS)

Nguyen, S. T.; Chen, C. F.; Chen, C. R.

2017-12-01

Central America is one of the world's regions most vulnerable to negative effects of agricultural drought due to impacts of climate change. Famers in the region have been confronting risks of crop damages and production losses due to intense droughts throughout the growing seasons. Drought information is thus deemed vital for policymakers to assess their crop management strategies in tackling issues of food insecurity in the region. This study aimed to delineate drought-prone areas associated with cropped areas from eight-day MODIS data in 2016 using the commonly used temperature dryness vegetation index (TVDI), calculated based on the land surface temperature (LST) and enhanced vegetation index (EVI) data. The advantages of MODIS data for agricultural drought monitoring at a national/regional scale are that it has the spatial resolution (500 m-1 km) and relatively high temporal resolution of eight days, but the data are often contaminated by clouds. Detecting and reconstructing the data under cloud-affected areas are generally a challenging task without any robust methods up to date. In this study, we reconstructed the eight-day MODIS EVI and LST data for agricultural drought assessment using machine-learning approaches. The reconstructed data were then used for drought assessment. The TVDI results verified with the soil moisture active passive (SMAP) data showed that the correlation coefficient values (r) obtained for the apante season (December-March) were between -0.4 to -0.8, while the values for the primera season (April-August) and postrera season (September-November) were in ranges of 0 to -0.6 and -0.2 to -0.7, respectively. The larger area of very dry soil moisture was generally observed during the dry season (December-April) and declined in the rainy season (May-November). The cropping areas affected by severe and moderate droughts observed for the primera season were respectively 11,846 km2 and 60,557 km2, while the values for the postera season were 14,174 km2 and 56,809 km2, and those for the postera season were 16,532 km2 and 40,018 km2, respectively. This study could provide quantitative information on distributions of drought at an eight-day interval, which is important to assist officials to mitigate economic costs for vulnerable populations in drought-prone areas.

Enhancing the spatial coverage of a regional high-quality hydraulic conductivity dataset with estimates made from domestic water-well specific-capacity tests

NASA Astrophysics Data System (ADS)

Priebe, Elizabeth H.; Neville, C. J.; Rudolph, D. L.

2018-03-01

The spatial coverage of hydraulic conductivity ( K) values for large-scale groundwater investigations is often poor because of the high costs associated with hydraulic testing and the large areas under investigation. Domestic water wells are ubiquitous and their well logs represent an untapped resource of information that includes mandatory specific-capacity tests, from which K can be estimated. These specific-capacity tests are routinely conducted at such low pumping rates that well losses are normally insignificant. In this study, a simple and practical approach to augmenting high-quality K values with reconnaissance-level K values from water-well specific-capacity tests is assessed. The integration of lesser quality K values from specific-capacity tests with a high-quality K data set is assessed through comparisons at two different scales: study-area-wide (a 600-km2 area in Ontario, Canada) and in a single geological formation within a portion of the broader study area (200 km2). Results of the comparisons demonstrate that reconnaissance-level K estimates from specific-capacity tests approximate the ranges and distributions of the high-quality K values. Sufficient detail about the physical basis and assumptions that are invoked in the development of the approach are presented here so that it can be applied with confidence by practitioners seeking to enhance their spatial coverage of K values with specific-capacity tests.

Aerosol Abundances and Optical Characteristics in the Pacific Basin Free Troposphere

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Livingston, J. M.; Ferry, G. V.; deFelice, T. E.

1994-01-01

During NASA's Global Backscatter Experiment (GLOBE) mission flights in November 1989 and May 1990, a DC-8 research aircraft probed the Pacific Basin free troposphere for about 90 flight hours in each month between +72 and -62 degrees latitude, +130 and -120 degrees longitude, and up to 39,000 feet pressure altitudes. Aerosols were sampled continuously in situ by optical particle counters to measure concentration and particle size, and during 48 10-min intervals during each mission by wire impactors for concentration, size, composition, phase and shape analyses. The optical particle counters cover a particle diameter range between 0.3 and 20 microns; wire impactors extend the range down to 0.03 microns. Results of particle number, size, shape, together with the assumption of a refractive index corresponding to (NH4)2SO4 to account for the prevalence of aerosol sulfur, were utilized in a Mie algorithm to calculate aerosol extinction and backscatter for a range of wavelengths (0.385 less than lambda less than 10.64 microns). Computations for 22 randomly selected size distributions yield coefficients of extinction E(0.525) = (2.03 +/- 1.20) x 10(exp -4) km(exp -1) and backscatter beta(0.525) = (6.45 +/- 3.49) x 10(exp -6) km(exp -1) sr(exp -1) in the visible, and E(10.64) = (8.13 +/- 6.47) x 10(exp -6) km(exp -1) and beta(10.64) = (9.98 +/- 10.69) x 10(exp -8) km(exp -1) sr(exp -1) in the infrared, respectively. Large particles (D greater than 0.3 microns) contribute two-thirds to the total extinction in the visible (lambda = 0.525 microns), and almost 100% in the infrared (lambda = 10.64 microns). These results have been used to define an IR optical aerosol climatology of the Pacific Basin free troposphere, from which it follows that the infrared backscatter coefficient at lambda = 9.25 microns wavelength fluctuates between 5.0 x 10(exp -10) and 2.0 x 10(exp -7) km(exp -1) sr(exp -1) with a modal value 2.0 x 10(exp -8) km(exp -1) sr(exp -1).

Space and habitat use by wild Bactrian camels in the Transaltai Gobi of southern Mongolia☆

PubMed Central

Kaczensky, Petra; Adiya, Yadamsuren; von Wehrden, Henrik; Mijiddorj, Batmunkh; Walzer, Chris; Güthlin, Denise; Enkhbileg, Dulamtseren; Reading, Richard P.

2014-01-01

Wild Bactrian camels (Camela ferus) are listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) and only persist in some of the most remote locations in northern China and southern Mongolia. Although the species has been recognized as an umbrella species for the fragile central Asian desert ecosystem and has been high on the conservation agenda, little is known about the species’ habitat requirements, with most information coming from anecdotal sightings and descriptive studies. We compiled the only available telemetry data from wild camels worldwide. Seven wild camels, which were followed for 11–378 monitoring days, covered a total range of 28,410 km2, with individual annual ranges being >12,000 km2 for three animals followed over a year. Camels reacted strongly to capture events, moving up to 64 km from the capture site within a day, whereas normal average daily straight line distances were 3.0–6.4 km/day. Camels showed a preference for intermediate productivity values (NDVI, habitat type) and landscape parameters (distance to water, elevation) and an avoidance of steep slopes. Our telemetry results suggest that wild camels still range throughout the entire Great Gobi A Strictly Protected Area (SPA), are highly mobile, and very sensitive to human disturbance. Their habitat preference may be a trade-off between dietary and safety requirements. Small sample size did not allow the development of a full habitat model testing all variables simultaneously and we urgently call for more data from additional wild camels as a foundation for evidence driven conservation actions. PMID:24695588

Mid-tropospheric Spectral Length-scale Analysis of Many Constituents from Aircraft, Satellite and Model Results During the 2013 SENEX Field Study.

NASA Astrophysics Data System (ADS)

McKeen, S. A.; Angevine, W. M.; Ahmadov, R.; Frost, G. J.; Kim, S. W.; Cui, Y.; McDonald, B.; Trainer, M.; Holloway, J. S.; Ryerson, T. B.; Peischl, J.; Gambacorta, A.; Barnet, C. D.; Smith, N.; Pierce, R. B.

2016-12-01

This study presents preliminary comparisons of satellite, aircraft, and model variance spectra for meteorological, thermodynamic and gas-phase species collected during the 2013 Southeastern Nexus Air Quality Experiment (SENEX). Fourier analysis of 8 constituents collected at 1 Hz by the NOAA W-P3 aircraft in the 25 to 200 km length-scale range exhibit properties consistent with previous scale dependence studies: when spectra are averaged over several 500 mb flight legs, very linear dependence is found on log-log plots of spectral density versus inverse length-scale. Derived slopes for wind speed, temperature, H2O, CO, CO2, CH4, NOy and O3 all fall within ±30% and close to the slope of -5/3 predicted from dimensional scaling theory of isotropic turbulence. Qualitative differences are seen when a similar analysis, without quality control, is applied to a preliminary set of NUCAPS satellite retrievals over the continental U.S. during SENEX. While 500mb water vapor and column integrated water show slopes close to the -5/3 value in the 200 to 1000 km length-scale range, other quantities show significantly shallower slopes, suggesting the need for rigorous quality control. Results from WRF-Chem regional air quality model simulations at 500mb show the model is unable to account for variance on length-scales less than 6ΔX, where ΔX is the model horizontal resolution (12km). Comparisons with satellite data in the 200 to 1000km range show slopes consistent with the -5/3 power law for species such as CO, CH4 and CO2 that do not undergo reinitialization, suggesting potential for future application.

Solar flare induced ionospheric D-region enhancements from VLF phase and amplitude observations

NASA Astrophysics Data System (ADS)

McRae, Wayne M.; Thomson, Neil R.

2004-01-01

Ionospheric perturbations due to solar flares, measured at VLF in both phase and amplitude on long subionospheric paths, are used to determine the accompanying D-region electron density enhancements as a function of the flare X-ray fluxes measured by the GOES satellites. The electron densities are characterised by the two traditional parameters, H' and β (being measures of the ionospheric height and the rate of increase of electron density with height, respectively), found by computational modelling of the observed phases and amplitudes using the NOSC Earth-ionosphere waveguide programs (LWPC and ModeFinder) over a wide range of VLF frequencies, 10.2-24.8kHz, along a number of transequatorial paths across the Pacific Ocean to Dunedin, New Zealand. The transmitters monitored include Omega Japan, Omega Hawaii, NPM in Hawaii, and NLK near Seattle, USA, for which the paths range in length from 8.1 to 12.3Mm. The observations include flares up to a magnitude of about X5(5×10-4Wm-2 at 0.1-0.8nm). These gave VLF phase delay reductions of up to about 52μs and amplitude enhancements up to nearly 10dB for the 12.3Mm NLK to Dunedin path on 24.8kHz which corresponded, under low to medium solar cycle conditions (1994-1998), to a reduction in H' from about 71km down to about 58km and an increase in β from about 0.39km-1 up to a definite `saturation' level of about 0.52km-1. These experimentally determined values of H' and β were then used in LWPC to predict flare-induced VLF phase and amplitude perturbations over a wider range of frequencies than were actually available for observation.

Martian Low-Aspect-Ratio Layered Ejecta (LARLE) craters: Distribution, characteristics, and relationship to pedestal craters

NASA Astrophysics Data System (ADS)

Barlow, Nadine G.; Boyce, Joseph M.; Cornwall, Carin

2014-09-01

Low-Aspect-Ratio Layered Ejecta (LARLE) craters are a unique landform found on Mars. LARLE craters are characterized by a crater and normal layered ejecta pattern surrounded by an extensive but thin outer deposit which terminates in a sinuous, almost flame-like morphology. We have conducted a survey to identify all LARLE craters ⩾1-km-diameter within the ±75° latitude zone and to determine their morphologic and morphometric characteristics. The survey reveals 140 LARLE craters, with the majority (91%) located poleward of 40°S and 35°N and all occurring within thick mantles of fine-grained deposits which are likely ice-rich. LARLE craters range in diameter from the cut-off limit of 1 km up to 12.2 km, with 83% being smaller than 5 km. The radius of the outer LARLE deposit displays a linear trend with the crater radius and is greatest at higher polar latitudes. The LARLE deposit ranges in length between 2.56 and 14.81 crater radii in average extent, with maximum length extending up to 21.4 crater radii. The LARLE layer is very sinuous, with lobateness values ranging between 1.45 and 4.35. LARLE craters display a number of characteristics in common with pedestal craters and we propose that pedestal craters are eroded versions of LARLE craters. The distribution and characteristics of the LARLE craters lead us to propose that impact excavation into ice-rich fine-grained deposits produces a dusty base surge cloud (like those produced by explosion craters) that deposits dust and ice particles to create the LARLE layers. Salts emplaced by upward migration of water through the LARLE deposit produce a surficial duricrust layer which protects the deposit from immediate removal by eolian processes.

Aerosols and lightning activity: The effect of vertical profile and aerosol type

NASA Astrophysics Data System (ADS)

Proestakis, E.; Kazadzis, S.; Lagouvardos, K.; Kotroni, V.; Amiridis, V.; Marinou, E.; Price, C.; Kazantzidis, A.

2016-12-01

The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite has been utilized for the first time in a study regarding lightning activity modulation due to aerosols. Lightning activity observations, obtained by the ZEUS long range Lightning Detection Network, European Centre for Medium range Weather Forecasts (ECMWF) Convective Available Potential Energy (CAPE) data and Cloud Fraction (CF) retrieved by MODIS on board Aqua satellite have been combined with CALIPSO CALIOP data over the Mediterranean basin and for the period March to November, from 2007 to 2014. The results indicate that lightning activity is enhanced during days characterized by higher Aerosol Optical Depth (AOD) values, compared to days with no lightning. This study contributes to existing studies on the link between lightning activity and aerosols, which have been based just on columnar AOD satellite retrievals, by performing a deeper analysis into the effect of aerosol profiles and aerosol types. Correlation coefficients of R = 0.73 between the CALIPSO AOD and the number of lightning strikes detected by ZEUS and of R = 0.93 between ECMWF CAPE and lightning activity are obtained. The analysis of extinction coefficient values at 532 nm indicates that at an altitudinal range exists, between 1.1 km and 2.9 km, where the values for extinction coefficient of lightning-active and non-lightning-active cases are statistically significantly different. Finally, based on the CALIPSO aerosol subtype classification, we have investigated the aerosol conditions of lightning-active and non-lightning-active cases. According to the results polluted dust aerosols are more frequently observed during non-lightning-active days, while dust and smoke aerosols are more abundant in the atmosphere during the lightning-active days.

Picos de Europa National and Regional parks (Northern Spain): the karst underground landscape

NASA Astrophysics Data System (ADS)

Ballesteros, Daniel; Jiménez-Sánchez, Montserrat; Rodríguez-Rodríguez, Laura; José Domínguez-Cuesta, María; Meléndez-Asensio, Mónica; García-Sansegundo, Joaquín

2015-04-01

Karst caves represent an environmental with a high value from the Geoheritage and Geodiversity points of view given by hidden underground landscape practically reserved to the speleologists. Nevertheless, cave surveys, 3d models of caves and DEMs, and pictures can be used to approach the endokarst geoheritage characterization. The Picos de Europa National and Regional parks include the 14% of World's Deepest Caves (>1 km depth); moreover these parks shows a high environmental value related with seven protection figures: Biosphere Reserve, Special Protection Area, the Site of Community Importance, and four Natural Monument. The aim of this work is to present the Geoheritage values of the underground landscape of the Picos de Europa National and Regional parks. These parks involve several alpine karst massifs up to 700 km2 and 2,600 m asl, as the Picos de Europa mountains (declared Global Geosite by its geomorphological interest), the Mampodre Massif, and the Peñas Pintas and Yordas peaks (sited in Riaño dam area). The alpine karst involves a large underground landscape formed by more than 3,700 epigenic caves with 403 km of conduits. The 95 % of the cave conduits are located in the Picos de Europa mountains and correspond to caves up to 18.9 km length and 1.6 km depth; the 5 % of cave conduits are sited in other small karst areas and include caves up to 1.5 km length and 200 m depth. The karst caves present high natural, scientific and cultural values. The natural value corresponds to the singularity and the spectacular vertical development of the caves and a very high Geodiversity of cave features. The karst shows a high concentration of deep caves (81 caves deeper than 500 m) that is twice higher than the concentration of other karst areas, as Arabika Massif (Western Caucasus). The natural value is mainly related to the presence of geomorphological and hydrogeological features, highlighting high vadose canyons and shafts, old phreatic and epiphreatic conduits, few fluvial deposits, some speleothems (dripstone, flowstone), few ice caves, many underground streams, and karst springs. The scientific value corresponds to the cave records related to the regional evolution of the Cantabrian Range. The scientific studies evidence that the caves are originated prior to, at least, the Middle Pleistocene, in relation to mountain uplift, glaciations, fluvial incision, and the erosion of the alpine lithological seriesthat were above the karst. The cultural value is related with the specific uses of the cavities by shepherds and speleologists, and the singularity of cave names. The uses include traditional customs, as the livestock farming, the water collection, the elaboration of five types of cheese with Certificated of Origin, and sport uses by speleologists from many countries of Europe. The educative values are low due to the limitations of access inside the caves, although two caves are touristic and the entrance of some caves can be used to explain vadose shafts, relations between caves and glaciers and rivers or the underground water flow. GEOCAVE project (MAGRAMA-580/12 OAPN)

Water vapour and methane coupling in the stratosphere observed using SCIAMACHY solar occultation measurements

NASA Astrophysics Data System (ADS)

Noël, Stefan; Weigel, Katja; Bramstedt, Klaus; Rozanov, Alexei; Weber, Mark; Bovensmann, Heinrich; Burrows, John P.

2018-04-01

An improved stratospheric water vapour data set has been retrieved from SCIAMACHY/ENVISAT solar occultation measurements. It is similar to that successfully applied to methane and carbon dioxide. There is now a consistent set of data products for the three constituents covering the altitudes 17-45 km, the latitude range between about 50 and 70° N, and the period August 2002 to April 2012. The new water vapour concentration profiles agree with collocated results from ACE-FTS and MLS/Aura to within ˜ 5 %. A significant positive linear change in water vapour for the time 2003-2011 is observed at lower stratospheric altitudes with a value of about 0.015 ± 0.008 ppmv year-1 around 17 km. Between 30 and 37 km the changes become significantly negative (about -0.01 ± 0.008 ppmv year-1); all errors are 2σ values. The combined analysis of the SCIAMACHY methane and water vapour time series shows the expected anti-correlation between stratospheric methane and water vapour and a clear temporal variation related to the Quasi-Biennial Oscillation (QBO). Above about 20 km most of the additional water vapour is attributed to the oxidation of methane. In addition short-term fluctuations and longer-term variations on a timescale of 5-6 years are observed. The SCIAMACHY data confirm that at lower altitudes the amount of water vapour and methane are transported from the tropics to higher latitudes via the shallow branch of the Brewer-Dobson circulation.

Depth dependence of earthquake frequency-magnitude distributions in California: Implications for rupture initiation

USGS Publications Warehouse

Mori, J.; Abercrombie, R.E.

1997-01-01

Statistics of earthquakes in California show linear frequency-magnitude relationships in the range of M2.0 to M5.5 for various data sets. Assuming Gutenberg-Richter distributions, there is a systematic decrease in b value with increasing depth of earthquakes. We find consistent results for various data sets from northern and southern California that both include and exclude the larger aftershock sequences. We suggest that at shallow depth (???0 to 6 km) conditions with more heterogeneous material properties and lower lithospheric stress prevail. Rupture initiations are more likely to stop before growing into large earthquakes, producing relatively more smaller earthquakes and consequently higher b values. These ideas help to explain the depth-dependent observations of foreshocks in the western United States. The higher occurrence rate of foreshocks preceding shallow earthquakes can be interpreted in terms of rupture initiations that are stopped before growing into the mainshock. At greater depth (9-15 km), any rupture initiation is more likely to continue growing into a larger event, so there are fewer foreshocks. If one assumes that frequency-magnitude statistics can be used to estimate probabilities of a small rupture initiation growing into a larger earthquake, then a small (M2) rupture initiation at 9 to 12 km depth is 18 times more likely to grow into a M5.5 or larger event, compared to the same small rupture initiation at 0 to 3 km. Copyright 1997 by the American Geophysical Union.

Global water vapor distributions in the stratosphere and upper troposphere derived from 5.5 years of SAGE II observations (1986-1991)

NASA Astrophysics Data System (ADS)

Chiou, E. W.; McCormick, M. P.; Chu, W. P.

1997-08-01

Global distributions of water vapor in the stratosphere and upper troposphere are presented on the basis of ˜5.5 years (January 1986 to May 1991) of observations from the Stratospheric Aerosol and Gas Experiment II (SAGE II) aboard the Earth Radiation Budget Satellite (ERBS). Tabulations are included for seasonal zonal mean water vapor mixing ratios (in parts per million by volume) with 1-km vertical resolution and an altitude range from 6 to 40 km. Several climatological features identified in a previous study [McCormick et al., 1993], based on 3 years of observations, have been confirmed by this study: (1) the existence of a region of minimum water vapor (the hygropause) at all latitude bands; (2) the increase in the distance between the tropopause and the hygropause from 1 km at low latitudes to 4 km at high latitudes; and (3) the appearance of a positive poleward gradient throughout all seasons for fixed altitudes between 20 km and 40 km. The latitudinal variation of water vapor mixing ratio at 20 km is characterized by a symmetric pattern with a minimum occurring at the equator. However, the corresponding variations at 25 and 30 km indicate a shift of the minimum toward the summer hemisphere. For the latitude zones 0°-20° and 20°-40° in both hemispheres, the seasonal variations of the hygropause reveal that the altitude as well as the value of the minimum water vapor mixing ratio remain essentially unchanged from December, January, and February to March, April, and May. During September, October, and November the weakening of the hygropause and the spreading of the region of minimum water vapor to a wider altitude range are identified throughout these low-latitude and midlatitude zones. For the upper troposphere the clear-sky relative humidities at 300 mbar show a typical range of 5-60%, which is consistent with previous findings based on Meteosat 6.3 μm measurements. In addition, the unique capability of SAGE II observations has provided us with unprecedented vertically resolved moisture information for the upper troposphere. For example, the integrated column water vapor content for the 300- to 100-mbar layer ranges from 0.002 to 0.01 g/cm2 with larger longitudinal variability in the tropics. The integrated column water vapor content from 500 to 100 mbar is found to be significantly larger in the eastern hemisphere than in the western hemisphere. The corresponding integrated water vapor content at high latitudes increases by a factor of 6 from winter to summer (0.02 g/cm2 compared with 0.13 g/cm2).

Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

NASA Technical Reports Server (NTRS)

Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

2011-01-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets.

Physical Properties of Gabbroic Rock Exposed in Oceanic Core Complexes- New Borehole Data From IODP Hole U1473A in the Indian Ocean and Prior Mid-Atlantic Ridge Results

NASA Astrophysics Data System (ADS)

Blackman, D. K.; Ildefonse, B.; Abe, N.; Harding, A. J.; Guerin, G.

2016-12-01

IODP Expedition 360 to Atlantis Bank on the Southwest Indian Ridge obtained physical property measurements of the 800 m section drilled into the footwall of the oceanic core complex. Compressional velocity (Vp) of core samples range from 5.9-7.2 km/s throughout the hole, with no simple relation to either basic rock type or alteration. Some intervals show a local trend, for example a general increase from 6.7-7.1 km/s over the interval 280-400 mbsf, above a major fault zone at 411-462 mbsf. Below the fault zone, core sample Vp is lower on average (6.6 km/s) than it is in the upper part of the hole (6.8 km/s). Some of this decrease is due to locally greater alteration, but higher oxide content also contributes. Borehole logs show lower Vp shallower than 400 m (6.3-6.4 km/s) and close match to olivine gabbro values below the fault zone, due to higher alteration levels and greater shallow fracturing. Local trends of decreasing Vp, over 10's of m correspond to increasing sample porosity within veined or fractured intervals. Porosities of core in Hole U1473A are low overall (<4.5%) and more variable above 570 mbsf than below. Electrical resistivity of the wallrock tracks logged velocity pattern, dropping below 100 ohm-m in altered or fractured intervals 20-50 m thick and rising over 1000 ohm-m where fresher rock was recovered. The range of velocity, density, and resistivity at Hole U1473A are similar to those in the other deep boreholes from Atlantis Bank (ODP Hole 735B, 1105A) and slightly higher than Vp in the gabbroic core of Atlantis Massif in the Atlantic, Hole U1309D. This may reflect erosion of the detachment zone when the bank was exposed at sealevel. Atlantis Massif displays an increase in Vp from the seafloor to a fault zone at 750 mbsf ( 4.0-6.2 km/s), followed by fairly constant values ( 6.7 km/s) at greater depths, interrupted by a highly altered olivine-rich troctolite interval 1080-1200 mbsf where velocity is up to 1 km/s slower. New analysis of seismic anisotropy based on sonic logs does not show any systematic signature for either core complex, but there are a few intervals up to 10 m thick where anisotropy due to local deformation or dominant fracture direction may be indicated. The new and prior borehole data will be presented in the context of available geophysical, lithologic and alteration results.

Electrical conductivity of the Earth's mantle after one year of SWARM magnetic field measurements

NASA Astrophysics Data System (ADS)

Civet, François; Thebault, Erwan; Verhoeven, Olivier; Langlais, Benoit; Saturnino, Diana

2015-04-01

We present a global EM induction study using L1b Swarm satellite magnetic field measurements data down to a depth of 2000 km. Starting from raw measurements, we first derive a model for the main magnetic field, correct the data for a lithospheric field model, and further select the data to reduce the contributions of the ionospheric field. These computations allowed us to keep a full control on the data processes. We correct residual field from outliers and estimate the spherical harmonic coefficients of the transient field for periods between 2 and 256 days. We used full latitude range and all local times to keep a maximum amount of data. We perform a Bayesian inversion and construct a Markov chain during which model parameters are randomly updated at each iteration. We first consider regular layers of equal thickness and extra layers are added where conductivity contrast between successive layers exceed a threshold value. The mean and maximum likelihood of the electrical conductivity profile is then estimated from the probability density function. The obtained profile particularly shows a conductivity jump in the 600-700 km depth range, consistent with the olivine phase transition at 660 km depth. Our study is the first one to show such a conductivity increase in this depth range without any a priori informations on the internal strucutres. Assuming a pyrolitic mantle composition, this profile is interpreted in terms of temperature variations in the depth range where the probability density function is the narrowest. We finally obtained a temperature gradient in the lower mantle close to adiabatic.

Anomalous Near-Surface Low-Salinity Pulses off the Central Oregon Coast

PubMed Central

Mazzini, Piero L. F.; Risien, Craig M.; Barth, John A.; Pierce, Stephen D.; Erofeev, Anatoli; Dever, Edward P.; Kosro, P. Michael; Levine, Murray D.; Shearman, R. Kipp; Vardaro, Michael F.

2015-01-01

From mid-May to August 2011, extreme runoff in the Columbia River ranged from 14,000 to over 17,000 m3/s, more than two standard deviations above the mean for this period. The extreme runoff was the direct result of both melting of anomalously high snowpack and rainfall associated with the 2010–2011 La Niña. The effects of this increased freshwater discharge were observed off Newport, Oregon, 180 km south of the Columbia River mouth. Salinity values as low as 22, nine standard deviations below the climatological value for this period, were registered at the mid-shelf. Using a network of ocean observing sensors and platforms, it was possible to capture the onshore advection of the Columbia River plume from the mid-shelf, 20 km offshore, to the coast and eventually into Yaquina Bay (Newport) during a sustained wind reversal event. Increased freshwater delivery can influence coastal ocean ecosystems and delivery of offshore, river-influenced water may influence estuarine biogeochemistry. PMID:26607750

Spectral analysis of temperature and Brunt-Vaisala frequency fluctuations observed by radiosondes

NASA Technical Reports Server (NTRS)

Tsuda, T.; Vanzandt, T. E.; Kato, S.; Fukao, S.; Sato, T.

1989-01-01

Recent studies have revealed that vertical wave number spectra of wind velocity and temperture fluctuations in the troposphere and the lower stratosphere are fairly well explained by a saturated gravity wave spectrum. But N(2) (N:Brunt-Vaisala (BV) frequency) spectra seem to be better for testing the scaling of the vertical wave number spectra in layers with different stratifications, beause its energy density is proportional only to the background value of N(2), while that for temperature depends on both the BV frequency and the potential temperature. From temperature profiles observed in June to August 1987 over the MU Observatory, Japan, by using a radiosonde with 30 m height resolution, N(2) spectra are determined in the 2 to 8.5 km (troposphere) and 18.5 to 25 km (lower stratosphere) ranges. Although individual spectra show fairly large day-by-day variability, the slope of the median of 34 spectra agrees reasonably with the theoretical value of -1 in the wave number range of 6 x 10(-4) similar to 3 x 10(-3) (c/m). The ratio of the spectral energy between these two height regions is about equal to the ratio of N(2), consistent with the prediction of saturated gravity wave theory.

Determination of the optimized single-layer ionospheric height for electron content measurements over China

NASA Astrophysics Data System (ADS)

Li, Min; Yuan, Yunbin; Zhang, Baocheng; Wang, Ningbo; Li, Zishen; Liu, Xifeng; Zhang, Xiao

2018-02-01

The ionosphere effective height (IEH) is a very important parameter in total electron content (TEC) measurements under the widely used single-layer model assumption. To overcome the requirement of a large amount of simultaneous vertical and slant ionospheric observations or dense "coinciding" pierce points data, a new approach comparing the converted vertical TEC (VTEC) value using mapping function based on a given IEH with the "ground truth" VTEC value provided by the combined International GNSS Service Global Ionospheric Maps is proposed for the determination of the optimal IEH. The optimal IEH in the Chinese region is determined using three different methods based on GNSS data. Based on the ionosonde data from three different locations in China, the altitude variation of the peak electron density (hmF2) is found to have clear diurnal, seasonal and latitudinal dependences, and the diurnal variation of hmF2 varies from approximately 210 to 520 km in Hainan. The determination of the optimal IEH employing the inverse method suggested by Birch et al. (Radio Sci 37, 2002. doi: 10.1029/2000rs002601) did not yield a consistent altitude in the Chinese region. Tests of the method minimizing the mapping function errors suggested by Nava et al. (Adv Space Res 39:1292-1297, 2007) indicate that the optimal IEH ranges from 400 to 600 km, and the height of 450 km is the most frequent IEH at both high and low solar activities. It is also confirmed that the IEH of 450-550 km is preferred for the Chinese region instead of the commonly adopted 350-450 km using the determination method of the optimal IEH proposed in this paper.

Electric structure of the Copahue Volcano (Neuquén Province, Argentina), from magnetotelluric soundings: 1D and 2D modellings

NASA Astrophysics Data System (ADS)

Mamaní, M. J.; Borzotta, E.; Venencia, J. E.; Maidana, A.; Moyano, C. E.; Castiglione, B.

2000-05-01

Four magnetotelluric soundings were carried out in 1993 in the region of the Copahue active volcano located at the border between Chile and Argentina (37°45'S, 71°18'W). Three soundings were located inside the caldera of the ancient stratovolcano (east of Copahue) and the fourth outside it. The soundings inside the caldera were situated at about 6, 11, and 14 km from the volcano. Digital data were obtained covering the range of periods from 1 sec to 10,000 sec using induction coils and a flux-gate magnetometer to obtain the magnetic data and Cu-SO 4Cu electrodes for electric field measurements. The apparent resistivity curves corresponding to principal directions were analyzed in conjunction with the geological background in order to eliminate distortion — which is very important in this hot volcanic region. Then, 1D modellings were performed using the "normal" curves — i.e., curves without distortions. Using the apparent resistivity curves with distortions, 2D modelling was also performed along a profile perpendicular to the regional tectonic trend suggested by MT soundings into the caldera. Results show low resistivity values of about 3-15 Ωm between 9 km to 20 km depth in the crust, suggesting high temperatures, with minimum values of about 700°C with partially melted zones in the upper crust between 9 km to 20 km depth under the caldera. The presence of a possible sulphide-carbonaceous layer (SC layer) in the upper basement could play an important role in lowering the electrical resistivities because of its high electronic conductivity.

Determination of annual and seasonal daytime and nighttime trends of MODIS LST over Greece - climate change implications.

PubMed

Eleftheriou, Dimitrios; Kiachidis, Kyriakos; Kalmintzis, Georgios; Kalea, Argiro; Bantasis, Christos; Koumadoraki, Paraskevi; Spathara, Maria Eleni; Tsolaki, Angeliki; Tzampazidou, Maria Irini; Gemitzi, Alexandra

2018-03-01

Climate change is one of the most challenging research topics during the last few decades, as temperature rise has already posed a significant impact on the earth's functions thus affecting all life of the planet. Land Surface Temperature (LST) is identified as a key variable in environmental and climate studies. The present study investigates the distribution of daytime and nighttime LST trends over Greece, a country in the Mediterranean area which is identified as one of the main "hot-spots" of climate change projections. Remotely sensed LST data were obtained from MODerate Resolution Imaging Spectroradiometer (MODIS) sensor in the form of 8-day composites of day and night values at a resolution of 1km for a 17-year period, i.e. from 2000 to 2017. Spatial aggregates of 10km×10km were computed and the annual and seasonal temporal trends were determined for each one of those sub-areas. Results showed that annual trends of daily LST in the majority of areas demonstrated decrease ranging from -1∗10 -2 °C to -1.3∗10 -3 °C, with some sporadic parts showing a slight increase. A totally different outcome is observed in the fate of night LST, with all areas over Greece demonstrating increasing annual trends ranging from 4.6∗10 -5 °C to 3.1∗10 -3 °C, with highest values in the South-East parts of the country. Seasonal trends in day and night LST showed the same pattern, i.e., a general decrease in the day LST and a definite increase in night. An interesting finding is the increase in winter LST trends observed both for day and night LST, indicating that the absolute minimum annual LST observed during winter in Greece increases. Our results also indicate that the annual diurnal LST range is decreasing. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensor Management for Tactical Surveillance Operations

DTIC Science & Technology

2007-11-01

active and passive sonar for submarine and tor- pedo detection, and mine avoidance. [range, bearing] range 1.8 km to 55 km Active or Passive AN/SLQ-501...finding (DF) unit [bearing, classification] maximum range 1100 km Passive Cameras (day- light/ night- vision) ( video & still) Record optical and...infrared still images or motion video of events for near-real time assessment or long term analysis and archiving. Range is limited by the image resolution

Regional Vp, Vs, Vp/Vs, and Poisson's ratios across earthquake source zones from Memphis, Tennessee, to St. Louis, Missouri

USGS Publications Warehouse

Catchings, R.D.

1999-01-01

Models of P- and S-wave velocity, Vp/Vs ratios, Poisson's ratios, and density for the crust and upper mantle are presented along a 400-km-long profile trending from Memphis, Tennessee, to St. Louis, Missouri. The profile crosses the New Madrid seismic zone and reveals distinct regional variations in the crustal velocity structure north and south of the latitude of New Madrid. In the south near Memphis, the upper few kilometers of the crust are dominated by upper crustal sedimentary basins or graben with P-wave velocities less than 5 km/sec and S-wave velocities of about 2 km/sec. P-wave velocities of the upper and middle crust range from 6.0 to 6.5 km/sec at depths above 25 km, and corresponding S-wave velocities range from 3.5 to 3.7 km/sec. The lower crust consists of a high-velocity layer (Vp = 7.4 km/sec; Vs ~4.2 km/sec) that is up to 20-km thick at the latitude of New Madrid but thins to about 15 km near Memphis. To the north, beneath the western-most Illinois basin, low-velocity (Vp < 5 km/sec; Vs < 2.3 km/sec) sedimentary basins are less than 1-km deep. The average velocities (Vp = 6.0 km/sec; Vs = 3.5 km/sec) of the underlying, near-surface rocks argue against large thickness of unconsolidated noncarbonate sediments within 50 km of the western edge of the Illinois basin. Most of the crust beneath the Illinois basin is modeled as one layer, with velocities up to 6.8 km/sec (Vs = 3.7 km/sec) at 37-km depth. The thick, high-velocity (Vp = 7.4 km/sec; Vs ~4.2 km/sec) lower crustal layer thins from about 20 km near New Madrid to about 6 km beneath the western Illinois basin. Refractions from the Moho and upper mantle occur as first arrivals over distances as a great as 160 km and reveal upper mantle layering to 60 km depth. Upper mantle layers with P-wave velocities of 8.2 km/sec (Vs = 4.5 km/sec) and 8.4 km/sec (Vs = 4.7 km/sec) are modeled at 43 and 60 km depth, respectively. Crustal Vp/Vs ratios range between 1.74 and 1.83, and upper mantle Vp/V s ratios range from 1.78 to 1.84. Poisson's ratios range from about 0.26 to 0.33 in the crust and from about 0.27 to 0.29 in the upper mantle. Modeled average densities range from about 2.55 in the sedimentary basins to 3.43 in the upper mantle. Geophysical characteristics of the crust and upper mantle within the New Madrid seismic zone are consistent with other continental rifts, but the crustal structure of the Illinois basin is not characteristics of most continental rift settings. Seismic and gravity data suggest a buried horst near the middle of Reelfoot rift, beneath which is a vertical zone of seismicity and velocity anomalies. The relative depth of the Reelfoot rift north and south of the Reelfoot graben suggests that the rift and its bounding faults may extend eastward beneath the city of Memphis.

Subduction zone seismicity and the thermo-mechanical evolution of downgoing lithosphere

NASA Astrophysics Data System (ADS)

Wortel, M. J. R.; Vlaar, N. J.

1988-09-01

In this paper we discuss characteristic features of subduction zone seismicity at depths between about 100 km and 700 km, with emphasis on the role of temperature and rheology in controlling the deformation of, and the seismic energy release in downgoing lithosphere. This is done in two steps. After a brief review of earlier developments, we first show that the depth distribution of hypocentres at depths between 100 km and 700 km in subducted lithosphere can be explained by a model in which seismic activity is confined to those parts of the slab which have temperatures below a depth-dependent critical value T cr. Second, the variation of seismic energy release (frequency of events, magnitude) with depth is addressed by inferring a rheological evolution from the slab's thermal evolution and by combining this with models for the system of forces acting on the subducting lithosphere. It is found that considerable stress concentration occurs in a reheating slab in the depth range of 400 to 650 700 km: the slab weakens, but the stress level strongly increases. On the basis of this stress concentration a model is formulated for earthquake generation within subducting slabs. The model predicts a maximum depth of seismic activity in the depth range of 635 to 760 km and, for deep earthquake zones, a relative maximum in seismic energy release near the maximum depth of earthquakes. From our modelling it follows that, whereas such a maximum is indeed likely to develop in deep earthquake zones, zones with a maximum depth around 300 km (such as the Aleutians) are expected to exhibit a smooth decay in seismic energy release with depth. This is in excellent agreement with observational data. In conclusion, the incoroporation of both depth-dependent forces and depth-dependent rheology provides new insight into the generation of intermediate and deep earthquakes and into the variation of seismic activity with depth. Our results imply that no barrier to slab penetration at a depth of 650 700 km is required to explain the maximum depth of seismic activity and the pattern of seismic energy release in deep earthquake zones.

Long distance quantum teleportation in a quantum relay configuration.

PubMed

de Riedmatten, H; Marcikic, I; Tittel, W; Zbinden, H; Collins, D; Gisin, N

2004-01-30

A long distance quantum teleportation experiment with a fiber-delayed Bell state measurement (BSM) is reported. The source creating the qubits to be teleported and the source creating the necessary entangled state are connected to the beam splitter realizing the BSM by two 2 km long optical fibers. In addition, the teleported qubits are analyzed after 2.2 km of optical fiber, in another laboratory separated by 55 m. Time-bin qubits carried by photons at 1310 nm are teleported onto photons at 1550 nm. The fidelity is of 77%, above the maximal value obtainable without entanglement. This is the first realization of an elementary quantum relay over significant distances, which will allow an increase in the range of quantum communication and quantum key distribution.

Vertical structure of cumulonimbus towers and intense convective clouds over the South Asian region during the summer monsoon season

NASA Astrophysics Data System (ADS)

Bhat, G. S.; Kumar, Shailendra

2015-03-01

The vertical structure of radar reflectivity factor in active convective clouds that form during the South Asian monsoon season is reported using the 2A25 version 6 data product derived from the precipitation radar measurements on board the Tropical Rainfall Measuring Mission satellite. We define two types of convective cells, namely, cumulonimbus towers (CbTs) and intense convective cells (ICCs). CbT is defined referring to a reflectivity threshold of 20 dBZ at 12 km altitude and is at least 9 km thick. ICCs are constructed referring to reflectivity thresholds at 8 km and 3 km altitudes. Cloud properties reported here are based on 10 year climatology. It is observed that the frequency of occurrence of CbTs is highest over the foothills of Himalayas, plains of northern India and Bangladesh, and minimum over the Arabian Sea and equatorial Indian Ocean west of 90°E. The regional differences depend on the reference height selected, namely, small in the case of CbTs and prominent in 6-13 km height range for ICCs. Land cells are more intense than the oceanic ones for convective cells defined using the reflectivity threshold at 3 km, whereas land versus ocean contrasts are not observed in the case of CbTs. Compared to cumulonimbus clouds elsewhere in the tropics, the South Asian counterparts have higher reflectivity values above 11 km altitude.

Calibration of the local magnitude scale ( M L ) for Peru

NASA Astrophysics Data System (ADS)

Condori, Cristobal; Tavera, Hernando; Marotta, Giuliano Sant'Anna; Rocha, Marcelo Peres; França, George Sand

2017-07-01

We propose a local magnitude scale ( M L ) for Peru, based on the original Richter definition, using 210 seismic events between 2011 and 2014, recorded by 35 broadband stations of the National Seismic Network operated by the Geophysical Institute of Peru. In the solution model, we considered 1057 traces of maximum amplitude records on the vertical channel from simulated Wood-Anderson seismograms of shallow events (depths between 0 and 60 km) and hypocentral distances less than 600 km. The attenuation factor has been evaluated in terms of geometrical spreading and anelastic attenuation coefficients. The magnitude M L was defined as M L = L o g 10 A W A +1.5855 L o g 10( R/100)+0.0008( R-100)+3± S, where, A W A is the displacement amplitude in millimeters (Wood-Anderson), R is the hypocentral distance (km), and S is the station correction. The results obtained for M L have good correlation with the m b , M s and M w values reported the ISC and NEIC. The anelastic attenuation curve obtained has a similar behavior to that other highly seismic regions. Station corrections were determined for all stations during the regression analysis resulting in values ranging between -0.97 and +0.73, suggesting a strong influence of local site effects on amplitude.

Shear velocity profiles in the crust and lithospheric mantle across Tibet

NASA Astrophysics Data System (ADS)

Agius, M. R.; Lebedev, S.

2010-12-01

We constrain variations in the crustal and lithospheric structure across Tibet, using phase velocities of seismic surface waves. The data are seismograms recorded by broadband instruments of permanent and temporary networks within and around the plateau. Phase-velocity measurements are performed in broad period ranges using an elaborate recent implementation of the 2-station method. A combination of the cross-correlation and multimode-waveform-inversion measurements using tens to hundreds of seismograms per station pair produces robust, accurate phase-velocity curves for Rayleigh and Love waves. We use our new measurements to infer phase-velocity variations and to constrain S-velocity profiles in different parts of the plateau, including radial anisotropy and depths of lithospheric discontinuities. We observe a mid-crustal low-velocity zone (LVZ) in the 20-45 km depth range across the plateau, with S-velocities within a 3.2-3.5 km/s range. This LVZ coincides with a low-resistivity layer inferred from magnetotelluric studies, interpreted as evidence for partial melting in the middle crust. Surface-wave data are also consistent with radial anisotropy in this layer, indicative of horizontal flow. At the north-eastern boundary of the plateau, past the Kunlun Fault, the mid-crustal LVZ, in the sense of an S-velocity decrease with depth in the 15-25 km depth range, is not required by the surface-wave data although the velocity is still relatively low. The mantle-lithosphere structure shows a pronounced contrast between the south-western and central-northern parts of the plateau. The south-west is underlain by a thick, high-velocity, craton-like lithospheric mantle. Below central Lhasa the uppermost mantle appears to be close to global average with an increase in velocity between 150 - 250 km depth. Beneath central and northern Tibet, the average S velocity between the Moho and 200 km depth is close to the global continental average (4.5 km/s). In order to investigate the finer detail of the lithosphere in the North we perform an extensive series of test inversions. We find that surface-wave dispersion measurements alone are consistent both with models that have low S velocity just beneath the Moho, increasing with depth below, and with models that display a thin high-velocity mantle lid underlain by a low-velocity zone (asthenosphere). To resolve this non-uniqueness from the inversion model, we combine our surface-wave measurements in the Qiangtang Block with receiver-function constraints on the Moho depth, and Sn constraints on the uppermost mantle S velocities. We show that the data is matched significantly better with models that contain a thin, high-velocity lithosphere (up to 90 km thick) underlain by a low-velocity zone than by models with no wave-speed decrease between the Moho and ~100 km depth. In the deeper upper mantle (below ~150 km depth), S velocity increases and is likely to exceed the global average value.

Retrieving aerosol profiles through horizon shadowing and polarimetry

NASA Astrophysics Data System (ADS)

Videen, G.; Pavlov, A.; Zubko, E.; Konstantinov, O.; Shmirko, K.; Mayor, A.

2017-12-01

We report polarimetric measurements of atmospheric aerosol in evening and morning twilight over Vladivostok, Russia in late winter-early spring of 2017 using a horizon-shadowing technique. The motion of the Sun beneath the horizon changes the altitude of the boundary of the shadowed atmosphere h, making it possible to constrain the altitude of aerosol particles contributing to the polarimetric response. We investigate the degree of linear polarization P in aerosol particles at different altitudes, ranging from 0 km up to 17 km. In two out of four experiments we found significant variations of the polarimetric response (ΔP 10%) with altitude; whereas, in the other measurements, the polarization appeared nearly the same (ΔP 2-3%) throughout the entire range of the studied altitude. Polarization P was measured in the zenith direction with the scattering angle being θ 90°. At such a scattering angle, the polarization is near its maximum value Pmax. Conclusions drawn from polarimetric measurements appear in qualitative accordance with results of remote sensing with a three-wavelength lidar.

Shuttle high resolution accelerometer package experiment results - Atmospheric density measurements between 60-160 km

NASA Technical Reports Server (NTRS)

Blanchard, R. C.; Hinson, E. W.; Nicholson, J. Y.

1988-01-01

Indirect or inferred values of atmospheric density encountered by the Shuttle Orbiter during reentry have been calculated from acceleration measurements made by the High Resolution Accelerometer Package (HiRAP) and the Orbiter Inertial Measurement Unit (IMU) liner accelerometers. The atmospheric density data developed from this study represent a significant gain with respect to the body of data collected to date by various techniques in the altitude range of 60 to 160 km. The data are unique in that they cover a very wide horizontal range during each flight and provide insight into the actual density variations encountered along the reentry flight path. The data, which were collected over about 3 years, are also characterized by variations in solar activity, geomagnetic index, and local solar time. Comparison of the flight-derived densities with various atmospheric models have been made, and analyses have attempted to characterize the data and to show correlation with selected physical variables.

Polyphenol oxidase activity and antioxidant properties of Yomra apple (Malus communis L.) from Turkey.

PubMed

Can, Zehra; Dincer, Barbaros; Sahin, Huseyin; Baltas, Nimet; Yildiz, Oktay; Kolayli, Sevgi

2014-12-01

In this study, firstly, antioxidant and polyphenol oxidase (PPO) properties of Yomra apple were investigated. Seventeen phenolic constituents were measured by reverse phase-high-performance liquid chromatography (RP-HPLC). Total phenolic compounds (TPCs), ferric reducing antioxidant power (FRAP) and 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activities were performed to measure antioxidant capacity. Some kinetic parameters (Km, Vmax), and inhibition behaviors against five different substrates were measured in the crude extract. Catechin and chlorogenic acid were found as the major components in the methanolic extract, while ferulic acid, caffeic acid, p-hydroxybenzoic acid, quercetin and p-coumaric acid were small quantities. Km values ranged from 0.70 to 10.10 mM in the substrates, and also 3-(4-hydroxyphenyl) propanoic acid (HPPA) and L-DOPA showed the highest affinity. The inhibition constant of Ki were ranged from 0.05 to 14.90 mM against sodium metabisulphite, ascorbic acid, sodium azide and benzoic acid, while ascorbic acid and sodium metabisulphite were the best inhibitors.

Ground-based microwave radiometry to determine stratospheric and mesospheric ozone profiles

NASA Astrophysics Data System (ADS)

Lobsiger, E.

1987-05-01

From April 1984 to April 1985 a microwave radiometer was operated at Bern measuring the thermal emission of the rotational ozone transition at 142.2 GHz to determine stratospheric and mesospheric ozone abundances in the range 25-75 km altitude. From a total of 334 retrieved daytime profiles, monthly mean ozone partial pressures for Umkehr layers 6-10 were calculated. On this basis ozone variations compare favorably with Umkehr data from the nearby Arosa station and with a monthly zonal mean model compiled from satellite data by Keating and Young (1985). From the microwave data, an annual mean ozone distribution was determined. The method retrieves somewhat larger ozone volume mixing ratios between 25 and 30 km altitude. For the rest of the measurement range of the sensor there is good agreement with 20-year annual mean ozone values from Arosa, with the Krueger and Minzner profile and with the respective annual mean data given by Keating and Young.

Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions

USGS Publications Warehouse

Abbott, M.L.; Susong, D.D.; Krabbenhoft, D.P.; Rood, A.S.

2002-01-01

Mercury (total and methyl) was evaluated in snow samples collected near a major mercury emission source on the Idaho National Engineering and Environmental Laboratory (INEEL) in southeastern Idaho and 160 km downwind in Teton Range in western Wyoming. The sampling was done to assess near-field (<12 km) deposition rates around the source, compare them to those measured in a relatively remote, pristine downwind location, and to use the measurements to develop improved, site-specific model input parameters for precipitation scavenging coefficient and the fraction of Hg emissions deposited locally. Measured snow water concentrations (ng L-1) were converted to deposition (ug m-2) using the sample location snow water equivalent. The deposition was then compared to that predicted using the ISC3 air dispersion/deposition model which was run with a range of particle and vapor scavenging coefficient input values. Accepted model statistical performance measures (fractional bias and normalized mean square error) were calculated for the different modeling runs, and the best model performance was selected. Measured concentrations close to the source (average = 5.3 ng L-1) were about twice those measured in the Teton Range (average = 2.7 ng L-1) which were within the expected range of values for remote background areas. For most of the sampling locations, the ISC3 model predicted within a factor of two of the observed deposition. The best modeling performance was obtained using a scavenging coefficient value for 0.25 ??m diameter particulate and the assumption that all of the mercury is reactive Hg(II) and subject to local deposition. A 0.1 ??m particle assumption provided conservative overprediction of the data, while a vapor assumption resulted in highly variable predictions. Partitioning a fraction of the Hg emissions to elemental Hg(0) (a U.S. EPA default assumption for combustion facility risk assessments) would have underpredicted the observed fallout.

Impacts of the spatial extent of pollen-climate calibration-set on the absolute values, range and trends of reconstructed Holocene precipitation

NASA Astrophysics Data System (ADS)

Cao, X.; Tian, F.; Telford, R.; Ni, J.; Xu, Q.; Chen, F.; Liu, X.; Stebich, M.; Zhao, Y.; Herzschuh, U.

2017-12-01

Pollen-based quantitative reconstructions of past climate variables is a standard palaeoclimatic approach. Despite knowing that the spatial extent of the calibration-set affects the reconstruction result, guidance is lacking as to how to determine a suitable spatial extent of the pollen-climate calibration-set. In this study, past mean annual precipitation (Pann) during the Holocene (since 11.5 cal ka BP) is reconstructed repeatedly for pollen records from Qinghai Lake (36.7°N, 100.5°E; north-east Tibetan Plateau), Gonghai Lake (38.9°N, 112.2°E; north China) and Sihailongwan Lake (42.3°N, 126.6°E; north-east China) using calibration-sets of varying spatial extents extracted from the modern pollen dataset of China and Mongolia (2559 sampling sites and 168 pollen taxa in total). Results indicate that the spatial extent of the calibration-set has a strong impact on model performance, analogue quality and reconstruction diagnostics (absolute value, range, trend, optimum). Generally, these effects are stronger with the modern analogue technique (MAT) than with weighted averaging partial least squares (WA-PLS). With respect to fossil spectra from northern China, the spatial extent of calibration-sets should be restricted to ca. 1000 km in radius because small-scale calibration-sets (<800 km radius) will likely fail to include enough spatial variation in the modern pollen assemblages to reflect the temporal range shifts during the Holocene, while too broad a scale calibration-set (>1500 km radius) will include taxa with very different pollen-climate relationships. Based on our results we conclude that the optimal calibration-set should 1) cover a reasonably large spatial extent with an even distribution of modern pollen samples; 2) possess good model performance as indicated by cross-validation, high analogue quality, and excellent fit with the target fossil pollen spectra; 3) possess high taxonomic resolution, and 4) obey the modern and past distribution ranges of taxa inferred from palaeo-genetic and macrofossil studies.

Global optical climatology of the free tropospheric aerosol from 1.0-micron satellite occultation measurements

NASA Technical Reports Server (NTRS)

Kent, G. S.; Schaffner, S. K.; Mccormick, M. P.

1991-01-01

Measurements of the aerosol/molecular extinction ratio at 1-micron wavelength, obtained from the SAGE I, SAGE II, and SAM II solar occultation satellite experiments between 1978 and 1986, have been used to study the global-scale behavior of the upper tropospheric aerosol. The distribution of extinction ratio values shows a pronounced mode between about 0.5 and 5 in all data subsets, regardless of latitude and season. Within a given latitude band and season with mode value is nearly constant over the altitude range from about 5 km above the earth's surface to 3 km below the tropopause. The mode shows a distinct seasonal variation, with maxima in local spring and summer, and is significantly enhanced following vlocanic injection of material into the stratosphere. South of latitude 20-deg N, mode values in the absence of volcanic contamination are normally between 0.5 and 1.0 north of 20-deg N, values up to about 5 are observed, probably associated with aerosol derived from surface dust or anthropogenic sources. A secondary mode, with extinction ratios of 30 or greater and little or no variation of extinction with wavelength, is apparent just below the tropopause. This mode is believed to be associated with thin cloud along the ray path from the sun to the satellite.

Heat flow from the Liberian Precambrian Shield

NASA Astrophysics Data System (ADS)

Sass, J. H.; Behrendt, J. C.

1980-06-01

Uncorrected heat flow in iron formation rocks from three areas within the Liberian part of the West African Shield ranges from 50 to more than 80 mW m-2. When corrections are applied for topography and refraction, the range of heat flow is narrowed to between 38 and 42 mW m-2. In comparison with heat flows from other parts of the West African Craton, these values are consistent with preliminary results from Ghana (42±8 mW m-2) and Nigeria (38±2 mW m-2) but are somewhat higher than values from Niger (20 mW m-2) and neighboring Sierra Leone (26 mW m-2). The Liberian values are significantly lower than the heat flow offshore in the equatorial Atlantic Ocean (58±8 m W m-2), suggesting large lateral temperature gradients within the lithosphere near the coast. Values of heat production from outcrops of crystalline basement rocks near the holes are between 2 and 2.3 /μW m-3. A heat-flow/heat-production relation cannot be established because of the small range of values; however, assuming a `characteristic depth' of 8 km (similar to the North American Craton) the reduced heat flow of from 20 to 25 mW m-2 is consistent with that from other Precambrian shields.

Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

PubMed

Martinelle, M; Hult, K

1995-09-06

The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid.

Glacier change in the Gangdise Mountains, southern Tibet, since the Little Ice Age

NASA Astrophysics Data System (ADS)

Zhang, Qian; Yi, Chaolu; Fu, Ping; Wu, Yubin; Liu, Jinhua; Wang, Ninglian

2018-04-01

Delineating glacier change during the Little Ice Age (LIA) is of great importance when attempting to understand regional climatic changes and can also help to improve the understanding of any predictions of future glacial changes. However, such knowledge is still lacking for some critical regions of the Tibetan Plateau (TP). In this study, we mapped 4188 contemporary glaciers and reconstructed 1216 LIA areas of glacial coverage in the Gangdise Mountains to the north of the Himalaya using Google Earth satellite imagery. We estimated their paleoglacial areas and equilibrium line altitudes (ELAs) based on the toe-to-headwall altitude ratio (THAR) method. Results show that most glaciers are small (<1 km2), with slope/hanging glaciers the most common (2844 out of 4188 glaciers), while valley glaciers have the greatest coverage (1009.0 km2 out of a total area of 1723.7 km2). Contemporary glaciers have retreated significantly since the LIA, with reductions in length of between 5.5% and 94.7% (mean glacier length 696 m; mean reduction in length 41.7%) and reductions in glacier area of between 4.1% and 94.9% (mean glacier area 0.42 km2; mean reduction in area 44.8%). These reductions have occurred under different local climatic and topographic conditions. The contemporary ELA ranges from 5516 to 6337 m asl; the LIA ELA ranged from 5476 to 6329 m asl. Contemporary and LIA ELA values rise from southeast to northwest. As a general rule, the rise in the ELA value decreases from the eastern to the central Gangdise Mountains and then increases westward, with a mean ELA rise of 45 m. Multiple regression models suggest that 46.8% of the glacier area loss can be explained by glacier elevation, area, and slope. However, only 15.5% of the rise in ELA values can be explained by glacial geometric, topographic, or locational parameters. The spatial pattern of modern ELA values in this region appears inversely related to precipitation, which decreases from southeast to northwest, implying that precipitation is one of the key controls of ELAs. This is also consistent with results from elsewhere in High Asia. In contrast to the Gangdise Mountains' eastern and western sectors, glaciers in the central sector have undergone less change, i.e., in terms of reductions in length, area loss, and rises in ELA. Topography can of course also influence glacial change by creating shielding and/or rainshadow effects and by affecting local temperatures.

[Analysis of surface composition of three-way catalysts of in-use vehicles].

PubMed

Xie, Shu-xia; Hu, Jing-nan; Bao, Xiao-feng; Zhang, Ke-song; Li, Zhen-hua; Wang, Hai-tao

2010-07-01

The kinds and contents of surface elements in three-way catalysts of six light-duty in-use taxi cabs, which were mainly operated in Beijing and whose driving mileages were in the range of 34 x 10(4)-59 x 10(4) km, were determined by X-ray fluorescence spectrometry (XRF), and the effect of driving mileage on element content was investigated. Results showed that nearly 30 kinds of elements were present on the catalyst surface. The main elements of different samples were similar. The common elements of the pollutant on the front and rear catalysts were P, Ca, Zn and Mn etc., most of which are from engine oil and gasoline. S was only observed on the rear catalysts, indicating that S tends to deposit on the rear catalysts. After 34 x 10(4) km run, the P content increased very slowly and 40 x 10(4) km run S content reached a saturated value. While the contents of Ca, Zn and Mn still exhibit an increase tendency after 56 x 10(4) km. That means after 40 x 10(4) km driving mileage, the effects of P and S on the catalyst activity are minor, and the continuous deposit of Ca, Zn and Mn will lead to further decrease of the activity.

Quantum key distribution in a multi-user network at gigahertz clock rates

NASA Astrophysics Data System (ADS)

Fernandez, Veronica; Gordon, Karen J.; Collins, Robert J.; Townsend, Paul D.; Cova, Sergio D.; Rech, Ivan; Buller, Gerald S.

2005-07-01

In recent years quantum information research has lead to the discovery of a number of remarkable new paradigms for information processing and communication. These developments include quantum cryptography schemes that offer unconditionally secure information transport guaranteed by quantum-mechanical laws. Such potentially disruptive security technologies could be of high strategic and economic value in the future. Two major issues confronting researchers in this field are the transmission range (typically <100km) and the key exchange rate, which can be as low as a few bits per second at long optical fiber distances. This paper describes further research of an approach to significantly enhance the key exchange rate in an optical fiber system at distances in the range of 1-20km. We will present results on a number of application scenarios, including point-to-point links and multi-user networks. Quantum key distribution systems have been developed, which use standard telecommunications optical fiber, and which are capable of operating at clock rates of up to 2GHz. They implement a polarization-encoded version of the B92 protocol and employ vertical-cavity surface-emitting lasers with emission wavelengths of 850 nm as weak coherent light sources, as well as silicon single-photon avalanche diodes as the single photon detectors. The point-to-point quantum key distribution system exhibited a quantum bit error rate of 1.4%, and an estimated net bit rate greater than 100,000 bits-1 for a 4.2 km transmission range.

Annual and seasonal distribution of day and night Land Surface Temperature trend over Greece.

NASA Astrophysics Data System (ADS)

Lakshmi, V.; Gemitzi, A.; Eleftheriou, D.; Kalea, A.; Kalmintzis, G.; Kiachidis, K.; Koumadoraki, P.; Mpantasis, C.; Spathara, M. E.; Tsolaki, A.; Tzampazidou, M. I.

2017-12-01

Climate change is one of the most challenging research topics during the last few decades, as temperature rise has already posed a significant impact on earth's functions affecting thus all life of the planet. The present study investigates the distribution of day and night Land Surface Temperature (LST) trends over Greece, a country in Mediterranean area which is identified as one of the main ``hot-spots" of climate change projections. Remotely sensed LST data were obtained from MODIS sensor in the form of 8-day composites of day and night values at a resolution of 1km for a 17-year period, i.e. from 2000 to 2017. Spatial aggregates of 10km x 10km were computed and the annual and seasonal temporal trends were determined for each one of those sub-areas. Results showed that annual trends of daily LST in the majority of areas demonstrated decrease ranging from -1*10-2 oC to -1.3*10-3 oC, with some sporadic parts showing a slight increase. A totally different outcome is observed in the fate of night LST, with all areas over Greece demonstrating increasing annual trends ranging from 4.6 * 10-5 oC to 3.1 * 10-3 oC, with highest values in the South-East parts of the country. Seasonal trends in day and night LST showed the same pattern, i.e., a general decrease in the day LST and a definite increase in night. An interesting finding is the increase in winter LST trends observed both for day and night LST, indicating that the absolute minimum annual LST observed during winter in Greece increases. Our results also indicate that the difference between the day and night LST is decreasing.

Water in the Cratonic Mantle: Insights from FTIR Data on Lac De Gras Xenoliths (Slave Craton, Canada)

NASA Technical Reports Server (NTRS)

Peslier, Anne H.; Brandon, Alan D.; Schaffer, Lillian Aurora; O'Reilly, Suzanne Yvette; Griffin, William L.; Morris, Richard V.; Graff, Trevor G.; Agresti, David G.

2014-01-01

The mantle lithosphere beneath the cratonic part of continents is the deepest (> 200 km) and oldest (>2-3 Ga) on Earth, remaining a conundrum as to how these cratonic roots could have resisted delamination by asthenospheric convection over time. Water, or trace H incorporated in mineral defects, could be a key player in the evolution of continental lithosphere because it influences melting and rheology of the mantle. Mantle xenoliths from the Lac de Gras kimberlite in the Slave craton were analyzed by FTIR. The cratonic mantle beneath Lac de Gras is stratified with shallow (<145 km) oxidized ultradepleted peridotites and pyroxenites with evidence for carbonatitic metasomatism, underlain by reduced and less depleted peridotites metasomatized by kimberlite melts. Peridotites analyzed so far have H O contents in ppm weight of 7-100 in their olivines, 58 to 255 in their orthopyroxenes (opx), 11 to 84 in their garnet, and 139 in one clinopyroxene. A pyroxenite contains 58 ppm H2O in opx and 5 ppm H2O in its olivine and garnet. Olivine and garnet from the deep peridotites have a range of water contents extending to higher values than those from the shallow ones. The FTIR spectra of olivines from the shallow samples have more prominent Group II OH bands compared to the olivines from the deep samples, consistent with a more oxidized mantle environment. The range of olivine water content is similar to that observed in Kaapvaal craton peridotites at the same depths (129-184 km) but does not extend to as high values as those from Udachnaya (Siberian craton). The Slave, Kaapvaal and Siberian cratons will be compared in terms of water content distribution, controls and role in cratonic root longevity.

Quantitative Comparison of Human Parainfluenza Virus Hemagglutinin-Neuraminidase Receptor Binding and Receptor Cleavage

PubMed Central

Tappert, Mary M.; Porterfield, J. Zachary; Mehta-D'Souza, Padmaja; Gulati, Shelly

2013-01-01

The human parainfluenza virus (hPIV) hemagglutinin-neuraminidase (HN) protein binds (H) oligosaccharide receptors that contain N-acetylneuraminic acid (Neu5Ac) and cleaves (N) Neu5Ac from these oligosaccharides. In order to determine if one of HN′s two functions is predominant, we measured the affinity of H for its ligands by a solid-phase binding assay with two glycoprotein substrates and by surface plasmon resonance with three monovalent glycans. We compared the dissociation constant (Kd) values from these experiments with previously determined Michaelis-Menten constants (Kms) for the enzyme activity. We found that glycoprotein substrates and monovalent glycans containing Neu5Acα2-3Galβ1-4GlcNAc bind HN with Kd values in the 10 to 100 μM range. Km values for HN were previously determined to be on the order of 1 mM (M. M. Tappert, D. F. Smith, and G. M. Air, J. Virol. 85:12146–12159, 2011). A Km value greater than the Kd value indicates that cleavage occurs faster than the dissociation of binding and will dominate under N-permissive conditions. We propose, therefore, that HN is a neuraminidase that can hold its substrate long enough to act as a binding protein. The N activity can therefore regulate binding by reducing virus-receptor interactions when the concentration of receptor is high. PMID:23740997

Direct recovery of mean gravity anomalies from satellite to satellite tracking

NASA Technical Reports Server (NTRS)

Hajela, D. P.

1974-01-01

The direct recovery was investigated of mean gravity anomalies from summed range rate observations, the signal path being ground station to a geosynchronous relay satellite to a close satellite significantly perturbed by the short wave features of the earth's gravitational field. To ensure realistic observations, these were simulated with the nominal orbital elements for the relay satellite corresponding to ATS-6, and for two different close satellites (one at about 250 km height, and the other at about 900 km height) corresponding to the nominal values for GEOS-C. The earth's gravitational field was represented by a reference set of potential coefficients up to degree and order 12, considered as known values, and by residual gravity anomalies obtained by subtracting the anomalies, implied by the potential coefficients, from their terrestrial estimates. It was found that gravity anomalies could be recovered from strong signal without using any a-priori terrestrial information, i.e. considering their initial values as zero and also assigning them a zero weight matrix. While recovering them from weak signal, it was necessary to use the a-priori estimate of the standard deviation of the anomalies to form their a-priori diagonal weight matrix.

Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

2011-11-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s-1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ~10,000 km s-1 (~0.03c) up to ~100,000 km s-1 (~0.3c), with a peak and mean value of ~42,000 km s-1 (~0.14c). The ionization parameter is very high and in the range log ξ ~ 3-6 erg s-1 cm, with a mean value of log ξ ~ 4.2 erg s-1 cm. The associated column densities are also large, in the range N H ~ 1022-1024 cm-2, with a mean value of N H ~ 1023 cm-2. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds, and jets.

Research of autonomous celestial navigation based on new measurement model of stellar refraction

NASA Astrophysics Data System (ADS)

Yu, Cong; Tian, Hong; Zhang, Hui; Xu, Bo

2014-09-01

Autonomous celestial navigation based on stellar refraction has attracted widespread attention for its high accuracy and full autonomy．In this navigation method, establishment of accurate stellar refraction measurement model is the fundament and key issue to achieve high accuracy navigation. However, the existing measurement models are limited due to the uncertainty of atmospheric parameters. Temperature, pressure and other factors which affect the stellar refraction within the height of earth's stratosphere are researched, and the varying model of atmosphere with altitude is derived on the basis of standard atmospheric data. Furthermore, a novel measurement model of stellar refraction in a continuous range of altitudes from 20 km to 50 km is produced by modifying the fixed altitude (25 km) measurement model, and equation of state with the orbit perturbations is established, then a simulation is performed using the improved Extended Kalman Filter. The results show that the new model improves the navigation accuracy, which has a certain practical application value.

Discovery and observation of BY Draconis variables

NASA Astrophysics Data System (ADS)

Bopp, B. W.; Noah, P. V.; Klimke, A.; Africano, J.

1981-10-01

The discovery of BY Draconis variables was efficiently accomplished by a spectroscopic survey of dK-M stars for weak H-alpha emissions, using 1-2 A resolution. The four BY Dra variables discovered are all spectroscopic binaries with P values lower than about 10 d, in light of which, it is noted that the onset of high surface activity and appearance of H-alpha emission occur sharply at v(equator) of approximately 5 km/sec. At v(equator) of about 3 km/sec, dK-M stars have low levels of surface activity. It is found that while there is a range of Ca II emission strength, and only the strongest emitters of this line are BY Dra and/or flare stars, the H-alpha feature changes abruptly to an emission feature signaling the onset of flaring and/or the BY Dra syndrome. An increase of the rotation rate above v(equator) 5 km/sec does not appear to increase the level of surface activity.

Large Volcanic Rises on Venus

NASA Technical Reports Server (NTRS)

Smrekar, Suzanne E.; Kiefer, Walter S.; Stofan, Ellen R.

1997-01-01

Large volcanic rises on Venus have been interpreted as hotspots, or the surface manifestation of mantle upwelling, on the basis of their broad topographic rises, abundant volcanism, and large positive gravity anomalies. Hotspots offer an important opportunity to study the behavior of the lithosphere in response to mantle forces. In addition to the four previously known hotspots, Atla, Bell, Beta, and western Eistla Regiones, five new probable hotspots, Dione, central Eistla, eastern Eistla, Imdr, and Themis, have been identified in the Magellan radar, gravity and topography data. These nine regions exhibit a wider range of volcano-tectonic characteristics than previously recognized for venusian hotspots, and have been classified as rift-dominated (Atla, Beta), coronae-dominated (central and eastern Eistla, Themis), or volcano-dominated (Bell, Dione, western Eistla, Imdr). The apparent depths of compensation for these regions ranges from 65 to 260 km. New estimates of the elastic thickness, using the 90 deg and order spherical harmonic field, are 15-40 km at Bell Regio, and 25 km at western Eistla Regio. Phillips et al. find a value of 30 km at Atla Regio. Numerous models of lithospheric and mantle behavior have been proposed to interpret the gravity and topography signature of the hotspots, with most studies focusing on Atla or Beta Regiones. Convective models with Earth-like parameters result in estimates of the thickness of the thermal lithosphere of approximately 100 km. Models of stagnant lid convection or thermal thinning infer the thickness of the thermal lithosphere to be 300 km or more. Without additional constraints, any of the model fits are equally valid. The thinner thermal lithosphere estimates are most consistent with the volcanic and tectonic characteristics of the hotspots. Estimates of the thermal gradient based on estimates of the elastic thickness also support a relatively thin lithosphere (Phillips et al.). The advantage of larger estimates of the thermal lithospheric thickness is that they provide an explanation for the apparently modest levels of geologic activity on Venus over the last half billion years.

Thirty years of seismic network recording in South Australia: Selected results

NASA Astrophysics Data System (ADS)

Greenhalgh, S. A.; Love, D.; Sinadinovski, C.

1994-11-01

The year 1993 marks 30 years of seismic network recording of earthquakes in South Australia. The network currently comprises 17 short-period instruments, of which six use digital recording and five employ triaxial sensors. Approximately 350 earthquakes are located within the State each year using a computerized seismic analysis system developed by the Phillip Institute of Technology. A duration-based magnitude scale, equivalent to the Richter M(sub L) scale, has been developed for most stations. The pre-network (historical) record of earthquake activity in South Australia dates back to 1837. Epicenters are available for just 45 earthquakes. Of these, ten are of magnitude five or greater. The instrumental data over the last 30 years show a similar trend in epicentral pattern to the historical earthquakes, with the major zones being the Flinders Ranges, Eyre Peninsula and the Southeast. There have been 40 earthquakes of magnitude four or greater since 1963, the largest earthquake being of magnitude six in the Musgrave Ranges during 1986. Mine and quarry blasts within the State have been useful in calibration of the network, both in terms of hypocentral location and amplitude studies. The explosions have also furnished valuable information on the crustal velocity distribution. Epicentral co-ordinates of mine blasts are generally good to within 3-5 km. The explosions yield Richter magnitudes of one (charge size 1 or 2 tons) to 2.5 (charge size 50 tons). The crustal S waves, used in earthquake magnitude determinations, exhibit an amplitude-distance decay coefficient of 1.2. The P-wave velocity function of the crust increases non-linearly with depth, from about 5.0 km /s near the surface to 6.4 km /s at 20 km depth, where the gradient reduces, with the velocity reaching a value of about 7.4 km /s at a depth of 40 km.

Arylsulfatase Activity in Salt Marsh Soils †

PubMed Central

Oshrain, R. L.; Wiebe, W. J.

1979-01-01

The presence of arylsulfatase(s) was confirmed in salt marsh soils. The temperatures of maximum activity and inactivation, the pH range over which the enzyme was active, and the Km values were similar to those of soil enzymes. Unlike soil arylsulfatases, however, the salt marsh enzymes do not appear to be repressed by sulfate. It is postulated that these enzymes may be necessary for the initiation of arylsulfate ester metabolism. PMID:16345425

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottar, B.

Results of the LRTAP program and other European studies are discussed which show that considerable long-range transport of air pollutants from the UK and central Europe to Scandinavia occurs. Data are examined which reveal that the sulfate deposition pattern in Scandinavia is largely governed by precipitation and wind direction and that sulfates deposition reaches maximum values of 3 to 5 metric tons/sq km in southern Scandinavia. The contribution from precipitation is found to outweigh the dry deposition, particularly in southern Norway.

Geologic map of the Hecate Chasma quadrangle (V-28), Venus

USGS Publications Warehouse

Stofan, Ellen R.; Guest, John E.; Brian, Antony W.

2012-01-01

The overall topography of V–28 consists of plains located slightly below mean planetary radius (MPR, 6051.84). The lowest regions are found in the rift trough (3.3 m below MPR), and the highest along the rift rim (4.3 km above MPR). The regions that are the roughest at Magellan radar wavelengths in the quadrangle occur along Hecate Chasma (root mean square [rms] slopes >10°), with most regions being relatively smooth (roughnesses comparable to the average Venus surface value of 2.84°). Emissivity values in the quadrangle are typical of most venusian plains regions, with a range in values for the quadrangle of 0.68–0.91. The highest emissivity values in the quadrangle lie at the highest elevations in the quadrangle (corona rims and interiors).

Magma transport and olivine crystallization depths in Kīlauea’s East Rift Zone inferred from experimentally rehomogenized melt inclusions

USGS Publications Warehouse

Tuohy, Robin M; Wallace, Paul J.; Loewen, Matthew W; Swanson, Don; Kent, Adam J R

2016-01-01

Concentrations of H2O and CO2 in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO2concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO2 is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To investigate this problem, we heated olivine from the 1959 Kīlauea Iki and 1960 Kapoho (Hawai‘i) eruptions in a 1-atm furnace to temperatures above the melt inclusion trapping temperature to redissolve the CO2 in shrinkage bubbles. The measured CO2 concentrations of the experimentally rehomogenized inclusions (⩽590 ppm for Kīlauea Iki [n=10]; ⩽880 ppm for Kapoho, with one inclusion at 1863 ppm [n=38]) overlap with values for naturally quenched inclusions from the same samples, but experimentally rehomogenized inclusions have higher within-sample median CO2 values than naturally quenched inclusions, indicating at least partial dissolution of CO2 from the vapor bubble during heating. Comparison of our data with predictions from modeling of vapor bubble formation and published Raman data on the density of CO2 in the vapor bubbles suggests that 55-85% of the dissolved CO2 in the melt inclusions at the time of trapping was lost to post-entrapment shrinkage bubbles. Our results combined with the Raman data demonstrate that olivine from the early part of the Kīlauea Iki eruption crystallized at <6 km depth, with the majority of olivine in the 1-3 km depth range. These depths are consistent with the interpretation that the Kīlauea Iki magma was supplied from Kīlauea’s summit magma reservoir (∼2-5 km depth). In contrast, olivine from Kapoho, which was the rift zone extension of the Kīlauea Iki eruption, crystallized over a much wider range of depths (∼1-16 km). The wider depth range requires magma transport during the Kapoho eruption from deep beneath the summit region and/or from deep beneath Kīlauea’s east rift zone. The deeply derived olivine crystals and their host magma mixed with stored, more evolved magma in the rift zone, and the mixture was later erupted at Kapoho.

Magma transport and olivine crystallization depths in Kīlauea's east rift zone inferred from experimentally rehomogenized melt inclusions

NASA Astrophysics Data System (ADS)

Tuohy, Robin M.; Wallace, Paul J.; Loewen, Matthew W.; Swanson, Donald A.; Kent, Adam J. R.

2016-07-01

Concentrations of H2O and CO2 in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO2 concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO2 is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To investigate this problem, we heated olivine from the 1959 Kīlauea Iki and 1960 Kapoho (Hawai'i) eruptions in a 1-atm furnace to temperatures above the melt inclusion trapping temperature to redissolve the CO2 in shrinkage bubbles. The measured CO2 concentrations of the experimentally rehomogenized inclusions (⩽590 ppm for Kīlauea Iki [n = 10]; ⩽880 ppm for Kapoho, with one inclusion at 1863 ppm [n = 38]) overlap with values for naturally quenched inclusions from the same samples, but experimentally rehomogenized inclusions have higher within-sample median CO2 values than naturally quenched inclusions, indicating at least partial dissolution of CO2 from the vapor bubble during heating. Comparison of our data with predictions from modeling of vapor bubble formation and published Raman data on the density of CO2 in the vapor bubbles suggests that 55-85% of the dissolved CO2 in the melt inclusions at the time of trapping was lost to post-entrapment shrinkage bubbles. Our results combined with the Raman data demonstrate that olivine from the early part of the Kīlauea Iki eruption crystallized at <6 km depth, with the majority of olivine in the 1-3 km depth range. These depths are consistent with the interpretation that the Kīlauea Iki magma was supplied from Kīlauea's summit magma reservoir (∼2-5 km depth). In contrast, olivine from Kapoho, which was the rift zone extension of the Kīlauea Iki eruption, crystallized over a much wider range of depths (∼1-16 km). The wider depth range requires magma transport during the Kapoho eruption from deep beneath the summit region and/or from deep beneath Kīlauea's east rift zone. The deeply derived olivine crystals and their host magma mixed with stored, more evolved magma in the rift zone, and the mixture was later erupted at Kapoho.

S-wave velocity down to the uppermost mantle below the East European Craton in northern Poland from the inversion of ambient noise recorded at "13 BB star" seismic array

NASA Astrophysics Data System (ADS)

Lepore, S.; Polkowski, M.; Grad, M.

2016-12-01

The East European Craton (EEC) occupies the northeastern half of Europe. In the most external sedimentary crust (SC), the P-wave velocity (Vp) raises from 2.5 to 4.3 km/s. In the underlying upper crust (UC) the Vp ranges within 6.1-6.4 km/s, 6.5-6.8 km/s in the middle crust (MC), and 6.9-7.2 km/s in the lower crust (LC). The Moho, whose depth is 40-45 km, shows a relatively flat topography, which is advantageous when studying the deep velocity structure. The Vp in the uppermost mantle (UM) down to 100 km is 8.3 km/s. Seismic experiments conducted in Poland along refraction profiles provided significant information about the structure in any layer, but not sufficient for the study of the S-wave velocity (Vs). Thus, Vs and Vp/Vs profiles down to 100 m were evaluated by the Monte Carlo inversion of surface wave velocity dispersion (SWVD) curves retrieved from the crosscorrelation (CC) of ambient noise recorded in northern Poland. The records were carried out during 2014 at the "13 BB star" array equipped with thirteen broadband stations installed during 2013 and scheduled to operate until the end of 2016. Those stations, covering an area of 120 km in diameter, are arranged in a circular, regular geometry, allowing a thorough study of the deep structures. The extraction of the SWVD was performed in the 0.1-1 Hz and 0.02-0.1 Hz frequency bands, to have a good resolution within 0-20 km and 20-100 km. The dispersion curves show different modes because remarkable changes of surface wave attenuation are present in the different layers. All the modes of the SWVD curves were together inverted assuming the characteristics and the Vp values in every layer as known. The Vs [km/s] ranges within 1.0-2.4 in SC, 3.1-3.6 in UC, 3.2-4.3 in MC, 3.2-4.3 in LC, and 4.5-5.1 in UM; Vp/Vs within 1.8-2.0 in SC, 1.7-2.0 in UC, 1.5-2.1 in MC, 1.8-2.1 in LC, and 1.6-1.8 in UM. National Science Centre Poland provided financial support for this work by NCN grant DEC-2011/02/A/ST10/00284.

Geomechanical models of impact cratering: Puchezh-Katunki structure

NASA Technical Reports Server (NTRS)

Ivanov, B. A.

1992-01-01

Impact cratering is a complex natural phenomenon that involves various physical and mechanical processes. Simulating these processes may be improved using the data obtained during the deep drilling at the central mound of the Puchezh-Katunki impact structure. A research deep drillhole (named Vorotilovskaya) has been drilled in the Puchezh-Katunki impact structure (European Russia, 57 deg 06 min N, 43 deg 35 min E). The age of the structure is estimated at about 180 to 200 m.y. The initial rim crater diameter is estimated at about 40 km. The central uplift is composed of large blocks of crystalline basement rocks. Preliminary study of the core shows that crystalline rocks are shock metamorphosed by shock pressure from 45 GPa near the surface to 15-20 GPa at a depth of about 5 km. The drill core allows the possibility of investigating many previously poorly studied cratering processes in the central part of the impact structure. As a first step one can use the estimates of energy for the homogeneous rock target. The diameter of the crater rim may be estimated as 40 km. The models elaborated earlier show that such a crater may be formed after collapse of a transient cavity with a radius of 10 km. The most probable range of impact velocities from 11.2 to 30 km/s may be inferred for the asteroidal impactor. For the density of a projectile of 2 g/cu cm the energy of the impact is estimated as 1E28 to 3E28 erg. In the case of vertical impact, the diameter of an asteroidal projectile is from 1.5 to 3 km for the velocity range from 11 to 30 km/s. For the most probable impact angle of 45 deg, the estimated diameter of an asteroid is slightly larger: from 2 to 4 km. Numerical simulation of the transient crater collapse has been done using several models of rock rheology during collapse. Results show that the column at the final position beneath the central mound is about 5 km in length. This value is close to the shock-pressure decay observed along the drill core. Further improvement of the model needs to take into account the blocky structure of target rocks revealed by drilling.

Tailpipe, resuspended road dust, and brake-wear emission factors from on-road vehicles

NASA Astrophysics Data System (ADS)

Abu-Allaban, Mahmoud; Gillies, John A.; Gertler, Alan W.; Clayton, Russ; Proffitt, David

Intensive mass and chemical measurements were performed at roadside locations in Reno, Nevada, and Durham/Research Triangle Park), North Carolina to derive tailpipe, resuspended road dust, and brake-wear emission factors from in-use vehicles. Continuous particulate matter (PM) data were utilized to derive total emission factors while integrated PM data were used to attribute the calculated emission factors to different mechanisms using chemical mass balance receptor modeling and scanning electron microscopy techniques. Resuspended road dust and tailpipe emissions were found to be the dominant mechanisms that contribute significantly to the total PM 10 and PM 2.5 emission factors, respectively. Small contributions from brake-wear were observed at locations where strong braking occurs, but no tire-wear was seen at any sampling location. PM 10 emission rates from light-duty spark ignition (LDSI) vehicles ranged from 40 to 780 mg/km, 10 to 70 mg/km, and 0 to 80 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. PM 10 emission rates from heavy-duty vehicles ranged from 230 to 7800 mg/km, 60 to 570 mg/km, and 0 to 610 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. PM 2.5 emission rates from LDSI vehicles ranged from 2 to 25 mg/km, 10 to 50 mg/km, and 0 to 5 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively. PM 2.5 emission rates from heavy-duty vehicles ranged from 15 to 300 mg/km, 60 to 480 mg/km, and 0 to 15 mg/km per vehicle for road dust, tailpipe, and brake-wear, respectively.

A simple parameterization for the height of maximum ozone heating rate

NASA Astrophysics Data System (ADS)

Zhang, Feng; Hou, Can; Li, Jiangnan; Liu, Renqiang; Liu, Cuiping

2017-12-01

It is well-known that the height of the maximum ozone heating rate is much higher than the height of the maximum ozone concentration in the stratosphere. However, it lacks an analytical expression to explain it. A simple theoretical model has been proposed to calculate the height of maximum ozone heating rate and further understand this phenomenon. Strong absorption of ozone causes the incoming solar flux to be largely attenuated before reaching the location of the maximum ozone concentration. By comparing with the exact radiative transfer calculations, the heights of the maximum ozone heating rate produced by the theoretical model are generally very close to the true values. When the cosine of solar zenith angle μ0 = 1.0 , in US Standard atmosphere, the heights of the maximum ozone heating rate by the theoretical model are 41.4 km in the band 0.204-0.233 μm, 47.9 km in the band 0.233-0.270 μm, 44.5 km in the band 0.270-0.286 μm, 37.1 km in the band 0.286-0.303 μm, and 30.2 km in the band 0.303-0.323 μm, respectively. The location of the maximum ozone heating rate is sensitive to the solar spectral range. In band 1, the heights of the maximum ozone heating rate by the theoretical model are 52.3 km for μ0 = 0.1 , 47.1 km for μ0 = 0.3 , 44.6 km for μ0 = 0.5 , 43.1 km for μ0 = 0.7 , 41.9 km for μ0 = 0.9 , 41.4 km for μ0 = 1.0 in US Standard atmosphere, respectively. This model also illustrates that the location of the maximum ozone heating rate is sensitive to the solar zenith angle.

Redefinition of the crater-density and absolute-age boundaries for the chronostratigraphic system of Mars

USGS Publications Warehouse

Werner, S.C.; Tanaka, K.L.

2011-01-01

For the boundaries of each chronostratigraphic epoch on Mars, we present systematically derived crater-size frequencies based on crater counts of geologic referent surfaces and three proposed " standard" crater size-frequency production distributions as defined by (a) a simple -2 power law, (b) Neukum and Ivanov, (c) Hartmann. In turn, these crater count values are converted to model-absolute ages based on the inferred cratering rate histories. We present a new boundary definition for the Late Hesperian-Early Amazonian transition. Our fitting of crater size-frequency distributions to the chronostratigraphic record of Mars permits the assignment of cumulative counts of craters down to 100. m, 1. km, 2. km, 5. km, and 16. km diameters to martian epochs. Due to differences in the " standard" crater size-frequency production distributions, a generalized crater-density-based definition to the chronostratigraphic system cannot be provided. For the diameter range used for the boundary definitions, the resulting model absolute age fits vary within 1.5% for a given set of production function and chronology model ages. Crater distributions translated to absolute ages utilizing different curve descriptions can result in absolute age differences exceeding 10%. ?? 2011 Elsevier Inc.

Occultation of Epsilon Geminorum by Mars. II - The structure and extinction of the Martian upper atmosphere

NASA Technical Reports Server (NTRS)

Elliot, J. L.; French, R. G.; Dunham, E.; Gierasch, P. J.; Veverka, J.; Church, C.; Sagan, C.

1977-01-01

The occultation of Epsilon Geminorum by Mars on April 8, 1976, was observed at three wavelengths and 4-ms time resolution with the 91-cm telescope aboard NASA's G. P. Kuiper Airborne Observatory. Temperature, pressure, and number-density profiles of the Martian atmosphere were obtained for both the immersion and emersion events. Within the altitude range 50-80 km above the mean surface, the mean temperature is about 145 K, and the profiles exhibit wavelike structures with a peak-to-peak amplitude of 35 K and a vertical scale of about 20 km. The ratio of the refractivity of the atmosphere at 4500 A and 7500 A is consistent with the atmospheric composition measured by Viking 1. From the 'central flash' - a bright feature in the light curve midway between immersion and emersion - an optical depth at 4500 A of 3.3 + or - 1.7 per km atm (about 0.23 per equivalent Martian air mass) is found for the atmosphere about 25 km above the mean surface near the south polar region. This large value and its weak wavelength dependence rule out Rayleigh scattering as the principal cause of the observed extinction.

Observation of several chlorine nitrate (ClONO2) bands in stratospheric infrared spectra

NASA Technical Reports Server (NTRS)

Zander, R.; Rinsland, C. P.; Farmer, C. B.; Brown, L. R.; Norton, R. H.

1986-01-01

Four of the most prominent and sharpest infrared absorption features of chlorine nitrate at 780.2, 807.7, 809.4, and 1292.6/cm have been observed in a series of infrared solar spectra obtained at an unapodized spectral resolution of 0.01/cm, using the Atmospheric Trace Molecule Spectroscopy instrument from on-board Sapcelab 3. A quantitative analysis of the nu4 Q branch at 780.2/cm has provided insight into the concentration of ClONO2 between 19 and 40 km altitude. While the mean profile deduced from three sunset occultations near 30 deg N latitude exhibits a shape close to that predicted by model calculations, its concentrations in the 20 to 32 km altitude range are, however, about 30 percent larger, reaching a peak concentration of 9 x 10 to the 8th molecules/cu cm at 25 km. The concentrations above 32 km, deduced from one sunrise occultation at 47 deg JS, are even larger than the corresponding sunset values at 30 deg N latitude. Some of these discrepancies may be caused by the rather large uncertainty in the assumed Q branch strength.

The RF spectra of first and subsequent lightning return strokes in the 1- to 200-km range

NASA Technical Reports Server (NTRS)

Serhan, G. I.; Uman, M. A.; Childers, D. G.; Lin, Y. T.

1980-01-01

An experimental characterization of the frequency spectra of first and subsequent stroke electric fields are presented over a distance range from about 1 km, where the fields are primarily electrostatic, to 200 km, where they are primarily radiation. Spectra are presented to about 700 kHz for lightning within 12 km and to about 300 kHz for lightning at 50 and 200 km. It is shown that the return stroke ground wave spectrum beyond 50 km has a peak near 4 kHz but that within 10 km the spectrum shows a steady increase with decreasing frequency to 1 kHz. Frequency spectra at all ranges fall off roughly as 1/f for frequencies between 5 and 100 kHz, while the falloff above 100 kHz is faster as the distance to the stroke increases. From this high-frequency attenuation an RF conductivity for central Florida of between 0.002 and 0.005/ohm/m was determined.

Moho depth and equivalent elastic thickness of the lithosphere over the Vema Channel: A new evidence of an aborted ridge

NASA Astrophysics Data System (ADS)

Constantino, Renata Regina; Costa, Iago Sousa Lima; Hackspacher, Peter Christian; de Souza, Iata Anderson

2018-03-01

We investigate the Vema Channel in terms of spatial variations of the elastic thickness (Te) in the frame of the thin plate flexure model using the convolutive method. The modeling of the Moho in terms of the thin plate flexure model is done by a least squares approximation of the Moho obtained from gravity inversion. The flexure is calculated by the convolution of the crustal load with the point-load flexure response curves. The RMS difference between the gravity and flexure Moho surfaces is minimized by varying the Te by inverse modeling. The result is a solution of the flexed crust that is in best agreement with the long-wavelength component of the gravity field. The flexure Moho depths vary between 12 and 18 km and agree well with those obtained from gravity inversion. The spatial variations of Te range from 2 to 30 km and have a good correlation with the geological interpretation for an aborted ridge near Vema Channel, called in this paper as the Vema Aborted Ridge (VAR). The occurring of seamounts appears to be correlated to a weak and deformed region. Attempts of crustal breakup are marked by high Te values (30 km) while lower values (3-12 km) are found for the suggested aborted ridge. The VAR is on Isochron of 93 Ma and shows symmetrical older along both sides of its axis. Asymmetric magnetic anomalies are found over the ridge and may be related to upper-extended continental crust broken by the Vema.

Infrasonic array observations at I53US of the 2006 Augustine Volcano eruptions

USGS Publications Warehouse

Wilson, C.R.; Olson, J.V.; Szuberla, Curt A.L.; McNutt, Steve; Tytgat, Guy; Drob, Douglas P.

2006-01-01

The recent January 2006 Augustine eruptions, from the 11th to the 28th, have produced a series of 12 infrasonic signals that were observed at the I53US array at UAF. the eruption times for the signals were provided by the Alaska Volcanic Observatory at UAF using seismic sensors and a Chaparral microphone that are installed on Augustine Island. The bearing and distance of Augustine from I53US are, respectively, 207.8 degrees and 675 km. The analysis of the signals is done with a least-squares detector/estimator that calculates, from the 28 different sensor-pairs in the array, the mean of the cross-correlation maxima (MCCM), the horizontal trace-velocity and the azimuth of arrival of the signal using a sliding-window of 2000 data points. The data were bandpass filtered from 0.03 to 0.10 Hz. The data are digitized at a rate of 20 Hz. The average values of the signal parameters for all 12 Augustine signals are as follows: MCCM=0.85 (std 0.14), Trace-velocity=0.346 (std 0.016) km/sec, Azimuth=209 (std 2) deg. The celerity for each signal was calculated using the range 675 km and the individual travel times to I53US. The average celerity for all ten eruption signals was 0.27 (std 0.02) km/sec. Ray tracing studies, using mean values of the wind speed and temperature profiles (along the path) from NRL, have shown that there was propagation to I53US by both stratospheric and thermospheric ray paths from the volcano.

Magnetotelluric investigations of the lithosphere beneath the central Rae craton, mainland Nunavut, Canada

NASA Astrophysics Data System (ADS)

Spratt, Jessica E.; Skulski, Thomas; Craven, James A.; Jones, Alan G.; Snyder, David B.; Kiyan, Duygu

2014-03-01

New magnetotelluric soundings at 64 locations throughout the central Rae craton on mainland Nunavut constrain 2-D resistivity models of the crust and lithospheric mantle beneath three regional transects. Responses determined from colocated broadband and long-period magnetotelluric recording instruments enabled resistivity imaging to depths of > 300 km. Strike analysis and distortion decomposition on all data reveal a regional trend of 45-53°, but locally the geoelectric strike angle varies laterally and with depth. The 2-D models reveal a resistive upper crust to depths of 15-35 km that is underlain by a conductive layer that appears to be discontinuous at or near major mapped geological boundaries. Surface projections of the conductive layer coincide with areas of high grade, Archean metasedimentary rocks. Tectonic burial of these rocks and thickening of the crust occurred during the Paleoproterozoic Arrowsmith (2.3 Ga) and Trans-Hudson orogenies (1.85 Ga). Overall, the uppermost mantle of the Rae craton shows resistivity values that range from 3000 Ω m in the northeast (beneath Baffin Island and the Melville Peninsula) to 10,000 Ω m beneath the central Rae craton, to >50,000 Ω m in the south near the Hearne Domain. Near-vertical zones of reduced resistivity are identified within the uppermost mantle lithosphere that may be related to areas affected by mantle melt or metasomatism associated with emplacement of Hudsonian granites. A regional decrease in resistivities to values of 500 Ω m at depths of 180-220 km, increasing to 300 km near the southern margin of the Rae craton, is interpreted as the lithosphere-asthenosphere boundary.

Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

NASA Astrophysics Data System (ADS)

Mancilla, Flor de Lis; Stich, Daniel; Morales, José; Martín, Rosa; Diaz, Jordi; Pazos, Antonio; Córdoba, Diego; Pulgar, Javier A.; Ibarra, Pedro; Harnafi, Mimoun; Gonzalez-Lodeiro, Francisco

2015-12-01

The Gibraltar arc and surrounding areas are a complex tectonic region and its tectonic evolution since Miocene is still under debate. Knowledge of its lithospheric structure will help to understand the mechanisms that produced extension and westward motion of the Alboran domain, simultaneously with NW-SE compression driven by Africa-Europe plates convergence. We perform a P-wave receiver function analysis in which we analyse new data recorded at 83 permanent and temporary seismic broad-band stations located in the South of the Iberian peninsula. These data are stacked and combined with data from a previous study in northern Morocco to build maps of thickness and average vP/vS ratio for the crust, and cross-sections to image the lithospheric discontinuities beneath the Gibraltar arc, the Betic and Rif Ranges and their Iberian and Moroccan forelands. Crustal thickness values show strong lateral variations in the southern Iberia peninsula, ranging from ˜19 to ˜46 km. The Variscan foreland is characterized by a relatively flat Moho at ˜31 km depth, and an average vP/vS ratio of ˜1.72, similar to other Variscan terranes, which may indicate that part of the lower crustal orogenic root was lost. The thickest crust is found at the contact between the Alboran domain and the External Zones of the Betic Range, while crustal thinning is observed southeastern Iberia (down to 19 km) and in the Guadalquivir basin where the thinning at the Iberian paleomargin could be still preserved. In the cross-sections, we see a strong change between the eastern Betics, where the Iberian crust underthrusts and couples to the Alboran crust, and the western Betics, where the underthrusting Iberian crust becomes partially delaminated and enters into the mantle. The structures largely mirror those on the Moroccan side where a similar detachment was observed in northern Morocco. We attribute a relatively shallow strong negative-polarity discontinuity to the lithosphere-asthenosphere boundary. This means relatively thin lithosphere ranging from ˜50 km thickness in southeastern Iberia and northeastern Morocco to ˜90-100 km beneath the western Betics and the Rif, with abrupt changes of ˜30 km under the central Betics and northern Morocco. Our observations support a geodynamic scenario where in western Betics oceanic subduction has developed into ongoing continental subduction/delamination while in eastern Betics this process is inactive.

Heat flow and thermotectonic problems of the central Ventura Basin, southern California

USGS Publications Warehouse

De Rito, R. F.; Lachenbruch, A.H.; Moses, T.H.; Munroe, R.J.

1989-01-01

The Ventura Basin, southern California, is located near the Big Bend area of the San Andreas fault system, within the Transverse Ranges physiographic province. Negative curvature of the Ventura Avenue temperature profiles may be explained by an increase in thermal conductivity associated with tectonic compaction of the underlying Pliocene clastic sequence. Basinwide, heat flow averages about 48 mW/m2, a value which is low relative to most of southern California. As heat flow does not vary systematically to the maximum measured depth of about 4 km, this anomly is not easily explained in terms of hydrologic effects or recent uplift and erosion. However, a diminution of heat flow is an expectable consequence of the accumulation of cold sediments (up to 12 km) since Eocene time. -from Authors

The slab thickness of the mid-latitude ionosphere.

NASA Technical Reports Server (NTRS)

Titheridge, J. E.

1973-01-01

The thickness of the peak of the ionosphere depends primarily on the temperature T sub n of the neutral gas, and corresponds approximately to an alpha-Chapman layer at a temperature of 0.87T sub n. The overall slab thickness, as given by Faraday rotation measurements, is then tau = 0.22T sub n + 7 km. Expansion of the topside ionosphere, and changes in the E- and F1-regions increase tau by about 20 km during the day in summer. Near solar minimum, tau is increased by a lowering of the O(+)/H(+) transition height; if the neutral temperature T sub n is estimated, this height can be obtained from observed values of tau. Hourly values of slab thickness were determined over a period of 6 yr at 34 and 42 S. Near solar maximum the nighttime values were about 260 km in all seasons. The corresponding neutral temperatures agree with satellite drag values; they show a semiannual variation of 14% and a seasonal change of 5%. Daytime values of tau were about 230 km in winter and 320 km in summer, implying a seasonal change of 30% in T sub n.

Surface wave imaging of the Lithosphere-Asthenosphere system beneath 0-80 My seafloor of the equatorial Mid-Atlantic Ridge from the PI-LAB Experiment

NASA Astrophysics Data System (ADS)

Rychert, C.; Harmon, N.; Kendall, J. M.; Agius, M. R.; Tharimena, S.

2017-12-01

Oceanic lithosphere is the simplest realization of the tectonic plate, yet there are several indications that the evolution of oceanic lithosphere is more complicated than simple half space cooling models, i.e. sharp seismic discontinuities at 60-80 km depth, flattening of bathymetry at > 80 My. A deeper understanding of the complexities of oceanic lithosphere requires in situ measurements, and to date much work has focused on the Pacific ocean. The PI-LAB (Passive Imaging of the Lithosphere-Asthenosphere Boundary) experiment deployed 39 ocean bottom seismometers and 39 ocean bottom magnetotelluric instruments around the equatorial Mid Atlantic ridge from 0-80 My old seafloor. We analysed Rayleigh wave dispersion at 18-143 s period using teleseismic events and Rayleigh wave and Love wave dispersion from 5-22 s period using ambient noise. We observe both fundamental mode and first higher mode Rayleigh waves at 5 - 18 s periods, with average phase velocities that range from 1.5 km/s at 5 s period to 4.31 km/s at 143 s, and fundamental mode Love waves, with average phase velocities ranging from 4.00 km/s at 5 s to 4.51 at 22 s. We invert these phase velocities for radially anisotropic shear velocity structure and find a 60 km thick fast lid for the region with velocities of 4.62 km/s, and x values up to 1.08 indicating radial anisotropy is required in the upper 200 km. We also examined the variation in phase velocity as function seafloor age across the region using the teleseismic Rayleigh wave dataset. From 25-81 s period we find low velocities beneath young seafloor ages. We find velocity systematically increases with seafloor age. At 40 My old seafloor, the phase velocities stop increasing and flatten out. At the longest periods (> 81 s) we observe no clear relationship with seafloor age, suggesting that lithospheric thickening ceases beneath seafloor > 50 My old.

11beta-hydroxysteroid dehydrogenase in the testis of Bufo arenarum: changes in its seasonal activity.

PubMed

Denari, Daniela; Ceballos, Nora R

2005-09-01

In rat Leydig cells, glucocorticoids (GC) inhibit testosterone (T) synthesis via glucocorticoid receptor (GR). However, GC access to GR is regulated by the local expression of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). Two isoforms were identified in mammals: type 1, a NADP+-preferring enzyme with K(m) in the muM range for GC and type 2, NAD+-dependent, with K(m) in the nM range for GC. In amphibians, a seasonal rhythm in baseline GC levels was described. However, a shift in the amount of deactivating 11beta-HSD activity could alter GC effects. The purpose of this work is to describe seasonal changes in testicular activity of 11beta-HSD in Bufo arenarum as well as the annual and seasonal patterns of plasma corticosterone (B) and T. The activity of 11beta-HSD was assayed in homogenate and subcellular fractions in pre-reproductive (Pre-R), reproductive (R) and post-reproductive (Post-R) periods, using [3H]B. Plasma B and T were determined by RIA. Testicular 11beta-HSD is a microsomal NAD+-dependent enzyme with a K(m) in the nM order, its activity being strongly reduced by glycyrrhetinic acid. These results indicate that toad testes express an 11beta-HSD similar to mammalian type 2. Although 11beta-HSD activity is higher in the Post-R than in the R and Pre-R seasons (V(max): Pre-R: 0.26+/-0.10, R: 0.14+/-0.01, Post-R: 1.37+/-0.45, pmol/minmg protein), K(m) value remains constant throughout the year. A seasonal rhythm in baseline GC concentrations inversely correlated with plasma T was also described. T concentration is lower in the R season than in the other periods (Pre-R: 90+/-6; R: 12+/-1; Post-R: 56+/-3, nM) while total B concentration is higher in the breeding than in the other seasons (Pre-R: 62+/-10; R: 145+/-18; Post-R: 96+/-10, nM). Furthermore, free B (Pre-R: 51+/-8; R: 94+/-12; Post-R: 70+/-7, nM) was always below K(m) values. In conclusion, this work shows that the activity of 11beta-HSD in toad testes could modulate GC action by transforming active hormones in the corresponding inactive steroid.

Coupled prediction of flash flood response and debris flow occurrence in an alpine basin

NASA Astrophysics Data System (ADS)

Amponsah, William

2015-04-01

Coupled prediction of flash flood response and debris flow occurrence in an alpine basin Author(s): William Amponsah1, E.I. Nikolopoulos2, Lorenzo Marchi1, Roberto Dinale4, Francesco Marra3,Davide Zoccatelli2 , Marco Borga2 Affiliation(s): 1CNR - IRPI, Corso Stati Uniti 4, 35127, Padova, ITALY, 2Department of Land, Environment, Agriculture and Forestry, University of Padova,VialeDell'Università 16, 35020, Legnaro PD, ITALY 3Department of Geography, Hebrew University of Jerusalem, ISRAEL 4Ufficio Idrografico, Provincia Autonoma di Bolzano, Bolzano, Italy This contribution examines the main hydrologic and morphologic metrics responsible for widespread triggering of debris-flows associated with flash flood occurrences in headwater alpine catchments.To achieve this objective, we investigate the precipitation forcing, hydrologic responses and landslides and debris-flow occurrences that prevailed during the August 4-5, 2012 extreme flash flood on the 140 km2 Vizze basin in the Eastern Alps of Italy. An intensive post-event survey was carried out a few days after the flood. This included the surveys of cross-sectional geometry and flood marks for the estimation of the peak discharges at multiple river sections and of the initiation and deposition areas of several debris flows. Rainfall estimates are based on careful analysis of weather radar observations and raingauge data. These data and observations permitted the implementation and calibration of a spatially distributed hydrological model, which was used to derive simulated flood hydrographs in 58 tributaries of the Vizze basin. Of these, 33 generated debris-flows, with area ranging from 0.02 km2 to 10 km2, with an average of 1.5 km2. With 130 mm peak event rainfall and a duration of 4 hours (with a max intensity of 90 mm h-1 for 10 min), model-simulated unit peak discharges range from 4 m3 s-1 km-2for elementary catchments up to 10 km2 to 2 m3 s-1 km-2 for catchments in the range of 50 - 100 km2. These are very high values when considering the local runoff regime. We used a threshold criterion based on past works (Tognaccaet al., 2000; Berti and Simoni, 2005; Gregoretti and Dalla Fontana, 2008) to identify tributaries associated to debris flow events. The threshold is defined for each channel grid as a function of the simulated unit width peak flow, of the local channel bed slope and of the mean grain size. Based on assumptions concerning the mean grain size and given the distribution of the threshold values over the river network, we derive a catchment scale threshold index for the tributaries. The results show that the index has considerable skill in identifying the catchments where the studied rainstorm caused debris-flows. Berti, M. andA.Simoni, 2005: Experimental evidences and numerical modelling of debris flow initiated by channel runoff. Landslides, 2 (3), 171-182. Gregoretti, C. and G. Dalla Fontana, 2008:The triggering of debris flow due to channel-bed failure in some alpine headwater basins of the Dolomites: analyses of critical runoff. Hydrol. Process. 22, 2248-2263. Tognacca C., G.R. Bezzola andH.E.Minor, 2000: Threshold criterion fodebrisflow initiation due to channel bed failure. In Proceedings of the Second International Conference on Debris Flow Hazards Mitigation Taipei,August, Wiezczorek, Naeser (eds): 89-97.

Coupling of thermal evolution and despinning of early Iapetus

NASA Astrophysics Data System (ADS)

Robuchon, G.; Choblet, G.; Tobie, G.; Čadek, O.; Sotin, C.; Grasset, O.

2010-06-01

The Cassini mission revealed two spectacular characteristics of Iapetus: (1) a geologically old and high equatorial ridge, which is unique in the Solar System and (2) a large flattening of 35 km consistent with the equilibrium figure for a hydrostatic body rotating with a period of 16 h, whereas the current spin period is 79.33 days. This study describes three-dimensional simulations of solid-state convection within an undifferentiated Iapetus. It investigates the implications for the evolution of the interior thermal structure and its spin rate and global shape using radially layered viscoelastic models. The role of the concentration in the short-lived radiogenic element [ 26Al], just after accretion is completed, is specifically addressed. The first result is to show that whatever the [ 26Al] value, convection occurs. As suggested by Castillo-Rogez et al. [Castillo-Rogez, J., Matson, D., Sotin, C., Johnson, T., Lunine, J., Thomas, P. [2007] Icarus, 190, 179-202], convection reduces the warming of the interior compared to the conductive evolution and therefore limits the conditions for despinning. In our calculations, two conceptual linear viscoelastic models are used. When considering a Maxwell rheology, the interior temperature (viscosity) never reaches a value high (low) enough to induce despinning. In order to promote dissipation at low temperature, a Burgers rheology, which includes an additional dissipation peak, is introduced. For favorable parameter values, this latter rheology leads to despinning. However, only models associated with large amounts of short-lived radiogenic elements ([26Al]⩾25ppb) lead to the observed flattening. This suggests that the accretion process needs to be completed shortly after the formation of CAIs (Calcium-Aluminum-rich Inclusions) (⩽4 Myr). For [ 26Al] varying between 72 and 46 ppb, the observed flattening is obtained only for a limited range of initial spin period, between 9.5 and 10.2 h. For [ 26Al] ranging between 30 and 15 ppb, initial spin rates smaller than 8.5 h are required. For smaller values of [ 26Al], the body is too cold and viscous to acquire a significant flattening even if a rotation period close to the body disruption limit is considered. Even with a thin lithosphere during the early stage, our simulations show that Iapetus never reaches the equilibrium figure for a hydrostatic body due to the non-zero rigidity of the lithosphere. The 35 km value of the flattening is the result of the partial relaxation of an ancient larger flattening ranging between 45 and 80 km, depending on the evolution of the lithosphere thickness mainly controlled by the radiogenic content. A thin lithosphere is consistent with an early building of the equatorial ridge. The lithosphere thickening due to interior cooling can explain the preservation of the ridge throughout the remaining evolution of Iapetus.

Km and kcat. values for [6,6,7,7-2H]7,8(6H)-dihydropterin and 2,6-diamino-5-iminopyrimidin-4-one with dihydropteridine reductase.

PubMed Central

Armarego, W L; Randles, D; Taguchi, H

1983-01-01

The Km and kcat. values for [6,6,7,7-2H]7,8(6H)-dihydropterin and 2,6-diamino-5-iminopyrimidin-4-one were determined for dihydropteridine reductase (EC 1.6.99.10) from two sources. The parameters of the pterin are of the same order as those of the most effective substrates of dihydropteridine reductase. The Km values of the pterin are one order of magnitude smaller than those of the pyrimidinone, although the kcat. values are of the same order. PMID:6870836

Understanding the complexity of the Lévy-walk nature of human mobility with a multi-scale cost∕benefit model.

PubMed

Scafetta, Nicola

2011-12-01

Probability distributions of human displacements have been fit with exponentially truncated Lévy flights or fat tailed Pareto inverse power law probability distributions. Thus, people usually stay within a given location (for example, the city of residence), but with a non-vanishing frequency they visit nearby or far locations too. Herein, we show that an important empirical distribution of human displacements (range: from 1 to 1000 km) can be well fit by three consecutive Pareto distributions with simple integer exponents equal to 1, 2, and (>) 3. These three exponents correspond to three displacement range zones of about 1 km ≲Δr≲10 km, 10 km ≲Δr≲300 km, and 300 km ≲Δr≲1000 km, respectively. These three zones can be geographically and physically well determined as displacements within a city, visits to nearby cities that may occur within just one-day trips, and visit to far locations that may require multi-days trips. The incremental integer values of the three exponents can be easily explained with a three-scale mobility cost∕benefit model for human displacements based on simple geometrical constrains. Essentially, people would divide the space into three major regions (close, medium, and far distances) and would assume that the travel benefits are randomly∕uniformly distributed mostly only within specific urban-like areas. The three displacement distribution zones appear to be characterized by an integer (1, 2, or >3) inverse power exponent because of the specific number (1, 2, or >3) of cost mechanisms (each of which is proportional to the displacement length). The distributions in the first two zones would be associated to Pareto distributions with exponent β = 1 and β = 2 because of simple geometrical statistical considerations due to the a priori assumption that most benefits are searched in the urban area of the city of residence or in the urban area of specific nearby cities. We also show, by using independent records of human mobility, that the proposed model predicts the statistical properties of human mobility below 1 km ranges, where people just walk. In the latter case, the threshold between zone 1 and zone 2 may be around 100-200 m and, perhaps, may have been evolutionary determined by the natural human high resolution visual range, which characterizes an area of interest where the benefits are assumed to be randomly and uniformly distributed. This rich and suggestive interpretation of human mobility may characterize other complex random walk phenomena that may also be described by a N-piece fit Pareto distributions with increasing integer exponents. This study also suggests that distribution functions used to fit experimental probability distributions must be carefully chosen for not improperly obscuring the physics underlying a phenomenon.

The role of CYP2D6 in primary and secondary oxidative metabolism of dextromethorphan: in vitro studies using human liver microsomes.

PubMed Central

Kerry, N L; Somogyi, A A; Bochner, F; Mikus, G

1994-01-01

1. The enzyme kinetics of dextromethorphan O-demethylation in liver microsomes from three extensive metabolisers (EM) with respect to CYP2D6 indicated high (Km1 2.2-9.4 microM) and low (Km2 55.5-307.3 microM) affinity sites whereas microsomes from two poor metabolisers (PM) indicated a single site (Km 560 and 157 microM). Similar differences were shown for 3-methoxymorphinan O-demethylation to 3-hydroxymorphinan (Km 6.9-9.6 microM in EM subjects; Km 307 and 213 microM in PM subjects). 2. Dextromethorphan O-demethylation was inhibited competitively by quinidine (Ki 0.1 microM), rac-perhexiline (Ki 0.4 microM), dextropropoxyphene (Ki 6 microM), rac-methadone (Ki 8 microM), and 3-methoxymorphinan (Ki 15 microM). These compounds were also potent inhibitors of 3-methoxymorphinan O-demethylation with IC50 values ranging from 0.02-12 microM. Anti-LKM1 serum inhibited both dextromethorphan and 3-methoxymorphinan O-demethylations in a titre-dependent manner. 3. The Michaelis-Menten constant for dextromethorphan N-demethylation to 3-methoxymorphinan (Km 632-977 microM) and dextrorphan N-demethylation to 3-hydroxymorphinan (Km 1571-4286 microM) did not differ between EM and PM microsomes. These N-demethylation reactions were not inhibited by quinidine and rac-methadone or LKM1 antibodies. 4. Dextromethorphan and 3-methoxymorphinan are metabolised by the same P450 isoform, CYP2D6, whereas the N-demethylation reactions are not carried out by CYP2D6. PMID:7826826

On the evolution of the geothermal regime of the North China Basin

NASA Astrophysics Data System (ADS)

Wang, Ji-yang; Chen, Mo-xiang; Wang, Ji-an; Deng, Xiao

1985-12-01

Recent heat flow and regional geothermal studies indicate that the North China Basin is characterized by relatively high heat flow compared with most stable areas in other parts of the world, but lower heat flow than most active tectonic areas. Measured heat flow values range from 61 to 74 mW m -2. The temperature at a depth of 2000 m is generally in the range 75 to 85°C, but sometimes is 90°C or higher. The geothermal gradient in Cenozoic sediments is in the range 30 to 40°C/km for most of the area. The calculated temperature at the Moho is 560 and 640°C for surface heat flow values of 63 and 71 mW m -2, respectively. These thermal data are consistent with other geophysical observations for the North China Basin. Relatively high heat flow in this area is related to Late Cretaceous-Paleogene rifting as described in this paper.

Sources, Load, Vertical Distribution, and Fate of Wintertime Aerosols North of Svalbard From Combined V4 CALIOP Data, Ground-Based IAOOS Lidar Observations and Trajectory Analysis

NASA Astrophysics Data System (ADS)

Di Biagio, C.; Pelon, J.; Ancellet, G.; Bazureau, A.; Mariage, V.

2018-01-01

We have analyzed aerosol properties at the regional scale over high Arctic north of Svalbard between October 2014 and June 2015 from version 4 (V4) CALIOP (Cloud and Aerosol Lidar with Orthogonal Polarization) spaceborne observations and compared results with surface lidar observations from IAOOS (Ice-Atmosphere-Ocean Observing System) platforms. CALIOP data indicate a maximum in aerosol occurrence at the end of winter attributed to low-level (0-2 km) and midtropospheric (2-5 km) particles identified in CALIOP V4 product as being mostly of dust origin. Another maximum was observed in October-December attributed to clean marine particles below 2 km and smoke and dust above. The 532 nm aerosol extinction was in the range 1-8 Mm-1 (0-2 km), 1-18 Mm-1 (2-5 km), and 0-6 Mm-1 (5-10 km), a factor 2 lower compared to values previously reported using CALIOP V3 data set. Aerosols are identified from trajectory analyses to originate mostly from Russia/Europe at all altitudes, and also North America above 2 km, and it is concluded that dust and clean marine types are most probably overrepresented in the analyzed CALIOP data set. It is proposed that most part of dust types are diamond dust, while part of clean marine are polluted species, as corroborated from colocated polarized lidar IAOOS observations. IAOOS observations allowed confirming the identified sensitivity of CALIOP with a particle backscatter coefficient of 0.001 km-1 sr-1 at 532 nm. For optically thicker layers CALIOP is shown to be a valuable tool to follow transport of aerosol layers in the Arctic and identify their possible modifications.

Examination about the Spatial Representation of PM2.5 Obtained from Limited Stations Using a Network Observation

NASA Astrophysics Data System (ADS)

Shi, X.; Zhao, C.

2017-12-01

Haze aerosol pollution has been a focus issue in China, and its characteristics is highly demanded. With limited observation sites, aerosol properties obtained from a single site is frequently used to represent the haze condition over a large domain, such as tens of kilometers. This could result in high uncertainties in the haze characteristics due to their spatial variation. Using a network observation from November 2015 to February 2016 over an urban city in North China with high spatial resolution, this study examines the spatial representation of ground site observations. A method is first developed to determine the representative area of measurements from limited stations. The key idea of this method is to determine the spatial variability of particulate matter with diameters less than 2.5 μm (PM2.5) concentration using a variance function in 2km x 2km grids. Based on the high spatial resolution (0.5km x 0.5km) measurements of PM2.5, the grids in which PM2.5 have high correlations and weak value differences are determined as the representation area of measurements at these grids. Note that the size representation area is not exactly a circle region. It shows that the size representation are for the study region and study period ranges from 0.25 km2 to 16.25 km2. The representation area varies with locations. For the 20 km x 20 km study region, 10 station observations would have a good representation of the PM2.5 observations obtained from current 169 stations at the four-month time scale.

A Deep X-Ray View of the Synchrotron-dominated Supernova Remnant G330.2+1.0

NASA Astrophysics Data System (ADS)

Williams, Brian J.; Hewitt, John W.; Petre, Robert; Temim, Tea

2018-03-01

We present moderately deep (125 ks) XMM-Newton observations of supernova remnant G330.2+1.0. This remnant is one of only a few known that fall into the “synchrotron-dominated” category, with the emission almost entirely dominated by a nonthermal continuum. Previous X-ray observations could only characterize the spectra of a few regions. Here, we examine the spectra from 14 regions surrounding the entire rim, finding that the spectral properties of the nonthermal emission do not vary significantly in any systematic way from one part of the forward shock to another, unlike several other remnants of this class. We confirm earlier findings that the power-law index, Γ, ranges from about 2.1–2.5, while the absorbing column density is generally between (2.0–2.6) × 1022 cm‑2. Fits with the srcut model find values of the roll-off frequency in the range of 1017.1–1017.5 Hz, implying energies of accelerated electrons of ∼100 TeV. These values imply a high shock velocity of ∼4600 km s‑1, favoring a young age of the remnant. Diffuse emission from the interior is nonthermal in origin as well, and fits to these regions yield similar values to those along the rim, also implying a young age. Thermal emission is present in the east, and the spectrum is consistent with a ∼650 km s‑1 shock wave encountering interstellar or circumstellar material with a density of ∼1 cm‑3.

Storm impacts upon the composition of organic matrices in Nagara River--a study based on molecular weight and activated carbon adsorbability.

PubMed

Li, Fusheng; Yuasa, Akira; Chiharada, Hajime; Matsui, Yoshihiko

2003-09-01

The impacts of a heavy storm of rain on the composition of natural organic matter (NOM) in Nagara River water were studied in terms of molecular weights (MWs) and activated carbon (AC) adsorbabilities using six water samples collected during a critical Typhoon weather condition. The composition in MWs was analyzed using a HPSEC system and that in adsorbabilities was characterized using parameters devised to reflect NOMs average adsorptive strength (K(M)), adsorptive strength polydispersity (sigma), affinity to AC (1/n) and non-adsorbable fraction (C(non)/C(T0)), respectively. These parameters were determined by model description of observed isotherms with a distributed fictive component method. The heavy storm of rain brought higher content of larger organic components into the river source, thus causing changes of NOMs weight-averaged MWs in the range of 2962-3495 Dalton and MW polydispersity in the narrow range of 1.153-1.226. Comparison of K(M) and sigma values for all samples assessed with both indices of TOC and UV260 showed that large proportions of the storm-induced organic components had adsorptive strengths similar to those existent before the storm, with the presence levels for components revealing much strong and weak adsorbabilities being low. Among all organic components brought into the river by the storm of rain, the percentages of non-adsorbable ones was lower (smaller C(non)/C(T0) values); and the adsorbable ones had generally more affinity to the adsorbents used (smaller 1/n values).

Spatial variations in the frequency-magnitude distribution of earthquakes at Soufriere Hills Volcano, Montserrat, West Indies

USGS Publications Warehouse

Power, J.A.; Wyss, M.; Latchman, J.L.

1998-01-01

The frequency-magnitude distribution of earthquakes measured by the b-value is determined as a function of space beneath Soufriere Hills Volcano, Montserrat, from data recorded between August 1, 1995 and March 31, 1996. A volume of anomalously high b-values (b > 3.0) with a 1.5 km radius is imaged at depths of 0 and 1.5 km beneath English's Crater and Chance's Peak. This high b-value anomaly extends southwest to Gage's Soufriere. At depths greater than 2.5 km volumes of comparatively low b-values (b-1) are found beneath St. George's Hill, Windy Hill, and below 2.5 km depth and to the south of English's Crater. We speculate the depth of high b-value anomalies under volcanoes may be a function of silica content, modified by some additional factors, with the most siliceous having these volumes that are highly fractured or contain high pore pressure at the shallowest depths. Copyright 1998 by the American Geophysical Union.

Lithospheric Structure Beneath the Hangay Dome, Central Mongolia

NASA Astrophysics Data System (ADS)

Stachnik, J. C.; Meltzer, A.; Souza, S.; Munkhuu, U.; Tsaagan, B.; Russo, R. M.

2014-12-01

The Mongolian Plateau is a broad regional uplift positioned between the Siberian Craton to the north and the far northern edge of the India-Asia collision to the south. Within this intracontinental setting of high topography, the Hangay Dome in central Mongolia reaches elevations of 4 km and contains intermittent basaltic magmatism over the last 30 Ma. The relationship between high topography, magmatism, and geodynamic processes remains largely unsolved although processes ranging from lithospheric delamination to mantle plume effects have been proposed. A temporary array of seismic stations was deployed around the Hangay Dome to determine lithospheric structure. Preliminary results are shown from receiver function analysis, ambient noise tomography, and teleseismic P-wave tomography. Crustal thickness measurements from H-k stacking of receiver functions range from 42 km to 57 km across the array, with thicker crust beneath the highest topography. The bulk crustal Vp/Vs ratio ranges from 1.71 to 1.9 with a median value for the array of 1.77, perhaps indicating a variable crustal composition with some regions having a more mafic crust. The stacked receiver functions are also combined with ambient noise phase velocity dispersion measurements in a joint inversion for shear velocity profiles at each station which reveals crustal thickness estimates consistent with the H-k stacks while also determining the shear velocity step at the Moho. Teleseismic P-wave travel time residuals ranging between +/-1 second are inverted for a 3D P-wave velocity model using finite-frequency kernels. Notable features include 1) a low velocity anomaly (-3%) in the upper 200 km beneath the eastern part of the Hangay Dome near the Orkhon River Valley, , 2) a steeply dipping low velocity anomaly to the north of the Hangay Dome, perhaps related to the nearby Baikal Rift, and 3) generally higher velocities in the upper 200 km surrounding the high topography. To first order, the high topography of the Hangay Dome appears to be largely supported by thickened crust. However, lower P-wave velocities in the upper mantle beneath the dome are observed. The relative contributions of crustal thickness and upper mantle structure for support of topography and their relationship to magmatism will be determined with further refinement of the models.

Diurnal and Semidiurnal Tides in the Middle Atmosphere over Balasore (21.5°N, 86.9°E).

NASA Astrophysics Data System (ADS)

Sasi, M. N.; Krishna Murthy, B. V.

1990-09-01

Using rocket wind data at a tropical station, Balasore (21.5°N, 86.9°E), the diurnal and semidiurnal tidal amplitudes and phases of the zonal and meridional components have been obtained over an altitude range of 20-65 km for equinox, summer and winter seasons. Comparison with the theoretical values revealed some important differences between the two and the implications of these are discussed.

Temporal and spatial variability of rainfall pH

Treesearch

Richard G. Semonin

1977-01-01

The distribution of average rainwater pH over an area of 1,800 km² containing 81 collectors was determined from 25 storm events. The areal average of the data was pH 4.9, with a range of values from 4.3 to 6.8. A single storm event was studied to determine the change of pH as a function of time. The initial rain was pH 7.1, decreasing to 4.1. An excellent...

Canaveral National Seashore Water Quality and Aquatic Resource Inventory

NASA Technical Reports Server (NTRS)

Hall, C. R.; Provancha, J. A.; Oddy, D. M.; Lowers, R. L.; Drese, J. D.

2001-01-01

Mosquito Lagoon is a shallow, bar-built estuary located on the east central Florida Coast, primarily within the KSC boundary. The lagoon and watershed cover approximately 327 sq km (79422 acres) .The Lagoon occupies 159 sq km (37853 acres). Water depths average approximately 1m. The lagoon volume is approximately 1.6 x 10(exp 8)cu m. Water quality in Mosquito Lagoon is good. Salinity data typically range between 20 ppt and 35 ppt. The lowest value recorded was 4.5 ppt and the highest value was 37 ppt. Water temperatures fluctuate 2 - 3 C over a 24 h period. Cold front passage can rapidly alter water temperatures by 5 - 10 C or more in a short period of time. The highest temperature was 33.4 C and the lowest temperature was 8.8 C after a winter storm. Dissolved oxygen concentrations ranged from a low of 0.4 mg/l to a high of 15.3 mg/l. Extended periods of measurements below the Florida Department of Environmental Protection criteria of 4.0 mg/l were observed in fall and spring months suggesting high system respiration and oxygen demand. Metals such as antimony, arsenic, molybdenum and mercury were report as below detection limits for all samples. Cadmium, copper, chromium, silver, and zinc were found to be periodically above the Florida Department of Environmental Protection criteria for Class II and Class III surface waters.

Two-dimensional seismic image of the San Andreas Fault in the Northern Gabilan Range, central California: Evidence for fluids in the fault zone

USGS Publications Warehouse

Thurber, C.; Roecker, S.; Ellsworth, W.; Chen, Y.; Lutter, W.; Sessions, R.

1997-01-01

A joint inversion for two-dimensional P-wave velocity (Vp), P-to-S velocity ratio (Vp/Vs), and earthquake locations along the San Andreas fault (SAF) in central California reveals a complex relationship among seismicity, fault zone structure, and the surface fault trace. A zone of low Vp and high Vp/Vs lies beneath the SAF surface trace (SAFST), extending to a depth of about 6 km. Most of the seismic activity along the SAF occurs at depths of 3 to 7 km in a southwest-dipping zone that roughly intersects the SAFST, and lies near the southwest edge of the low Vp and high Vp/Vs zones. Tests indicate that models in which this seismic zone is significantly closer to vertical can be confidently rejected. A second high Vp/Vs zone extends to the northeast, apparently dipping beneath the Diablo Range. Another zone of seismicity underlies the northeast portion of this Vp/Vs high. The high Vp/Vs zones cut across areas of very different Vp values, indicating that the high Vp/Vs values are due to the presence of fluids, not just lithology. The close association between the zones of high Vp/Vs and seismicity suggests a direct involvement of fluids in the faulting process. Copyright 1997 by the American Geophysical Union.

Petrology and geochronology of metamorphosed volcanic rocks and a middle Cretaceous volcanic neck in the east-central Sierra Nevada, California.

USGS Publications Warehouse

Kistler, R.W.; Swanson, S.E.

1981-01-01

Metamorphosed Mesozoic volcanic rocks from the E-central Sierra Nevada range in composition from basalt to rhyolite and have ages, based on whole rock Rb-Sr and U-Pb zircon dating, of about 237- 224, 185, 163, 134, and 100Ma. The major plutons of the batholith in this area are of Triassic (215-200Ma) and Cretaceous (94-80Ma) ages. Initial 87Sr/86Sr values for the metamorphosed volcanic rocks of the area are in the range from 0.7042 to 0.7058 and are generally different from the values for the surrounding batholithic rocks (0.7056-0.7066). A circular, zoned granitic pluton, with an outcrop area of 2.5km2, similar in appearance to a ring dike complex, was apparently a conduit for some or possibly all of the middle-Cretaceous metamorphosed volcanic rocks exposed about 5km to the S in the western part of the Ritter Range. Samples from the metamorphosed volcanic rocks and the pluton yield a Rb/Sr whole rock isochron age of 99.9+ or -2.2Ma with an intitial 87Sr/86Sr of 0.7048+ or -0.00001. Major element variation diagrams of the pluton and volcanic rocks define coincident compositional trends. The ages of volcanic events relative to the ages of the major intrusive epochs and the major element and isotopic compositions of the volcanic rocks relative to the major plutons indicate that the volcanic rocks are not simply or directly related to the major plutons in the Sierra Nevada. -from Authors

Statistical analysis of hydrological response in urbanising catchments based on adaptive sampling using inter-amount times

NASA Astrophysics Data System (ADS)

ten Veldhuis, Marie-Claire; Schleiss, Marc

2017-04-01

In this study, we introduced an alternative approach for analysis of hydrological flow time series, using an adaptive sampling framework based on inter-amount times (IATs). The main difference with conventional flow time series is the rate at which low and high flows are sampled: the unit of analysis for IATs is a fixed flow amount, instead of a fixed time window. We analysed statistical distributions of flows and IATs across a wide range of sampling scales to investigate sensitivity of statistical properties such as quantiles, variance, skewness, scaling parameters and flashiness indicators to the sampling scale. We did this based on streamflow time series for 17 (semi)urbanised basins in North Carolina, US, ranging from 13 km2 to 238 km2 in size. Results showed that adaptive sampling of flow time series based on inter-amounts leads to a more balanced representation of low flow and peak flow values in the statistical distribution. While conventional sampling gives a lot of weight to low flows, as these are most ubiquitous in flow time series, IAT sampling gives relatively more weight to high flow values, when given flow amounts are accumulated in shorter time. As a consequence, IAT sampling gives more information about the tail of the distribution associated with high flows, while conventional sampling gives relatively more information about low flow periods. We will present results of statistical analyses across a range of subdaily to seasonal scales and will highlight some interesting insights that can be derived from IAT statistics with respect to basin flashiness and impact urbanisation on hydrological response.

A survey of the kinetic parameters of class C beta-lactamases. Penicillins.

PubMed Central

Galleni, M; Frère, J M

1988-01-01

The interaction between six class C beta-lactamases and various penicillins has been studied. All the enzymes behaved in a very uniform manner. Benzylpenicillin exhibited relatively low kcat. values (14-75 s-1) but low values of Km resulted in high catalytic efficiencies [kcat./Km = 10 X 10(6)-75 X 10(6) M-1.s-1]. The kcat. values for ampicillin were 10-100-fold lower. Carbenicillin, oxacillin cloxacillin and methicillin were very poor substrates, exhibiting kcat. values between 1 x 10(-3) and 0.1 s-1. The Km values were correspondingly small. It could safely be hypothesized that, with all the tested substrates, deacylation was rate-limiting, resulting in acyl-enzyme accumulation. PMID:3264154

The Cretaceous Okhotsk-Chukotka Volcanic Belt (NE Russia): Geology, geochronology, magma output rates, and implications on the genesis of silicic LIPs

NASA Astrophysics Data System (ADS)

Tikhomirov, P. L.; Kalinina, E. A.; Moriguti, T.; Makishima, A.; Kobayashi, K.; Cherepanova, I. Yu.; Nakamura, E.

2012-04-01

The Cretaceous Okhotsk-Chukotka volcanic belt (OCVB) is a prominent subduction-related magmatic province, having the remarkably high proportion of silicic rocks (ca. 53% of the present-day crop area, and presumably over 70% of the total volcanic volume). Its estimated total extrusive volume ranges between 5.5 × 105 km3 (the most conservative estimate) and over 106 km3. This article presents a brief outline of the geology of OCVB, yet poorly described in international scientific literature, and results of a geochronological study on the northern part of the volcanic belt. On the base of new and published U-Pb and 40Ar/39Ar age determinations, a new chronological model is proposed. Our study indicates that the activity of the volcanic belt was highly discontinuous and comprised at least five main episodes at 106-98 Ma, 94-91 Ma, 89-87 Ma, 85.5-84 Ma, and 82-79 Ma. The new data allow a semi-quantitative estimate of the volcanic output rate for the observed part of the OCVB (area and volume approximately 105 km2 and 2.5 × 105 km3, respectively). The average extrusion rate for the entire lifetime of the volcanic belt ranges between 1.6 and 3.6 × 10- 5 km3yr- 1 km- 1, depending on the assumed average thickness of the volcanic pile; the optimal value is 2.6 × 10- 5 km3yr- 1 km- 1. Despite imprecise, such estimates infer the time-averaged volcanic productivity of the OCVB is similar to that of silicic LIPs and most active recent subduction-related volcanic areas of the Earth. However, the most extensive volcanic flare-ups at 89-87 and 85.5-84 Ma had higher rates of over 9.0 × 10- 5 km3yr- 1 km- 1. The main volumetric, temporal and compositional parameters of the OCVB are similar to those of silicic LIPs. This gives ground for discussion about the geodynamic setting of the latters, because the widely accepted definition of a LIP implies a strictly intraplate environment. Considering the genesis of the OCVB and other large provinces of silicic volcanism, we propose that residual thermal energy preserved in the continental crust after a previous major magmatic event may have been one of major reasons for high proportion of felsic rocks in a volcanic pile. In this scenario, underplating of mantle-derived basalts causes fast and extensive melting of still hot continental crust and generation of voluminous silicic magmas.

Properties of the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope multi-orbit observations

NASA Astrophysics Data System (ADS)

Lamy, P. L.; Toth, I.; Weaver, H. A.; A'Hearn, M. F.; Jorda, L.

2011-04-01

We report on our on-going effort to detect and characterize cometary nuclei with the Hubble Space Telescope (HST). During cycle 9 (2000 July to 2001 June), we performed multi-orbit observations of 10 ecliptic comets with the Wide Field Planetary Camera 2. Nominally, eight contiguous orbits covering a time interval of ˜11 h were devoted to each comet but a few orbits were occasionally lost. In addition to the standard R band, we could additionally observe four of them in the V band and the two brightest ones in the B band. Time series photometry was used to constrain the size, shape and rotational period of the 10 nuclei. Assuming a geometric albedo of 0.04 for the R band, a linear phase law with a coefficient of 0.04 mag deg-1 and an opposition effect similar to that of comet 19P/Borrelly, we determined the following mean values of the effective radii 47P/Ashbrook-Jackson: 2.86±0.08 km, 61P/Shajn-Schaldach: 0.62±0.02 km, 70P/Kojima: 1.83±0.05 km, 74P/Smirnova-Chernykh: 2.23±0.04 km, 76P/West-Kohoutek-Ikemura: 0.30±0.02 km, 82P/Gehrels 3: 0.69±0.02 km, 86P/Wild 3: 0.41±0.03 km, 87P/Bus: 0.270.01 km, 110P/Hartley 3: 2.15±0.04 km and 147P/Kushida-Muramatsu: 0.21±0.01 km. Because of the limited time coverage (˜11 h), the rotational periods could not be accurately determined, multiple solutions were sometime found and three periods were not constrained at all. Our estimates range from ˜5 to ˜32 h. The lower limits for the ratio a/b of the semi-axis of the equivalent spheroids range from 1.10 (70P) to 2.20 (87P). The four nuclei for which we could measure (V-R) are all significantly redder than the Sun, with 86P/Wild 3 (V-R) = 0.86 ± 0.10 appearing as an ultrared object. We finally determined the dust activity parameter Afρ of their coma in the R band, the colour indices and the reflectivity spectra of four of them. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS 5-26555.

Air quality over Europe and Iberian Peninsula for 2004 at high horizontal resolution: evaluation of the CALIOPE modelling system

NASA Astrophysics Data System (ADS)

Jorba, O.; Piot, M.; Pay, M. T.; Jiménez-Guerrero, P.; López, E.; Pérez, C.; Gassó, S.; Baldasano, J. M.

2009-09-01

In the frame of the CALIOPE project (Baldasano et al., 2008a), a high-resolution air quality forecasting system, WRF-ARW/HERMES/CMAQ/DREAM, is under development and applied to the European domain (12km x 12km, 1hr) as well as to the Iberian Peninsula domain (4km x 4km, 1hr) to provide air quality forecasts for Spain (http://www.bsc.es/caliope/). The simulation of such high-resolution model system is possible by its implementation on the MareNostrum supercomputer. To reassure potential users and reduce uncertainties, the model system must be evaluated to assess its performances in terms of air quality levels and dynamics reproducibility. The present contribution describes a thorough quantitative evaluation study performed for a reference year (2004). CALIOPE is a complex system that integrates a variety of environmental models. WRF-ARW provides high-resolution meteorological fields to the system. It is configured with 38 vertical layers reaching up to 50 hPa. Meteorological initial and boundary conditions are obtained from the NCEP final analysis data. The HERMES emission model (Baldasano et al., 2008b) computes the emissions for the Iberian Peninsula simulation at 4 km horizontal resolution every hour using a bottom-up approach. For the European domain, HERMES disaggregates the EMEP expert emission inventory for 2004. The CMAQ chemical transport model solves the physico-chemical processes in the system. The vertical resolution of CMAQ for gas-phase and aerosols has been increased from 8 to 15 layers in order to simulate vertical exchanges more accurately. Chemical boundary conditions are provided by the LMDz-INCA2 global climate-chemistry model (see Hauglustaine et al., 2004). Finally, the DREAM model simulates long-range transport of mineral dust over the domains under study. In order to evaluate the performances of the CALIOPE system, model simulations were compared with ground-based measurements from the EMEP and Spanish air quality networks. For the European domain, 45 stations have been used to evaluate NO2, 60 for O3, 39 for SO2, 25 for PM10 and 16 for PM2.5. On the other hand, the Iberian Peninsula domain has been evaluated against 75 NO2 stations, 84 O3 stations, 69 for SO2, and 46 for PM10. Such large number of observations allows us to provide a detailed discussion of the model skills over quite different geographical locations and meteorological situations. The model simulation for Europe satisfactorily reproduces O3 concentrations throughout the year with small errors: monthly MNGE values range from 13% to 24%, and MNBE values show a slight negative bias ranging from -15% to 0%. These values lie within the range defined by the US-EPA guidelines (MNGE: +/- 30-35%; MNBE: +/- 10-15%). The reproduction of SO2 concentrations is relatively correct but false peaks are reported (mean MNBE=22%). The simulated variation of particulate matter is reliable, with a mean correlation of 0.5. False peaks were reduced by use of an improved 8-bin aerosol description in the DREAM dust model, but mean aerosol levels are still underestimated. This problem is most probably related to uncertainties in our knowledge of the sources and in the description of organic aerosols. The nested high-resolution simulation of Spain (4 km) shows a very good agreement with observations for O3 (monthly MNGE range from 13 to 19%). Particulate matter results are in agreement with the European simulation, and a net improvement on nitrate and sulphate is observed in several stations in Spain. Such high-resolution simulation will allow analysing the small scale features observed over Spain. REFERENCES Baldasano J.M, P. Jiménez-Guerrero, O. Jorba, C. Pérez, E. López, P. Güereca, F. Martin, M. García-Vivanco, I. Palomino, X. Querol, M. Pandolfi, M.J. Sanz and J.J. Diéguez, 2008a: CALIOPE: An operational air quality forecasting system for the Iberian Peninsula, Balearic Islands and Canary Islands- First annual evaluation and ongoing developments. Adv. Sci. and Res., 2: 89-98. Baldasano J.M., L. P. Güereca, E. López, S. Gassó, P. Jimenez-Guerrero, 2008b: Development of a high-resolution (1 km x 1 km, 1 h) emission model for Spain: the High-Elective Resolution Modelling Emission System (HERMES). Atm. Environ., 42 (31): 7215-7233. Hauglustaine, D. A. and F. Hourdin and L. Jourdain and M.A. Filiberti and S. Walters and J. F. Lamarque and E. A. Holland, 2004: Interactive chemistry in the Laboratoire de Meteorologie Dynamique general circulation model: Description and background tropospheric chemistry evaluation. J. Geophys. Res., doi:10.1029/2003JD003,957.

Altitude effect on leaf wax carbon isotopic composition in humid tropical forests

NASA Astrophysics Data System (ADS)

Wu, Mong Sin; Feakins, Sarah J.; Martin, Roberta E.; Shenkin, Alexander; Bentley, Lisa Patrick; Blonder, Benjamin; Salinas, Norma; Asner, Gregory P.; Malhi, Yadvinder

2017-06-01

The carbon isotopic composition of plant leaf wax biomarkers is commonly used to reconstruct paleoenvironmental conditions. Adding to the limited calibration information available for modern tropical forests, we analyzed plant leaf and leaf wax carbon isotopic compositions in forest canopy trees across a highly biodiverse, 3.3 km elevation gradient on the eastern flank of the Andes Mountains. We sampled the dominant tree species and assessed their relative abundance in each tree community. In total, 405 sunlit canopy leaves were sampled across 129 species and nine forest plots along the elevation profile for bulk leaf and leaf wax n-alkane (C27-C33) concentration and carbon isotopic analyses (δ13C); a subset (76 individuals, 29 species, five forest plots) were additionally analyzed for n-alkanoic acid (C22-C32) concentrations and δ13C. δ13C values display trends of +0.87 ± 0.16‰ km-1 (95% CI, r2 = 0.96, p < 0.01) for bulk leaves and +1.45 ± 0.33‰ km-1 (95% CI, r2 = 0.94, p < 0.01) for C29n-alkane, the dominant chain length. These carbon isotopic gradients are defined in multi-species sample sets and corroborated in a widespread genus and several families, suggesting the biochemical response to environment is robust to taxonomic turnover. We calculate fractionations and compare to adiabatic gradients, environmental variables, leaf wax n-alkane concentrations, and sun/shade position to assess factors influencing foliar chemical response. For the 4 km forested elevation range of the Andes, 4-6‰ higher δ13C values are expected for upland versus lowland C3 plant bulk leaves and their n-alkyl lipids, and we expect this pattern to be a systematic feature of very wet tropical montane environments. This elevation dependency of δ13C values should inform interpretations of sedimentary archives, as 13C-enriched values may derive from C4 grasses, petrogenic inputs or upland C3 plants. Finally, we outline the potential for leaf wax carbon isotopes to trace biomarker sourcing within catchments and for paleoaltimetry.

Comparison of Oxidation Kinetics of Nitrite-Oxidizing Bacteria: Nitrite Availability as a Key Factor in Niche Differentiation

PubMed Central

Nowka, Boris; Daims, Holger

2014-01-01

Nitrification has an immense impact on nitrogen cycling in natural ecosystems and in wastewater treatment plants. Mathematical models function as tools to capture the complexity of these biological systems, but kinetic parameters especially of nitrite-oxidizing bacteria (NOB) are lacking because of a limited number of pure cultures until recently. In this study, we compared the nitrite oxidation kinetics of six pure cultures and one enrichment culture representing three genera of NOB (Nitrobacter, Nitrospira, Nitrotoga). With half-saturation constants (Km) between 9 and 27 μM nitrite, Nitrospira bacteria are adapted to live under significant substrate limitation. Nitrobacter showed a wide range of lower substrate affinities, with Km values between 49 and 544 μM nitrite. However, the advantage of Nitrobacter emerged under excess nitrite supply, sustaining high maximum specific activities (Vmax) of 64 to 164 μmol nitrite/mg protein/h, contrary to the lower activities of Nitrospira of 18 to 48 μmol nitrite/mg protein/h. The Vmax (26 μmol nitrite/mg protein/h) and Km (58 μM nitrite) of “Candidatus Nitrotoga arctica” measured at a low temperature of 17°C suggest that Nitrotoga can advantageously compete with other NOB, especially in cold habitats. The kinetic parameters determined represent improved basis values for nitrifying models and will support predictions of community structure and nitrification rates in natural and engineered ecosystems. PMID:25398863

Hydrostatic and non-hydrostatic simulations of dense waters cascading off a shelf: The East Greenland case

NASA Astrophysics Data System (ADS)

Magaldi, Marcello G.; Haine, Thomas W. N.

2015-02-01

The cascade of dense waters of the Southeast Greenland shelf during summer 2003 is investigated with two very high-resolution (0.5-km) simulations. The first simulation is non-hydrostatic. The second simulation is hydrostatic and about 3.75 times less expensive. Both simulations are compared to a 2-km hydrostatic run, about 31 times less expensive than the 0.5 km non-hydrostatic case. Time-averaged volume transport values for deep waters are insensitive to the changes in horizontal resolution and vertical momentum dynamics. By this metric, both lateral stirring and vertical shear instabilities associated with the cascading process are accurately parameterized by the turbulent schemes used at 2-km horizontal resolution. All runs compare well with observations and confirm that the cascade is mainly driven by cyclones which are linked to dense overflow boluses at depth. The passage of the cyclones is also associated with the generation of internal gravity waves (IGWs) near the shelf. Surface fields and kinetic energy spectra do not differ significantly between the runs for horizontal scales L > 30 km. Complex structures emerge and the spectra flatten at scales L < 30 km in the 0.5-km runs. In the non-hydrostatic case, additional energy is found in the vertical kinetic energy spectra at depth in the 2 km < L < 10 km range and with frequencies around 7 times the inertial frequency. This enhancement is missing in both hydrostatic runs and is here argued to be due to the different IGW evolution and propagation offshore. The different IGW behavior in the non-hydrostatic case has strong implications for the energetics: compared to the 2-km case, the baroclinic conversion term and vertical kinetic energy are about 1.4 and at least 34 times larger, respectively. This indicates that the energy transfer from the geostrophic eddy field to IGWs and their propagation away from the continental slope is not properly represented in the hydrostatic runs.

Seasonal movements and Home-range use by female pronghorns in sagebrush-steppe communities of western South Dakota

USGS Publications Warehouse

Jacques, C.N.; Jenks, J.A.; Klaver, R.W.

2009-01-01

Knowledge of seasonal movements by pronghorns (Antilocapra americana) within the easternmost extension of sagebrush-steppe communities is limited. Current hypotheses regarding movement patterns suggest that pronghorns initiate seasonal movements in response to severe winter weather, snowfall patterns, spatial and temporal variation in forage abundance, and availability of water. From January 2002 to August 2005, we monitored movements of 76 adult (≥1.5 years) female pronghorns on 2 study areas (Harding and Fall River counties) in western South Dakota. We collected 8,750 visual locations, calculated 204 home ranges, and documented 17 seasonal movements. Eighty-four percent (n = 55) of pronghorns were nonmigratory and 10% (n = 6) were conditional migrators. Mean distance between summer and winter range was 23.1 km (SE = 2.8 km, n = 13). Five adult pronghorns (8%) dispersed a mean distance of 37.6 km (SE = 12.4 km); of which 1 female moved a straight-line distance of 75.0 km. Winter and summer home-range size varied (P < 0.0001) between study sites. Mean 95% adaptive kernel winter and summer home-range size of pronghorns was 55.5 and 19.7 km2, respectively, in Harding County and 127.2 and 65.9 km2, respectively, in Fall River County. Nonmigratory behavior exhibited by pronghorns was likely associated with minimal snow cover and moderate temperatures during winter 2002–2004. Variation in size of adult seasonal home ranges between sites was likely associated with differences in forage distribution and availability between regions.

Flow of neutral interstellar helium into the heliosphere as inferred from IBEX-Lo observations and simulations

NASA Astrophysics Data System (ADS)

Bzowski, M.; Kubiak, M. A.; Hlond, M.; Moebius, E.; Leonard, T.; Heirtzler, D.; Kucharek, H.; Bochsler, P. A.; Schwadron, N. A.; Crew, G. B.; McComas, D. J.; Fuselier, S. A.

2010-12-01

Previously, a team coordinated through the International Space Science Institute (ISSI) examined direct neutral gas, pickup ion, and UV backscatter observations to produce consensus values for the inflow direction (λ, β), speed v, and temperature T of neutral interstellar helium from the Local Interstellar Cloud (LIC) with relatively small uncertainties. Since then, NASA’s Interstellar Boundary Explorer (IBEX) has started to provide new observations of the interstellar He flow in Earth orbit, with data currently available from the spring seasons of 2009 and 2010. Using a test-particle simulation to compute the spin-phase distributions that IBEX observes during each orbit, we optimize input LIC parameters to best fit the observations. The simulations take into account actual ionization rates as derived from solar EUV observations by SOHO CELIAS SEM, the OMNI solar wind data set, the positions and velocity vectors of the Earth during the actual integration intervals for each orbit, and the IBEX-Lo field-of-view. The simulations were performed on a grid of bulk flow vectors and temperatures, starting with the ISSI team consensus values based most heavily on Ulysses GAS observations (v = 26.4 km/s, T = 6318 K, and λ = 255.4o, β = -5.31o in J2000 coordinates). The Mach number of the flow derived from the IBEX observations is generally lower than derived from Ulysses measurements, which would be consistent with a higher temperature (up to 10 000 K) and/or a lower flow speed (down to ≈22.5 km/s) of the LIC. Based on these findings, the possible LIC parameter sets most probably lie within a narrow range between (λ = 255.4°, β = 5.3°, v = 26.4 km/s, M = 4.5 or T = 10,000 K) and (λ = 261.2°, β = 4.9, v = 23.05 km/s, M = 4.9, or T = 6300 K). At one end of the acceptable range, the parameters agree with the previous values except for the temperature, and at the other end, the temperatures agree, but the direction is different by almost 6° and the velocity is lower by ≈4 km/s. The simulations appear to agree with the IBEX observations slightly better for the different inflow direction. The results obtained separately from the two passes through the He flow (in 2009 and 2010) are identical within observational uncertainties. Potential reasons for the differences from previous results will be discussed. Any modifications in these critical inflow parameters will require modification of current global heliosphere models. In particular, a reduced flow speed and thus reduced ram pressure would require an increase in the total LIC density and/or the magnetic field strength to maintain pressure balance at the heliopause.

Martian interior structure models with different crustal density

NASA Astrophysics Data System (ADS)

Gudkova, T. V.; Zharkov, V. N.

2007-08-01

The information necessary to construct a model of Mars (observation data, a choice of a chemical model, a cosmogonic aspect of the problem) is discussed. We consider an interior structure model which comprises four submodels - a model of the outer porous layer, a model of the crust, a model of the mantle and a model of the core. The first 10-11 km layer is considered as an averaged transition from regolith to consolidated rock. The mineral composition of the crustal basaltic rock varies with depth because of the gabbro-eclogite phase transition. Mineralogical and seismic models of the Martian crust were constructed by numerical thermodynamic simulation by Babeiko and Zharkov (2000). For the obtained from this simulation densities at the crust-mantle boundary (about 3.3-3.4 g/cm3) a density contrast between the crust and the mantle is low enough. However, the joint interpretation of gravity and topography data assumes that there is a noticeable density jump at the crust-mantle boundary. As discussed by many authors a plausible range of bulk crustal densities is from 2.7 to 3.1 g/ cm3. It can be interpreted as either the composition of rocks at the surface of Mars is somewhat different than those of the Martian basaltic meteorites or a certain amount of crustal porosity might be expected if water (or some other substances) is present in the subsurface. Assuming a range of crustal densities (2.7-3.2 g/cm3) and the average thickness of the martian crust of 50 and 100 km we have recalculated a set of interior structure models of Mars to determine this effect on the other model parameters. The models are stronly constrained by new values of Love number k2 and the mean moment of inertia have been derived by Konopliv et al. (2006). The inferred radius of Martian core (from the Love number k2) is between 1700 and 1800 km. Keeping in mind that the estimated value of the correction introduced to the Love number k2 due to the inelasticity of the interior can be both somewhat higher (~ 0.005) or slightly lower (~ 0.003) we have the inferred model radius of Martian core between 1650 and 1830 km. As the radius of the core is increasing two tendencies are seen: the density of the core is decreasing and the Fe/Si weight ratio is approaching to its chondritic value 1.7. From cosmochemical point of view, it is difficult to assume that the core contains more than 20 wt % of sulfur. The radius of such core is about 1600 km. Therefore, if the core of Mars turns out to be larger, it should contain some light admixture elements.

Extension of the energy-to-moment parameter Θ to intermediate and deep earthquakes

NASA Astrophysics Data System (ADS)

Saloor, Nooshin; Okal, Emile A.

2018-01-01

We extend to intermediate and deep earthquakes the slowness parameter Θ originally introduced by Newman and Okal (1998). Because of the increasing time lag with depth between the phases P, pP and sP, and of variations in anelastic attenuation parameters t∗ , we define four depth bins featuring slightly different algorithms for the computation of Θ . We apply this methodology to a global dataset of 598 intermediate and deep earthquakes with moments greater than 1025 dyn∗cm. We find a slight increase with depth in average values of Θ (from -4.81 between 80 and 135 km to -4.48 between 450 and 700 km), which however all have intersecting one- σ bands. With widths ranging from 0.26 to 0.31 logarithmic units, these are narrower than their counterpart for a reference dataset of 146 shallow earthquakes (σ = 0.55). Similarly, we find no correlation between values of Θ and focal geometry. These results point to stress conditions within the seismogenic zones inside the Wadati-Benioff slabs more homogeneous than those prevailing at the shallow contacts between tectonic plates.

Determination of spectral limits imposed by four-wave mixing and amplified spontaneous emission in the 1550 nm region

NASA Astrophysics Data System (ADS)

Alvarez-Chavez, J. A.; Sanchez-Lara, R.; Martinez-Piñon, F.; Mendez-Martinez, F.; de la Cruz-May, L.; Perez-Sanchez, G. G.

2015-04-01

Dense wavelength division multiplexing (DWDM) systems are normally limited by stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), self-phase modulation (SPM), cross-phase modulation (XPM) and four-wave mixing (FWM) besides amplified spontaneous emission (ASE) noise from erbium-doped fiber amplifiers (EDFAs). In this paper, theoretical calculation of FWM-based limits and noise from EDFAs in the 1535-1565 nm region, are reported. Results show that FWM power per channel extended from -55 to -20 dBm for dispersion values of 0.0, 0.5, 1.0 and 1.5 ps (nmṡkm)-1. In a similar manner, for negative dispersion coefficient (D) values ranging from 0.0 to -1.5 ps (nmṡkm)-1, the FWM power per channel extended from -60 to -30 dBm. As for the maximum span length, the calculations demonstrated a rigorous limitation due to noise, suggesting error compensation techniques. A full set of results for the design of multi-span links is included.

Running energetics in the pronghorn antelope.

PubMed

Lindstedt, S L; Hokanson, J F; Wells, D J; Swain, S D; Hoppeler, H; Navarro, V

1991-10-24

The pronghorn antelope (Antilocapra americana) has an alleged top speed of 100 km h-1, second only to the cheetah (Acionyx jubatus) among land vertebrates, a possible response to predation in the exposed habitat of the North American prairie. Unlike cheetahs, however, pronghorn antelope are distance runners rather than sprinters, and can run 11 km in 10 min, an average speed of 65 km h-1. We measured maximum oxygen uptake in pronghorn antelope to distinguish between two potential explanations for this ability: either they have evolved a uniquely high muscular efficiency (low cost of transport) or they can supply oxygen to the muscles at unusually high levels. Because the cost of transport (energy per unit distance covered per unit body mass) varies as a predictable function of body mass among terrestrial vertebrates, we can calculate the predicted cost to maintain speeds of 65 and 100 km h-1 in an average 32-kg animal. The resulting range of predicted values, 3.2-5.1 ml O2 kg-1 s-1, far surpasses the predicted maximum aerobic capacity of a 32-kg mammal (1.5 ml O2 kg-1 s-1). We conclude that their performance is achieved by an extraordinary capacity to consume and process enough oxygen to support a predicted running speed greater than 20 ms-1 (70 km h-1), attained without unique respiratory-system structures.

Range Management Affects Native Ungulate Populations in Península Valdés, a World Natural Heritage

PubMed Central

Nabte, Marcela J.; Marino, Andrea I.; Rodríguez, María Victoria; Monjeau, Adrián; Saba, Sergio L.

2013-01-01

Sheep rearing is the main productive activity in Patagonian rangelands, where guanacos are the only native ungulate. Ranchers perceive a decrease in range carrying capacity as guanaco numbers increase, therefore guanaco conservation within private lands becomes a considerable challenge. This issue is particularly evident in the World Natural Heritage Península Valdés (PV), where there is a need to harmonize livestock production and biodiversity conservation. While sheep rearing prevails as the primary land use in the area, some ecotourism initiatives have been implemented to complement livestock production. In order to study how land use affected guanaco distribution, we characterized PV's ranches in terms of land subdivision, primary productivity, stocking-rate and management type, and assess how these variables affected guanaco encounter rates. Smaller ranches were composed of smaller paddocks (mean size 4.8 km2), which showed higher values of the remote-sensing derived Enhance Vegetation Index (EVI) (mean 0.14) and held higher sheep densities (mean 108.0 sheep/km2), while larger management units (mean size 23.8 km2), showed lower EVI values (mean 0.12) and lower stocking-rates (mean 36.7 sheep/km2). This pattern suggests that primary productivity has been a decisive factor to determine the minimal paddock size set by ranchers in PV, apparently precluding excessive land-subdivision in less productive areas. Guanaco encounter rate, expressed as number of guanacos per travelled kilometre, was inversely related to EVI and stocking-rate. However, land subdivision was the better predictor of guanaco encounter-rate within only sheep ranches, finding more guanacos per kilometre as paddock size increased. In contrast, in ranches where ecotourism was implemented as a complementary activity, guanaco encounter-rates were greater, regardless of paddock size. Our results suggest that the implementation of an additional activity by which landowners derive benefits from wildlife has prompted a beneficial outcome for guanacos, presumably through a decrease in harassment intensity. Finally, we propose possible mechanisms by which land subdivision may affect guanaco distribution and potential alternatives for the inclusion of wildlife conservation in a context of extensive livestock production. PMID:23390546

Range management affects native ungulate populations in Península Valdés, a World Natural Heritage.

PubMed

Nabte, Marcela J; Marino, Andrea I; Rodríguez, María Victoria; Monjeau, Adrián; Saba, Sergio L

2013-01-01

Sheep rearing is the main productive activity in Patagonian rangelands, where guanacos are the only native ungulate. Ranchers perceive a decrease in range carrying capacity as guanaco numbers increase, therefore guanaco conservation within private lands becomes a considerable challenge. This issue is particularly evident in the World Natural Heritage Península Valdés (PV), where there is a need to harmonize livestock production and biodiversity conservation. While sheep rearing prevails as the primary land use in the area, some ecotourism initiatives have been implemented to complement livestock production. In order to study how land use affected guanaco distribution, we characterized PV's ranches in terms of land subdivision, primary productivity, stocking-rate and management type, and assess how these variables affected guanaco encounter rates. Smaller ranches were composed of smaller paddocks (mean size 4.8 km(2)), which showed higher values of the remote-sensing derived Enhance Vegetation Index (EVI) (mean 0.14) and held higher sheep densities (mean 108.0 sheep/km(2)), while larger management units (mean size 23.8 km(2)), showed lower EVI values (mean 0.12) and lower stocking-rates (mean 36.7 sheep/km(2)). This pattern suggests that primary productivity has been a decisive factor to determine the minimal paddock size set by ranchers in PV, apparently precluding excessive land-subdivision in less productive areas. Guanaco encounter rate, expressed as number of guanacos per travelled kilometre, was inversely related to EVI and stocking-rate. However, land subdivision was the better predictor of guanaco encounter-rate within only sheep ranches, finding more guanacos per kilometre as paddock size increased. In contrast, in ranches where ecotourism was implemented as a complementary activity, guanaco encounter-rates were greater, regardless of paddock size. Our results suggest that the implementation of an additional activity by which landowners derive benefits from wildlife has prompted a beneficial outcome for guanacos, presumably through a decrease in harassment intensity. Finally, we propose possible mechanisms by which land subdivision may affect guanaco distribution and potential alternatives for the inclusion of wildlife conservation in a context of extensive livestock production.

Frictional properties of low-angle normal fault gouges and implications for low-angle normal fault slip

NASA Astrophysics Data System (ADS)

Haines, Samuel; Marone, Chris; Saffer, Demian

2014-12-01

The mechanics of slip on low-angle normal faults (LANFs) remain an enduring problem in structural geology and fault mechanics. In most cases, new faults should form rather than having slip occur on LANFs, assuming values of fault friction consistent with Byerlee's Law. We present results of laboratory measurements on the frictional properties of natural clay-rich gouges from low-angle normal faults (LANF) in the American Cordillera, from the Whipple Mts. Detachment, the Panamint range-front detachment, and the Waterman Hills detachment. These clay-rich gouges are dominated by neoformed clay minerals and are an integral part of fault zones in many LANFs, yet their frictional properties under in situ conditions remain relatively unknown. We conducted measurements under saturated and controlled pore pressure conditions at effective normal stresses ranging from 20 to 60 MPa (corresponding to depths of 0.9-2.9 km), on both powdered and intact wafers of fault rock. For the Whipple Mountains detachment, friction coefficient (μ) varies depending on clast content, with values ranging from 0.40 to 0.58 for clast-rich material, and 0.29-0.30 for clay-rich gouge. Samples from the Panamint range-front detachment were clay-rich, and exhibit friction values of 0.28 to 0.38, significantly lower than reported from previous studies on fault gouges tested under room humidity (nominally dry) conditions, including samples from the same exposure. Samples from the Waterman Hills detachment are slightly stronger, with μ ranging from 0.38 to 0.43. The neoformed gouge materials from all three localities exhibits velocity-strengthening frictional behavior under almost all of the experimental conditions we explored, with values of the friction rate parameter (a - b) ranging from -0.001 to +0.025. Clast-rich samples exhibited frictional healing (strength increases with hold time), whereas clay-rich samples do not. Our results indicate that where clay-rich neoformed gouges are present along LANFs, they provide a mechanically viable explanation for slip on faults with dips <20°, requiring only moderate (Pf <σ3) overpressures and/or correcting for ∼5° of footwall tilting. Furthermore, the low rates of frictional strength recovery and velocity-strengthening frictional behavior we observe provide an explanation for the lack of observed seismicity on these structures. We suggest that LANFs in the upper crust (depth <8 km) slip via a combination of a) reaction-weakening of initially high-angle fault zones by the formation of neoformed clay-rich gouges, and b) regional tectonic accommodation of rotating fault blocks.

Heat flow from the Liberian precambrian shield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sass, J.H.; Behrendt, J.C.

1980-06-10

Uncorrected heat flow in iron formation rocks from three areas within the Liberian part of the West African Shield ranges from 50 to more than 80 mW m/sup -2/. When corrections are applied for topography and refraction, the range of heat flow is narrowed to between 38 and 42 mW m/sup -2/. In comparison with heat flows from other parts of the West African Craton, these values are consistent with preliminary results from Ghana (42 +- 8 mW m/sup -2/) and Nigeria (38 +- 2 mW /sup -2/) but are somewhat higher than values from Niger (20 mW m/sup -2/)more » and neighboring Sierra Leone (26 mW m/sup -2/). The Liberian values are significantly lower than the heat flow offshore in the equatorial Atlantic Ocean (58 +- 8 mW m/sup -2/), suggesting large lateral temperature gradients within the lithosphere near the coast. Values of heat production from outcrops of crystalline basement rocks near the holes are between 2 and 2.3 ..mu..W m/sup -3/. A heat-flow/heat-production relation cannot be established because of the small range of values; however, assuming a 'characteristic depth' of 8 km (similar to the North American Craton) the reduced heat flow of from 20 to 25 mW m/sup -2/ is consistent with that from other Precambrian shields.« less

Spatial and seasonal variations in stream water delta34S-dissolved organic matter in northern Sweden.

PubMed

Giesler, Reiner; Björkvald, Louise; Laudon, Hoalmar; Mörth, Carl-Magnus

2009-01-15

The discharge of terrestrial dissolved organic matter (DOM) by streams is an important cross-system linkage that strongly influences downstream aquatic ecosystems. Isotopic tracers are important tools that can help to unravel the source of DOM from different terrestrial compartments in the landscape. Here we demonstrate the spatial and seasonal variation of delta34S of DOM in 10 boreal streams to test if the tracer could provide new insights into the origin of DOM. We found large spatial and seasonal variations in stream water delta34S-DOM values ranging from -5.2 per thousand to +9.6 per thousand with an average of +4.0 +/- 0.6 (N = 62; average and 95% confidence interval). Large seasonal variations were found in stream water delta34S-DOM values: for example, a shift of more than 10 per thousand during the spring snowmelt in a wetland-dominated stream. Spatial differences were also observed during the winter base flow with higher delta34S-DOM values in the fourth-order Krycklan stream at the outlet of the 68 km2 catchment compared to the small (< 1 km2) headwater streams. Our data clearly show that the delta34S-DOM values have the potential to be used as a tracer to identify and generate new insights about terrestrial DOM sources in the boreal landscape.

Uranium isotopes in tree bark as a spatial tracer of environmental contamination near former uranium processing facilities in southwest Ohio.

PubMed

Conte, Elise; Widom, Elisabeth; Kuentz, David

2017-11-01

Inappropriate handling of radioactive waste at nuclear facilities can introduce non-natural uranium (U) into the environment via the air or groundwater, leading to anthropogenic increases in U concentrations. Uranium isotopic analyses of natural materials (e.g. soil, plants or water) provide a means to distinguish between natural and anthropogenic U in areas near sources of radionuclides to the environment. This study examines the utility of two different tree bark transects for resolving the areal extent of U atmospheric contamination using several locations in southwest Ohio that historically processed U. This study is the first to utilize tree bark sampling transects to assess environmental contamination emanating from a nuclear facility. The former Fernald Feed Materials Production Center (FFMPC; Ross, Ohio) produced U metal from natural U ores and recycled nuclear materials from 1951 to 1989. Alba Craft Laboratory (Oxford, Ohio) machined several hundred tons of natural U metal from the FFMPC between 1952 and 1957. The Herring-Hall-Marvin Safe Company (HHM; Hamilton, Ohio) intermittently fabricated slugs rolled from natural U metal stock for use in nuclear reactors from 1943 to 1951. We have measured U concentrations and isotope signatures in tree bark sampled along an ∼35 km SSE-NNW transect from the former FFMPC to the vicinity of the former Alba Craft laboratories (transect #1) and an ∼20 km SW- NE (prevailing local wind direction) transect from the FFMPC to the vicinity of the former HHM (transect #2), with a focus on old trees with thick, persistent bark that could potentially record a time-integrated signature of environmental releases of U related to anthropogenic activity. Our results demonstrate the presence of anthropogenic U contamination in tree bark from the entire study area in both transects, with U concentrations within 1 km of the FFMPC up to ∼400 times local background levels of 0.066 ppm. Tree bark samples from the Alba Craft and HHM transects exhibit increasing U concentrations within ∼5 and ∼10 km, respectively of the FFMPC. The 236 U/ 238 U isotopic ratios in tree bark from both transects increase progressively towards the FFMPC with values as high as 2.00 × 10 -4  at the FFMPC. Tree bark sampled within 1 km of the FFMPC exhibits clear evidence for both enriched and depleted uranium with 235 U/ 238 U values from 0.00461 to 0.00736, with 234 U/ 238 U activity ratio ranging from 0.53 to 0.96, and 236 U/ 238 U from 6.05 × 10 -5 to 1.05 × 10 -4 . Tree bark from transect #1 between 1 and 30 km from the FFMPC exhibits depleted and natural 235 U/ 238 U values ranging from 0.00552 to 0.00726 [ 234 U/ 238 U activity ratio: 0.69-1.04; 236 U/ 238 U: 2.49 × 10 -6 - 2.00 × 10 -4 ]. Tree bark from transect #2 sampled between 1 and ∼20 km away from the FFMPC exhibits evidence of enriched and depleted U in the environment with 235 U/ 238 U ranging from 0.00635 to 0.00738 [ 234 U/ 238 U activity ratio: 0.83-0.98; 236 U/ 238 U: 1.43 × 10 -5 - 2.00 × 10 -4 ]. Results from scanning electron microscopy with energy dispersive spectrometry provides evidence for U-rich particles as the source of contamination found in tree bark growing within 1-3 km of the former FFMPC. Such observations are consistent with the previously observed 14 μm U-rich particle identified in tree bark sampled within 1 km of the FFMPC (Conte et al., 2015). Overall, this study shows the usefulness of a tree bark sample transect to assess the areal extent of atmospheric contaminant U stemming from nuclear facilities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Incorporating AFEWC IMOM as an Instructional Asset for NPS Radar and Electronic Warfare Curricula

DTIC Science & Technology

1992-09-01

Backlobe EL. dB down - 20 dB Backlobe AZ. dB down = 20 dB Ru - 400 km 215.983 nmi Scope Range = 200 km 107.991 nmi PRF = 375 Hz Pay = 600 W RCS = 10 sq m...10 dB Backlobe EL. dB down = 20 dB Backlobe AZ. dB down = 20 dB Ru = 400 km 215.983 nmi Scope Range = 400 km 215.983 nmi PRF = 375 Hz Pay = 93.75 W

Estimating the urban bias of surface shelter temperatures using upper-air and satellite data. Part 2: Estimation of the urban bias

NASA Technical Reports Server (NTRS)

Epperson, David L.; Davis, Jerry M.; Bloomfield, Peter; Karl, Thomas R.; Mcnab, Alan L.; Gallo, Kevin P.

1995-01-01

A methodology is presented for estimating the urban bias of surface shelter temperatures due to the effect of the urban heat island. Multiple regression techniques were used to predict surface shelter temperatures based on the time period 1986-89 using upper-air data from the European Centre for Medium-Range Weather Forecasts (ECMWF) to represent the background climate, site-specific data to represent the local landscape, and satellite-derived data -- the normalized difference vegetation index (NDVI) and the Defense Meteorological Satellite Program (DMSP) nighttime brightness data -- to represent the urban and rural landscape. Local NDVI and DMSP values were calculated for each station using the mean NDVI and DMSP values from a 3 km x 3 km area centered over the given station. Regional NDVI and DMSP values were calculated to represent a typical rural value for each station using the mean NDVI and DMSP values from a 1 deg x 1 deg latitude-longitude area in which the given station was located. Models for the United States were then developed for monthly maximum, mean, and minimum temperatures using data from over 1000 stations in the U.S. Cooperative (COOP) Network and for monthly mean temperatures with data from over 1150 stations in the Global Historical Climate Network (GHCN). Local biases, or the differences between the model predictions using the observed NDVI and DMSP values, and the predictions using the background regional values were calculated and compared with the results of other research. The local or urban bias of U.S. temperatures, as derived from all U.S. stations (urban and rural) used in the models, averaged near 0.40 C for monthly minimum temperatures, near 0.25 C for monthly mean temperatures, and near 0.10 C for monthly maximum temperatures. The biases of monthly minimum temperatures for individual stations ranged from near -1.1 C for rural stations to 2.4 C for stations from the largest urban areas. The results of this study indicate minimal problems for global application once global NDVI and DMSP data become available.

THE IMPORTANCE OF OBTAINING INFORMATION ON THE SPECIFIC CONTENT OF TISSUE ENZYMES METABOLIZING ORGANOPHOSPHORUS PESTICIDES, PRIOR TO DETERMINE VMAX, KM VALUES FOR USE IN PBPK MODELS

EPA Science Inventory

Physiological pharmacokinetic/pharmacodynamic models require Vmax, Km values for the metabolism of OPs by tissue enzymes. Current literature values cannot be easily used in OP PBPK models (i.e., parathion and chlorpyrifos) because standard methodologies were not used in their ...

THE IMPORTANCE OF OBTAINING INFORMATION ON THE SPECIFIC CONTENT OF TISSUE ENZYMES METABOLIZING ORGANOPHOSPHORUS PESTICIDES, PRIOR TO DETERMINING VMAX, KM VALUES FOR USE IN PBPK MODELS

EPA Science Inventory

Physiological pharmacokinetic\\pharmacodynamic models require Vmax, Km values for the metabolism of OPs by tissue enzymes. Current literature values cannot be easily used in OP PBPK models (i.e., parathion and chlorpyrifos) because standard methodologies were not used in their ...

The structure of Greater Caucasus in scales of sedimentary cover and crust, based on restored structural sections, which were obtained from study of fold-related strain

NASA Astrophysics Data System (ADS)

Yakovlev, Fedor

2015-04-01

Geological setting. Greater Caucasus (GC) belongs to a linear branch of the Alpine belt (Crimea, Caucasus, Kopet-Dag) which is not arc-like as the Alps. The main stripe of the Alpine deformations in GC occupies space about 1000 x 50 km between the Scythian plate and the Transcaucasian massif. Folded structure prevails and it is accompanied by almost total absence of thrust in a hinterland and by limited thrusts in forelands. The Paleozoic basement outcrops only in a northern half of this linear structure, occupying about 1/8 part of GC. Alpine sedimentary cover (J1 - Pg2) has 10-15 km thickness of flysch-like sequences of sands, argillites, limestones. These sediments formed numerous folds of 0.1 - 1.0 km width. Because each fold has information about strain, the existence of so rich material allows to restore geometry of a sedimentary cover from soil to its top. Method. Three regions were studied due based on 24 detailed structural sections of 510 km total actual length. Two kind of isometric objects of different scale were established: domains and structural cells. There were domains as associations of 2-5 folds; sections were split on 505 one. In these domains, three parameters of morphology were measured as elements of strain ellipsoid (ellipse): dip of axial plain, dip of envelope plain, value of shortening as interlimb angle [1, 2, 3]. It was possible to restore actual state of domain to its pre-folded state (from ellipse to circle) by sequence of three kinematic operations: by rotation to horizontal position of envelope plain, by horizontal simple shear to vertical axial plain and by vertical flattening (pure shear). Pre-folded state of whole section is forming by aggregation of pre-folded states of domains. "Structural cells" were formed by aggregation of 5-10 domains in each cell for correct measuring of shortening value in scale of whole sedimentary cover; there were 78 for three regions. "Stratigraphic models" from bottom to top of cover for each cell were found based on famous (outcropped) column and on some interpolations. It allow to find vertical positions (depth) of section lines inside models. Initial thickness of cover was reformed to new post-folded thickness and knowledge of section line depth allow to find a depth of cover bottom and virtual heigth position of cover top (uplift amplitude). Results. North-Western Caucasus (NWC) was studied on 250x50 km stripe in 11 sections and 42 cells [1]. Initial thickness of sedimentary cover was 13 km (7.3÷17.3 km). Shortening value for structural cells deviated from small (-10%, 2%) at pericline part to 15-67% and it has 35% in average. Actual depth of basement top (soil of sedimentary cover ) was -13 km (-2.2÷-31.7 km). Three sectors along strike of NWC were found: with central depression at pericline (-19, -23 km), with sinking of south part of structure (-27, -32 km) and with central depression again on East (-25 km). Amplitude of erosion has reasonable distribution on NWC: from small in average at pericline (3 km) to high value at center (15 km) with smaller values on edges of sections. Average value was 8.9 km (+0÷+22.2 km). Chiaur tectonic zone in South Ossetia (ChZ) and two zones in South-Eastern Caucasus - Tfan Zone (TZ) and Shakhdag zone (ShZ) have formed together the other part of Caucasus [3]. Initial and actual depths of sedimentary cover have had close values -15 (-21) km, -10 (-10) km, -13 (-12) km. Southern part of structure (ChZ) has had considerable actual subsidence of basement top (-13.6÷-26.3 km). The shortening values were found as 57% in average for ChZ (with deviations 46÷67%), 55% for TZ (36÷67%), 49% for ShZ (37÷62%). Amplitudes of erosion were calculated as 16 km for ChZ (10÷22), 19 km for TZ (12÷24), 10 km for ShZ (7÷12). On the southern border of GC, depths of basement top were found as -8 km for Trans-Caucasian massif (stable block) and -19 km for adjacent cell of ChZ (GC). It means that: 1) value of shortening of sedimentary cover of ChZ 57% is equal to shortening of basement, 2) regional detachment and thrusts in GC above basement cannot exist. Based on these data, calculation of vertical movements of former Moho (-40 km for beginning of J1) shows that actual position of these rocks may has depth about 110 km [3]. It means that considerable part of crust rocks should became "mantle" in density and this kind of rocks transformation is inescapable condition of folding formation for structure of GC. 1. Yakovlev F.L. // Izvestiya, Physics of the Solid Earth. 2009. 45. 11. 1023-1034. 2. Yakovlev F.L. // Comptes Rendus Geoscience. 2012. 344 (3-4). 125-137. 3. Yakovlev F.L. // Bulletin of "KRAESC". Earth Sciences. 2012. 1 (19). 191-214. (in Russian)

Simultaneous retrieval of daytime O(3P) and O3 concentrations in the altitude interval 80 - 100 km.

NASA Astrophysics Data System (ADS)

Yankovsky, Valentine; Manuilova, Rada; Koval, Andrey

2017-04-01

We propose methods of simultaneously independent retrievals of the key components of Mesosphere and Lower Thermosphere (MLT) [O3] and [O(3P)]. The altitude profile of ozone concentration, [O3], can be measured by direct method of the measurement of absorbing radiation from the Sun or the stars in the UV range of the spectrum. However, this method is most often realized in twilight. Retrieval of daytime [O3] depends on a prior information about the O(3P) altitude profile. Vice versa, atomic oxygen concentration, [O(3P)], is usually retrieved from the measured values of [O3]. The problem of independent and simultaneous retrieval of [O3] and [O(3P)] can be solved by using individual proxy for each of the target component. Using a sensitivity study and uncertainty analysis of the contemporary model of O3 and O2 photolysis in the MLT, YM2011, we determined that populations of three excited electronic-vibrational levels O2(b1, v = 0, 1, 2) and of metastable O(1D) atom depend on [O(3P)] and [O3] concentrations. For [O(3P)] retrieval the following transitions should be used: O2(b1, v') -> O2(X3, v") which produce emissions: (a) at 780.4 nm in the band (v' = 2, v" = 2) and at 697.0 nm in the band (2, 1) with the uncertainty of retrieval smaller than 30% for the whole altitude range 80 - 100 km; (b) at 771.0 nm in the band (1, 1), 688.4 nm in the band (1, 0) and at 874.4 nm in the band (1, 2) with the uncertainty of retrieval about 30% above 90 km. For [O3] retrieval the following transitions should be used: O2(b1, v') -> O2(X3, v") which produce emissions: (c) at 762.1 nm in the band (0, 0) and at 864.7 nm in the band (0, 1) with the uncertainty of retrieval 20 - 25% for the altitude range 80 - 85 km and smaller than 20% in the interval 85 - 95 km; (d) in the line of O(1D) 630.0 nm with the uncertainty of retrieval 10 - 15% in the interval 80 - 95 km. Above 95 km the uncertainty of [O3] retrieval grows and reaches up to 80% at 100 km for all suggested proxies. For simultaneously [O3] and [O(3P)] retrievals the observations of above mentioned emissions (a) or (b) and (c) or (d) could be used.

Surface fault slip associated with the 2004 Parkfield, California, earthquake

USGS Publications Warehouse

Rymer, M.J.; Tinsley, J. C.; Treiman, J.A.; Arrowsmith, J.R.; Ciahan, K.B.; Rosinski, A.M.; Bryant, W.A.; Snyder, H.A.; Fuis, G.S.; Toke, N.A.; Bawden, G.W.

2006-01-01

Surface fracturing occurred along the San Andreas fault, the subparallel Southwest Fracture Zone, and six secondary faults in association with the 28 September 2004 (M 6.0) Parkfield earthquake. Fractures formed discontinuous breaks along a 32-km-long stretch of the San Andreas fault. Sense of slip was right lateral; only locally was there a minor (1-11 mm) vertical component of slip. Right-lateral slip in the first few weeks after the event, early in its afterslip period, ranged from 1 to 44 mm. Our observations in the weeks following the earthquake indicated that the highest slip values are in the Middle Mountain area, northwest of the mainshock epicenter (creepmeter measurements indicate a similar distribution of slip). Surface slip along the San Andreas fault developed soon after the mainshock; field checks in the area near Parkfield and about 5 km to the southeast indicated that surface slip developed more than 1 hr but generally less than 1 day after the event. Slip along the Southwest Fracture Zone developed coseismically and extended about 8 km. Sense of slip was right lateral; locally there was a minor to moderate (1-29 mm) vertical component of slip. Right-lateral slip ranged from 1 to 41 mm. Surface slip along secondary faults was right lateral; the right-lateral component of slip ranged from 3 to 5 mm. Surface slip in the 1966 and 2004 events occurred along both the San Andreas fault and the Southwest Fracture Zone. In 1966 the length of ground breakage along the San Andreas fault extended 5 km longer than that mapped in 2004. In contrast, the length of ground breakage along the Southwest Fracture Zone was the same in both events, yet the surface fractures were more continuous in 2004. Surface slip on secondary faults in 2004 indicated previously unmapped structural connections between the San Andreas fault and the Southwest Fracture Zone, further revealing aspects of the structural setting and fault interactions in the Parkfield area.

Research study on neutral thermodynamic atmospheric model. [for space shuttle mission and abort trajectory

NASA Technical Reports Server (NTRS)

Hargraves, W. R.; Delulio, E. B.; Justus, C. G.

1977-01-01

The Global Reference Atmospheric Model is used along with the revised perturbation statistics to evaluate and computer graph various atmospheric statistics along a space shuttle reference mission and abort trajectory. The trajectory plots are height vs. ground range, with height from ground level to 155 km and ground range along the reentry trajectory. Cross sectional plots, height vs. latitude or longitude, are also generated for 80 deg longitude, with heights from 30 km to 90 km and latitude from -90 deg to +90 deg, and for 45 deg latitude, with heights from 30 km to 90 km and longitudes from 180 deg E to 180 deg W. The variables plotted are monthly average pressure, density, temperature, wind components, and wind speed and standard deviations and 99th inter-percentile range for each of these variables.

Influence of air quality model resolution on uncertainty associated with health impacts

NASA Astrophysics Data System (ADS)

Thompson, T. M.; Selin, N. E.

2012-10-01

We use regional air quality modeling to evaluate the impact of model resolution on uncertainty associated with the human health benefits resulting from proposed air quality regulations. Using a regional photochemical model (CAMx), we ran a modeling episode with meteorological inputs simulating conditions as they occurred during August through September 2006 (a period representative of conditions leading to high ozone), and two emissions inventories (a 2006 base case and a 2018 proposed control scenario, both for Houston, Texas) at 36, 12, 4 and 2 km resolution. The base case model performance was evaluated for each resolution against daily maximum 8-h averaged ozone measured at monitoring stations. Results from each resolution were more similar to each other than they were to measured values. Population-weighted ozone concentrations were calculated for each resolution and applied to concentration response functions (with 95% confidence intervals) to estimate the health impacts of modeled ozone reduction from the base case to the control scenario. We found that estimated avoided mortalities were not significantly different between the 2, 4 and 12 km resolution runs, but the 36 km resolution may over-predict some potential health impacts. Given the cost/benefit analysis requirements motivated by Executive Order 12866 as it applies to the Clean Air Act, the uncertainty associated with human health impacts and therefore the results reported in this study, we conclude that health impacts calculated from population weighted ozone concentrations obtained using regional photochemical models at 36 km resolution fall within the range of values obtained using fine (12 km or finer) resolution modeling. However, in some cases, 36 km resolution may not be fine enough to statistically replicate the results achieved using 2, 4 or 12 km resolution. On average, when modeling at 36 km resolution, an estimated 5 deaths per week during the May through September ozone season are avoided because of ozone reductions resulting from the proposed emissions reductions (95% confidence interval was 2-8). When modeling at 2, 4 or 12 km finer scale resolution, on average 4 deaths are avoided due to the same reductions (95% confidence interval was 1-7). Study results show that ozone modeling at a resolution finer than 12 km is unlikely to reduce uncertainty in benefits analysis for this specific region. We suggest that 12 km resolution may be appropriate for uncertainty analyses of health impacts due to ozone control scenarios, in areas with similar chemistry, meteorology and population density, but that resolution requirements should be assessed on a case-by-case basis and revised as confidence intervals for concentration-response functions are updated.

Well-behaved relativistic charged super-dense star models

NASA Astrophysics Data System (ADS)

Faruqi, Shahab; Pant, Neeraj

2012-10-01

A new class of charged super-dense star models is obtained by using an electric intensity, which involves a parameter, K. The metric describing the model shares its metric potential g 44 with that of Durgapal's fourth solution (J. Phys. A, Math. Gen. 15:2637, 1982). The pressure-free surface is kept at the density ρ b =2×1014 g/cm3 and joins smoothly with the Reissner-Nordstrom solution. The charge analogues are well-behaved for a wide range, 0≤ K≤59, with the optimum value of X=0.264 i.e. the pressure, density, pressure-density ratio and velocity of sound are monotonically decreasing and the electric intensity is monotonically increasing in nature for the given range of the parameter K. The maximum mass and the corresponding radius occupied by the neutral solution are 4.22 M Θ and 20 km, respectively for X=0.264. For the charged solution, the maximum mass and radius are defined by the expressions M≈(0.0059 K+4.22) M Θ and r b ≈-0.021464 K+20 km respectively.

Finite-fault slip model of the 2011 Mw 5.6 Prague, Oklahoma earthquake from regional waveforms

USGS Publications Warehouse

Sun, Xiaodan; Hartzell, Stephen

2014-01-01

The slip model for the 2011 Mw 5.6 Prague, Oklahoma, earthquake is inferred using a linear least squares methodology. Waveforms of six aftershocks recorded at 21 regional stations are used as empirical Green's functions (EGFs). The solution indicates two large slip patches: one located around the hypocenter with a depth range of 3–5.5 km; the other located to the southwest of the epicenter with a depth range from 7.5 to 9.5 km. The total moment of the solution is estimated at 3.37 × 1024 dyne cm (Mw 5.65). The peak slip and average stress drop for the source at the hypocenter are 70 cm and 90 bars, respectively, approximately one half the values for the Mw 5.8 2011 Mineral, Virginia, earthquake. The stress drop averaged over all areas of slip is 16 bars. The relatively low peak slip and stress drop may indicate an induced component in the origin of the Prague earthquake from deep fluid injection.

Discrimination of growth and water stress in wheat by various vegetation indices through a clear a turbid atmosphere

NASA Technical Reports Server (NTRS)

Jackson, R. D.; Slater, P. M.; Pinter, P. J. (Principal Investigator)

1982-01-01

Reflectance data were obtained over a drought-stressed and a well-watered wheat plot with a hand-held radiometer having bands similar to the MSS bands of the LANDSAT satellites. Data for 48 clear days were interpolated to yield reflectance values for each day of the growing season, from planting until harvest. With an atmospheric path radiance model and LANDSAT-2 calibration data, the reflectance were used to simulate LANDSAT digital counts (not quantized) for the four LANDSAT bands for each day of the growing season, through a clear (approximately 100 km meteorological range) and a turbid (approximately 10 km meteorological range) atmosphere. Several ratios and linear combinations of bands were calculated using the simulated data, then assessed for their relative ability to discriminate vegetative growth and plant stress through the two atmospheres. The results show that water stress was not detected by any of the indices until after growth was retarded, and the sensitivity of the various indices to vegetation depended on plant growth stage and atmospheric path radiance.

Integrated study of Mississippian Lodgepole Waulsortian Mounds, Williston Basin, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kupecz, J.A.; Arestad, J.F.; Blott, J. E.

1996-06-01

Waulsortian-type carbonate buildups in the Mississippian Lodgepole Formation, Williston Basin, constitute prolific oil reservoirs. Since the initial discovery in 1993, five fields have been discovered: Dickinson Field (Lodgepole pool); Eland Field; Duck Creek Field, Versippi Field; and Hiline Field. Cumulative production (October, 1995) is 2.32 million barrels of oil and 1.34 BCF gas, with only 69,000 barrels of water. Oil gravity ranges from 41.4 to 45.3 API. Both subsurface cores from these fields as well as outcrop (Bridget Range, Big Snowy and Little Belt Mountains, Montana) are composed of facies representing deposition in mound, reworked mound, distal reworked mound, proximalmore » flank, distal flank, and intermound settings. Porosity values within the mound and reworked mound facies are up to 15%; permeability values (in places fracture-enhanced) are up to tens of Darcies. Geometries of the mounds are variable. Mound thicknesses in the subsurface range from approximately 130-325 feet (40-100 meters); in outcrop thicknesses range from less than 30 ft (9 m) to over 250 ft (76 m). Subsurface areal dimensions range from approximately 0.5 x 1.0 mi (0.8 x 1.6 km) to 3.5 x 5.5 mi (5.6 x 8.8 km). Integration of seismic data with core and well-log models sheds light on the exploration for Lodgepole mounds. Seismic modeling of productive mounds in the Dickinson and Eland fields identifies characteristics useful for exploration, such as local thickening of the Lodgepole to Three Forks interval. These observations are confirmed in reprocessed seismic data across Eland field and on regional seismic data. Importantly, amplitude versus offset modeling identifies problems with directly detecting and identifying porosity within these features with amplitude analyses. In contrast, multicomponent seismic data has great potential for imaging these features and quantifying porous zones within them.« less

Geochemical structure of the Hawaiian plume: Sr, Nd, and Os isotopes in the 2.8 km HSDP-2 section of Mauna Kea volcano

NASA Astrophysics Data System (ADS)

Bryce, Julia G.; Depaolo, Donald J.; Lassiter, John C.

2005-09-01

Sr, Nd, and Os isotopic measurements were made on 110 Mauna Kea lava and hyaloclastite samples from the drillcore retrieved from the second phase of the Hawaii Scientific Drilling Project (HSDP-2). The samples come from depths of 255 to 3098 meters below sea level, span an age range from 200 to about 550-600 kyr, and represent an ordered record of the lava output from Mauna Kea volcano as it drifted a distance of about 40 km over the magma-producing region of the Hawaiian hot spot. The deepest (oldest) samples represent the time when Mauna Kea was closest to the center of the melting region of the Hawaiian plume. The Sr and Os isotopic ratios in HSDP-2 lavas show only subtle isotopic shifts over the ˜400 kyr history represented by the core. Neodymium isotopes (ɛNd values) increase systematically with decreasing age from an average value of nearly +6.5 to an average value of +7.5. This small change corresponds to subtle shifts in 87Sr/86Sr and 187Os/188Os isotope ratios, with small shifts of ɛHf, a large shift in 208Pb/204Pb and 208Pb/207Pb values, and with a very large shift in He isotope ratios from R/RA values of about 7-8 to values as high as 25. When Mauna Kea was closest to the plume core, the magma source did not have primitive characteristics for Nd, Sr, Pb, Hf, and Os isotopes but did have variable amounts of "primitive" helium. The systematic shifts in Nd, Hf, Pb, and He isotopes are consistent with radial isotopic zoning within the melting region of the plume. The melting region constitutes only the innermost, highest-temperature part of the thermally anomalous plume mantle. The different ranges of values observed for each isotopic system, and comparison of Mauna Kea lavas with those of Mauna Loa, suggest that the axial region of the plume, which has a radius of ˜20 km, is a mixture of recycled subducted components and primitive lower mantle materials, recently combined during the formational stages of the plume at the base of the mantle. The proportions of recycled and primitive components are not constant, and this requires there be longitudinal (vertical) heterogeneity within the core of the plume. The remainder of the plume, outside this plume "core zone," is less heterogeneous but distinct from upper mantle as represented by mid-ocean ridge basalt (MORB). The plume structure may provide a detailed view of mantle isotopic composition near the core-mantle boundary.

Graphite in the Bishop Tuff and its effect on postcaldera oxygen fugacity

USGS Publications Warehouse

Hildreth, Edward; Ryan-Davis, Juliet; Harlow, Benjamin

2017-01-01

Several cubic kilometers of Paleozoic graphite-bearing argillitic country rocks are present as lithic fragments in Bishop Tuff ignimbrite and fallout. The lithics were entrained by the 650 km3 of rhyolite magma that vented during the 5- to 6-day-long, caldera-forming eruption at Long Valley, California. The caldera is floored by a 350 km2 roof plate that collapsed during the eruption and consists in large part of the Paleozoic strata that provided the abundant hornfelsed metapelitic lithic clasts in the tuff. Graphite has been identified by Raman spectroscopy, electron-dispersive spectroscopy, and X-ray diffraction as an irregularly dispersed component in the small fraction of Bishop Tuff pumice that is dark-colored. Carbon concentration has been determined in pumice, lithics, and wall rocks. Values of δ13C range from –21‰ to –29‰ Vienna Peedee Belemnite (VPDB) for pumice, lithics, and argillitic wall rocks, reflecting the biogenic origin of the reduced carbon in oxygen-limited black Paleozoic marine mudrocks. Carbonate contents, measured separately, are negligible in fresh pumice and lithics. Microprobe analyses of titanomagnetite-ilmenite pairs show that oxygen-fugacity values of numerous batches of postcaldera Early Rhyolite (750–640 ka; ~100 km3) are up to one log unit more reduced than those of the temperature–oxygen fugacity (T-fO2) array of the Bishop Tuff (767 ka), despite similar major-element compositions and Fe-Ti–oxide temperature ranges. All of the many batches of Early Rhyolite, which erupted episodically over an interval of ~125,000 years, yield the reduced fO2 values, indicating that reaction with graphite lowered magmatic fO2 after the caldera-forming eruption but before the first eruption of Early Rhyolite. It is inferred that reaction of postcaldera rhyolite magma with the reduced carbon in a great mass of subsided roof rocks lowered its fO2. It is suggested that comparable effects could have attended caldera collapse of other magma chambers hosted in continental sedimentary rocks.

Timing performance of a self-cancelling turn-signal mechanism in motorcycles based on the ATMega328P microcontroller

NASA Astrophysics Data System (ADS)

Nurbuwat, Adzin Kondo; Eryandi, Kholid Yusuf; Estriyanto, Yuyun; Widiastuti, Indah; Pambudi, Nugroho Agung

2018-02-01

The objective of this study is to measure the time performance of a self-cancelling turn signal mechanism based on the In this study the performance of self-cancelling turn signal based on ATMega328P microcontroller is measured at low speed and high speed treatment on motorcycles commonly used in Indonesia. Time performance measurements were made by comparing the self-cancelling turn signal based on ATMega328P microcontroller with standard motor turn time. Measurements of time at low speed treatment were performed at a speed range of 15 km / h, 20 km / h, 25 km / h on the U-turn test trajectory. The angle of the turning angle of the potentiometer is determined at 3°. The limit of steering wheel turning angle at the potentiometer is set at 3°. For high-speed treatment is 30 km / h, 40 km / h, 50km / h, and 60 km / h, on the L-turn test track with a tilt angle (roll angle) read by the L3G4200D gyroscope sensor. Each speed test is repeated 3 replications. Standard time is a reference for self-cancelling turn signal performance. The standard time obtained is 15.68 s, 11.96 s, 9.34 s at low speed and 4.63 s, 4.06 s, 3.61 s, 3.13 s at high speed. The time test of self-cancelling turn signal shows 16.10 s, 12.42 s, 10.24 s at the low speed and 5.18, 4.51, 3.73, 3.21 at the high speed. At a speed of 15 km / h occurs the instability of motion turns motorcycle so that testing is more difficult. Small time deviations indicate the tool works well. The largest time deviation value is 0.9 seconds at low speed and 0.55 seconds at high speed. The conclusion at low velocity of the highest deviation value occurred at the speed of 25 km / h test due to the movement of slope with inclination has started to happen which resulted in slow reading of steering movement. At higher speeds the time slows down due to rapid sensor readings on the tilt when turning fast at ever higher speeds. The timing performance of self-cancelling turn signal decreases as the motorcycle turning characteristics move from the turn using the steering angle to using a tilt angle based on speed, or vice versa.

MISR Level 2 TOA/Cloud Classifier parameters (MIL2TCCL_V2)

NASA Technical Reports Server (NTRS)

Diner, David J. (Principal Investigator)

The TOA/Cloud Classifiers contain the Angular Signature Cloud Mask (ASCM), a scene classifier calculated using support vector machine technology (SVM) both of which are on a 1.1 km grid, and cloud fractions at 17.6 km resolution that are available in different height bins (low, middle, high) and are also calculated on an angle-by-angle basis. [Location=GLOBAL] [Temporal_Coverage: Start_Date=2000-02-24; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=17.6 km; Longitude_Resolution=17.6 km; Horizontal_Resolution_Range=10 km - < 50 km or approximately .09 degree - < .5 degree; Temporal_Resolution=about 15 orbits/day; Temporal_Resolution_Range=Daily - < Weekly, Daily - < Weekly].

Experimental research of thermal loading of the rocket payload fairing element during the atmospheric phase of the descent trajectory

NASA Astrophysics Data System (ADS)

Trushlyakov, V.; Iordan, Yu; Davydovich, D.; Zharikov, K.; Dron, M.

2018-01-01

The thermal loading physical simulation in the experimental wind tunnel on the design element of the payload fairing made of carbon fiber was done. The experimental study is given in the speed range below 70 m/s, which corresponds to the interval of heights of the descent trajectory of the payload fairing half below 10 km. The values of heat transfer coefficient are obtained. The analysis of the results is carried out.

High altitude flights by ruddy shelduck Tadorna ferruginea during trans-Himalayan migrations

USGS Publications Warehouse

Parr, N.; Bearhop, S.; Douglas, David C.; Takekawa, J.Y.; Prosser, Diann J.; Newman, S.H.; Perry, W.M.; Balachandran, S.; Witt, M.J.; Hou, Y.; Luo, Z.; Hawkes, L.A.

2017-01-01

Birds that migrate across high altitude mountain ranges are faced with the challenge of maintaining vigorous exercise in environments with limited oxygen. Ruddy shelducks are known to use wintering grounds south of the Tibetan Plateau at sea level and breeding grounds north of Himalayan mountain range. Therefore, it is likely these shelducks are preforming high altitude migrations. In this study we analyse satellite telemetry data collected from 15 ruddy shelduck from two populations wintering south of the Tibetan Plateau from 2007 to 2011. During north and south migrations ruddy shelduck travelled 1481 km (range 548–2671 km) and 1238 km (range 548–2689 km) respectively. We find mean maximum altitudes of birds in flight reached 5590 m (range of means 4755–6800 m) and mean maximum climb rates of 0.45 m s–1 (range 0.23–0.74 m s–1). The ruddy shelduck is therefore an extreme high altitude migrant that has likely evolved a range of physiological adaptations in order to complete their migrations.

Geocoronal imaging with Dynamics Explorer

NASA Technical Reports Server (NTRS)

Rairden, R. L.; Frank, L. A.; Craven, J. D.

1986-01-01

The ultraviolet photometer of the University of Iowa spin-scan auroral imaging instrumentation on board Dynamics Explorer-1 has returned numerous hydrogen Lyman alpha images of the geocorona from altitudes of 570 km to 23,300 km (1.09 R sub E to 4.66 R sub E geocentric radial distance). The hydrogen density gradient is shown by a plot of the zenith intensities throughout this range, which decrease to near celestial background values as the spacecraft approaches apogee. Characterizing the upper geocorona as optically thin (single-scattering), the zenith intensity is converted directly to vertical column density. This approximation loses its validity deeper in the geocorona, where the hydrogen is demonstrated to be optically thick in that there is no Lyman alpha limb brightening. Further study of the geocoronal hydrogen distribution will require computer modeling of the radiative transfer.

The role of lithospheric stress in the support of the Tharsis rise

NASA Technical Reports Server (NTRS)

Willemann, R. J.; Turcotte, D. L.

1982-01-01

It is hypothesized that the Tharsis rise can be approximated as an axisymmetrical igneous construct. Linear theory for the deflection of planetary lithospheres is used to demonstrate that the lithospheric stresses required partially to support the construct are reasonable and consistent with the observed radial grabens around Tharsis. The computed thickness of the elastic lithosphere is between 110 and 260 km, depending of the values assumed for crustal thickness and crustal density. The computed thickness of the Tharsis load ranges from 40 to 70 km. Since in this model the height of the geoid is not specified a priori, the agreement between the observed and computed geoid is evidence for the validity of the model. The tectonics of the Tharsis region are briefly reviewed, and it is contended that all observations are consistent with the loading model.

Resident areas and migrations of female green turtles nesting at Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands

USGS Publications Warehouse

Hart, Kristen M.; Iverson, Autumn; Benscoter, Allison M.; Fujisaki, Ikuko; Cherkiss, Michael S.; Pollock, Clayton; Lundgren, Ian; Hillis-Starr, Zandy

2017-01-01

Satellite tracking in marine turtle studies can reveal much about their spatial use of breeding areas, migration zones, and foraging sites. We assessed spatial habitat-use patterns of 10 adult female green turtles (Chelonia mydas) nesting at Buck Island Reef National Monument, U.S. Virgin Islands (BIRNM) from 2011 – 2014. Turtles ranged in size from 89.0 – 115.9 cm CCL (mean + SD = 106.8 + 7.7 cm). The inter-nesting period across all turtles ranged from 31 July to 4 November, and sizes of the 50% core-use areas during inter-nesting ranged from 4.2 – 19.0 km2. Inter-nesting core-use areas were located up to1.4 km from shore and had bathymetry values ranging from -17.0 to -13.0 m. Seven of the ten turtles remained locally resident after the nesting season. Five turtles (50%) foraged around Buck Island, two foraged around the island of St. Croix, and the other three (30%) made longer-distance migrations to Antigua, St. Kitts & Nevis, and Venezuela. Further, five turtles had foraging centroids within protected areas. Delineating spatial areas and identifying temporal periods of nearshore habitat-use can be useful for natural resource managers with responsibility for overseeing vulnerable habitats and protected marine turtle populations.

Validity of Lactate Thresholds in Inline Speed Skating.

PubMed

Hecksteden, Anne; Heinze, Tobias; Faude, Oliver; Kindermann, Wilfried; Meyer, Tim

2015-09-01

Lactate thresholds are commonly used as estimates of the highest workload where lactate production and elimination are in equilibrium (maximum lactate steady state [MLSS]). However, because of the high static load on propulsive muscles, lactate kinetics in inline speed skating may differ significantly from other endurance exercise modes. Therefore, the discipline-specific validity of lactate thresholds has to be verified. Sixteen competitive inline-speed skaters (age: 30 ± 10 years; training per week: 10 ± 4 hours) completed an exhaustive stepwise incremental exercise test (start 24 km·h, step duration 3 minutes, increment 2 km·h) to determine individual anaerobic threshold (IAT) and the workload corresponding to a blood lactate concentration of 4 mmol·L (LT4) and 2-5 continuous load tests of (up to) 30 minutes to determine MLSS. The IAT and LT4 correlated significantly with MLSS, and the mean differences were almost negligible (MLSS 29.5 ± 2.5 km·h; IAT 29.2 ± 2.0 km·h; LT4 29.6 ± 2.3 km·h; p > 0.1 for all differences). However, the variability of differences was considerable resulting in 95% limits of agreement in the upper range of values known from other endurance disciplines (2.6 km·h [8.8%] for IAT and 3.1 km·h [10.3%] for LT4). Consequently, IAT and LT4 may be considered as valid estimates of the MLSS in inline speed skating, but verification by means of a constant load test should be considered in cases of doubt or when optimal accuracy is needed (e.g., in elite athletes or scientific studies).

Experimental Infrasound Studies in Nevada

NASA Astrophysics Data System (ADS)

Herrin, E. T.; Negraru, P. T.; Golden, P.; Williams, A.

2009-12-01

An experimental propagation study was carried out in Nevada in June 2009 on Julian days 173-177. During this field experiment we deployed 16 single channel digital infrasound recorders to monitor the munitions disposal activities near Hawthorne, NV. The sensors were deployed in a single line and placed approximately 12 km apart at distances ranging from 2 to 177 km. A four element semi-permanent infrasound array named FNIAR was installed approximately 154 km north of the detonation site in line with the individual temporary recorders. Tropospheric arrivals were observed during all days of the experiment, but during day 176 the observed arrivals had very large amplitudes. A large signal was observed at 58 km from the detonation site with amplitude as large as 4 Pascals, while at 94 km no signal was observed. At FNIAR the amplitude of the tropospheric arrival was 1 Pascal. During this day meteorological data acquired in the propagation path showed a strong jet stream to the north. On day 177 we were not able to identify tropospheric arrivals beyond 34 km, but at stations beyond 152 km we observed stratospheric arrivals. Continuous monitoring of these signals at FNIAR shows that stratospheric arrivals are the most numerous. In a two month period, from 06/15/2009 to 08/15/2009 there were 35 operational days at the Hawthorne disposal facility resulting in 212 explosions with known origin times. Based on the celerity values there were 115 explosions that have only stratospheric arrivals (celerities of 300-275 m/s), 72 explosions with both tropospheric (celerities above 330 m/s) and stratospheric arrivals, 20 explosions that were not detected and five explosions that have only tropospheric arrivals.

Unusual Childhood Waking as a Possible Precursor of the 1995 Kobe Earthquake

PubMed Central

Ikeya, Motoji; Whitehead, Neil E.

2013-01-01

Simple Summary The paper investigates whether young children may waken before earthquakes through a cause other than foreshocks. It concludes there is statistical evidence for this, but the mechanism best supported is anxiety produced by Ultra Low Frequency (ULF) electromagnetic waves. Abstract Nearly 1,100 young students living in Japan at a range of distances up to 500 km from the 1995 Kobe M7 earthquake were interviewed. A statistically significant abnormal rate of early wakening before the earthquake was found, having exponential decrease with distance and a half value approaching 100 km, but decreasing much slower than from a point source such as an epicentre; instead originating from an extended area of more than 100 km in diameter. Because an improbably high amount of variance is explained, this effect is unlikely to be simply psychological and must reflect another mechanism—perhaps Ultra-Low Frequency (ULF) electromagnetic waves creating anxiety—but probably not 222Rn excess. Other work reviewed suggests these conclusions may be valid for animals in general, not just children, but would be very difficult to apply for practical earthquake prediction. PMID:26487316

High-precision two-way optic-fiber time transfer using an improved time code.

PubMed

Wu, Guiling; Hu, Liang; Zhang, Hao; Chen, Jianping

2014-11-01

We present a novel high-precision two-way optic-fiber time transfer scheme. The Inter-Range Instrumentation Group (IRIG-B) time code is modified by increasing bit rate and defining new fields. The modified time code can be transmitted directly using commercial optical transceivers and is able to efficiently suppress the effect of the Rayleigh backscattering in the optical fiber. A dedicated codec (encoder and decoder) with low delay fluctuation is developed. The synchronization issue is addressed by adopting a mask technique and combinational logic circuit. Its delay fluctuation is less than 27 ps in terms of the standard deviation. The two-way optic-fiber time transfer using the improved codec scheme is verified experimentally over 2 m to100 km fiber links. The results show that the stability over 100 km fiber link is always less than 35 ps with the minimum value of about 2 ps at the averaging time around 1000 s. The uncertainty of time difference induced by the chromatic dispersion over 100 km is less than 22 ps.

Balloon-based interferometric techniques

NASA Technical Reports Server (NTRS)

Rees, David

1985-01-01

A balloon-borne triple-etalon Fabry-Perot Interferometer, observing the Doppler shifts of absorption lines caused by molecular oxygen and water vapor in the far red/near infrared spectrum of backscattered sunlight, has been used to evaluate a passive spaceborne remote sensing technique for measuring winds in the troposphere and stratosphere. There have been two successful high altitude balloon flights of the prototype UCL instrument from the National Scientific Balloon Facility at Palestine, TE (May 80, Oct. 83). The results from these flights have demonstrated that an interferometer with adequate resolution, stability and sensitivity can be built. The wind data are of comparable quality to those obtained from operational techniques (balloon and rocket sonde, cloud-top drift analysis, and from the gradient wind analysis of satellite radiance measurements). However, the interferometric data can provide a regular global grid, over a height range from 5 to 50 km in regions of clear air. Between the middle troposphere (5 km) and the upper stratosphere (40 to 50 km), an optimized instrument can make wind measurements over the daylit hemisphere with an accuracy of about 3 to 5 m/sec (2 sigma). It is possible to obtain full height profiles between altitudes of 5 and 50 km, with 4 km height resolution, and a spatial resolution of about 200 km, along the orbit track. Below an altitude of about 10 km, Fraunhofer lines of solar origin are possible targets of the Doppler wind analysis. Above an altitude of 50 km, the weakness of the backscattered solar spectrum (decreasing air density) is coupled with the low absorption crosssection of all atmospheric species in the spectral region up to 800 nm (where imaging photon detectors can be used), causing the along-the-track resolution (or error) to increase beyond values useful for operational purposes. Within the region of optimum performance (5 to 50 km), however, the technique is a valuable potential complement to existing wind measuring systems and can provide a low cost addition to powerful active (LIDAR) wind measuring systems now under development.

Anomalous top layer in the inner core beneath the eastern hemisphere

NASA Astrophysics Data System (ADS)

Yu, W.; Wen, L.; Niu, F.

2003-12-01

Recent studies reported hemispheric variations in seismic velocity and attenuation in the top of the inner core. It, however, remains unclear how the inner core hemisphericity extends deep in the inner core. Here, we analyze PKPbc-PKIKP and PKiKP-PKIKP waveforms collected from the Global Seismographic Network (GSN), regional recordings from the German Regional Seismic Network (GRSN) and Graefenberg (GRF) sampling along the equatorial path (the ray path whose ray angle is larger than 35o from the Earth's rotation axis). The observed global and regional PKPbc-PKIKP differential traveltimes and PKIKP/PKPbc amplitude ratios suggest a simple W2 model (Wen/Niu:2002) in the western hemisphere with a constant velocity gradient of 0.049(km/sec)/100km and a Q value of 600 in the top 400 km of the inner core. In the eastern hemisphere, the data require a change of velocity gradient and Q value at about 235 km below the inner core boundary (ICB). Based on forward modeling, we construct radial velocity and attenuation models in the eastern hemisphere which can explain both the PKiKP-PKIKP and PKPbc-PKIKP observations. The inner core in the eastern hemisphere has a flat velocity gradient extending to about 235 km below the ICB. We test two solutions for the velocity models in the deeper portion of the inner core, with one having a first-order discontinuity at 235 km below the ICB with a velocity jump of 0.07(km/sec) followed by the PREM gradient, and the other having a gradual velocity transition with 0.1(km/sec)/100km gradient extended from 235 km to 375 km below the ICB followed by the PREM gradient. The observed traveltimes exclude the sharp discontinuity velocity model, as it predicts a kink in differential traveltimes at distance of 151o-152o which is not observed in the global and regional datasets. The observed PKIKP/PKPbc amplitude ratios can be best explained by a step function of attenuation with a Q value of 250 at the top 300 km and a Q value of 600 at 300-400 km below the ICB. The top portion of the inner core in the eastern hemisphere is anomalous compared to the rest of the inner core, in having a flat velocity gradient, higher velocities and higher attenuation.

Effect of convection on the thermal structure of the troposphere and lower stratosphere including the tropical tropopause layer in the South Asian monsoon region

NASA Astrophysics Data System (ADS)

Muhsin, M.; Sunilkumar, S. V.; Venkat Ratnam, M.; Parameswaran, K.; Krishna Murthy, B. V.; Emmanuel, Maria

2018-04-01

Influence of convection on the thermal structure of Troposphere and Lower Stratosphere (TLS) is investigated using radiosonde data, obtained from Trivandrum (8.5°N, 76.9°E), Gadanki (13.5°N, 79.2°E), Bhubaneswar (20.25°N, 85.83°E), Kolkata (22.65°N, 88.45°E) and Singapore (1.37°N, 103.98°E), collected during different convective categories classified based on the altitude of deep convective cloud tops (CT) in the period 2008-2014. During deep convective events, the temperature showed lower tropospheric cooling, an upper tropospheric warming and an anomalous cooling (warming) below (above) the cold point tropopause (CPT) with respect to the clear-sky value. While warming in the upper troposphere is strongest (∼2-4 K) around 10-12 km, anomalous cooling (warming) below (above) the CPT is maximum around 15.5 km (17.5 km) with values in the range of-2 to -4 K (3-6 K). These temperature perturbations are observed 5-6 days prior to the convective events. In response to deep convection, surface cooling up to ∼ -4 K is also observed. This study showed that the magnitude of cold and warm anomalies increases with strength of convection. During deep convection, the potential temperature (θ) shows a decrease (<5 K) in the tropical tropopause layer (TTL) from the TTL-base up to CPT compared to that on clear-sky days, confirming the vertical mixing of convective air from the lower atmosphere to the TTL-levels. Correlation analysis between different TTL parameters suggests that, as the cloud top altitude increases, along with the adiabatic process, diabatic process also plays a major role in the TTL. An interesting feature observed during deep convection is the ascent of TTL-base by ∼1.5 km and descent of CPT and TTL-top by 0.5 km, which effectively thins the TTL by ∼2 km.

Tropospheric ozone maxima observed over the Arabian Sea during the pre-monsoon

NASA Astrophysics Data System (ADS)

Jia, Jia; Ladstätter-Weißenmayer, Annette; Hou, Xuewei; Rozanov, Alexei; Burrows, John P.

2017-04-01

An enhancement of the tropospheric ozone column (TOC) over Arabian Sea (AS) during the pre-monsoon season is reported in this study. The potential sources of the AS spring ozone pool are investigated by use of multiple data sets (e.g., SCIAMACHY Limb-Nadir-Matching TOC, OMI/MLS TOC, TES TOC, MACC reanalysis data, MOZART-4 model and HYSPLIT model). Three-quarters of the enhanced ozone concentrations are attributed to the 0-8 km height range. The main source of the ozone enhancement is considered to be caused by long-range transport of ozone pollutants from India (˜ 50 % contributions to the lowest 4 km, ˜ 20 % contributions to the 4-8 km height range), the Middle East, Africa and Europe (˜ 30 % in total). In addition, the vertical pollution accumulation in the lower troposphere, especially at 4-8 km, was found to be important for the AS spring ozone pool formation. Local photochemistry, on the other hand, plays a negligible role in producing ozone at the 4-8 km height range. In the 0-4 km height range, ozone is quickly removed by wet deposition. The AS spring TOC maxima are influenced by the dynamical variations caused by the sea surface temperature (SST) anomaly during the El Niño period in 2005 and 2010 with a ˜ 5 DU decrease.

[Spatial variability of soil nutrients based on geostatistics combined with GIS--a case study in Zunghua City of Hebei Province].

PubMed

Guo, X; Fu, B; Ma, K; Chen, L

2000-08-01

Geostatistics combined with GIS was applied to analyze the spatial variability of soil nutrients in topsoil (0-20 cm) in Zunghua City of Hebei Province. GIS can integrate attribute data with geographical data of system variables, which makes the application of geostatistics technique for large spatial scale more convenient. Soil nutrient data in this study included available N (alkaline hydrolyzing nitrogen), total N, available K, available P and organic matter. The results showed that the semivariograms of soil nutrients were best described by spherical model, except for that of available K, which was best fitted by complex structure of exponential model and linear with sill model. The spatial variability of available K was mainly produced by structural factor, while that of available N, total N, available P and organic matter was primarily caused by random factor. However, their spatial heterogeneity degree was different: the degree of total N and organic matter was higher, and that of available P and available N was lower. The results also indicated that the spatial correlation of the five tested soil nutrients at this large scale was moderately dependent. The ranges of available N and available P were almost same, which were 5 km and 5.5 km, respectively. The range of total N was up to 18 km, and that of organic matter was 8.5 km. For available K, the spatial variability scale primarily expressed exponential model between 0-3.5 km, but linear with sill model between 3.5-25.5 km. In addition, five soil nutrients exhibited different isotropic ranges. Available N and available P were isotropic through the whole research range (0-28 km). The isotropic range of available K was 0-8 km, and that of total N and organic matter was 0-10 km.

Estimation of the local and long-range contributions to particulate matter levels using continuous measurements in a single urban background site

NASA Astrophysics Data System (ADS)

Diamantopoulou, Marianna; Skyllakou, Ksakousti; Pandis, Spyros N.

2016-06-01

The Particulate Matter Source Apportionment Technology (PSAT) algorithm is used together with PMCAMx, a regional chemical transport model, to develop a simple observation-based method (OBM) for the estimation of local and regional contributions of sources of primary and secondary pollutants in urban areas. We test the hypothesis that the minimum of the diurnal average concentration profile of the pollutant is a good estimate of the average contribution of long range transport levels. We use PMCAMx to generate "pseudo-observations" for four different European cities (Paris, London, Milan, and Dusseldorf) and PSAT to estimate the corresponding "true" local and regional contributions. The predictions of the proposed OBM are compared to the "true" values for different definitions of the source area. During winter, the estimates by the OBM for the local contributions to the concentrations of total PM2.5, primary pollutants, and sulfate are within 25% of the "true" contributions of the urban area sources. For secondary organic aerosol the OBM overestimates the importance of the local sources and it actually estimates the contributions of sources within 200 km from the receptor. During summer for primary pollutants and cities with low nearby emissions (ratio of emissions in an area extending 100 km from the city over local emissions lower than 10) the OBM estimates correspond to the city emissions within 25% or so. For cities with relatively high nearby emissions the OBM estimates correspond to emissions within 100 km from the receptor. For secondary PM2.5 components like sulfate and secondary organic aerosol the OBM's estimates correspond to sources within 200 km from the receptor. Finally, for total PM2.5 the OBM provides approximately the contribution of city emissions during the winter and the contribution of sources within 100 km from the receptor during the summer.

Number concentration, size distribution and horizontal mass flux of Asian dust particles collected over free troposphere of Chinese desert region in calm weather condition using balloon borne measurements.

NASA Astrophysics Data System (ADS)

Habib, A.; Chen, B.

2017-12-01

Balloon borne measurements were carried out during calm weather conditions in Taklamakan Desert, which is considered as one of the major source areas of Asian dust (KOSA) particles. Vertical distribution of aerosols number concentration, size distribution, mass concentration and horizontal mass flux due to westerly wind was investigated .Vertical distribution of aerosol number concentration and size distribution at Dunhuang (40 °00'N, 94°30'E) China were observed by optical particle counter (OPC) on August 17, 2001, October 17, 2011, January 11, 2002, April 30, 2002. Five channels (0.3, 0.5, 0.8, 1.2 and 3.6 µm) were used in OPC for particle sizing measurements. Aerosol number concentration in winter season (January 11, 2002) at 3-5 km was very high. Variation of free tropospheric aerosols in April 30, 2002 was noticeable. Many inversions of temperature and aerosol concentration change are found at these inversion points. Super micron range was noticeable in size distribution of all balloon borne measurements. High values of estimated mass concentration of aerosols were observed at the ground atmosphere (1-2 km), and interestingly relatively high concentrations were frequently detected above about 2 km. Wind pattern observed by ERA-interim data sets at 500 and 850 hPa, shows that westerly winds were dominated in Taklamakan Desert during balloon borne observation period. Average horizontal mass flux of background Asian dust due to westerly wind was about in the range of 1219-58.5 μg/m³ tons/km2/day. Most of the profiles showed active transport of aerosols in the westerly dominated region, while, fluxes were found to be very low on January 11, 2002, compared with the other seasons. Vertical profiles of aerosols number concentration showed that significant transport of aerosols was dominated in westerly region (4-7 km). Low horizontal mass flux of aerosols was found in winter season

Lyα vs. fundamental properties of galaxies

NASA Astrophysics Data System (ADS)

Wofford, Aida; Leitherer, Claus; Salzer, John; COS Science Team

2013-03-01

We obtained HST COS Lyα spectroscopy for 20 galaxies that were Hα-selected from the Kitt Peak International Spectroscopic Survey data release. We cover redshifts of z=0.02-0.06 and a broad range in metallicity, reddening, and luminosity. We investigate correlations between the properties of the Lyα-lines and fundamental properties of the galaxies. Our seven emitters have: equivalent widths in the range EW(Lyα)=1-12 Å, i.e., below the completeness limits of higher redshift studies; extinction corrected Lyα/Hα ratios of at most 12-15% of the case B recombination theory value; and O I λ1302 ISM absorptions blueshifted to = - 117±40 km/s, which are consistent with H I gas outflows. Six emitters have P-Cygni-like Lyα profiles with peaks redshifted to =172±25 km/s, and one of our face-on spiral galaxies has two Lyα peaks separated by 370 km/s. The latter peaks are such that the blueshifted peak is twice as strong as the redshifted peak. The rest of the galaxies show Lyα absorption troughs centered at =19 km/s and O I λ1302 absorptions centered at = - 34±25 km/s, which is consistent with static or low velocity H I gas. Our two most metal poor and least reddened galaxies, which have large Hα equivalent widths are absorbers. The spiral galaxies in our sample have Lyα in single emission, double emission, or absorption. There appears to be a correlation between the Hα derived SFR and the strength of the Lyα emission but our sample is small. Our observations cover regions of at most 3 kpc in diameter and may miss a significant fraction of the resonantly scattered Lyα emission. This work is supported by NASA grant N1317.

S-wave velocities of the lithosphere-asthenosphere system in the Lesser Antilles from the joint inversion of surface wave dispersion and receiver function analysis

NASA Astrophysics Data System (ADS)

González, O'Leary; Clouard, Valerie; Tait, Stephen; Panza, Giuliano F.

2018-06-01

We present an overview of S-wave velocities (Vs) within the crust and upper mantle of the Lesser Antilles as determined with 19 seismic broadband stations. Receiver functions (RF) have been computed from teleseismic recordings of earthquakes, and Rayleigh wave group velocity dispersion relations have been taken from earlier surface wave tomographic studies in the Caribbean area. Local smoothness optimization (LSO) procedure has been applied, combined with an H-K stacking method, the spatial distribution of hypocenters of local earthquakes and of the energy they released, in order to identify an optimum 1D model of Vs below each station. Several features of the Caribbean plate and its interaction with the Atlantic subducting slab are visible in the resulting models: (a) relatively thick oceanic crust below these stations ranges from 21 km to 33 km, being slight thinner in the middle of the island arc; (b) crustal low velocity zones are present below stations SABA, SEUS, SKI, SMRT, CBE, DSD, GCMP and TDBA; (c) lithospheric thickness range from 40 km to 105 km but lithosphere-asthenosphere boundary was not straightforward to correlate between stations; (d) the aseismic mantle wedge between the Caribbean seismic lithosphere and the subducted slab varies in thickness as well as Vs values which are, in general, lower below the West of Martinique than below the West of Guadeloupe; (e) the depth of the subducted slab beneath the volcanic arc, appears to be greater to the North, and relatively shallower below some stations (e.g. DLPL, SAM, BIM and FDF) than was estimated in previous studies based on the depth-distribution of seismicity; f) the WBZ is >10-15 km deeper than the top of the slab below the Central Lesser Antilles (Martinique and Dominica) where the presence of partial melt in the mantle wedge seems also to be more evident.

Estimation of ground motion parameters

USGS Publications Warehouse

Boore, David M.; Joyner, W.B.; Oliver, A.A.; Page, R.A.

1978-01-01

Strong motion data from western North America for earthquakes of magnitude greater than 5 are examined to provide the basis for estimating peak acceleration, velocity, displacement, and duration as a function of distance for three magnitude classes. A subset of the data (from the San Fernando earthquake) is used to assess the effects of structural size and of geologic site conditions on peak motions recorded at the base of structures. Small but statistically significant differences are observed in peak values of horizontal acceleration, velocity and displacement recorded on soil at the base of small structures compared with values recorded at the base of large structures. The peak acceleration tends to b3e less and the peak velocity and displacement tend to be greater on the average at the base of large structures than at the base of small structures. In the distance range used in the regression analysis (15-100 km) the values of peak horizontal acceleration recorded at soil sites in the San Fernando earthquake are not significantly different from the values recorded at rock sites, but values of peak horizontal velocity and displacement are significantly greater at soil sites than at rock sites. Some consideration is given to the prediction of ground motions at close distances where there are insufficient recorded data points. As might be expected from the lack of data, published relations for predicting peak horizontal acceleration give widely divergent estimates at close distances (three well known relations predict accelerations between 0.33 g to slightly over 1 g at a distance of 5 km from a magnitude 6.5 earthquake). After considering the physics of the faulting process, the few available data close to faults, and the modifying effects of surface topography, at the present time it would be difficult to accept estimates less than about 0.8 g, 110 cm/s, and 40 cm, respectively, for the mean values of peak acceleration, velocity, and displacement at rock sites within 5 km of fault rupture in a magnitude 6.5 earthquake. These estimates can be expected to change as more data become available.

Occultation studies of planets and satellites: The occultation of epsilon Geminorum by Mars

NASA Technical Reports Server (NTRS)

Elliot, J. L.; Veverka, J.; Sagan, C.

1977-01-01

The occultation of epsilon Geminorum by Mars on 1976 April 8 was observed at three wavelengths and 4 ms time resolution with the 91 cm telescope. Temperature, pressure, and number density profiles of the Martian atmosphere were obtained for both the immersion and emersion events. Within the altitude range of 50 to 80 km above the mean surface, the mean temperature is 145 K, and the profiles exhibit wavelike structures with a peak to peak amplitude of 35 K and a vertical scale of about 20 km. The ratio of the refractivity of the atmosphere at 4500 A and 7500 A, determined from the time shift of the light curves for these wavelengths, is consistent with the atmospheric composition measured by Viking 1, 15 weeks later. From the central flash - a bright feature in the light curve midway between immersion and emersion - an optical depth is found at 4500 A of 3.3 plus or minus 1.7 per km atm (about 0.23 per equivalent Martian air mass) for the atmosphere about 25 km above the mean surface, near the south polar region. This large value and its weak wavelength dependence rule out Rayleigh scattering as the principal cause of the observed extinction.

Gravity field and nature of continent-continent collision along the Himalaya

NASA Astrophysics Data System (ADS)

Verma, R. K.

Gravity field (Bouguer) in the Himalaya is characterised by large negative-values ranging from nearly -180 mGal to over -450 mGal in Naga-Parbat/Haramosh massif which go up to -550 mGal in the Karakoram region. The observed Bouguer anomaly in NW Himalaya has been interpreted along a profile passing from Gujranwala (located at the edge of the Indian shield) to the Haramosh massif in terms of Moho depth and density contrast between the crust and the mantle. The Moho depth is interpreted to increase from nearly 35 km near the edge of Indian shield to 75 km (below sea level) underneath the Haramosh massif. A similar model is applicable to a profile passing to the west of Nanga Parbat massif, from Gujranwala to Ghizar, through the Kohistan region. However, along this profile high density lower crustal rocks appear to have been emplaced in the upper part along the Main Mantle thrust. The gravityanomalies in the Nepal-Tibet region hasbeen interpreted in terms of a northward sloping Moho which down faulted by about 15 km to attain a depth of 65 km around Tingri which corresponds to explosion seismology data. The nature of isostatic compensation prevailing underneath the Himalaya has been discussed.

Australian aerosol backscatter survey

NASA Technical Reports Server (NTRS)

Gras, John L.; Jones, William D.

1989-01-01

This paper describes measurements of the atmospheric backscatter coefficient in and around Australia during May and June 1986. One set of backscatter measurements was made with a CO2 lidar operating at 10.6 microns; the other set was obtained from calculations using measured aerosol parameters. Despite the two quite different data collection techniques, there is quite good agreement between the two methods. Backscatter values range from near 1 x 10 to the -8th/m per sr near the surface to 4 - 5 x 10 to the -11th/m per sr in the free troposphere at 5-7-km altitude. The values in the free troposphere are somewhat lower than those typically measured at the same height in the Northern Hemisphere.

Laser Doppler systems in atmospheric turbulence

NASA Technical Reports Server (NTRS)

Murty, S. S. R.

1976-01-01

The loss of heterodyne signal power for the Marshall Space Flight Center laser Doppler system due to the random changes in the atmospheric index of refraction is investigated. The current status in the physics of low energy laser propagation through turbulent atmosphere is presented. The analysis and approximate evaluation of the loss of the heterodyne signal power due to the atmospheric absorption, scattering, and turbulence are estimated for the conditions of the January 1973 flight tests. Theoretical and experimental signal to noise values are compared. Maximum and minimum values of the atmospheric attenuation over a two way path of 20 km range are calculated as a function of altitude using models of atmosphere, aerosol concentration, and turbulence.

Home range and habitat utilization of breeding male merlins, Falco columbarius, in southeastern Montana

Treesearch

Dale M. Becker; Carolyn Hull Sieg

1987-01-01

Home range size and habitat utilization of three breeding male Richardson’s Merlins (Falco columbarius richardsonii) in southeastern Montana were studied using radio telemetry. Home ranges of these birds encompassed 13,23, and 28 km2. Each bird traveled up to 9 km from its nest. Each home range encompassed five habitats;...

Reconnaissance exploration geochemistry in the central Brooks Range, northern Alaska: Implications for exploration of sediment-hosted zinc-lead-silver deposits

USGS Publications Warehouse

Kelley, K.D.; Kelley, D.L.

1992-01-01

A reconnaissance geochemical survey was conducted in the southern Killik River quadrangle, central Brooks Range, northern Alaska. The Brooks Range lies within the zone of continuous permafrost which may partially inhibit chemical weathering and oxidation. The minus 30-mesh and nonmagnetic heavy-mineral concentrate fractions of sediment samples were chosen as the sample media for the survey so that mechanical rather than chemical dispersion patterns would be enhanced. A total of 263 sites were sampled within the southern half of the Killik River quadrangle at an average sample density of approximately one sample per 12 km2. All samples were submitted for multi-element analyses. In the western and central Brooks Range, several known sediment-hosted Zn-Pb-Ag(-Ba) deposits occur within a belt of Paleozoic rocks of the Endicott Mountains allochthon. Exploration for this type of deposit in the Brook Range is difficult, due to the inherently high background values for Ba, Zn and Pb in shale and the common occurrence of metamorphic quartz-calcite veins, many of which contain traces of sulfide minerals. Stream sediments derived from these sources produce numerous geochemical anomalies which are not necessarily associated with significant mineralization. R-mode factor analysis provides a means of distinguishing between element associations related to lithology and those related to possible mineralization. Factor analysis applied to the multi-element data from the southern Killik River quadrangle resulted in the discovery of two additional Zn-Pb-Ag mineral occurrences of considerable areal extent which are 80-100 km east of any previously known deposit. These have been informally named the Kady and Vidlee. Several lithogeochemical element associations, or factors, and three factors which represent sulfide mineralization were identified: Ag-Pb-Zn (galena and sphalerite) and Fe-Ni-Co-Cu (pyrite ?? chalcopyrite) in the concentrate samples and Cd-Zn-Pb-As-Mn in the sediment samples. The distribution of high scores for each individual mineralization factor outlined several relatively large (200-250 km2) geochemically favorable areas. When the distribution of high scores for all three factors were superimposed, samples characterized by high scores for one or both of the concentrate mineralization factors and the mineralization factor in sediments define basin areas of approximately 48 and 64 km2 surrounding Kady and Vidlee, respectively. ?? 1992.

Low shear velocity in a normal fault system imaged by ambient noise cross correlation: The case of the Irpinia fault zone, Southern Italy

NASA Astrophysics Data System (ADS)

Vassallo, Maurizio; Festa, Gaetano; Bobbio, Antonella; Serra, Marcello

2016-06-01

We extracted the Green's functions from cross correlation of ambient noise recorded at broadband stations located across the Apennine belt, Southern Italy. Continuous records at 26 seismic stations acquired for 3 years were analyzed. We found the emergence of surface waves in the whole range of the investigated distances (10-140 km) with energy confined in the frequency band 0.04-0.09 Hz. This phase reproduces Rayleigh waves generated by earthquakes in the same frequency range. Arrival time of Rayleigh waves was picked at all the couples of stations to obtain the average group velocity along the path connecting the two stations. The picks were inverted in separated frequency bands to get group velocity maps then used to obtain an S wave velocity model. Penetration depth of the model ranges between 12 and 25 km, depending on the velocity values and on the depth of the interfaces, here associated to strong velocity gradients. We found a low-velocity anomaly in the region bounded by the two main faults that generated the 1980, M 6.9 Irpinia earthquake. A second anomaly was retrieved in the southeast part of the region and can be ascribed to a reminiscence of the Adria slab under the Apennine Chain.

Six years of mesospheric CO estimated from ground-based frequency-switched microwave radiometry at 57° N compared with satellite instruments

NASA Astrophysics Data System (ADS)

Forkman, P.; Christensen, O. M.; Eriksson, P.; Urban, J.; Funke, B.

2012-06-01

Measurements of mesospheric carbon monoxide, CO, provide important information about the dynamics in the mesosphere region since CO has a long lifetime at these altitudes. Ground-based measurements of mesospheric CO made at the Onsala Space Observatory, OSO, (57° N, 12° E) are presented. The dataset covers the period 2002-2008 and is hence uniquely long. The simple and stable 115 GHz frequency-switched radiometer, calibration method, retrieval procedure and error characterization are described. A comparison between our measurements and co-located CO measurements from the satellite sensors ACE-FTS on Scisat (v2.2), MLS on Aura (v3-3), MIPAS on Envisat (V3O_CO_12 + 13 and V4O_CO_200) and SMR on Odin (v225 and v021) is done. Our instrument, OSO, and the four satellite instruments show the same general variation of the vertical distribution of mesospheric CO in both the annual cycle and in shorter time period events with high CO mixing ratios during winter and very low amounts during summer in the observed 55-85 km altitude range. During 2004-2008 the agreement of the OSO instrument and the satellite sensors ACE-FTS, MLS and MIPAS(200) is good in the altitude range 55-70 km. Above 70 km OSO show up to 25% higher CO column values compared to both ACE and MLS. For the time period 2002-2003 CO from MIPAS(12 + 13) is up to 60% lower than OSO between 55 and 70 km. Mesospheric CO from the two versions of SMR deviates up to ±65% when compared to OSO, but the analysis is based on only a few co-locations.

Six years of mesospheric CO estimated from ground-based frequency-switched microwave radiometry at 57° N compared with satellite instruments

NASA Astrophysics Data System (ADS)

Forkman, P.; Christensen, O. M.; Eriksson, P.; Urban, J.; Funke, B.

2012-11-01

Measurements of mesospheric carbon monoxide, CO, provide important information about the dynamics in the mesosphere region since CO has a long lifetime at these altitudes. Ground-based measurements of mesospheric CO made at the Onsala Space Observatory, OSO, (57° N, 12° E) are presented. The dataset covers the period 2002-2008 and is hence uniquely long for ground-based observations. The simple and stable 115 GHz frequency-switched radiometer, calibration method, retrieval procedure and error characterization are described. A comparison between our measurements and co-located CO measurements from the satellite sensors ACE-FTS on Scisat (v2.2), MLS on Aura (v3-3), MIPAS on Envisat (V3O_CO_12 + 13 and V4O_CO_200) and SMR on Odin (v225 and v021) is carried out. Our instrument, OSO, and the four satellite instruments show the same general variation of the vertical distribution of mesospheric CO in both the annual cycle and in shorter time period events, with high CO mixing ratios during winter and very low amounts during summer in the observed 55-100 km altitude range. During 2004-2008 the agreement of the OSO instrument and the satellite sensors ACE-FTS, MLS and MIPAS (200) is good in the altitude range 55-70 km. Above 70 km, OSO shows up to 25% higher CO column values compared to both ACE and MLS. For the time period 2002-2004, CO from MIPAS (12 + 13) is up to 50% lower than OSO between 55 and 70 km. Mesospheric CO from the two versions of SMR deviates up to ±65% when compared to OSO, but the analysis is based on only a few co-locations.

Attenuating reaches and the regional flood response of an urbanizing drainage basin

NASA Astrophysics Data System (ADS)

Turner-Gillespie, Daniel F.; Smith, James A.; Bates, Paul D.

The Charlotte, North Carolina metropolitan area has experienced extensive urban and suburban growth and sharply increasing trends in the magnitude and frequency of flooding. The hydraulics and hydrology of flood response in the region are examined through a combination of numerical modeling studies and diagnostic analyses of paired discharge observations from upstream-downstream gaging stations. The regional flood response is shown to strongly reflect urbanization effects, which increase flood peaks and decrease response times, and geologically controlled attenuating reaches, which decrease flood peaks and increase lag times. Attenuating reaches are characterized by systematic changes in valley bottom geometry and longitudinal profile. The morphology of the fluvial system is controlled by the bedrock geology, with pronounced changes occurring at or near contacts between intrusive igneous and metamorphic rocks. Analyses of wave celerity and flood peak attenuation over a range of discharge values for an 8.3 km valley bottom section of Little Sugar Creek are consistent with Knight and Shiono's characterization of the variation of flood wave velocity from in-channel conditions to valley bottom full conditions. The cumulative effect of variation in longitudinal profile, expansions and contractions of the valley bottom, floodplain roughness and sub-basin flood response is investigated using a two-dimensional, depth-averaged, finite element hydrodynamic model coupled with a distributed hydrologic model. For a 10.1 km stream reach of Briar Creek, with drainage area ranging from 13 km 2 at the upstream end of the reach to 49 km 2 at the downstream end, it is shown that flood response reflects a complex interplay of hydrologic and hydraulic processes on hillslopes and valley bottoms.

Estimating CO2 Fluxes Pre and Post Drought Using Remote Sensing Data in the Sierra Nevada Range

NASA Astrophysics Data System (ADS)

Mazzi, J. R.; Grigsby, S.; Goulden, M.; Ustin, S.

2015-12-01

The recent California drought presents an opportunity to study CO2 flux changes over time due to insufficient water uptake by plant life using remote sensing data. Three flux towers were used to create linear regressions between AVIRIS derived Net Ecosystem Exchange (NEE = PRI * NDVI * PAR) and tower measured CO2 flux in the San Joaquin Experimental Range. To estimate CO2 from NEE, two linear regressions were used based on time of day and season, with R2 values of 0.85 and 0.87 respectively. Per-pixel CO2 flux was estimated for AVIRIS flights flown in June 2013, 2014, and 2015, as well as September 2011 and October 2014. There was a significant decrease in post drought photosynthetic CO2 uptake over the 6,700 km2 studied, totaling 2,977 grams per minute less (15.9% decrease) from June 2013 to June 2014. Data from the 2015 HyspIRI flights suggest a continuation of this trend for June 2015. Pre-drought conditions over a 33 km2 area show that the photosynthetic CO2 uptake dropped from 74 mg per minute on September 24, 2011, to 35 mg per minute on October 6, 2014 (a 53% decrease). HyspIRI flight lines also include 434 km2 of the Rim Fire, an area that saw a decrease in CO2 uptake of 413 grams per minute (71.7% decrease from June 2013 to June 2014) from the burn alone. It is estimated that the entire Rim Fire (1,041 km2) has caused a total decrease in photosynthetic CO2 uptake totaling 988 grams less per minute from 2013 to 2014, with some recovery evident in 2015.

Distribution and Kinematics of O VI in the Galactic Halo

NASA Astrophysics Data System (ADS)

Savage, B. D.; Sembach, K. R.; Wakker, B. P.; Richter, P.; Meade, M.; Jenkins, E. B.; Shull, J. M.; Moos, H. W.; Sonneborn, G.

2003-05-01

Far-Ultraviolet Spectroscopic Explorer (FUSE) spectra of 100 extragalactic objects and two distant halo stars are analyzed to obtain measures of O VI λλ1031.93, 1037.62 absorption along paths through the Milky Way thick disk/halo. Strong O VI absorption over the velocity range from -100 to 100 km s-1 reveals a widespread but highly irregular distribution of O VI, implying the existence of substantial amounts of hot gas with T~3×105 K in the Milky Way thick disk/halo. The integrated column density, log[N(O VI) cm-2], ranges from 13.85 to 14.78 with an average value of 14.38 and a standard deviation of 0.18. Large irregularities in the gas distribution are found to be similar over angular scales extending from <1° to 180°, implying a considerable amount of small- and large-scale structure in the absorbing gas. The overall distribution of O VI is not well described by a symmetrical plane-parallel layer of patchy O VI absorption. The simplest departure from such a model that provides a reasonable fit to the observations is a plane-parallel patchy absorbing layer with an average O VI midplane density of n0(O VI)=1.7×10-8 cm-3, a scale height of ~2.3 kpc, and a ~0.25 dex excess of O VI in the northern Galactic polar region. The distribution of O VI over the sky is poorly correlated with other tracers of gas in the halo, including low- and intermediate-velocity H I, Hα emission from the warm ionized gas at ~104 K, and hot X-ray-emitting gas at ~106 K. The O VI has an average velocity dispersion, b~60 km s-1, and standard deviation of 15 km s-1. Thermal broadening alone cannot explain the large observed profile widths. The average O VI absorption velocities toward high-latitude objects (|b|>45deg) range from -46 to 82 km s-1, with a high-latitude sample average of 0 km s-1 and a standard deviation of 21 km s-1. High positive velocity O VI absorbing wings extending from ~100 to ~250 km s-1 observed along 21 lines of sight may be tracing the flow of O VI into the halo. A combination of models involving the radiative cooling of hot fountain gas, the cooling of supernova bubbles in the halo, and the turbulent mixing of warm and hot halo gases is required to explain the presence of O VI and other highly ionized atoms found in the halo. The preferential venting of hot gas from local bubbles and superbubbles into the northern Galactic polar region may explain the enhancement of O VI in the north. If a fountain flow dominates, a mass flow rate of approximately 1.4 Msolar yr-1 of cooling hot gas to each side of the Galactic plane with an average density of 10-3 cm-3 is required to explain the average value of log[N(O VI)sin|b|] observed in the southern Galactic hemisphere. Such a flow rate is comparable to that estimated for the Galactic intermediate-velocity clouds.

Tropospheric ozone profiles by DIAL at Maïdo Observatory (Reunion Island): system description, instrumental performance and result comparison with ozone external data set

NASA Astrophysics Data System (ADS)

Duflot, Valentin; Baray, Jean-Luc; Payen, Guillaume; Marquestaut, Nicolas; Posny, Francoise; Metzger, Jean-Marc; Langerock, Bavo; Vigouroux, Corinne; Hadji-Lazaro, Juliette; Portafaix, Thierry; De Mazière, Martine; Coheur, Pierre-Francois; Clerbaux, Cathy; Cammas, Jean-Pierre

2017-09-01

In order to recognize the importance of ozone (O3) in the troposphere and lower stratosphere in the tropics, a DIAL (differential absorption lidar) tropospheric O3 lidar system (LIO3TUR) was developed and installed at the Université de la Réunion campus site (close to the sea) on Reunion Island (southern tropics) in 1998. From 1998 to 2010, it acquired 427 O3 profiles from the low to the upper troposphere and has been central to several studies. In 2012, the system was moved up to the new Maïdo Observatory facility (2160 m a.m.s.l. - metres above mean sea level) where it started operation in February 2013. The current system (LIO3T) configuration generates a 266 nm beam obtained with the fourth harmonic of a Nd:YAG laser sent into a Raman cell filled up with deuterium (using helium as buffer gas), generating the 289 and 316 nm beams to enable the use of the DIAL method for O3 profile measurements. The optimal range for the actual system is 6-19 km a.m.s.l., depending on the instrumental and atmospheric conditions. For a 1 h integration time, vertical resolution varies from 0.7 km at 6 km a.m.s.l. to 1.3 km at 19 km a.m.s.l., and mean uncertainty within the 6-19 km range is between 6 and 13 %. Comparisons with eight electrochemical concentration cell (ECC) sondes simultaneously launched from the Maïdo Observatory show good agreement between data sets with a 6.8 % mean absolute relative difference (D) between 6 and 17 km a.m.s.l. (LIO3T lower than ECC). Comparisons with 37 ECC sondes launched from the nearby Gillot site during the daytime in a ±24 h window around lidar shooting result in a 9.4 % D between 6 and 19 km a.m.s.l. (LIO3T lower than ECC). Comparisons with 11 ground-based Network for Detection of Atmospheric Composition Change (NDACC) Fourier transform infrared (FTIR) spectrometer measurements acquired during the daytime in a ±24 h window around lidar shooting show good agreement between data sets with a D of 11.8 % for the 8.5-16 km partial column (LIO3T higher than FTIR), and comparisons with 39 simultaneous Infrared Atmospheric Sounding Interferometer (IASI) observations over Reunion Island show good agreement between data sets with a D of 11.3 % for the 6-16 km partial column (LIO3T higher than IASI). ECC, LIO3TUR and LIO3T O3 monthly climatologies all exhibit the same range of values and patterns. In particular, the Southern Hemisphere biomass burning seasonal enhancement and the ozonopause altitude decrease in late austral winter-spring, as well as the sign of deep convection bringing boundary layer O3-poor air masses up to the middle-upper troposphere in late austral summer, are clearly visible in all data sets.

A gradient of radioactive contamination in Dolon village near the SNTS and comparison of computed dose values with instrumental estimates for the 29 August, 1949 nuclear test.

PubMed

Stepanenko, Valeriy F; Hoshi, Masaharu; Dubasov, Yuriy V; Sakaguchi, Aya; Yamamoto, Masayoshi; Orlov, Mark Y; Bailiff, Ian K; Ivannikov, Alexander I; Skvortsov, Valeriy G; Iaskova, Elena K; Kryukova, Irina G; Zhumadilov, Kassym S; Endo, Satoru; Tanaka, Kenichi; Apsalikov, Kazbek N; Gusev, Boris I

2006-02-01

Spatial distributions of soil contamination by 137Cs (89 sampling points) and 239+240Pu (76 points) near and within Dolon village were analyzed. An essential exponential decrease of contamination was found in Dolon village: the distance of a half reduction in contamination is about 0.87-1.25 km (in a northwest-southeast direction from the supposed centerline of the radioactive trace). This fact is in agreement with the available exposure rate measurements near Dolon (September 1949 archive data): on the basis of a few measurements the pattern of the trace was estimated to comprise a narrow 2 km corridor of maximum exposure rate. To compare computed external doses in air with local dose estimates by retrospective luminescence dosimetry (RLD) the gradient of radioactive soil contamination within the village was accounted for. The computed dose associated with the central axis of the trace was found to be equal to 2260 mGy (calculations based on archive exposure rate data). Local doses near the RLD sampling points (southeast of the village) were calculated to be in the range 466-780 mGy (averaged value: 645+/-70 mGy), which is comparable with RLD data (averaged value 460+/-92 mGy with range 380-618 mGy). A comparison of the computed mean dose in the settlement with dose estimates by ESR tooth enamel dosimetry makes it possible to estimate the "upper level" of the "shielding and behavior" factor in dose reduction for inhabitants of Dolon village which was found to be 0.28+/-0.068.

Tectonothermal evolution of the Triassic flysch in the Bayan Har Orogen, Tibetan plateau

NASA Astrophysics Data System (ADS)

Wang, Hejing; Rahn, Meinert; Zhou, Jian

2018-01-01

The Bayan Har Orogen comprises a major part of the "Qingzang-Dianxi fold region" in western China. It preserves important information of the tectono-thermal evolution covering the time span from the closure of the Paleo-Tethys Ocean up to the formation of the Himalayas. Low temperature metamorphic indicators, such as mineral assemblages, illite "crystallinity" (IC), chlorite "crystallinity" (CC), illite polytype, b-cell dimension of K-white micas, geothermometry of selected minerals were analyzed. The values of Kübler index (KI) of the Triassic flysch in the Bayan Har Orogen range from 0.23-1.63°Δ2θ while Árkai index (ÁI) in a range of 0.21-0.60°Δ2θ. Iso-thermal zones mapped with KI describe a pair of anchizones and an anchiregion within the Bayan Har Orogen: the "Giant Yushu Anchizone" in the southwest (extending > 750 km long and 100 km wide), the "Zaling-Eling-Lakes Anchizone" in the center (about 150 km long and 40 km wide) and the "Xing-Tong-Zhe Anchiregion" in the northeast (covering an area of roughly 60,000 km2). They are separated by diagenetic zones. Peak metamorphic conditions are estimated around 280-330 °C and a low to intermediate (N. New Hampshire) pressure type. A slight change with increasing then decreasing pressure was observed from SW to NE. The relationship between anchimetamorphic pattern of Triassic flysch and large-scale folds and faults indicates syn- to post structural metamorphism. Compression at the end of the Triassic, induced by the interaction of the Tarim, North China and Indian blocks caused the closure of the Paleo-Tethys Ocean and led to the folding of the Triassic flysch within the Paleo-Tethys Ocean basin. Anchimetamorphism may have been caused by crustal thickening of > 10 km due to an accretionary wedge setting and a temperature increase in those rocks due to burial. Such a regional metamorphic pattern would provide important information for reconstruction of palaeotectonic-palaeogeograph and the evolutionary history of Tibetan plateau.

Complex N-S variations in Moho depth and Vp/Vs ratio beneath the western Tibetan Plateau as revealed by receiver function analysis

NASA Astrophysics Data System (ADS)

Murodov, Davlatkhudzha; Zhao, Junmeng; Xu, Qiang; Liu, Hongbing; Pei, Shunping

2018-04-01

We present herein detailed images of the Moho depth and Vp/Vs ratio along ANTILOPE-1 profile beneath the western Tibetan Plateau derived from receiver function analysis. Along the ANTILOPE -1 profile, a rapidly northward dipping Moho extends from ˜50 km below the Himalaya to ˜80 km across the Indus-Yarlung suture (IYS), shallowing to ˜66 km under the central Lhasa terrane. The Moho depth shows a dramatic increase from ˜66 km north of the Bangong-Nujiang suture (BNS) to ˜93 km beneath central Qiangtang terrane where it reaches the maximum depth observed along this profile before steeply rising to ˜73 km. We interpret both the 15 km and 20 km offsets of Moho depth occurring beneath the central Lhasa and central Qiangtang terranes as being related to the northern frontiers of the decoupled underthrusting Indian lower crust and lithospheric mantle, respectively. The Moho remains at a depth of ˜70 km with a slight undulation beneath the northern Qiangtang and Songpan-Ganzi terranes, and then abruptly shallows to ˜45 km near the Altyn Tagh Fault. The ˜25 km Moho offset observed at the conjunction of the Tarim Basin and the Altyn Tagh mountain range suggests that the crustal shortening is achieved by pure shear thickening without much underthrusting. The average crustal Vp/Vs ratio changes from 1.66 to 1.80 beneath the Himalaya, the Lhasa terrane and the Tarim Basin indicating a felsic-to-intermediate composition. However, higher Vp/Vs ratios between 1.76 and 1.83 (except for a few outlying low values) are found beneath the Qiangtang and Songpan-Ganzi terranes, which could be attributed to the joint effects of the more mafic composition and partial melt within the crust. The Moho depth and Vp/Vs ratio exhibit complex N-S variations along this profile, which can be attributed to the joint effects of Indian lower crust underthrusting, the low velocity zone of the mid-upper crust, crustal shortening and thickening and other involved dynamic mechanisms.

Local time variations of the middle atmosphere of Venus: Solar-related structures

NASA Astrophysics Data System (ADS)

Zasova, L.; Khatountsev, I. V.; Ignatiev, N. I.; Moroz, V. I.

Three-dimensional fields (latitude — altitude — local time) of temperature and aerosol in the upper clouds, obtained from the Venera-15 IR spectrometry data, were studied to search for the solar-related structures. The temperature variation at the isobaric levels vs. solar longitude was presented as a superposition of the cosines with periods of 1, 1/2, 1/3 and 1/4 Venusian days. At low latitudes the diurnal tidal component reaches a maximum above 0.2 mb (92km) level. At high latitudes it dominates at P> 50 mb (68 km) in the cold collar, being roughly twice as much as the semidiurnal one and passing through the maximum of 13 K at 400 mb (57 km). The semidiurnal tidal amplitude exceeds the diurnal one below 90 km (where its maximum locates near 83 km), and also in the upper clouds, above 58 km. At low latitudes the 1/3 days component predominates at 10 - 50 mb (68-76 km). In the upper clouds, where most of the solar energy, absorbed in the middle atmosphere, deposits, all four tidal components, including wavenumbers 3 and 4, have significant amplitudes. A position of the upper boundary of the clouds depends on local time in such a way that the lowest height of the clouds is observed in the morning at all selected latitude ranges. At low latitudes the highest position of the upper boundary of the clouds (at 1218 cm -1) is found at 8 - 9 PM, whereas the lowest one is near the morning terminator. At high latitudes the lowest position of the upper boundary of the clouds shifts towards the dayside being at 10:30 AM at 75° in the cold collar and the highest one shifts to 4 PM. The zonal mean altitude of the upper boundary of the clouds decreases from 69 km at 15° to 59 km at 75°. The diurnal tidal component has the highest amplitude in the cold collar (1.5 km). At low latitudes both amplitudes, diurnal and semidiurnal, reach the values 0.8 - 1 km.

Experimental demonstration of multiuser communication in deep water using time reversal.

PubMed

Shimura, T; Ochi, H; Song, H C

2013-10-01

Multiuser communication is demonstrated using experimental data (450-550 Hz) collected in deep water, south of Japan. The multiple users are spatially distributed either in depth or range while a 114-m long, 20-element vertical array (i.e., base station) is deployed to around the sound channel axis (~1000 m). First, signals received separately from ranges of 150 km and 180 km at various depths are combined asynchronously to generate multiuser communication sequences for subsequent processing, achieving an aggregate data rate of 300 bits/s for up to three users. Adaptive time reversal is employed to separate collided packets at the base station, followed by a single channel decision feedback equalizer. Then it is demonstrated that two users separated by 3 km in range at ~1000 m depth can transmit information simultaneously to the base station at ~500 km range with an aggregate data rate of 200 bits/s.

Questa baseline and pre-mining ground-water quality investigation. 12. Geochemical and reactive-transport modeling based on tracer injection-synoptic sampling studies for the Red River, New Mexico, 2001-2002

USGS Publications Warehouse

Ball, James W.; Runkel, Robert L.; Nordstrom, D. Kirk

2005-01-01

Reactive-transport processes in the Red River, downstream from the town of Red River in north-central New Mexico, were simulated using the OTEQ reactive-transport model. The simulations were calibrated using physical and chemical data from synoptic studies conducted during low-flow conditions in August 2001 and during March/April 2002. Discharge over the 20-km reach from the town of Red River to the USGS streamflow-gaging station near the town of Questa ranged from 395 to 1,180 L/s during the 2001 tracer and from 234 to 421 L/s during the 2002 tracer. The pH of the Red River ranged from 7.4 to 8.5 during the 2001 tracer and from 7.1 to 8.7 during the 2002 tracer, and seep and tributary samples had pH values of 2.8 to 9.0 during the 2001 tracer and 3.8 to 7.2 during the 2002 tracer. Mass-loading calculations allowed identification of several specific locations where elevated concentrations of potential contaminants entered the Red River . These locations, characterized by features on the north side of the Red River that are known to be sources of low-pH water containing elevated metal and sulfate concentrations, are: the initial 2.4 km of the study reach, including Bitter Creek, the stream section from 6.2 to 7.8 km, encompassing La Bobita well and the Hansen debris fan, Sulphur Gulch, at about 10.5 km, the area near Portal Springs, from 12.2 to 12.6 km, and the largest contributors of mass loading, the 13.7 to 13.9 km stream section near Cabin Springs and the 14.7 to 17.5 km stream section from Shaft Spring to Thunder Bridge, Goathill Gulch, and Capulin Canyon. Speciation and saturation index calculations indicated that although solubility limits the concentration of aluminum above pH 5.0, at pH values above 7 and aluminum concentrations below 0.3 mg/L inorganic speciation and mineral solubility controls no longer dominate and aluminum-organic complexing may occur. The August 2001 reactive-transport simulations included dissolved iron(II) oxidation, constrained using measured concentrations of dissolved iron(II) and dissolved iron(total). Both simulations included precipitation of amorphous Al(OH)3 and hydrous ferric oxide as Fe(OH)3, and sorption of copper and zinc to the precipitated hydrous ferric oxide. Simulations revealed that hydrogen, iron, aluminum, copper, and zinc were non-conservative and that mineral precipitation can account for iron and aluminum concentrations. Copper and zinc concentrations can be accounted for by simulating their sorption to hydrous ferric oxide forming in the water column of the Red River , although hydrous manganese oxides also may be important sorption substrates.

Assessing Conservation Values: Biodiversity and Endemicity in Tropical Land Use Systems

PubMed Central

Waltert, Matthias; Bobo, Kadiri Serge; Kaupa, Stefanie; Montoya, Marcela Leija; Nsanyi, Moses Sainge; Fermon, Heleen

2011-01-01

Despite an increasing amount of data on the effects of tropical land use on continental forest fauna and flora, it is debatable whether the choice of the indicator variables allows for a proper evaluation of the role of modified habitats in mitigating the global biodiversity crisis. While many single-taxon studies have highlighted that species with narrow geographic ranges especially suffer from habitat modification, there is no multi-taxa study available which consistently focuses on geographic range composition of the studied indicator groups. We compiled geographic range data for 180 bird, 119 butterfly, 204 tree and 219 understorey plant species sampled along a gradient of habitat modification ranging from near-primary forest through young secondary forest and agroforestry systems to annual crops in the southwestern lowlands of Cameroon. We found very similar patterns of declining species richness with increasing habitat modification between taxon-specific groups of similar geographic range categories. At the 8 km2 spatial level, estimated richness of endemic species declined in all groups by 21% (birds) to 91% (trees) from forests to annual crops, while estimated richness of widespread species increased by +101% (trees) to +275% (understorey plants), or remained stable (- 2%, butterflies). Even traditional agroforestry systems lost estimated endemic species richness by - 18% (birds) to - 90% (understorey plants). Endemic species richness of one taxon explained between 37% and 57% of others (positive correlations) and taxon-specific richness in widespread species explained up to 76% of variation in richness of endemic species (negative correlations). The key implication of this study is that the range size aspect is fundamental in assessments of conservation value via species inventory data from modified habitats. The study also suggests that even ecologically friendly agricultural matrices may be of much lower value for tropical conservation than indicated by mere biodiversity value. PMID:21298054

Comparative Analysis of Peak Ground Acceleration Before and After Padang Earthquake 2009 Using Mc. Guirre Method

NASA Astrophysics Data System (ADS)

Ayu Rahmalia, Diah; Nilamprasasti, Hesti

2017-04-01

We have analyzed the earthquakes data in West Sumatra province to determine peak ground acceleration value. The peak ground acceleration is a parameter that describes the strength of the tremor that ever happened. This paper aims to compare the value of the peak ground acceleration by considering the b-value before and after the Padang earthquake 2009. This research was carried out in stages, starting by taking the earthquake data in West Sumatra province with boundary coordinates 0.923° LU - 2.811° LS and 97.075° - 102.261° BT, before and after the 2009 Padang earthquake with a magnitude ≥ 3 and depth of ≤ 300 km, calculation of the b-value, and ended by creating peak ground acceleration map based on Mc. Guirre empirical formula with Excel and Surfer software. Based on earthquake data from 2002 until before Padang earthquake 2009, the b-value is 0.874 while the b-value after the Padang earthquake in 2009 to 2016 is 0.891. Considering b value, it can be known that peak ground acceleration before and after the 2009 Padang earthquake might be different. Based on the seismic data before 2009, the peak ground acceleration value of West Sumatra province is ranged from 7,002 to 308.875 gal. This value will be compared by the value of the peak ground acceleration after the Padang earthquake in 2009 which ranged from 7,946 to 372,736 gal.

Prediction of Tibial Rotation Pathologies Using Particle Swarm Optimization and K-Means Algorithms.

PubMed

Sari, Murat; Tuna, Can; Akogul, Serkan

2018-03-28

The aim of this article is to investigate pathological subjects from a population through different physical factors. To achieve this, particle swarm optimization (PSO) and K-means (KM) clustering algorithms have been combined (PSO-KM). Datasets provided by the literature were divided into three clusters based on age and weight parameters and each one of right tibial external rotation (RTER), right tibial internal rotation (RTIR), left tibial external rotation (LTER), and left tibial internal rotation (LTIR) values were divided into three types as Type 1, Type 2 and Type 3 (Type 2 is non-pathological (normal) and the other two types are pathological (abnormal)), respectively. The rotation values of every subject in any cluster were noted. Then the algorithm was run and the produced values were also considered. The values of the produced algorithm, the PSO-KM, have been compared with the real values. The hybrid PSO-KM algorithm has been very successful on the optimal clustering of the tibial rotation types through the physical criteria. In this investigation, Type 2 (pathological subjects) is of especially high predictability and the PSO-KM algorithm has been very successful as an operation system for clustering and optimizing the tibial motion data assessments. These research findings are expected to be very useful for health providers, such as physiotherapists, orthopedists, and so on, in which this consequence may help clinicians to appropriately designing proper treatment schedules for patients.

Photochemistry of Triton's atmosphere and ionosphere.

PubMed

Krasnopolsky, V A; Cruikshank, D P

1995-10-25

The photochemistry of 32 neutral and 21 ion species in Triton's atmosphere is considered. Parent species N2, CH4, and CO (with a mixing ratio of 3 x 10(-4) in our basic model) sublime from the ice with rates of 40, 208, and 0.3 g/cm2/b.y., respectively. Chemistry below 50 km is driven mostly by photolysis of methane by the solar and interstellar medium Lyman-alpha photons, producing hydrocarbons C2H4, C2H6, and C2H2 which form haze particles with precipitation rates of 135, 28, and 1.3 g/cm2/b.y., respectively. Some processes are discussed which increase the production of HCN (by an order of magnitude to a value of 29 g/cm2/b.y.) and involve indirect photolysis of N2 by neutrals. Reanalysis of the measured methane profiles gives an eddy diffusion coefficient K = 4 x 10(3) cm2/s above the tropopause and a more accurate methane number density near the surface, (3.1 +/- 0.8) x 10(11) cm-3. Chemistry above 200 km is driven by the solar EUV radiation (lambda < 1000 angstroms) and by precipitation of magnetospheric electrons with a total energy input of 10(8) W (based on thermal balance calculations). The most abundant photochemical species are N, H2, H, O, and C. They escape with the total rates of 7.7 x 10(24) s-1, 4.5 x 10(25) s-1, 2.4 x 10(25) s-1, 4.4 x 10(22) s-1, and 1.1 x 10(24) s-1, respectively. Atomic species are transported to a region of 50-200 km and drive the chemistry there. Ionospheric chemistry explains the formation of an E region at 150-240 km with HCO+ as a major ion, and of an F region above 240 km with a peak at 320 km and C+ as a major ion. The ionosphere above 500 km consists of almost equal densities of C+ and N+ ions. The model profiles agree with the measured atomic nitrogen and electron density profiles. A number of other models with varying rate coefficients of some reactions, differing properties of the haze particles (chemically passive or active), etc., were developed. These models show that there are four basic unknown values which have strong impacts on the composition and structure of the atmosphere and ionosphere. These values and their plausible ranges are the CO mixing ratio fco = 10(-4)-10(-3), the magnetospheric electron energy input (1 +/- 0.5) x 10(8) W, the rate coefficient of charge-exchange reaction N2(+) + C k = 10(-11)-10(-10) cm3/s, and the ion escape velocity Vi approximately equal to 150 cm/s.

Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Ill.

NASA Technical Reports Server (NTRS)

Gardner, C. S.; Miller, M. S.; Liu, C. H.

1988-01-01

During 13 nights of Rayleigh lidar measurements at Urbana, Ill. in 1984 to 1986, thirty-six quasi-monochromatic gravity waves were observed in the 35 to 50 km altitude region of the stratosphere. The characteristics of the waves are compared with other lidar and radar measurements of gravity waves and the theoretical models of wave saturation and dissipation phenomena. The measured vertical wavelengths ranged from 2 to 11.5 km and the measured vertical phase velocities ranged from 10 to 85 cm/s. The vertical wavelengths and vertical phase velocities were used to infer observed wave periods which ranged from 100 to 1000 min and horizontal wavelengths which ranged from 70 to 2000 km. Dominant wave activity was found at vertical wavelengths between 2 to 4 km and 7 to 10 km. No significant seasonal variations were evident in the observed parameters. Vertical and horizontal wavelengths showed a clear tendency to increase with wave periods, which is consistent with recent sodium lidar studies of quasi-monochromatic waves near the mesopause. An average amplitude growth length of 20.9 km for the rms wind perturbations was estimated from the data. Kinetic energy density associated with the waves decreased with height, suggesting that waves in this altitude region were subject to dissipation or saturation effects.

Analysis and validation of severe storm parameters derived from TITAN in Southeast Brazil

NASA Astrophysics Data System (ADS)

Gomes, Ana Maria; Held, Gerhard; Vernini, Rafael; Demetrio Souza, Caio

2014-05-01

The implementation of TITAN (Thundestorm Identification, Tracking and Nowcasting) System at IPMet in December 2005 has provided real-time access to the storm severity parameters derived from radar reflectivity, which are being used to identify and alert of potentially severe storms within the 240 km quantitative ranges of the Bauru and Presidente Prudente S-band radars. The potential of these tools available with the TITAN system is being evaluated by using the hail reports received from voluntary hail observers to cross-check the occurrence of hail within the radar range against the TITAN predictions. Part of the ongoing research at IPMet aims to determine "signatures" in severe events and therefore, as from 2008, an online standard form was introduced, allowing for greater detail on the occurrence of a severe event within the 240 km ranges of both radars. The model for the hail report was based on the one initially deployed by the Alberta Hail Program, in Canada, and also by the Hail Observer Network established by the CSIR (Council for Scientific and Industrial Research), in Pretoria, South Africa, where it was used for more than 25 years. The TITAN system was deployed to obtain the tracking properties of storms for this analysis. A cell was defined by the thresholds of 40 dBZ for the reflectivity and 16 km3 for the volume, observed at least in two consecutive volume scans (15 minutes). Besides tracking and Nowcasting the movement of storm cells, TITAN comprises algorithms that allow the identification of potentially severe storm "signatures", such as the hail metrics, to indicate the probability of hail (POH), based on a combination of radar data and the knowledge of the vertical temperature distribution of the atmosphere. Another two parameters, also related to hail producing storms, called FOKR (Foote-Krauss) index and HMA (Hail Mass Aloft) index is also included. The period from 2008 to 2013 was used to process all available information about storm characteristics, such as, onset time, duration and size of hail. The results of the analysis for the time evolution of the storm cells properties enabled the identification of the following key signatures for hail-producing cells: storm volume varying between at least 250 km3 and 1850 km3; average speed of more than 50 km/h; FOKR and POH indices with values between 3 and 4 and 0,8 to 1, respectively, observed at the same time as hail was reported to have fallen on the ground; HMA parameters (mass of hail accumulated aloft) peaking between 80 tons and 808 tons, preceding the time of the hail observed on the ground. The onset of hail, indicated in the reports, corroborates the time near the observed collapse of the cell indicated by a decreasing value of the severity indices provided by TITAN. This ongoing research will add more cases to include not only hail-producing cells, but also those associated with extreme winds and flash floods, to contribute towards the improvement of IPMet's radar bulletins issued routinely by the operational sector for the private and public sector, like the Civil Defense Authorities of the state of São Paulo.

Why geodiversity matters in valuing nature's stage.

PubMed

Hjort, Jan; Gordon, John E; Gray, Murray; Hunter, Malcolm L

2015-06-01

Geodiversity--the variability of Earth's surface materials, forms, and physical processes-is an integral part of nature and crucial for sustaining ecosystems and their services. It provides the substrates, landform mosaics, and dynamic physical processes for habitat development and maintenance. By determining the heterogeneity of the physical environment in conjunction with climate interactions, geodiversity has a crucial influence on biodiversity across a wide range of scales. From a literature review, we identified the diverse values of geodiversity; examined examples of the dependencies of biodiversity on geodiversity at a site-specific scale (for geosites <1 km(2) in area); and evaluated various human-induced threats to geosites and geodiversity. We found that geosites are important to biodiversity because they often support rare or unique biota adapted to distinctive environmental conditions or create a diversity of microenvironments that enhance species richness. Conservation of geodiversity in the face of a range of threats is critical both for effective management of nature's stage and for its own particular values. This requires approaches to nature conservation that integrate climate, biodiversity, and geodiversity at all spatial scales. © 2015 Society for Conservation Biology.

Compressional reactivation of hyperextended domains on a rifted margin: a requirement for a reappraisal of traditional restoration procedures?

NASA Astrophysics Data System (ADS)

Cadenas Martínez, P.; Fernandez Viejo, G.; Pulgar, J. A.

2017-12-01

The North Iberian margin is an inverted hyperextended rifted margin that preserves the initial stages of compressional reactivation. Rift inheritance conditioned in a determinant way the contractional reactivation. The underthrusting of the hyperextended distal domains beneath the platform and the formation of an accretionary wedge at the toe of the slope focused most of the compression. The underthrusting gave place to the formation of a crustal root and the uplifting of the Cantabrian Mountains onshore. Meanwhile, the main rift basins within the continental platform were slightly inverted. Plate kinematic reconstructions and palinspatic restorations have provided different shortening values. Thereby, the amount of shortening linked with the Cenozoic compression is still unclear and a matter of debate on this area.In this work, we present a full cross-section at the central part of the North Iberian margin developed from the restoration of a high quality depth migrated seismic profile running from the continental platform to the Biscay abyssal plain. A shortening calculation gives an estimate of about 1 km within the Asturian Basin, in the continental platform, while in the accretionary wedge at the bottom of the slope, shortening values ranges between 12 km and 15 km. The limited values estimated within the Asturian Basin support the mild inversion observed within this basin, which preserves most of the extensional imprint. Within the abyssal plain, shortening values differ from previous estimations and cannot account for a high amount of compression in the upper crust. Deformation of the hyperextended crust and the exhumed mantle domains inherited from the rifting processes would have accommodated most of the compression. Restoration of these domains seems to be the key to decipher the structure and the tectonic evolution of the reactivated rifted margin but cannot be solved accurately using traditional restoration methods. This leads to a reappraisal of the traditional way of restoring compressional belt transects and particularly, when previous hyperextended domains within the rifted margins are involved.

Nicotinamide riboside, an unusual, non-typical, substrate of purified purine-nucleoside phosphorylases.

PubMed

Wielgus-Kutrowska, B; Kulikowska, E; Wierzchowski, J; Bzowska, A; Shugar, D

1997-01-15

Nicotinamide 1-beta-D-riboside (Nir), the cationic, reducible moiety of the coenzyme NAD+, has been confirmed as an unusual substrate for purified purine-nucleoside phosphorylase (PNP) from a mammalian source (calf spleen). It is also a substrate of the enzyme from Escherichia coli. The Km values at pH 7, 1.48 mM and 0.62 mM, respectively, were 1-2 orders of magnitude higher than for the natural substrate inosine, but the Vmax values were comparable, 96% and 35% that for Ino. The pseudo first-order rate constants, Vmax/Km, were 1.1% and 2.5% for the calf spleen and E. coli enzymes. The aglycon, nicotinamide, was neither a substrate nor an inhibitor of PNP. Nir was a weak inhibitor of inosine phosphorolysis catalyzed by both enzymes, with Ki values close to the Km for its phosphorolysis, consistent with simple competitive inhibition; this was further confirmed by Dixon plots. Phosphorolysis of the fluorescent positively charged substrate 7-methylguanosine was also inhibited in a competitive manner by both Ino and Nir. Phosphorolysis of Nir by both enzymes was inhibited competitively by several specific inhibitors of calf spleen and E. coli PNP, with Ki values similar to those for inhibition of other natural substrates. The pH dependence of the kinetic constants for the phosphorolysis of Nir and of a variety of other substrates, was extensively investigated, particularly in the alkaline pH range, where Nir exhibited abnormally high substrate activity relative to the reduced reaction rates of both enzymes towards other anionic or neutral substrates. The overall results are discussed in relation to present concepts regarding binding and phosphorolysis of substrates by PNP based on crystallographic data of enzyme-inhibitor complexes, and current studies on enzymatic and nonenzymatic mechanisms of the cleavage of the Nir glycosidic bond.

Remote sensing and geologic studies of the Balmer-Kapteyn region of the Moon

NASA Astrophysics Data System (ADS)

Hawke, B. Ray; Gillis, J. J.; Giguere, T. A.; Blewett, D. T.; Lawrence, D. J.; Lucey, P. G.; Smith, G. A.; Spudis, P. D.; Taylor, G. Jeffrey

2005-06-01

The Balmer-Kapteyn (B-K) region is located just east of Mare Fecunditatis on the east limb of the Moon. It is centered on the Balmer-Kapteyn basin, a pre-Nectarian impact structure that exhibits two rings, approximately 225 km and 450 km in diameter. Clementine multispectral images and Lunar Prospector (LP) gamma-ray spectrometer (GRS) data were used to investigate the composition, age, and origin of geologic units in the region. A major expanse of cryptomare was mapped within the B-K basin. Spectral and chemical data obtained for dark-haloed craters (DHCs) established that these impact craters excavated mare basalt from beneath higher-albedo, highland-rich surface units. The buried basalts exposed by DHCs in the region are dominated by low-titanium mare basalts. The fresh DHC FeO values (15.0-15.7 wt.%) that best represent those of buried mare basalts are well within the range of values exhibited by high-alumina mare basalts. While most cryptomare deposits occur beneath surfaces that range in age from Imbrian to Nectarian, it is possible that some mare flows were emplaced during pre-Nectarian time. Most cryptomare deposits in the B-K region were formed by the contamination of mare surfaces by highland-rich distal ejecta from surrounding impact craters. These Balmer-type cryptomare deposits are usually associated with light plains units. Major LP-GRS FeO enhancements are associated with cryptomaria in the Balmer-Kapteyn, Lomonosov-Fleming, Schiller-Schickard, and Mendel-Rydberg regions.

Evaluation of extreme ionospheric total electron content gradient associated with plasma bubbles for GNSS Ground-Based Augmentation System

NASA Astrophysics Data System (ADS)

Saito, S.; Yoshihara, T.

2017-08-01

Associated with plasma bubbles, extreme spatial gradients in ionospheric total electron content (TEC) were observed on 8 April 2008 at Ishigaki (24.3°N, 124.2°E, +19.6° magnetic latitude), Japan. The largest gradient was 3.38 TECU km-1 (total electron content unit, 1 TECU = 1016 el m-2), which is equivalent to an ionospheric delay gradient of 540 mm km-1 at the GPS L1 frequency (1.57542 GHz). This value is confirmed by using multiple estimating methods. The observed value exceeds the maximum ionospheric gradient that has ever been observed (412 mm km-1 or 2.59 TECU km-1) to be associated with a severe magnetic storm. It also exceeds the assumed maximum value (500 mm km-1 or 3.08 TECU km-1) which was used to validate the draft international standard for Global Navigation Satellite System (GNSS) Ground-Based Augmentation Systems (GBAS) to support Category II/III approaches and landings. The steepest part of this extreme gradient had a scale size of 5.3 km, and the front-normal velocities were estimated to be 71 m s-1 with a wavefront-normal direction of east-northeastward. The total width of the transition region from outside to inside the plasma bubble was estimated to be 35.3 km. The gradient of relatively small spatial scale size may fall between an aircraft and a GBAS ground subsystem and may be undetectable by both aircraft and ground.

Oxygen isotope geochemistry of the lassen volcanic center, California: Resolving crustal and mantle contributions to continental Arc magmatism

USGS Publications Warehouse

Feeley, T.C.; Clynne, M.A.; Winer, G.S.; Grice, W.C.

2008-01-01

This study reports oxygen isotope ratios determined by laser fluorination of mineral separates (mainly plagioclase) from basaltic andesitic to rhyolitic composition volcanic rocks erupted from the Lassen Volcanic Center (LVC), northern California. Plagioclase separates from nearly all rocks have ??18O values (6.1-8.4%) higher than expected for production of the magmas by partial melting of little evolved basaltic lavas erupted in the arc front and back-arc regions of the southernmost Cascades during the late Cenozoic. Most LVC magmas must therefore contain high 18O crustal material. In this regard, the ??18O values of the volcanic rocks show strong spatial patterns, particularly for young rhyodacitic rocks that best represent unmodified partial melts of the continental crust. Rhyodacitic magmas erupted from vents located within 3.5 km of the inferred center of the LVC have consistently lower ??18 O values (average 6.3% ?? 0.1%) at given SiO2 contents relative to rocks erupted from distal vents (>7.0 km; average 7.1% ?? 0.1%). Further, magmas erupted from vents situated at transitional distances have intermediate values and span a larger range (average 6.8% ?? 0.2%). Basaltic andesitic to andesitic composition rocks show similar spatial variations, although as a group the ??18O values of these rocks are more variable and extend to higher values than the rhyodacitic rocks. These features are interpreted to reflect assimilation of heterogeneous lower continental crust by mafic magmas, followed by mixing or mingling with silicic magmas formed by partial melting of initially high 18O continental crust (??? 9.0%) increasingly hybridized by lower ??18O (???6.0%) mantle-derived basaltic magmas toward the center of the system. Mixing calculations using estimated endmember source ??18O values imply that LVC magmas contain on a molar oxygen basis approximately 42 to 4% isotopically heavy continental crust, with proportions declining in a broadly regular fashion toward the center of the LVC. Conversely, the ??18O values of the rhyodacitic rocks suggest that the continental crust in the melt generation zones beneath the LVC has been substantially modified by intrusion of mantle-derived basaltic magmas, with the degree of hybridization ranging on a molar oxygen basis from approximately 60% at distances up to 12 km from the center of the system to 97% directly beneath the focus region. These results demonstrate on a relatively small scale the strong influence that intrusion of mantle-derived mafic magmas can have on modifying the composition of pre-existing continental crust in regions of melt production. Given this result, similar, but larger-scale, regional trends in magma compositions may reflect an analogous but more extensive process wherein the continental crust becomes progressively hybridized beneath frontal arc localities as a result of protracted intrusion of subduction-related basaltic magmas. ?? The Author 2008. Published by Oxford University Press. All rights reserved.

Determination of critical habitat for the endangered Nelson's bighorn sheep in southern California

USGS Publications Warehouse

Turner, J.C.; Douglas, C.L.; Hallum, C.R.; Krausman, P.R.; Ramey, R.R.

2004-01-01

The United States Fish and Wildlife Service's (USFWS) designation of critical habitat for the endangered Nelson's bighorn sheep (Ovis canadensis nelsoni) in the Peninsular Ranges of southern California has been controversial because of an absence of a quantitative, repeatable scientific approach to the designation of critical habitat. We used 12,411 locations of Nelson's bighorn sheep collected from 1984-1998 to evaluate habitat use within 398 km2 of the USFWS-designated critical habitat in the northern Santa Rosa Mountains, Riverside County, California. We developed a multiple logistic regression model to evaluate and predict the probability of bighorn use versus non-use of native landscapes. Habitat predictor variables included elevation, slope, ruggedness, slope aspect, proximity to water, and distance from minimum expanses of escape habitat. We used Earth Resources Data Analysis System Geographic Information System (ERDAS-GIS) software to view, retrieve, and format predictor values for input to the Statistical Analysis Systems (SAS) software. To adequately account for habitat landscape diversity, we carried out an unsupervised classification at the outset of data inquiry using a maximum-likelihood clustering scheme implemented in ERDAS. We used the strata resulting from the unsupervised classification in a stratified random sampling scheme to minimize data loads required for model development. Based on 5 predictor variables, the habitat model correctly classified >96% of observed bighorn sheep locations. Proximity to perennial water was the best predictor variable. Ninety-seven percent of the observations were within 3 km of perennial water. Exercising the model over the northern Santa Rosa Mountain study area provided probabilities of bighorn use at a 30 x 30-m2 pixel level. Within the 398 km 2 of USFWS-designated critical habitat, only 34% had a graded probability of bighorn use to non-use ranging from ???1:1 to 6,044:1. The remaining 66% of the study area had odds of having bighorn use <1:1 or it was more likely not to be used by bighorn sheep. The USFWS designation of critical habitat included areas (45 km2) of importance (2.5 to ???40 observations per km2 per year) to Nelson's bighorn sheep and large landscapes (353 km2) that do not appear to be used (<1 observation per km2 per year).

How Many Ultra-Low Delta-v Near Earth Objects Remain Undiscovered? Implications for missions.

NASA Astrophysics Data System (ADS)

Elvis, Martin; Ranjan, Sukrit; Galache, Jose Luis; Murphy, Max

2015-08-01

The past decade has witnessed considerable growth of interest in missions to Near-Earth Objects (NEOs). NEOs are considered prime targets for manned and robotic missions, for both scientific objectives as well as in-situ resource utilization including harvesting of water for propellant and life support and mining of high-value elements for sale on Earth. Appropriate targets are crucial to such missions. Hence, ultra-low delta-v mission targets are strongly favored. Some mission architectures rely on the discovery of more ultra-low delta-v NEOs. In fact the approved and executed NEO missions have all targeted asteroids with ultra-low LEO to asteroid rendezvous delta-v <5.5 km/s.In this paper, we estimate the total NEO population as a function of delta-v, and how many remain to be discovered in various size ranges down to ~100m. We couple the NEOSSat-1 model (Greenstreet et al., 2012) to the NEO size distribution derived from the NEOWISE survey (Mainzer et al., 2011b) to compute an absolute NEO population model. We compare the Minor Planet Center (MPC) catalog of known NEOs to this NEO population model. We compute the delta-v from LEO to asteroid rendezvous orbits using a modified Shoemaker-Helin (S-H) formalism that empirically removes biases found comparing S-H with the results from NHATS. The median delta-v of the known NEOs is 7.3 km/s, the median delta-v predicted by our NEO model is 9.8 km/s, suggesting that undiscovered objects are biased to higher delta-v. The survey of delta-v <10.3 km/s NEOs is essentially complete for objects with diameter D >300 m. However, there are tens of thousands of objects with delta-v <10.3 km/s to be discovered in the D = 50 - 300 m size class (H = 20.4 - 24.3). Our work suggests that there are 100 yet-undiscovered NEOs with delta-v < 5:8 km/s, and 1000 undiscovered NEOs with v < 6.3 km/s. We conclude that, even with complete NEO surveys, the selection of good (i.e. ultra-low delta-v) mission targets is limited given current propulsion technology. Visiting the full range of NEO sub-types will likely require improved propulsion systems.

A new distribution range of Ateles chamek (Humboldt 1812) in an ecotone of three biomes in the Paraguay River Basin.

PubMed

Dos Santos-Filho, Manoel; Bernardo, Christine Steiner São; Van der Laan Barbosa, Henry Willian; Gusmão, Almério Câmara; Jerusalinsky, Leandro; Canale, Gustavo Rodrigues

2017-07-01

Historical records of Ateles chamek (black-faced black spider monkey) suggest that the species range extends further south of the known species distribution, within an ecotonal region between the Amazonia, Cerrado and Pantanal biomes in Brazil. Ecotones are zones of habitat transition with high species richness that remain undersampled as conservationists often prioritize biodiversity hotspots. Thus, distribution ranges may be inaccurately measured when species occur in ecotonal zones. We report the first precise records of A. chamek in 24 new localities surveyed in the ecotonal zone of the Upper Paraguay River Basin, and we present subgroup encounter rates in the 11 largest patches (>70 ha) along 207 km of the line transects surveyed. The new records represent an expansion of the distribution of A. chamek approximately 200 km to the south, increasing the known extent of its occurrence by 10.8%. Local tributaries may not be barriers for spider monkeys, which are able to swim and cross slow-moving rivers. However, the dry forests of the Cerrado and the flooded areas of the Pantanal, formed by grassland and scarce trees, may be habitat barriers for A. chamek. The populations living in this ecotonal zone are relatively abundant (1.1-6.67 subgroup sightings/10 km) compared to the heavily hunted continuous forests of northern Amazonia. Furthermore, these values are similar to those for other Ateles spp. inhabiting forests with low or no hunting pressure. We highlight the need for specific conservation action to protect the spider monkeys living in these landscapes, which are threatened by agriculture expansion.

Earth Global Reference Atmospheric Model 2007 (Earth-GRAM07) Applications for the NASA Constellation Program

NASA Technical Reports Server (NTRS)

Leslie, Fred W.; Justus, C. G.

2008-01-01

Engineering models of the atmosphere are used extensively by the aerospace community for design issues related to vehicle ascent and descent. The Earth Global Reference Atmosphere Model version 2007 (Earth-GRAM07) is the latest in this series and includes a number of new features. Like previous versions, Earth-GRAM07 provides both mean values and perturbations for density, temperature, pressure, and winds, as well as monthly- and geographically-varying trace constituent concentrations. From 0 km to 27 km, thermodynamics and winds are based on the National Oceanic and Atmospheric Administration Global Upper Air Climatic Atlas (GUACA) climatology. For altitudes between 20 km and 120 km, the model uses data from the Middle Atmosphere Program (MAP). Above 120 km, EarthGRAM07 now provides users with a choice of three thermosphere models: the Marshall Engineering Thermosphere (MET-2007) model; the Jacchia-Bowman 2006 thermosphere model (JB2006); and the Naval Research Labs Mass Spectrometer, Incoherent Scatter Radar Extended Model (NRL MSIS E-OO) with the associated Harmonic Wind Model (HWM-93). In place of these datasets, Earth-GRAM07 has the option of using the new 2006 revised Range Reference Atmosphere (RRA) data, the earlier (1983) RRA data, or the user may also provide their own data as an auxiliary profile. Refinements of the perturbation model are also discussed which include wind shears more similar to those observed at the Kennedy Space Center than the previous version Earth-GRAM99.

Hybrid modeling of spatial continuity for application to numerical inverse problems

USGS Publications Warehouse

Friedel, Michael J.; Iwashita, Fabio

2013-01-01

A novel two-step modeling approach is presented to obtain optimal starting values and geostatistical constraints for numerical inverse problems otherwise characterized by spatially-limited field data. First, a type of unsupervised neural network, called the self-organizing map (SOM), is trained to recognize nonlinear relations among environmental variables (covariates) occurring at various scales. The values of these variables are then estimated at random locations across the model domain by iterative minimization of SOM topographic error vectors. Cross-validation is used to ensure unbiasedness and compute prediction uncertainty for select subsets of the data. Second, analytical functions are fit to experimental variograms derived from original plus resampled SOM estimates producing model variograms. Sequential Gaussian simulation is used to evaluate spatial uncertainty associated with the analytical functions and probable range for constraining variables. The hybrid modeling of spatial continuity is demonstrated using spatially-limited hydrologic measurements at different scales in Brazil: (1) physical soil properties (sand, silt, clay, hydraulic conductivity) in the 42 km2 Vargem de Caldas basin; (2) well yield and electrical conductivity of groundwater in the 132 km2 fractured crystalline aquifer; and (3) specific capacity, hydraulic head, and major ions in a 100,000 km2 transboundary fractured-basalt aquifer. These results illustrate the benefits of exploiting nonlinear relations among sparse and disparate data sets for modeling spatial continuity, but the actual application of these spatial data to improve numerical inverse modeling requires testing.

UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

NASA Astrophysics Data System (ADS)

Watkins, Brenton; Fallen, Christopher; Secan, James

Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF frequency increasing near the gyro-harmonic value were conducted. The FM scan rate was sufficiently slow that the electron density was approximately in an equilibrium state. For these experiments the altitude of the HF interaction follows a near straight line downward parallel to the altitude-dependent gyro-harmonic level.

Skin temperature, thermal comfort, sweating, clothing and activity of men sledging in Antarctica

PubMed Central

Budd, G. M.

1966-01-01

1. Three men were studied while dog-sledging 320 km in 12 days in Antarctica. Conventional Antarctic clothing (`sweaters and windproofs') was worn. Four hundred observations were made of medial thigh skin temperature, thermal comfort, sweating, clothing, activity and environmental conditions. 2. Work occupied an average of 11·0 hr/day and sleep 7·5 hr. Estimated daily energy expenditure averaged 5100 kcal (range 2740-6660 kcal). 3. Skin temperature fell on exposure to cold despite the clothing worn, but was not changed by the level of activity. Sweating, and thermal comfort, were directly related to both skin temperature and activity. 4. Inside the tent, the modal value of skin temperature was 33° C (range 27-36° C) and the men were comfortable in 94% of observations. 5. During the 9·2 hr/day spent outdoors the modal value of skin temperature was 27° C (range 18-33° C) and the men felt too cold (but did not shiver) in 11% (range 7-20%) of observations, suggesting that cold stress was not negligible. However, they also felt too hot in 20% of observations and were sweating in 23%. PMID:5914254

High-resolution spectroscopy of Venus: Detection of OCS, upper limit to H 2S, and latitudinal variations of CO and HF in the upper cloud layer

NASA Astrophysics Data System (ADS)

Krasnopolsky, Vladimir A.

2008-10-01

Venus was observed at 2.4 and 3.7 μm with a resolving power of 4×10 using the long-slit high-resolution spectrograph CSHELL at NASA IRTF. The observations were made along a chord that covered a latitude range of ± 60° at a local time near 8:00. The continuous reflectivity and limb brightening at 2.4 μm are fitted by the clouds with a single scattering albedo 1-a=0.01 and a pure absorbing layer with τ=0.09 above the clouds. The value of 1-a agrees with the refractive index of H 2SO 4 (85%) and the particle radius of 1 μm. The absorbing layer is similar to that observed by the UV spectrometer at the Pioneer Venus orbiter. However, its nature is puzzling. CO 2 was measured using its R32 and R34 lines. The retrieved product of the CO 2 abundance and airmass is constant at 1.9 km-atm along the instrument slit in the latitude range of ± 60°. The CO mixing ratio (measured using the P21 line) is rather constant at 70 ppm, and its variations of ˜10% may be caused by atmospheric dynamics. The observed value is higher than the 50 ppm retrieved previously from a spectrum of the full disk, possibly, because of some downward extension of the mesospheric morningside bulge of CO. The observations of the HF R3 line reveal a constant HF mixing ratio of 3.5±0.5 ppb within ± 60° of latitude, which is within the scatter in the previous measurements of HF. OCS has been detected for the first time at the cloud tops by summing 17 lines of the P-branch. The previous detections of OCS refer to the lower atmosphere at 30-35 km. The retrieved OCS mixing ratio varies with a scale height of 1 to 3 km. The mean OCS mixing ratio is ˜2 ppb at 70 km and ˜14 ppb at 64 km. Vertical motions in the atmosphere may change the OCS abundance. The detected OCS should significantly affect Venus' photochemistry. A sensitive search for H 2S using its line at 2688.93 cm -1 results in a 3 sigma upper limit of 23 ppb, which is more restrictive than the previous limit of 100 ppb.

Abundances of O3 and O2 in the Martian Atmosphere Retrieved from MAVEN/IUVS Stellar Occultations

NASA Astrophysics Data System (ADS)

Gröller, H.; Lefèvre, F.; Gonzalez-Galindo, F.; Yelle, R. V.; Koskinen, T.; Montmessin, F.; Schneider, N.; Deighan, J.; Jain, S.

2017-12-01

We present O3 and O2 abundances retrieved from stellar occultations taken with the Imaging UltraViolet Spectrometer (IUVS) on MAVEN. The IUVS instrument has two separate spectral channels, the FUV and the MUV channel from 110 to 190 nm and from 180 to 340 nm, respectively. The O3 absorption feature is present in the MUV channel, whereas the O2 absorption features are in the FUV channel. So far, 15 stellar occultation campaigns have been executed on average every two to three months; covering more than one Martian year. During these campaigns, more than 900 stellar occultations were recorded. From those 900 stellar occultations, around 50 % can be used for O2 detection and around 25 % for O3. We detect O3 in almost 40 % of the occultations that can be used for O3 retrievals. The obtained O3 profiles are between 20 and 60 km and show a maximum number density around 30 to 40 km. The peak O3 number density varies almost one order of magnitude; between a few times 108 cm-3 and 2 x 109 cm-3. Our measurements show that the most O3 is present during the first half of the Martian year (up to a solar longitude of around 140°, end of northern summer) with a maximum around 60° solar longitude (close to aphelion). In most of the cases, the retrieved O3 profiles are in agreement with the LMD-MGCM predicted values. However, in some cases a difference in altitude and pressure space can be seen. Furthermore, during the northern early spring season, higher number densities at altitudes above 40 km can be seen in the data. The retrieved density profiles of O2 cover an altitude range from around 90 km up to 150 km. The corresponding O2 mixing ratios range from 1 to 9 x 10-3, also in agreement with previous observations. Even though the O2 mixing ratio shows high variability, the mean value seems to be constant with solar longitude. The obtained O2 profiles agree with previous measurements obtained by the Mars Express SPICAM instrument and by the Viking mass spectrometer. Furthermore, the retrieved O2mixing ratios are in agreement with the LMD-MGCM ratios for solar longitudes greater than around 65° (close to aphelion). However, the O2 mixing ratios predicted with the LMD-MGCM are up to a factor of 10 higher than the mixing ratios derived from stellar occultations during the northern spring season.

Phenanthrene and 2,2',5,5'-PCB sorption by several soils from methanol-water solutions: the effect of weathering and solute structure.

PubMed

Hyun, Seunghun; Kim, Minhee; Baek, Kitae; Lee, Linda S

2010-01-01

The effect of the sorption of phenanthrene and 2,2',5,5'-polychlorinated biphenyl (PCB52) by five differently weathered soils were measured in water and low methanol volume fraction (f(c)0.5) as a function of the apparent solution pH (pH(app)). Two weathered oxisols (A2 and DRC), and moderately weathered alfisols (Toronto) and two young soils (K5 and Webster) were used. The K(m) (linear sorption coefficient) values, which log-linearly decreases with f(c), were interpreted using a cosolvency sorption model. For phenanthrene sorption at the natural pH, the empirical constant (alpha) ranged between 0.95 and 1.14, and was in the order of oxisols (A2 and DRC)

Crustal thickening in Gansu-Qinghai, lithospheric mantle subduction, and oblique, strike-slip controlled growth of the Tibet plateau

NASA Astrophysics Data System (ADS)

Meyer, B.; Tapponnier, P.; Bourjot, L.; Métivier, F.; Gaudemer, Y.; Peltzer, G.; Shunmin, Guo; Zhitai, Chen

1998-10-01

Fieldwork complemented by SPOT image analysis throws light on current crustal shortening processes in the ranges of northeastern Tibet (Gansu and Qinghai provinces, China). The ongoing deformation of Late-Pleistocene bajada aprons in the forelands of the ranges involves folding, at various scales, and chiefly north-vergent, seismogenic thrusts. The most active thrusts usually break the ground many kilometres north of the range-fronts, along the northeast limbs of growing, asymmetric ramp-anticlines. Normal faulting at the apex of other growing anticlines, between the range fronts and the thrust breaks, implies slip on blind ramps connecting distinct active décollement levels that deepen southwards. The various patterns of uplift of the bajada surfaces can be used to constrain plausible links between contemporary thrusts downsection. Typically, the foreland thrusts and décollements appear to splay from master thrusts that plunge at least 15-20 km down beneath the high ranges. Plio-Quaternary anticlinal ridges rising to more than 3000 m a.s.l. expose Palaeozoic metamorphic basement in their core. In general, the geology and topography of the ranges and forelands imply that structural reliefs of the order of 5-10 km have accrued at rates of 1-2 mm yr-1 in approximately the last 5 Ma. From hill to range size, the elongated reliefs that result from such Late-Cenozoic, NE-SW shortening appear to follow a simple scaling law, with roughly constant length/width ratio, suggesting that they have grown self-similarly. The greatest mountain ranges, which are over 5.5 km high, tens of kilometres wide and hundreds of kilometres long may thus be interpreted to have formed as NW-trending ramp anticlines, at the scale of the middle-upper crust. The fairly regular, large-scale arrangement of those ranges, with parallel crests separated by piggy-back basins, the coevality of many parallel, south-dipping thrusts, and a change in the scaling ratio (from ~5 to 8) for range widths greater than ~30 km further suggests that they developed as a result of the northeastward migration of large thrust ramps above a broad décollement dipping SW at a shallow angle in the middle-lower crust. This, in turn, suggests that the 400-500 km-wide crustal wedge that forms the northeastern edge of the Tibet-Qinghai plateau shortens and thickens as a thick-skinned accretionary prism decoupled from the stronger upper mantle underneath. Such a thickening process must have been coupled with propagation of the Altyn Tagh fault towards the ENE because most thrust traces merge northwestwards with active branches of this fault, after veering clockwise. This process appears to typify the manner in which the Tibet-Qinghai highlands have expanded their surface area in the Neogene. The present topography and structure imply that, during much of that period, the Tibet plateau grew predominantly towards the northeast or east-northeast, but only marginally towards the north-northwest. This was accomplished by the rise, in fairly fast succession, of the Arka Tagh, Qiman Tagh, Mahan shan, Tanghenan Shan, and other NW-trending mountain ranges splaying southeastwards from the Altyn Tagh, isolating the Aqqik-Ayakkum Kol, Qaidam, Suhai and other catchments and basins that became incorporated into the highland mass as intermontane troughs. The tectonic cut-off of catchments and the ultimate infilling of basins by debris from the adjacent ranges, a result of tectonically forced internal drainage, have thus been essential relief-smoothing factors, yielding the outstandingly flat topography that makes Tibet a plateau. Using Late-Mesozoic and Neogene horizons as markers, the retrodeformation of sections across the West Qilian Ranges and Qaidam basin implies at least ~150 km of N30°E Neogene shortening. On a broader scale, taking erosion into account, and assuming isostatic compensation and an initial crustal thickness comparable to that of the Gobi platform (47.5+/-5 km), minimum amounts of Late-Cenozoic crustal shortening on NE sections between the Kunlun fault and the Hexi corridor are estimated to range between 100 and 200 km. In keeping with the inference of a deep crustal décollement and with the existence of Mid-Miocene to Pliocene plutonism and volcanism south of the Kunlun range, such values suggest that the lithospheric mantle of the Qaidam plunged obliquely into the asthenosphere south of that range to minimum depths of the order of 200-300 km. A minimum of ~150 km of shortening in the last ~10 Ma, consistent with the average age of the earliest volcanic-plutonic rocks just south of the Kunlun (~10.8 Ma) would imply average Late-Cenozoic rates of shortening and regional uplift in NE Tibet of at least ~15 mm yr-1 and ~0.2 mm yr-1, respectively. Such numbers are consistent with a cumulative sinistral offset and slip rate of at least ~200 km and ~2 cm yr-1, respectively, on the Altyn Tagh fault east of 88°E. The fault may have propagated more than 1000 km, to 102°E, in the last 10 Ma. Our study of ongoing tectonics in northeast Tibet is consistent with a scenario in which, while the Himalayas-Gangdese essentially `stagnated' above India's subducting mantle, much of Tibet grew by thickening of the Asian crust, as propagation of large, lithospheric, strike-slip shear zones caused the opposite edge of the plateau to migrate far into Asia. The Asian lithospheric mantle, decoupled from the crust, appears to have subducted southwards along the two Mesozoic sutures that cut Tibet north of the Gangdese, rather than to have thickened. The Bangong-Nujiang suture was probably reactivated earlier than the Jinsha-Kunlun suture, located farther north. Overall, the large-scale deformation bears a resemblance to plate tectonics at obliquely convergent margins, including slip-partioning along large strike-slip faults such as the Altyn Tagh and Kunlun faults. Simple mechanisms at the level of the lithospheric mantle are merely hidden by the broader distribution and greater complexity of strain in the crust.

Effects of multi-frequency power ultrasound on the enzymolysis of corn gluten meal: Kinetics and thermodynamics study.

PubMed

Jin, Jian; Ma, Haile; Qu, Wenjuan; Wang, Kai; Zhou, Cunshan; He, Ronghai; Luo, Lin; Owusu, John

2015-11-01

The effects of multi-frequency power ultrasound (MPU) pretreatment on the kinetics and thermodynamics of corn gluten meal (CGM) were investigated in this research. The apparent constant (KM), apparent break-down rate constant (kA), reaction rate constants (k), energy of activation (Ea), enthalpy of activation (ΔH), entropy of activation (ΔS) and Gibbs free energy of activation (ΔG) were determined by means of the Michaelis-Menten equation, first-order kinetics model, Arrhenius equation and transition state theory, respectively. The results showed that MPU pretreatment can accelerate the enzymolysis of CGM under different enzymolysis conditions, viz. substrate concentration, enzyme concentration, pH, and temperature. Kinetics analysis revealed that MPU pretreatment decreased the KM value by 26.1% and increased the kA value by 7.3%, indicating ultrasound pretreatment increased the affinity between enzyme and substrate. In addition, the values of k for ultrasound pretreatment were increased by 84.8%, 41.9%, 28.9%, and 18.8% at the temperature of 293, 303, 313 and 323 K, respectively. For the thermodynamic parameters, ultrasound decreased Ea, ΔH and ΔS by 23.0%, 24.3% and 25.3%, respectively, but ultrasound had little change in ΔG value in the temperature range of 293-323 K. In conclusion, MPU pretreatment could remarkably enhance the enzymolysis of CGM, and this method can be applied to protein proteolysis industry to produce peptides. Copyright © 2015 Elsevier B.V. All rights reserved.

Observations of Sprites and Elves Associated With Winter Thunderstorms in the Eastern Mediterranean

NASA Astrophysics Data System (ADS)

Ganot, M.; Yair, Y.; Price, C.; Ziv, B.; Sherez, Y.; Greenberg, E.; Devir, A.; Yaniv, R.; Bor, J.; Satori, G.

2006-12-01

The results of the 2005-6 winter sprite campaign in Israel are reported. We conducted optical ground-based observations aiming to detect transient luminous events (TLEs) above winter thunderstorms in Israel and in the area over the Mediterranean Sea between Israel, Cyprus and Lebanon. We alternated between two observation sites: the Tel-Aviv University campus in central Tel-Aviv (32.5N, 34.5E) and the Wise astronomical observatory in the Negev desert, near Mitzpe-Ramon (30N, 34.5E). We used 2 WATEC cameras, mounted on a pan-and- tilt unit with GPS time-base and event-detection software (UFO-Capture). The system was remote-controlled via the Internet and targets were chosen in real-time based on lightning locations derived from a BOLTEK lightning detection system stationed in Tel-Aviv. Detailed weather forecasts and careful analysis of lightning probability allowed us to choose between the two observation sites. The optical campaign was accompanied by ELF and VLF electromagnetic measurements from the existing TAU array in southern Israel. During five separate winter storms (December 2005 through March 2006) we detected 31 events: 27 sprites (4 halo sprites) and 4 elves. Detection ranges varied from 250 to 450km. Sprites were found to occur almost exclusively over the sea, in the height range 44-105km. Most sprites were columnar, and the number of elements varied from 1 to 9 with lengths varying from 10 to 48km. The average duration of sprites was ~43ms. All TLEs were accompanied by distinct positive ELF transients, which were clearly identified by our ELF station in Mizpe-Ramon and by the ELF station near Sopron, Hungary (range ~2500km). Calculated charge moment values were 800-1870 C·km, with some events exceeding 2500 C·km. We employed different lightning location systems (Israel Electrical Company LPATS and TOGA, ZEUS global networks) to determine the ground location of the parent lightning and succeeded in geo-locating 7 events. Based on weather radar and satellite images, it was found that most of the thunderclouds that produced sprites were isolated Cumulonimbus cells embedded within a matrix of lower rain clouds, associated with the cold sector of Cyprus lows. The relationship between the meteorological parameters, storm size, vertical cloud development and lightning properties, as well as a comparison with the properties of thunderstorms producing winter sprites in Japan, will be presented.

Long-term evolution of a propagating non-transform offset on the Mid-Atlantic Ridge over the last 26 m.y.

NASA Astrophysics Data System (ADS)

Zheng, T.; Tucholke, B. E.; Lin, J.

2017-12-01

By making plate reconstructions from Chron 8n ( 26.54 Ma) to present and analyzing multibeam bathymetry, long-range HMR1 sidescan sonar images, residual mantle Bouguer gravity anomaly (RMBA) and gravity-derived crust thickness, we investigated the structure and evolution of a propagating non-transform discontinuity (NTD) and adjacent ridge segments that now intersect the Mid-Atlantic Ridge (MAR) axis at 25°37'N. The NTD has propagated consistently northward since Chron 8n at a rate of 4.76 km/m.y. Offset across the NTD since Chron 6an (22 Ma) has been right lateral and has ranged from 8-52 km. Key features are: 1) Inside-corner (IC) crust consistently has higher values of RMBA than the adjacent ridge segments, implying thinner crust. 2) IC crust typically exhibits elevated, irregular edifices. Slopes of the NTD walls are steeper at ICs than at outside corners (OCs). Steep (up to 40°), abrupt slopes are particularly pronounced at the IC on the north side of the NTD. 3) OC crust is deeper and normally exhibits long linear ridges that curve toward the MAR axis at the southern edge of the NTD but show little curvature at the northern edge. 4) Width of the NTD between its northern and southern walls (at mid-depth) has ranged from 2 to 22 km, averaging 15 km. 5) The NTD valley was intermittently crossed by individual ridges or blocks every 5-60 km (average 20 km) along the run of the NTD. The ridges curve along the transtensional plate boundary within the NTD but are often discontinuous. HMR1 data show lumpy small-scale topography and occasional volcanic cones on the ridges and blocks. Their intermittency indicates that melt intruded sporadically into the NTD. Propagation of the NTD occurred as the transtensional plate boundary within the NTD jumped northward from a volcanic ridge axis or block, apparently as magmatism waned. The jumps captured crust and transferred it to the east flank only within the NTD, not from the northern IC edifices. We propose two possible causes for the northward propagation: 1) Enhanced melt supply (implied by more negative RMBA) in the segment south of the NTD may have driven the northward propagation; however, RMBA data are limited prior to Chron 5n, so the validity of this mechanism is uncertain. 2) The loci of rising parcels of fertile mantle that supplied melt to the crust may have shifted northward through time.

Anomalously high b-values in the South Flank of Kilauea volcano, Hawaii: Evidence for the distribution of magma below Kilauea's East rift zone

USGS Publications Warehouse

Wyss, M.; Klein, F.; Nagamine, K.; Wiemer, S.

2001-01-01

The pattern of b-value of the frequency-magnitude relation, or mean magnitude, varies little in the Kaoiki-Hilea area of Hawaii, and the b-values are normal, with b = 0.8 in the top 10 km and somewhat lower values below that depth. We interpret the Kaoiki-Hilea area as relatively stable, normal Hawaiian crust. In contrast, the b-values beneath Kilauea's South Flank are anomalously high (b = 1.3-1.7) at depths between 4 and 8 km, with the highest values near the East Rift zone, but extending 5-8 km away from the rift. Also, the anomalously high b-values vary along strike, parallel to the rift zone. The highest b-values are observed near Hiiaka and Pauahi craters at the bend in the rift, the next highest are near Makaopuhi and also near Puu Kaliu. The mildest anomalies occur adjacent to the central section of the rift. The locations of the three major and two minor b-value anomalies correspond to places where shallow magma reservoirs have been proposed based on analyses of seismicity, geodetic data and differentiated lava chemistry. The existence of the magma reservoirs is also supported by magnetic anomalies, which may be areas of dike concentration, and self-potential anomalies, which are areas of thermal upwelling above a hot source. The simplest explanation of these anomalously high b-values is that they are due to the presence of active magma bodies beneath the East Rift zone at depths down to 8 km. In other volcanoes, anomalously high b-values correlate with volumes adjacent to active magma chambers. This supports a model of a magma body beneath the East Rift zone, which may widen and thin along strike, and which may reach 8 km depth and extend from Kilauea's summit to a distance of at least 40 km down rift. The anomalously high b-values at the center of the South Flank, several kilometers away from the rift, may be explained by unusually high pore pressure throughout the South Flank, or by anomalously strong heterogeneity due to extensive cracking, or by both phenomena. The major b-value anomalies are located SSE of their parent reservoirs, in the direction of motion of the flank, suggesting that magma reservoirs leave an imprint in the mobile flank. We hypothesize that the extensive cracking may have been acquired when the anomalous parts of the South Flank, now several kilometers distant from the rift zone, were generated at the rift zone near persistent reservoirs. Since their generation, these volumes may have moved seaward, away from the rift, but earthquakes occurring in them still use the preexisting complex crack distribution. Along the decollement plane at 10 km depth, the b-values are exceptionally low (b = 0.5), suggesting faulting in a more homogeneous medium. ?? 2001 Elsevier Science B.V. All rights reserved.

Assembly and Initial Analysis of a Database of the Characteristics of Fixed-Wing Unmanned Aircraft Systems

DTIC Science & Technology

2014-11-01

sea level (evaluated for turbojet- and turbofan -powered UAVs and targets only) R range (km) ferryR ferry range (km) radiusR mission radius (km...operating airspeed for manned turbofan -powered aircraft, and a power law for birds derived by Alerstam et al. [22...UAVs in the Database; and ratio of operating to maximum airspeed for turbojet- or turbofan -powered UAVs with mmax > 103 kg

Spatial and temporal movements in Pyrenean bearded vultures (Gypaetus barbatus): Integrating movement ecology into conservation practice

NASA Astrophysics Data System (ADS)

Margalida, Antoni; Pérez-García, Juan Manuel; Afonso, Ivan; Moreno-Opo, Rubén

2016-10-01

Understanding the movement of threatened species is important if we are to optimize management and conservation actions. Here, we describe the age and sex specific spatial and temporal ranging patterns of 19 bearded vultures Gypaetus barbatus tracked with GPS technology. Our findings suggest that spatial asymmetries are a consequence of breeding status and age-classes. Territorial individuals exploited home ranges of about 50 km2, while non-territorial birds used areas of around 10 000 km2 (with no seasonal differences). Mean daily movements differed between territorial (23.8 km) and non-territorial birds (46.1 km), and differences were also found between sexes in non-territorial birds. Daily maximum distances travelled per day also differed between territorial (8.2 km) and non-territorial individuals (26.5 km). Territorial females moved greater distances (12 km) than males (6.6 km). Taking into account high-use core areas (K20), Supplementary Feeding Sites (SFS) do not seem to play an important role in the use of space by bearded vultures. For non-territorial and territorial individuals, 54% and 46% of their home ranges (K90), respectively, were outside protected areas. Our findings will help develop guidelines for establishing priority areas based on spatial use, and also optimize management and conservation actions for this threatened species.

Comparison of Cone Model Parameters for Halo Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Na, Hyeonock; Moon, Y.-J.; Jang, Soojeong; Lee, Kyoung-Sun; Kim, Hae-Yeon

2013-11-01

Halo coronal mass ejections (HCMEs) are a major cause of geomagnetic storms, hence their three-dimensional structures are important for space weather. We compare three cone models: an elliptical-cone model, an ice-cream-cone model, and an asymmetric-cone model. These models allow us to determine three-dimensional parameters of HCMEs such as radial speed, angular width, and the angle [ γ] between sky plane and cone axis. We compare these parameters obtained from three models using 62 HCMEs observed by SOHO/LASCO from 2001 to 2002. Then we obtain the root-mean-square (RMS) error between the highest measured projection speeds and their calculated projection speeds from the cone models. As a result, we find that the radial speeds obtained from the models are well correlated with one another ( R > 0.8). The correlation coefficients between angular widths range from 0.1 to 0.48 and those between γ-values range from -0.08 to 0.47, which is much smaller than expected. The reason may be the different assumptions and methods. The RMS errors between the highest measured projection speeds and the highest estimated projection speeds of the elliptical-cone model, the ice-cream-cone model, and the asymmetric-cone model are 376 km s-1, 169 km s-1, and 152 km s-1. We obtain the correlation coefficients between the location from the models and the flare location ( R > 0.45). Finally, we discuss strengths and weaknesses of these models in terms of space-weather application.

Validation of LIRIC aerosol concentration retrievals using airborne measurements during a biomass burning episode over Athens

NASA Astrophysics Data System (ADS)

Kokkalis, Panagiotis; Amiridis, Vassilis; Allan, James D.; Papayannis, Alexandros; Solomos, Stavros; Binietoglou, Ioannis; Bougiatioti, Aikaterini; Tsekeri, Alexandra; Nenes, Athanasios; Rosenberg, Philip D.; Marenco, Franco; Marinou, Eleni; Vasilescu, Jeni; Nicolae, Doina; Coe, Hugh; Bacak, Asan; Chaikovsky, Anatoli

2017-01-01

In this paper we validate the Lidar-Radiometer Inversion Code (LIRIC) retrievals of the aerosol concentration in the fine mode, using the airborne aerosol chemical composition dataset obtained over the Greater Athens Area (GAA) in Greece, during the ACEMED campaign. The study focuses on the 2nd of September 2011, when a long-range transported smoke layer was observed in the free troposphere over Greece, in the height range from 2 to 3 km. CIMEL sun-photometric measurements revealed high AOD ( 0.4 at 532 nm) and Ångström exponent values ( 1.7 at 440/870 nm), in agreement with coincident ground-based lidar observations. Airborne chemical composition measurements performed over the GAA, revealed increased CO volume concentration ( 110 ppbv), with 57% sulphate dominance in the PM1 fraction. For this case, we compare LIRIC retrievals of the aerosol concentration in the fine mode with the airborne Aerosol Mass Spectrometer (AMS) and Passive Cavity Aerosol Spectrometer Probe (PCASP) measurements. Our analysis shows that the remote sensing retrievals are in a good agreement with the measured airborne in-situ data from 2 to 4 km. The discrepancies observed between LIRIC and airborne measurements at the lower troposphere (below 2 km), could be explained by the spatial and temporal variability of the aerosol load within the area where the airborne data were averaged along with the different time windows of the retrievals.

Using Predictions Based on Geostatistics to Monitor Trends in Aspergillus flavus Strain Composition.

PubMed

Orum, T V; Bigelow, D M; Cotty, P J; Nelson, M R

1999-09-01

ABSTRACT Aspergillus flavus is a soil-inhabiting fungus that frequently produces aflatoxins, potent carcinogens, in cottonseed and other seed crops. A. flavus S strain isolates, characterized on the basis of sclerotial morphology, are highly toxigenic. Spatial and temporal characteristics of the percentage of the A. flavus isolates that are S strain (S strain incidence) were used to predict patterns across areas of more than 30 km(2). Spatial autocorrelation in S strain incidence in Yuma County, AZ, was shown to extend beyond field boundaries to adjacent fields. Variograms revealed both short-range (2 to 6 km) and long-range (20 to 30 km) spatial structure in S strain incidence. S strain incidence at 36 locations sampled in July 1997 was predicted with a high correlation between expected and observed values (R = 0.85, P = 0.0001) by kriging data from July 1995 and July 1996. S strain incidence at locations sampled in October 1997 and March 1998 was markedly less than predicted by kriging data from the same months in prior years. Temporal analysis of four locations repeatedly sampled from April 1995 through July 1998 also indicated a major reduction in S strain incidence in the Texas Hill area after July 1997. Surface maps generated by kriging point data indicated a similarity in the spatial pattern of S strain incidence among all sampling dates despite temporal changes in the overall S strain incidence. Geostatistics provided useful descriptions of variability in S strain incidence over space and time.

Exploration of S-wave velocity profiles at strong motion stations in Eskisehir, Turkey, using microtremor phase velocity and S-wave amplification

NASA Astrophysics Data System (ADS)

Yamanaka, Hiroaki; Özmen, Ögur Tuna; Chimoto, Kosuke; Alkan, Mehmet Akif; Tün, Muammer; Pekkan, Emrah; Özel, Oguz; Polat, Derya; Nurlu, Murat

2018-05-01

We have explored 1D S-wave velocity profiles of shallow and deep soil layers over a basement at strong motion stations in Eskisehir Province, Turkey. Microtremor array explorations were conducted at eight strong motion stations in the area to know shallow 1D S-wave velocity models. Rayleigh wave phase velocity at a frequency range from 3 to 30 Hz was estimated with the spatial autocorrelation analysis of array records of vertical microtremors at each station. Individual phase velocity was inverted to a shallow S-wave velocity profile. Low-velocity layers were identified at the stations in the basin. Site amplification factors from S-wave parts of earthquake records that had been estimated at the strong motion stations by Yamanaka et al. (2017) were inverted to the S-wave velocities and Q-values of the sedimentary layers. The depths to the basement with an S-wave velocity of 2.2 km/s are about 1 km in the central part of the basin, while the basement becomes shallow as 0.3 km in the marginal part of the basin. We finally discussed the effects of the shallow and deep sedimentary layers on the 1D S-wave amplification characteristics using the revealed profiles. It is found that the shallow soil layers have no significant effects in the amplification at a frequency range lower than 3 Hz in the area.

Energy cost of physical activities in 12-y-old girls: MET values and the influence of body weight.

PubMed

Spadano, J L; Must, A; Bandini, L G; Dallal, G E; Dietz, W H

2003-12-01

Few data exist on the energy cost of specific activities in children. The influence of body weight on the energy cost of activity when expressed as metabolic equivalents (METs) has not been vigorously explored. To provide MET data on five specific activities in 12-y-old girls and to test the hypothesis that measured MET values are independent of body weight. In 17 12-y-old girls, resting metabolic rate (RMR) and the energy expended while sitting, standing, walking on a flat treadmill at 3.2 and at 4.8 km/h, and walking on a treadmill at a 10% incline at 4.8 km/h were measured using indirect calorimetry. MET values were calculated by dividing the energy expenditure of an activity by the subject's RMR. The influence of body weight was assessed using simple linear regression. The observed METs were more consistent with published values for similar activities in adults than those offered for children. Body weight was a statistically significant predictor of the MET of all three walking activities, but not the MET of sitting or standing. Body weight explained 25% of the variance in the MET value for walking at 3.2 km/h, 39% for walking at 4.8 km/h, and 63% for walking at a 10% incline at 4.8 km/h. METs for the three walking activities were not independent of body weight. The use of average MET values to estimate the energy cost of these three activities would result in an underestimation of their energy cost in heavier girls and an overestimation in lighter girls. These results suggest that the estimation of total energy expenditure from activity diary, recall, and direct observation data using average MET values may be biased by body weight.

Magnetopause surface fluctuations observed by Voyager 1

NASA Technical Reports Server (NTRS)

Lepping, R. P.; Burlaga, L. F.

1979-01-01

Moving out of the dawnside of the earth's magnetosphere, Voyager 1 crossed the magnetopause apparently seven times, despite the high spacecraft speed of 11 km/sec. Normals to the magnetopause and their associated error cones were estimated for each of the crossings using a minimum variance analysis of the internal magnetic field. The oscillating nature of the ecliptic plane component of these normals indicates that most of the multiple crossings were due to a wave-like surface disturbance moving tailward along the magnetopause. The wave, which was aperiodic, was modeled as a sequence of sine waves. The amplitude, wavelength, and speed were determined for two pairs of intervals from the measured slopes, occurrence times, and relative positions of six magnetopause crossings. The magnetopause thickness was estimated to lie in the range 300 to 700 km with higher values possible. The estimated amplitude of these waves was obviously small compared to their wavelengths.

Singularity spectrum of intermittent seismic tremor at Kilauea Volcano, Hawaii

USGS Publications Warehouse

Shaw, H.R.; Chouet, B.

1989-01-01

Fractal singularity analysis (FSA) is used to study a 22-yr record of deep seismic tremor (30-60 km depth) for regions below Kilauea Volcano on the assumption that magma transport and fracture can be treated as a system of coupled nonlinear oscillators. Tremor episodes range from 1 to 100 min (cumulative duration = 1.60 ?? 104 min; yearly average - 727 min yr-1; mean gradient = 24.2 min yr-1km-1). Partitioning of probabilities, Pi, in the phase space of normalized durations, xi, are expressed in terms of a function f(??), where ?? is a variable exponent of a length scale, l. Plots of f(??) vs. ?? are called multifractal singularity spectra. The spectrum for deep tremor durations is bounded by ?? values of about 0.4 and 1.9 at f = O; fmax ???1.0 for ?? ??? 1. Results for tremor are similar to those found for systems transitional between complete mode locking and chaos. -Authors

Geocoronal imaging with Dynamics Explorer - A first look

NASA Technical Reports Server (NTRS)

Rairden, R. L.; Frank, L. A.; Craven, J. D.

1983-01-01

The ultraviolet photometer of the University of Iowa spin-scan auroral imaging instrumentation on board Dynamics Explorer-1 has returned numerous hydrogen Lyman alpha images of the geocorona from altitudes of 570 km to 23,300 km (1.09 R sub E to 4.66 R sub E geocentric radial distance). The hydrogen density gradient is shown by a plot of the zenith intensities throughout this range, which decrease to near celestial background values as the spacecraft approaches apogee. Characterizing the upper geocorona as optically thin (single-scattering), the zenith intensity is converted directly to vertical column density. This approximation loses its validity deeper in the geocorona, where the hydrogen is demonstrated to be optically thick in that there is no Lyman alpha limb brightening. Further study of the geocoronal hydrogen distribution will require computer modeling of the radiative transfer. Previously announced in STAR as N83-20889

Measurements of solar transition zone velocities and line broadening using the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission

NASA Technical Reports Server (NTRS)

Simon, G.; Mein, P.; Vial, J. C.; Shine, R. A.; Woodgate, B. E.

1982-01-01

The UVSP instrument on SMM is able to observe solar regions at two wavelengths in the same line with a band-pass of 0.3 A. Intensity and Doppler velocity maps are derived. It is shown that the numerical values are sensitive to the adopted Doppler width and the range of velocities is limited to within 30 km/sec. A method called Double Dopplergram Determination (DDD) is described for deriving both the Doppler width and the velocity (up to 80 km/sec), and the main sources of uncertainties are discussed. To illustrate the method, a set of C IV 1548 A observations is analyzed according to this procedure. The mean C IV Doppler width measured (0.15 A) is comparable to previous determinations. A relation is found between bright regions and down-flows. Large Doppler widths correspond to strong velocity gradients.

Atmospheric Modeling Using Accelerometer Data During Mars Atmosphere and Volatile Evolution (MAVEN) Flight Operations

NASA Technical Reports Server (NTRS)

Tolson, Robert H.; Lugo, Rafael A.; Baird, Darren T.; Cianciolo, Alicia D.; Bougher, Stephen W.; Zurek, Richard M.

2017-01-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is a NASA orbiter designed to explore the Mars upper atmosphere, typically from 140 to 160 km altitude. In addition to the nominal science mission, MAVEN has performed several Deep Dip campaigns in which the orbit's closest point of approach, also called periapsis, was lowered to an altitude range of 115 to 135 km. MAVEN accelerometer data were used during mission operations to estimate atmospheric parameters such as density, scale height, along-track gradients, and wave structures. Density and scale height estimates were compared against those obtained from the Mars Global Reference Atmospheric Model and used to aid the MAVEN navigation team in planning maneuvers to raise and lower periapsis during Deep Dip operations. This paper describes the processes used to reconstruct atmosphere parameters from accelerometers data and presents the results of their comparison to model and navigation-derived values.

Design and performance simulation of 532 nm Rayleigh-Mie Doppler lidar system for 5-50 km wind measurement

NASA Astrophysics Data System (ADS)

Shen, Fahua; Wang, Bangxin; Shi, Wenjuan; Zhuang, Peng; Zhu, Chengyun; Xie, Chenbo

2018-04-01

A novel design of the 532 nm Rayleigh-Mie Doppler lidar receiving system is carried out. The use of polarization isolation technology to effectively improve the receiving system optical reception efficiency, suppress the background noise, not only improves the system wind field detection accuracy, while achieving a high-accuracy temperature measurement. The wind speed and temperature measurement principle of the system are discussed in detail, and the triple Fabry-Perot etalon parameters are optimized. Utilizing the overall design parameters of the system, the system detection performance is simulated. The simulation results show that from 5 to 50 km altitude with vertical resolution of 0.1 km@5 ∼20 km, 0.5 km@20 ∼40 km, 1 km@40 ∼50 km, by using the laser with single pulse energy of 600 mJ, repetition frequency of 50 Hz and the receiving telescope with aperture of 0.8 m, with 2min integration time and in ±50 m/s radial wind speed range, the radial wind speed measurement accuracies of our designed lidar in the day and night are better than 2.6 m/s and 0.9 m/s respectively, and its performance is obviously superior to that of traditional system 5.6 m/s and 1.4 m/s wind speed accuracies; with 10min integration time and in 210 ∼280 K temperature range, the temperature measurement accuracies of the system in the day and night are better than 3.4 K and 1.2 K respectively; since the wind speed sensitivities of the Mie and Rayleigh scattering signals are not exactly the same, in ±50 m/s radial wind speed range, the wind speed bias induced by Mie signal is less than 1 m/s in the temperature range of 210-290 K and in the backscatter ratio range of 1-1.5 for pair measurement.

3-D Vp/Vs Ratio Distribution in the Geothermal Reservoir at Basel, Switzerland, from Microseismic Data

NASA Astrophysics Data System (ADS)

Kummerow, J.; Reshetnikov, A.; Häring, M.; Asanuma, H.

2012-12-01

Thousands of microseismic events occurred during and after the stimulation of the 4.5km deep Basel 1 well at the Deep Heat Mining Project in Basel, Switzerland, in December 2006. The located seismicity extends about 1km in vertical direction and also 1km in NNW-SSE direction, consistent with the orientation of the maximum horizontal stress. In this study, we analyze 2100 events with magnitudes Mw>0.0, which were recorded by six borehole seismometers between December 2, 2006, and June 7, 2007. We first identify event multiplets based on waveform similarity and apply an automatic, iterative arrival time optimization to calculate high-precision P and S time picks for the multiplet events. Local estimates of the Vp/Vs ratio in the stimulated Basel geothermal reservoir are then obtained from the slope of the demeaned differential S versus P arrival times. The average value of Vp/Vs=1.70 is close to the characteristic reservoir value of 1.72, which was determined independently from sonic log measurements. Also, in the vicinity of the borehole, the depth distribution of Vp/Vs correlates well with the low-pass filtered sonic log data: Vp/Vs values are less than 1.70 at the top of the seismicity cloud at <3.9km depth, close to average at 4.0-4.4km depth, and exceed the value of 1.75 at larger depth (4.4-4.6km), consistent with the sonic log data. Furthermore, we observe a correlation of anomalous Vp/Vs values with zones of enhanced seismic reflectivity which were resolved by microseismic reflection imaging. Away from the borehole, increased Vp/Vs ratios also seem to correlate with domains of high event density, possibly indicating fluid migration paths.

Ionization Efficiency in the Dayside Martian Upper Atmosphere

NASA Astrophysics Data System (ADS)

Cui, J.; Wu, X.-S.; Xu, S.-S.; Wang, X.-D.; Wellbrock, A.; Nordheim, T. A.; Cao, Y.-T.; Wang, W.-R.; Sun, W.-Q.; Wu, S.-Q.; Wei, Y.

2018-04-01

Combining the Mars Atmosphere and Volatile Evolution measurements of neutral atmospheric density, solar EUV/X-ray flux, and differential photoelectron intensity made during 240 nominal orbits, we calculate the ionization efficiency, defined as the ratio of the secondary (photoelectron impact) ionization rate to the primary (photon impact) ionization rate, in the dayside Martian upper atmosphere under a range of solar illumination conditions. Both the CO2 and O ionization efficiencies tend to be constant from 160 km up to 250 km, with respective median values of 0.19 ± 0.03 and 0.27 ± 0.04. These values are useful for fast calculation of the ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models. No substantial diurnal and solar cycle variations can be identified, except for a marginal trend of reduced ionization efficiency approaching the terminator. These observations are favorably interpreted by a simple scenario with ionization efficiencies, as a first approximation, determined by a comparison between relevant cross sections. Our analysis further reveals a connection between regions with strong crustal magnetic fields and regions with high ionization efficiencies, which are likely indicative of more efficient vertical transport of photoelectrons near magnetic anomalies.

Real-time measurements of the concentration and isotope composition of atmospheric and volcanic CO2 at Mount Etna (Italy)

NASA Astrophysics Data System (ADS)

Rizzo, Andrea Luca; Jost, Hans-Jürg; Caracausi, Antonio; Paonita, Antonio; Liotta, Marcello; Martelli, Mauro

2014-04-01

We present unprecedented data of real-time measurements of the concentration and isotope composition of CO2 in air and in fumarole-plume gases collected in 2013 during two campaigns at Mount Etna volcano, which were made using a laser-based isotope ratio infrared spectrometer. We performed approximately 360 measurements/h, which allowed calculation of the δ13C values of volcanic CO2. The fumarole gases of Torre del Filosofo (2900 m above sea level) range from -3.24 ± 0.06‰ to -3.71 ± 0.09‰, comparable to isotope ratio mass spectrometry (IRMS) measurements of discrete samples collected on the same dates. Plume gases sampled more than 1 km from the craters show a δ13C = -2.2 ± 0.4‰, in agreement with the crater fumarole gases analyzed by IRMS. Measurements performed along ~17 km driving track from Catania to Mount Etna show more negative δ13C values when passing through populated centers due to anthropogenic-derived CO2 inputs (e.g., car exhaust). The reported results demonstrate that this technique may represent an important advancement for volcanic and environmental monitoring.

Rarefied flow past a flat plate at incidence

NASA Technical Reports Server (NTRS)

Dogra, Virendra K.; Moss, James N.; Price, Joseph M.

1988-01-01

Results of a numerical study using the direct simulation Monte Carlo (DSMC) method are presented for the transitional flow about a flat plate at 40 deg incidence. The plate has zero thickness and a length of 1.0 m. The flow conditions simulated are those experienced by the Shuttle Orbiter during reentry at 7.5 km/s. The range of freestream conditions are such that the freestream Knudsen number values are between 0.02 and 8.4, i.e., conditions that encompass most of the transitional flow regime. The DSMC simulations show that transitional effects are evident when compared with free molecule results for all cases considered. The calculated results demonstrate clearly the necessity of having a means of identifying the effects of transitional flow when making aerodynamic flight measurements as are currently being made with the Space Shuttle Orbiter vehicles. Previous flight data analyses have relied exclusively on adjustments in the gas-surface interaction models without accounting for the transitional effect which can be comparable in magnitude. The present calculations show that the transitional effect at 175 km would increase the Space Shuttle Orbiter lift-drag ratio by 90 percent over the free molecule value.

Subsoil TPH contamination in two oil pipeline pumping stations and one pipeline right-of-way in north Mexico.

PubMed

Iturbe, R; Flores-Serrano, R M; Castro, A; Flores, C; Torres, L G

2010-11-01

This investigation deals with the characterization carried out in zones around two pipeline pumping stations and one pipeline right-of-way in the north of Mexico. In particular those areas where contamination was evaluated: (a) south area of the separation ditch in the Avalos station, (b) the area between the separation ditch at the Avalos station, (c) km 194+420 of the Moctuzma station, and (d) km 286+900 in the Candelaria station. Results of this investigation showed that only four samples showed TPH values higher than the Mexican limit for 2004: AVA 1B, with 21,191 mg kg(-1); AVA 1C, with 9348 mg kg(-1); AVA 2B, with 13,970 mg kg(-1); and MOC 2A, with 4108 mg kg(-1).None of the sampled points showed the presence of PAHs at values higher than those found in the Mexican or American legislations. PAH were detected in the range of 0.0004 and 13.05 mg kg(-1).It is suggested to implement surfactant soil washing as a remediation technique for the approximately 600 m(3) that need to be treated. Copyright 2010 Elsevier Ltd. All rights reserved.

Broadband spectra of seismic survey air-gun emissions, with reference to dolphin auditory thresholds.

PubMed

Goold, J C; Fish, P J

1998-04-01

Acoustic emissions from a 2120 cubic in air-gun array were recorded through a towed hydrophone assembly during an oil industry 2-D seismic survey off the West Wales Coast of the British Isles. Recorded seismic pulses were sampled, calibrated, and analyzed post-survey to investigate power levels of the pulses in the band 200 Hz-22 kHz at 750-m, 1-km, 2.2-km, and 8-km range from source. At 750-m range from source, seismic pulse power at the 200-Hz end of the spectrum was 140 dB re: 1 microPa2/Hz, and at the 20-kHz end of the spectrum seismic pulse power was 90 dB re: 1 microPa2/Hz. Although the background noise levels of the seismic recordings were far in excess of ambient, due to the proximity of engine, propeller, and flow sources of the ship towing the hydrophone, seismic power dominated the entire recorded bandwidth of 200 Hz-22 kHz at ranges of up to 2 km from the air-gun source. Even at 8-km range seismic power was still clearly in excess of the high background noise levels up to 8 kHz. Acoustic observations of common dolphins during preceding seismic surveys suggest that these animals avoided the immediate vicinity of the air-gun array while firing was in progress, i.e., localized disturbance occurred during seismic surveying. Although a general pattern of localized disturbance is suggested, one specific observation revealed that common dolphins were able to tolerate the seismic pulses at 1-km range from the air-gun array. Given the high broadband seismic pulse power levels across the entire recorded bandwidth, and known auditory thresholds for several dolphin species, we consider such seismic emissions to be clearly audible to dolphins across a bandwidth of tens on kilohertz, and at least out to 8-km range.

Spatio-temporal distribution of absorbing and non-absorbing aerosols derived from Aura-OMI Aerosol Index over Greece

NASA Astrophysics Data System (ADS)

Kaskaoutis, D. G.; Nastos, P. T.; Kosmopoulos, P. G.; Kambezidis, H. D.; Kharol, S. K.; Badarinath, K. V. S.

2009-04-01

The Aerosol Index (AI) observations derived from the Ozone Monitoring Instrument (OMI) on board the Dutch-Finnish Aura satellite are analyzed over Greece covering the whole period of the OMI available data, from September 2004 to August 2008. The objective of this study was to analyze the spatial, seasonal and inter-annual variability of AI over Greece, detected by OMI during 2004-2008, with an evaluation of potential contributing factors, including precipitation and long-range transport (Sahara dust and European pollution). The AI data cover the whole Greek territory (34o-42oN, 20o-28oE) with a spatial resolution of 0.25o x 0.25o (13 km x 24 km at nadir). The results show significant spatial and temporal variability of the seasonal and monthly mean AI, with higher values at the southern parts and lower values over northern Greece. On the other hand, the AI values do not show significant differences between the western and eastern parts and, therefore, the longitude-averaged AI values can be utilized to reveal the strong south-to-north gradient. This gradient significantly changes from season to season being more intense in spring and summer, while it is minimized in winter. Another significant remark is the dominance of negative AI values over northern Greece in the summer months, indicating the presence of non-UV absorbing aerosols, such as sulfate and sea-salt particles. The great geographical extent of the negative AI values in the summer months is indicative of long-range transport of such aerosols. In contrast, the high positive AI values over south Greece, mainly in spring, clearly reveal the UV-absorbing nature of desert-dust particles affecting the area during Saharan dust events. Synoptically, the spatial distribution in OMI-AI values was related to the Saharan dust events mainly over southern Greece and to the trans-boundary-pollution transport, consisting mainly of sulfate particles, in northern Greece. The annual variation of spatial-averaged AI values shows a predominant spring maximum (0.424±0.329, in April) and a summer minimum due to the negative AI values observed over northern Greece. In the cold period of the year (November to February) the AI values are higher over northern Greece compared to those in south, while in the rest of the year the opposite exists. This study is first of its kind utilizing OMI-AI data and its spatial and temporal distribution over Greece and can be the basis for other studies in the future.

Effects of study area size on home range estimates of common bottlenose dolphins Tursiops truncatus

PubMed Central

Nekolny, Samantha R; Denny, Matthew; Biedenbach, George; Howells, Elisabeth M; Mazzoil, Marilyn; Durden, Wendy N; Moreland, Lydia; David Lambert, J

2017-01-01

Abstract Knowledge of an animal’s home range is a crucial component in making informed management decisions. However, many home range studies are limited by study area size, and therefore may underestimate the size of the home range. In many cases, individuals have been shown to travel outside of the study area and utilize a larger area than estimated by the study design. In this study, data collected by multiple research groups studying bottlenose dolphins on the east coast of Florida were combined to determine how home range estimates increased with increasing study area size. Home range analyses utilized photo-identification data collected from 6 study areas throughout the St Johns River (SJR; Jacksonville, FL, USA) and adjacent waterways, extending a total of 253 km to the southern end of Mosquito Lagoon in the Indian River Lagoon Estuarine System. Univariate kernel density estimates (KDEs) were computed for individuals with 10 or more sightings (n = 20). Kernels were calculated for the primary study area (SJR) first, then additional kernels were calculated by combining the SJR and the next adjacent waterway; this continued in an additive fashion until all study areas were included. The 95% and 50% KDEs calculated for the SJR alone ranged from 21 to 35 km and 4 to 19 km, respectively. The 95% and 50% KDEs calculated for all combined study areas ranged from 116 to 217 km and 9 to 70 km, respectively. This study illustrates the degree to which home range may be underestimated by the use of limited study areas and demonstrates the benefits of conducting collaborative science. PMID:29492031

Effects of study area size on home range estimates of common bottlenose dolphins Tursiops truncatus.

PubMed

Nekolny, Samantha R; Denny, Matthew; Biedenbach, George; Howells, Elisabeth M; Mazzoil, Marilyn; Durden, Wendy N; Moreland, Lydia; David Lambert, J; Gibson, Quincy A

2017-12-01

Knowledge of an animal's home range is a crucial component in making informed management decisions. However, many home range studies are limited by study area size, and therefore may underestimate the size of the home range. In many cases, individuals have been shown to travel outside of the study area and utilize a larger area than estimated by the study design. In this study, data collected by multiple research groups studying bottlenose dolphins on the east coast of Florida were combined to determine how home range estimates increased with increasing study area size. Home range analyses utilized photo-identification data collected from 6 study areas throughout the St Johns River (SJR; Jacksonville, FL, USA) and adjacent waterways, extending a total of 253 km to the southern end of Mosquito Lagoon in the Indian River Lagoon Estuarine System. Univariate kernel density estimates (KDEs) were computed for individuals with 10 or more sightings ( n =  20). Kernels were calculated for the primary study area (SJR) first, then additional kernels were calculated by combining the SJR and the next adjacent waterway; this continued in an additive fashion until all study areas were included. The 95% and 50% KDEs calculated for the SJR alone ranged from 21 to 35 km and 4 to 19 km, respectively. The 95% and 50% KDEs calculated for all combined study areas ranged from 116 to 217 km and 9 to 70 km, respectively. This study illustrates the degree to which home range may be underestimated by the use of limited study areas and demonstrates the benefits of conducting collaborative science.

New Observations of Subarcsecond Photospheric Bright Points

NASA Technical Reports Server (NTRS)

Berger, T. E.; Schrijver, C. J.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Scharmer, G.

1995-01-01

We have used an interference filter centered at 4305 A within the bandhead of the CH radical (the 'G band') and real-time image selection at the Swedish Vacuum Solar Telescope on La Palma to produce very high contrast images of subarcsecond photospheric bright points at all locations on the solar disk. During the 6 day period of 15-20 Sept. 1993 we observed active region NOAA 7581 from its appearance on the East limb to a near-disk-center position on 20 Sept. A total of 1804 bright points were selected for analysis from the disk center image using feature extraction image processing techniques. The measured FWHM distribution of the bright points in the image is lognormal with a modal value of 220 km (0.30 sec) and an average value of 250 km (0.35 sec). The smallest measured bright point diameter is 120 km (0.17 sec) and the largest is 600 km (O.69 sec). Approximately 60% of the measured bright points are circular (eccentricity approx. 1.0), the average eccentricity is 1.5, and the maximum eccentricity corresponding to filigree in the image is 6.5. The peak contrast of the measured bright points is normally distributed. The contrast distribution variance is much greater than the measurement accuracy, indicating a large spread in intrinsic bright-point contrast. When referenced to an averaged 'quiet-Sun' area in the image, the modal contrast is 29% and the maximum value is 75%; when referenced to an average intergranular lane brightness in the image, the distribution has a modal value of 61% and a maximum of 119%. The bin-averaged contrast of G-band bright points is constant across the entire measured size range. The measured area of the bright points, corrected for pixelation and selection effects, covers about 1.8% of the total image area. Large pores and micropores occupy an additional 2% of the image area, implying a total area fraction of magnetic proxy features in the image of 3.8%. We discuss the implications of this area fraction measurement in the context of previously published measurements which show that typical active region plage has a magnetic filling factor on the order of 10% or greater. The results suggest that in the active region analyzed here, less than 50% of the small-scale magnetic flux tubes are demarcated by visible proxies such as bright points or pores.

Black Sea impact on its west-coast land surface temperature

NASA Astrophysics Data System (ADS)

Cheval, Sorin; Constantin, Sorin

2018-03-01

This study investigates the Black Sea influence on the thermal characteristics of its western hinterland based on satellite imagery acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS). The marine impact on the land surface temperature (LST) values is detected at daily, seasonal and annual time scales, and a strong linkage with the land cover is demonstrated. The remote sensing products used within the study supply LST data with complete areal coverage during clear sky conditions at 1-km spatial resolution, which is appropriate for climate studies. The sea influence is significant up to 4-5 km, by daytime, while the nighttime influence is very strong in the first 1-2 km, and it gradually decreases westward. Excepting the winter, the daytime temperature increases towards the plateau with the distance from the sea, e.g. with a gradient of 0.9 °C/km in the first 5 km in spring or with 0.7 °C/km in summer. By nighttime, the sea water usually remains warmer than the contiguous land triggering higher LST values in the immediate proximity of the coastline in all seasons, e.g. mean summer LST is 19.0 °C for the 1-km buffer, 16.6 °C for the 5-km buffer and 16.0 °C for the 10-km buffer. The results confirm a strong relationship between the land cover and thermal regime in the western hinterland of the Black Sea coast. The satellite-derived LST and air temperature values recorded at the meteorological stations are highly correlated for similar locations, but the marine influence propagates differently, pledging for distinct analysis. Identified anomalies in the general observed trends are investigated in correlation with sea surface temperature dynamics in the coastal area.

Kinetic measurement of 2-aminopurine X cytosine and 2-aminopurine X thymine base pairs as a test of DNA polymerase fidelity mechanisms.

PubMed Central

Watanabe, S M; Goodman, M F

1982-01-01

Enzyme kinetic measurements are presented showing that Km rather than maximum velocity (Vmax) discrimination governs the frequency of forming 2-aminopurine X cytosine base mispairs by DNA polymerase alpha. An in vitro system is used in which incorporation of dTMP or dCMP occurs opposite a template 2-aminopurine, and values for Km and Vmax are obtained. Results from a previous study in which dTTP and dCTP were competing simultaneously for insertion opposite 2-aminopurine indicated that dTMP is inserted 22 times more frequently than dCMP. We now report that the ratio of Km values KCm/KTm = 25 +/- 6, which agrees quantitatively with the dTMP/dCMP incorporation ratio obtained previously. We also report that VCmax is indistinguishable from VTmax. These Km and Vmax data are consistent with predictions from a model, the Km discrimination model, in which replication fidelity is determined by free energy differences between matched and mismatched base pairs. Central to this model is the prediction that the ratio of Km values for insertion of correct and incorrect nucleotides specifies the insertion fidelity, and the maximum velocities of insertion are the same for both nucleotides. PMID:6959128

Lithospheric-Mantle Structure of the Kaapvaal Craton, South Africa, Derived from Thermodynamically Self-Consistent Modelling of Magnetotelluric, Surface-Wave Dispersion, S-wave Receiver Function, Heat-flow, Elevation and Xenolith Observations

NASA Astrophysics Data System (ADS)

Muller, Mark; Fullea, Javier; Jones, Alan G.; Adam, Joanne; Lebedev, Sergei; Piana Agostinetti, Nicola

2013-04-01

Results from recent geophysical and mantle-xenolith geochemistry studies of the Kaapvaal Craton appear, at times, to provide disparate views of the physical, chemical and thermal structure of the lithosphere. Models from our recent SAMTEX magnetotelluric (MT) surveys across the Kaapvaal Craton indicate a resistive, 220-240 km thick lithosphere for the central core of the craton. One published S-wave receiver function (SRF) study and other surface-wave studies suggest a thinner lithosphere characterised by a ~160 km thick high-velocity "lid" underlain by a low-velocity zone (LVZ) of between 65-150 km in thickness. Other seismic studies suggest that the (high-velocity) lithosphere is thicker, in excess of 220 km. Mantle xenolith pressure-temperature arrays from Mesozoic kimberlites require that the base of the "thermal" lithosphere (i.e., the depth above which a conductive geotherm is maintained - the tLAB) is at least 220 km deep, to account for mantle geotherms in the range 35-38 mWm-2. Richly diamondiferous kimberlites across the Kaapvaal Craton require a lithospheric thickness substantially greater than 160 km - the depth of the top of the diamond stability field. In this paper we use the recently developed LitMod software code to derive, thermodynamically consistently, a range of 1-D electrical resistivity, seismic velocity, density and temperature models from layered geochemical models of the lithosphere based on mantle xenolith compositions. In our work, the "petrological" lithosphere-asthenosphere boundary (pLAB) (i.e., the top of the fertile asthenospheric-mantle) and the "thermal" LAB (tLAB) are coincident. Lithospheric-mantle models are found simultaneously satisfying all geophysical observables: MT responses, new surface-wave dispersion data, published SRFs, surface elevation and heat-flow. Our results show: 1. All lithospheric-mantle models are characterised by a seismic LVZ with a minimum velocity at the depth of the petrological/thermal LAB. The top of the LVZ does not correspond with the LAB. 2. Thin (~160 km-thick) lithospheric-mantle models are consistent with surface elevation and heat-flow observations only for unreasonably low average crustal heat production values (~0.4 µWm-3). However, such models are inconsistent both with the surface-wave dispersion data and youngest (Group I) palaeo-geotherms defined by xenolith P-T arrays. 3. A three-layered geochemical model, with lithospheric thickness in excess of 230 km, is required to match all geophysical and xenolith constraints. 4. The chemical transition from a depleted harzburgitic composition (above) to a refertilised high-T lherzolitic composition (below) at 160 km depth produces a sharp onset of the seismic LVZ and a sharp increase in density. Synthetic SRFs indicate that this chemical transition is able to account for the reported S-to-P conversion event at 160 km depth. In this this instance the 160 km deep SRF event does not represent the petrological/thermal LAB.

The thermal structure of the Venus atmosphere: Intercomparison of Venus Express and ground based observations of vertical temperature and density profiles✰

NASA Astrophysics Data System (ADS)

Limaye, Sanjay S.; Lebonnois, Sebastien; Mahieux, Arnaud; Pätzold, Martin; Bougher, Steven; Bruinsma, Sean; Chamberlain, Sarah; Clancy, R. Todd; Gérard, Jean-Claude; Gilli, Gabriella; Grassi, Davide; Haus, Rainer; Herrmann, Maren; Imamura, Takeshi; Kohler, Erika; Krause, Pia; Migliorini, Alessandra; Montmessin, Franck; Pere, Christophe; Persson, Moa; Piccialli, Arianna; Rengel, Miriam; Rodin, Alexander; Sandor, Brad; Sornig, Manuela; Svedhem, Håkan; Tellmann, Silvia; Tanga, Paolo; Vandaele, Ann C.; Widemann, Thomas; Wilson, Colin F.; Müller-Wodarg, Ingo; Zasova, Ludmila

2017-09-01

The Venus International Reference Atmosphere (VIRA) model contains tabulated values of temperature and number densities obtained by the experiments on the Venera entry probes, Pioneer Venus Orbiter and multi-probe missions in the 1980s. The instruments on the recent Venus Express orbiter mission generated a significant amount of new observational data on the vertical and horizontal structure of the Venus atmosphere from 40 km to about 180 km altitude from April 2006 to November 2014. Many ground based experiments have provided data on the upper atmosphere (90-130 km) temperature structure since the publication of VIRA in 1985. The "Thermal Structure of the Venus Atmosphere" Team was supported by the International Space Studies Institute (ISSI), Bern, Switzerland, from 2013 to 2015 in order to combine and compare the ground-based observations and the VEx observations of the thermal structure as a first step towards generating an updated VIRA model. Results of this comparison are presented in five latitude bins and three local time bins by assuming hemispheric symmetry. The intercomparison of the ground-based and VEx results provides for the first time a consistent picture of the temperature and density structure in the 40 km-180 km altitude range. The Venus Express observations have considerably increased our knowledge of the Venus atmospheric thermal structure above ∼40 km and provided new information above 100 km. There are, however, still observational gaps in latitude and local time above certain regions. Considerable variability in the temperatures and densities is seen above 100 km but certain features appear to be systematically present, such as a succession of warm and cool layers. Preliminary modeling studies support the existence of such layers in agreement with a global scale circulation. The intercomparison focuses on average profiles but some VEx experiments provide sufficient global coverage to identify solar thermal tidal components. The differences between the VEx temperature profiles and the VIRA below 0.1 mbar/95 km are small. There is, however, a clear discrepancy at high latitudes in the 10-30 mbar (70-80 km) range. The VEx observations will also allow the improvement of the empirical models (VTS3 by Hedin et al., 1983 and VIRA by Keating et al., 1985) above 0.03 mbar/100 km, in particular the 100-150 km region where a sufficient observational coverage was previously missing. The next steps in order to define the updated VIRA temperature structure up to 150 km altitude are (1) define the grid on which this database may be provided, (2) fill what is possible with the results of the data intercomparison, and (3) fill the observational gaps. An interpolation between the datasets may be performed by using available General Circulation Models as guidelines. An improved spatial coverage of observations is still necessary at all altitudes, in latitude-longitude and at all local solar times for a complete description of the atmospheric thermal structure, in particular on the dayside above 100 km. New in-situ observations in the atmosphere below 40 km are missing, an altitude region that cannot be accessed by occultation experiments. All these questions need to be addressed by future missions.

Comparison of tropospheric NO2 vertical columns in an urban environment using satellite, multi-axis differential optical absorption spectroscopy, and in situ measurements

NASA Astrophysics Data System (ADS)

Mendolia, D.; D'Souza, R. J. C.; Evans, G. J.; Brook, J.

2013-10-01

Tropospheric NO2 vertical column densities have been retrieved and compared for the first time in Toronto, Canada, using three methods of differing spatial scales. Remotely sensed NO2 vertical column densities, retrieved from multi-axis differential optical absorption spectroscopy and satellite remote sensing, were evaluated by comparison with in situ vertical column densities estimated using a pair of chemiluminescence monitors situated 0.01 and 0.5 km a.g.l. (above ground level). The chemiluminescence measurements were corrected for the influence of NOz, which reduced the NO2 concentrations at 0.01 and 0.5 km by an average of 8 ± 1% and 12 ± 1%, respectively. The average absolute decrease in the chemiluminescence NO2 measurement as a result of this correction was less than 1 ppb. The monthly averaged ratio of the NO2 concentration at 0.5 to 0.01 km varied seasonally, and exhibited a negative linear dependence on the monthly average temperature, with Pearson's R = 0.83. During the coldest month, February, this ratio was 0.52 ± 0.04, while during the warmest month, July, this ratio was 0.34 ± 0.04, illustrating that NO2 is not well mixed within 0.5 km above ground level. Good correlation was observed between the remotely sensed and in situ NO2 vertical column densities (Pearson's R value ranging from 0.72 to 0.81), but the in situ vertical column densities were 52 to 58% greater than the remotely sensed columns. These results indicate that NO2 horizontal heterogeneity strongly impacted the magnitude of the remotely sensed columns. The in situ columns reflected an urban environment with major traffic sources, while the remotely sensed NO2 vertical column densities were representative of the region, which included spatial heterogeneity introduced by residential neighbourhoods and Lake Ontario. Despite the difference in absolute values, the reasonable correlation between the vertical column densities determined by three distinct methods increased confidence in the validity of the values provided by each measurement technique.

Extreme-event geoelectric hazard maps: Chapter 9

USGS Publications Warehouse

Love, Jeffrey J.; Bedrosian, Paul A.

2018-01-01

Maps of geoelectric amplitude covering about half the continental United States are presented that will be exceeded, on average, once per century in response to an extreme-intensity geomagnetic disturbance. These maps are constructed using an empirical parameterization of induction: convolving latitude-dependent statistical maps of extreme-value geomagnetic disturbances, obtained from decades of 1-minute magnetic observatory data, with local estimates of Earth-surface impedance obtained at discrete geographic sites from magnetotelluric surveys. Geoelectric amplitudes are estimated for geomagnetic waveforms having a 240-s (and 1200-s) sinusoidal period and amplitudes over 10 min (1 h) that exceed a once-per-century threshold. As a result of the combination of geographic differences in geomagnetic variation and Earth-surface impedance, once-per-century geoelectric amplitudes span more than two orders of magnitude and are a highly granular function of location. Specifically for north-south 240-s induction, once-per-century geoelectric amplitudes across large parts of the United States have a median value of 0.34 V/km; for east-west variation, they have a median value of 0.23 V/km. In Northern Minnesota, amplitudes exceed 14.00 V/km for north-south geomagnetic variation (23.34 V/km for east-west variation), while just over 100 km away, amplitudes are only 0.08 V/km (0.02 V/km). At some sites in the northern-central United States, once-per-century geoelectric amplitudes exceed the 2 V/km realized in Québec during the March 1989 storm.

Twilight ozone measurement by solar occultation from AE 5

NASA Technical Reports Server (NTRS)

Guenther, B.; Heath, D.; Dasgupta, R.

1977-01-01

The BUV on AE 5 was used for a solar occultation measurement of atmospheric ozone. An observation was carried out during the morning twilight near 5 deg N, December 17, 1976, at the fixed wavelength of 255.5 nm, and a profile between 49 and 82 km was obtained. The number densities determined by this measurement were 3.7 x 10 to the 10th cu cm at 50 km, 5.1 x 10 to the 9th at 60 km, 3.9 x 10 to the 8th at 70 km, and 3.0 x 10 to the 7th at 80 km. No evidence of a high altitude secondary maximum was found. These concentrations are between a factor of 4 and 20 smaller than those midnight results reported from a Copernicus measurement, and similar to the values from the Krueger-Minzer Mid-latitude Model above 55 km. These values may be as much as a factor of 2 less than the Krueger-Minzer model below 50.

The value of coastal wetlands for hurricane protection.

PubMed

Costanza, Robert; Pérez-Maqueo, Octavio; Martinez, M Luisa; Sutton, Paul; Anderson, Sharolyn J; Mulder, Kenneth

2008-06-01

Coastal wetlands reduce the damaging effects of hurricanes on coastal communities. A regression model using 34 major US hurricanes since 1980 with the natural log of damage per unit gross domestic product in the hurricane swath as the dependent variable and the natural logs of wind speed and wetland area in the swath as the independent variables was highly significant and explained 60% of the variation in relative damages. A loss of 1 ha of wetland in the model corresponded to an average USD 33,000 (median = USD 5000) increase in storm damage from specific storms. Using this relationship, and taking into account the annual probability of hits by hurricanes of varying intensities, we mapped the annual value of coastal wetlands by 1 km x 1 km pixel and by state. The annual value ranged from USD 250 to USD 51,000 ha(-1) yr(-1), with a mean of USD 8240 ha(-1) yr(-1) (median = USD 3230 ha(-1) yr(-1)) significantly larger than previous estimates. Coastal wetlands in the US were estimated to currently provide USD 23.2 billion yr(-1) in storm protection services. Coastal wetlands function as valuable, selfmaintaining "horizontal levees" for storm protection, and also provide a host of other ecosystem services that vertical levees do not. Their restoration and preservation is an extremely cost-effective strategy for society.

GreenLITE: a new laser-based tool for near-real-time monitoring and mapping of CO2 and CH4 concentrations on scales from 0.04-25 km2

NASA Astrophysics Data System (ADS)

Dobler, Jeremy T.; Pernini, Timothy G.; Blume, Nathan; Zaccheo, T. Scott; Braun, Michael

2017-08-01

In 2013, Harris and Atmospheric and Environmental Research developed the greenhouse gas laser imaging tomography experiment (GreenLITE™) under a cooperative agreement with the National Energy Technology Laboratory of the Department of Energy. The system uses a pair of high-precision, intensity-modulated, continuous-wave (IMCW) transceivers and a series of retroreflectors to generate overlapping atmospheric density measurements from absorption of a particular greenhouse gas (e.g. CO2 or CH4), to provide an estimate of the two-dimensional spatial distribution of the gas within the area of interest. The system can take measurements over areas ranging from approximately 0.04 square kilometers (km2) to 25 km2 ( 200 meters (m) × 200 m, up to 5 km × 5 km). Multiple GreenLITE™ CO2 demonstrations have been carried out to date, including a full year, November 04, 2015 through November 14, 2016, deployment over a 25 km2 area of downtown Paris, France. In late 2016, the GreenLITE™ system was converted to provide similar measurements for CH4. Recent experiments showed that GreenLITE™ CH4 concentration readings correlated with an insitu instrument, calibrated with World Meteorological Organization traceable gas purchased from the NOAA Earth Systems Research Laboratory, to within approximately 0.5% of CH4 background or 10-15 parts per billion. Several experiments are planned in 2017 to further evaluate the accuracy of the CH4 and CO2 retrieved concentration values compared to the calibrated in situ instrument and to demonstrate the feasibility of GreenLITE™ for environmental and safety monitoring of CO2 and CH4 in industrial applications.

Cape Canaveral, Florida range reference atmosphere 0-70 km altitude

NASA Technical Reports Server (NTRS)

Tingle, A. (Editor)

1983-01-01

The RRA contains tabulations for monthly and annual means, standard deviations, skewness coefficients for wind speed, pressure temperature, density, water vapor pressure, virtual temperature, dew-point temperature, and the means and standard deviations for the zonal and meridional wind components and the linear (product moment) correlation coefficient between the wind components. These statistical parameters are tabulated at the station elevation and at 1 km intervals from sea level to 30 km and at 2 km intervals from 30 to 90 km altitude. The wind statistics are given at approximately 10 m above the station elevations and at altitudes with respect to mean sea level thereafter. For those range sites without rocketsonde measurements, the RRAs terminate at 30 km altitude or they are extended, if required, when rocketsonde data from a nearby launch site are available. There are four sets of tables for each of the 12 monthly reference periods and the annual reference period.

The thermal structure and dynamics of the atmosphere of Venus between 70 and 90 km from the Galileo-NIMS spectra

NASA Technical Reports Server (NTRS)

Roos-Serote, M.; Drossart, P.; Encrenaz, TH.; Lellouch, E.; Carlson, R. W.; Baines, K. H.; Taylor, F. W.; Calcutt, S. B.

1995-01-01

An analysis of thermal profiles and dynamics over a wide range of latitudes for the venusian atmosphere between 70 and 90 km is presented based on high spatial resolution infrared spectra of the night side obtained by the near infrared mapping spectrometer (NIMS) experiment during the Galileo-Venus encounter in February 1990. Using the 4.3-micrometer CO2 absorption band, the temperature profile is retrieved in the 75- to 91-km altitude region over a latitudinal range of -59 deg to +64 deg. Compared to earlier observations from the Pioneer Venus mission, the temperature at 91 km is about 10 K higher and between 74 and 83 km about 3.6 K colder. An equator to pole warming at constant pressure levels is found and implications for the zonal wind profiles are drawn under the assumption that the atmosphere is in cyclostrophic balance in the region of 70 to 90 km. The results are in correspondence with direct wind measurements from ground-based observations at 95 km and 105 km altitude.

Calibration of GPS based high accuracy speed meter for vehicles

NASA Astrophysics Data System (ADS)

Bai, Yin; Sun, Qiao; Du, Lei; Yu, Mei; Bai, Jie

2015-02-01

GPS based high accuracy speed meter for vehicles is a special type of GPS speed meter which uses Doppler Demodulation of GPS signals to calculate the speed of a moving target. It is increasingly used as reference equipment in the field of traffic speed measurement, but acknowledged standard calibration methods are still lacking. To solve this problem, this paper presents the set-ups of simulated calibration, field test signal replay calibration, and in-field test comparison with an optical sensor based non-contact speed meter. All the experiments were carried out on particular speed values in the range of (40-180) km/h with the same GPS speed meter. The speed measurement errors of simulated calibration fall in the range of +/-0.1 km/h or +/-0.1%, with uncertainties smaller than 0.02% (k=2). The errors of replay calibration fall in the range of +/-0.1% with uncertainties smaller than 0.10% (k=2). The calibration results justify the effectiveness of the two methods. The relative deviations of the GPS speed meter from the optical sensor based noncontact speed meter fall in the range of +/-0.3%, which validates the use of GPS speed meter as reference instruments. The results of this research can provide technical basis for the establishment of internationally standard calibration methods of GPS speed meters, and thus ensures the legal status of GPS speed meters as reference equipment in the field of traffic speed metrology.

Data archive for NO(y) from observations and construction and testing of airborne instrument for simultaneous measurement of NO, NO2, NO(y), and O3

NASA Technical Reports Server (NTRS)

Carroll, Mary Anne; Emmons, Louisa

1995-01-01

The compilation and archiving of NO(x) and NO(y) measurements began in mid-March 1994. Since the submission of the first report, data summaries have been obtained for the TROPOZ 2, STRATOZ 3, OCTA and TOR/Schauinsland campaigns, and the full data sets will become a part of this archive in the near future. Climatologies of NO(x) and NO(y) have been developed from these and previously archived data sets, including the available GTE campaigns (ABLE-2A, B, -3A, B, CITE-2, -3, TRACE-A, PEM WEST-A) and AASE 1 and 2. The data have been grouped by season and altitude (boundary layer and 3 km ranges in the free troposphere). Maps showing median values of midday NO, NO(x) and NO(y) have been produced for each season for the boundary layer and 3 km ranges of the free troposphere. The statistics of the data (median, mean, and standard deviation, central 67% and 90%) have also been determined, and are shown in representative figures included in this report.

The inference of atmospheric ozone using satellite horizon measurements in the 1042 per cm band.

NASA Technical Reports Server (NTRS)

Russell, J. M., III; Drayson, S. R.

1972-01-01

Description of a method for inferring atmospheric ozone information using infrared horizon radiance measurements in the 1042 per cm band. An analysis based on this method proves the feasibility of the horizon experiment for determining ozone information and shows that the ozone partial pressure can be determined in the altitude range from 50 down to 25 km. A comprehensive error study is conducted which considers effects of individual errors as well as the effect of all error sources acting simultaneously. The results show that in the absence of a temperature profile bias error, it should be possible to determine the ozone partial pressure to within an rms value of 15 to 20%. It may be possible to reduce this rms error to 5% by smoothing the solution profile. These results would be seriously degraded by an atmospheric temperature bias error of only 3 K; thus, great care should be taken to minimize this source of error in an experiment. It is probable, in view of recent technological developments, that these errors will be much smaller in future flight experiments and the altitude range will widen to include from about 60 km down to the tropopause region.

Satellite laser ranging using superconducting nanowire single-photon detectors at 1064  nm wavelength.

PubMed

Xue, Li; Li, Zhulian; Zhang, Labao; Zhai, Dongsheng; Li, Yuqiang; Zhang, Sen; Li, Ming; Kang, Lin; Chen, Jian; Wu, Peiheng; Xiong, Yaoheng

2016-08-15

Satellite laser ranging operating at 1064 nm wavelength using superconducting nanowire single-photon detectors (SNSPDs) is successfully demonstrated. A SNSPD with an intrinsic quantum efficiency of 80% and a dark count rate of 100 cps at 1064 nm wavelength is developed and introduced to Yunnan Observatory in China. With improved closed-loop telescope systems (field of view of about 26^''), satellites including Cryosat, Ajisai, and Glonass with ranges of 1600 km, 3100 km, and 19,500 km, respectively, are experimentally ranged with mean echo rates of 1200/min, 4200/min, and 320/min, respectively. To the best of our knowledge, this is the first demonstration of laser ranging for satellites using SNSPDs at 1064 nm wavelength. Theoretical analysis of the detection efficiency and the mean echo rate for typical satellites indicate that it is possible for a SNSPD to range satellites from low Earth orbit to geostationary Earth orbit.

Mismatch between marine plankton range movements and the velocity of climate change

NASA Astrophysics Data System (ADS)

Chivers, William J.; Walne, Anthony W.; Hays, Graeme C.

2017-02-01

The response of marine plankton to climate change is of critical importance to the oceanic food web and fish stocks. We use a 60-year ocean basin-wide data set comprising >148,000 samples to reveal huge differences in range changes associated with climate change across 35 plankton taxa. While the range of dinoflagellates and copepods tended to closely track the velocity of climate change (the rate of isotherm movement), the range of the diatoms moved much more slowly. Differences in range shifts were up to 900 km in a recent warming period, with average velocities of range movement between 7 km per decade northwards for taxa exhibiting niche plasticity and 99 km per decade for taxa exhibiting niche conservatism. The differing responses of taxa to global warming will cause spatial restructuring of the plankton ecosystem with likely consequences for grazing pressures on phytoplankton and hence for biogeochemical cycling, higher trophic levels and biodiversity.

VizieR Online Data Catalog: Interferometric CO obs. of 126 CALIFA galaxies (Bolatto+, 2017)

NASA Astrophysics Data System (ADS)

Bolatto, A. D.; Wong, T.; Utomo, D.; Blitz, L.; Vogel, S. N.; Sanchez, S. F.; Barrera-Ballesteros, J.; Cao, Y.; Colombo, D.; Dannerbauer, H.; Garcia-Benito, R.; Herrera-Camus, R.; Husemann, B.; Kalinova, V.; Leroy, A. K.; Leung, G.; Levy, R. C.; Mast, D.; Ostriker, E.; Rosolowsky, E.; Sandstrom, K. M.; Teuben, P.; van de Ven, G.; Walter, F.

2018-05-01

Observations of the original 177 CALIFA galaxies sample were conducted by CARMA's E-array in late 2014, integrating 40 minutes per galaxy. 125 galaxies were subsequently (from 2014 December to 2015 March) observed in the more extended D configuration, with an additional ~3.5hr of integration per target. The CARMA correlator was configured with five 250MHz windows covering the 12CO line with 3.4km/s resolution and a 3000km/s velocity range, and three 500MHz windows covering the 13CO line with 14.3km/s resolution and a 3800km/s velocity range. (3 data files).

Global distribution of vertical wavenumber spectra in the lower stratosphere observed using high-vertical-resolution temperature profiles from COSMIC GPS radio occultation

NASA Astrophysics Data System (ADS)

Noersomadi; Tsuda, T.

2016-02-01

We retrieved temperature (T) profiles with a high vertical resolution using the full spectrum inversion (FSI) method from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS radio occultation (GPS-RO) data from January 2007 to December 2009. We studied the characteristics of temperature perturbations in the stratosphere at 20-27 km altitude. This height range does not include a sharp jump in the background Brunt-Väisälä frequency squared (N2) near the tropopause, and it was reasonably stable regardless of season and latitude. We analyzed the vertical wavenumber spectra of gravity waves (GWs) with vertical wavelengths ranging from 0.5 to 3.5 km, and we integrated the (total) potential energy EpT. Another integration of the spectra from 0.5 to 1.75 km was defined as EpS for short vertical wavelength GWs, which was not studied with the conventional geometrical optics (GO) retrievals. We also estimated the logarithmic spectral slope (p) for the saturated portion of spectra with a linear regression fitting from 0.5 to 1.75 km.Latitude and time variations in the spectral parameters were investigated in two longitudinal regions: (a) 90-150° E, where the topography was more complicated, and (b) 170-230° E, which is dominated by oceans. We compared EpT, EpS, and p, with the mean zonal winds (U) and outgoing longwave radiation (OLR). We also show a ratio of EpS to EpT and discuss the generation source of EpS. EpT and p clearly showed an annual cycle, with their maximum values in winter at 30-50° N in region (a), and 50-70° N in region (b), which was related to the topography. At 30-50° N in region (b), EpT and p exhibited some irregular variations in addition to an annual cycle. In the Southern Hemisphere, we also found an annual oscillation in EpT and p, but it showed a time lag of about 2 months relative to U. Characteristics of EpTand p in the tropical region seem to be related to convective activity. The ratio of EpT to the theoretical model value, assuming saturated GWs, became larger in the equatorial region and over mountainous regions.

Regional characteristics of the relationship between columnar AOD and surface PM2.5: Application of lidar aerosol extinction profiles over Baltimore-Washington Corridor during DISCOVER-AQ

NASA Astrophysics Data System (ADS)

Chu, D. Allen; Ferrare, Richard; Szykman, James; Lewis, Jasper; Scarino, Amy; Hains, Jennifer; Burton, Sharon; Chen, Gao; Tsai, Tzuchin; Hostetler, Chris; Hair, Johnathan; Holben, Brent; Crawford, James

2015-01-01

The first field campaign of DISCOVER-AQ (Deriving Information on Surface conditions from COlumn and VERtically resolved observations relevant to Air Quality) took place in July 2011 over Baltimore-Washington Corridor (BWC). A suite of airborne remote sensing and in-situ sensors was deployed along with ground networks for mapping vertical and horizontal distribution of aerosols. Previous researches were based on a single lidar station because of the lack of regional coverage. This study uses the unique airborne HSRL (High Spectral Resolution Lidar) data to baseline PM2.5 (particulate matter of aerodynamic diameter less than 2.5 μm) estimates and applies to regional air quality with satellite AOD (Aerosol Optical Depth) retrievals over BWC (∼6500 km2). The linear approximation takes into account aerosols aloft above AML (Aerosol Mixing Layer) by normalizing AOD with haze layer height (i.e., AOD/HLH). The estimated PM2.5 mass concentrations by HSRL AOD/HLH are shown within 2 RMSE (Root Mean Square Error ∼9.6 μg/m3) with correlation ∼0.88 with the observed over BWC. Similar statistics are shown when applying HLH data from a single location over the distance of 100 km. In other words, a single lidar is feasible to cover the range of 100 km with expected uncertainties. The employment of MPLNET-AERONET (MicroPulse Lidar NETwork - AErosol RObotic NETwork) measurements at NASA GSFC produces similar statistics of PM2.5 estimates as those derived by HSRL. The synergy of active and passive remote sensing aerosol measurements provides the foundation for satellite application of air quality on a daily basis. For the optimal range of 10 km, the MODIS-estimated PM2.5 values are found satisfactory at 27 (out of 36) sunphotometer locations with mean RMSE of 1.6-3.3 μg/m3 relative to PM2.5 estimated by sunphotometers. The remaining 6 of 8 marginal sites are found in the coastal zone, for which associated large RMSE values ∼4.5-7.8 μg/m3 are most likely due to overestimated AOD because of water-contaminated pixels.

Numerical Simulations of Europa Hydrothermal Plumes

NASA Astrophysics Data System (ADS)

Goodman, J. C.; Lenferink, E.

2009-12-01

The liquid water interiors of Europa and other icy moons of the outer solar system are likely to be driven by geothermal heating from the sea floor, leading to the development of buoyant hydrothermal plumes. These plumes potentially control icy surface geomorphology, and are of interest to astrobiologists. We have performed a series of simulations of these plumes using the MITGCM. We assume in this experiment that Europa's ocean is deep (of order 100 km) and unstratified, and that plume buoyancy is controlled by temperature, not composition. A series of experiments was performed to explore a limited region of parameter space, with ocean depth H ranging from 50 to 100 km deep, source heat flux Q between 1 and 10 GW, and values of the Coriolis parameter f between 30% and 90% of the Europa average value. As predicted by earlier work, the plumes in our simulations form narrow cylindrical chimneys (a few km across) under the influence of the Coriolis effect. These plumes broaden over time until they become baroclinically unstable, breaking up into cone-shaped eddies when they become 20-35 km in diameter; the shed eddies are of a similar size. Large-scale currents in the region of the plume range between 1.5 and 5 cm/s; temperature anomalies in the plume far from the seafloor are tiny, varying between 30 and 160 microkelvin. Variations in plume size, shape, speed, and temperature are in excellent agreement with previous laboratory tank experiments, and in rough agreement with theoretical predictions. Plume dynamics and geometry are controlled by a "natural Rossby number" which depends strongly on depth H and Coriolis parameter f, but only weakly on source heat flux Q. However, some specific theoretical predictions are not borne out by these simulations. The time elapsed between startup of the source and the beginning of eddy-shedding is much less variable than predicted; also, the plume temperature varies with ocean depth H when our theory says it should not. Both of these results can be explained by noting that the theory assumes that mixing between plume fluid and ambient fluid occurs only very near the heat source, but this does not appear to be true in the simulations. 3-d view of simulated Europa plume. Boundary indicated by 3-d surface; flat surfaces at left and top show temperature in sections through the plume.

Structure of the Middle America trench in Oaxaca, Mexico

NASA Astrophysics Data System (ADS)

Nava, F.; Núñez-Cornú, F.; Córdoba, D.; Mena, M.; Ansorge, J.; González, J.; Rodríguez, M.; Banda, E.; Mueller, S.; Udías, A.; García-García, M.; Calderón, G.; the Mexican Working GroupDeep Seismic Profiling

1988-11-01

Deep seismic profiling was carried out in south and central Oaxaca as a multinational (Mexico, Spain and Switzerland) project. Sixteen sea-bottom explosions, ranging from 20 to 1000 kg were recorded by thirty portable instruments along three profiles, two along the coast and one going inland in an approximate N-S direction. Gravity surveys were carried out over the seismic profile lines, and the resulting Bouguer anomalies are interpreted together with the seismic data. Preliminary results indicate changes in the crustal thickness along the coast, near the town of Pinotepa Nacional, from 23.5 km in the northwest to 19 km in the southeast, reaching a minimum of some 15 km near the middle of the profile, about 140 km northwest of Puerto Angel. The coastal structure section consists roughly of two layers, an upper one with P-wave velocities that range from 5.1-5.4 to 5.8-6.0 km/s and a lower one where the P velocity range is from 6.0-6.2 to 6.3-6.4 km/s, overlying material with P-wave velocities of 7.45 km/s. Along the coast from Puerto Angel to Salina Cruz, the dip of the Cocos plate appears to be much less than it is to the northwest. A low-velocity zone, which corresponds to the top of the subducted oceanic crust, with P-wave velocities of 6.5-6.9 km/s, is found beneath the 2-3 km thick 7.45 km/s layer. The possible presence of an intrusive body is suggested by anomalous seismic arrivals and by a large gravimetric anomaly near Puerto Angel, close to the southern tip of Mexico.

Sources and fractionation processes influencing the isotopic distribution of H, O and C in the Long Valley hydrothermal system, California, U.S.A.

USGS Publications Warehouse

White, A.F.; Peterson, M.L.; Wollenberg, H.; Flexser, S.

1990-01-01

The isotopic ratios of H, O and C in water within the Long Valley caldera, California reflect input from sources external to the hydrothermal reservoir. A decrease in ??D in precipitation of 0.5??? km-1, from west to east across Long Valley, is caused by the introduction of less fractionated marine moisture through a low elevation embayment in the Sierra Nevada Mountain Range. Relative to seasonal fluctuations in precipitation (-158 to -35??.), ??D ranges in hot and cold surface and groundwaters are much less variable (-135 to -105??.). Only winter and spring moisture, reflecting higher precipitation rates with lighter isotopic signatures, recharge the hydrological system. The hydrothermal fluids are mixtures of isotopically heavy recharge (??D = - 115???, ??18O = - 15???) derived from the Mammoth embayment, and isotopically lighter cold water (??D = -135???, ??18O = -18???). This cold water is not representative of current local recharge. The ??13C values for dissolved carbon in hot water are significantly heavier (- 7 to - 3???) than in cold water (-18 to -10???) denoting a separate hydrothermal origin. These ??13C values overlie the range generally attributed to magmatic degassing of CO2. However, ??13C values of metamorphosed Paleozoic basement carbonates surrounding Long Valley fall in a similar range, indicating that hydrothermal decarbonization reactions are a probable source of CO2. The ??13C and ??18O values of secondary travertime and vein calcite indicate respective fractionation with CO2 and H2O at temperatures approximating current hydrothermal conditions. ?? 1990.

Evidence of equilibrium peak runoff rates in steep tropical terrain on the island of Dominica during Tropical Storm Erika, August 27, 2015

NASA Astrophysics Data System (ADS)

Ogden, Fred L.

2016-11-01

Tropical Storm Erika was a weakly organized tropical storm when its center of circulation passed more than 150 km north of the island of Dominica on August 27, 2015. Hurricane hunter flights had difficulty finding the center of circulation as the storm encountered a high shear environment. Satellite and radar observations showed gyres imbedded within the broader circulation. Radar observations from Guadeloupe show that one of these gyres formed in convergent mid-level flow triggered by orographic convection over the island of Dominica. Gauge-adjusted radar rainfall data indicated between 300 and 750 mm of rainfall on Dominica, most of it over a four hour period. The result was widespread flooding, destruction of property, and loss of life. The extremity of the rainfall on steep watersheds covered with shallow soils was hypothesized to result in near-equilibrium runoff conditions where peak runoff rates equal the watershed-average peak rainfall rate minus a small constant loss rate. Rain gauge adjusted radar rainfall estimates and indirect peak discharge (IPD) measurements from 16 rivers at watershed areas ranging from 0.9 to 31.4 km2 using the USGS Slope-Area method allowed testing of this hypothesis. IPD measurements were compared against the global envelope of maximum observed flood peaks versus drainage area and against simulations using the U.S. Army Corps of Engineers Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model to detect landslide-affected peak flows. Model parameter values were estimated from the literature. Reasonable agreement was found between GSSHA simulated peak flows and IPD measurements in some watersheds. Results showed that landslide dam failure affected peak flows in 5 of the 16 rivers, with peak flows significantly greater than the envelope curve values for the flood of record for like-sized watersheds on the planet. GSSHA simulated peak discharges showed that the remaining 11 peak flow values were plausible. Simulations of an additional 24 watersheds ranging in size from 2.2 to 75.4 km2 provided confirmation that the IPD measurements varied from 40 to nearly 100% of the envelope curve value depending on storm-total rainfall. Results presented in this paper support the hypothesis that on average, the peak discharges scaled linearly with drainage area, and the constant of proportionality was equivalent to 134 mm h-1, or a unit discharge of 37.22 m3 s-1 km-2. The results also indicate that after the available watershed storage was filled after approximately 450-500 mm of rain fell, runoff efficiencies exceeded 50-60%, and peak runoff rates were more than 80% of the peak rainfall rate minus a small constant loss rate of 20 mm h-1. These findings have important implications for design of resilient infrastructure, and means that rainfall rate was the primary determinant of peak flows once the available storage was filled in the absences of landslide dam failure.

Detailed seismic velocity structure beneath the Hokkaido corner, NE Japan: Collision process of the forearc sliver

NASA Astrophysics Data System (ADS)

Kita, S.; Hasegawa, A.; Okada, T.; Nakajima, J.; Matsuzawa, T.; Katsumata, K.

2010-12-01

1. Introduction In south-eastern Hokkaido, the Kuril forearc sliver is colliding with the northeastern Japan arc due to the oblique subduction of the Pacific plate. This collision causes the formation of the Hidaka mountain range since the late Miocene (Kimura, 1986) and delamination of the lower-crust materials of the Kuril forearc sliver, which would be expected to descend into the mantle wedge below (e.g., Ito 2000; Ito and Iwasaki, 2002). In this study, we precisely investigated the three-dimensional seismic velocity structure beneath the Hokkaido corner to examine the collision of two forearcs in this area by using both of data from a dense temporary seismic network deployed in this area (Katsumata et al. [2006]) and those from the Kiban observation network, which covers the entire Japanese Islands with a station separation of 15-20 km. 2. Data and method The double-difference tomography method (Zhang and Thurber, 2003; 2006) was applied to a large number of arrival time data of 201,527 for P-waves and 150,963 for S-waves that were recorded at 125 stations from 10,971 earthquakes that occurred from 1999 to 2010. Grid intervals were set at 10 km in the along-arc direction, 12.5 km perpendicular to it, and 5-10 km in the vertical direction. 3. Results and discussion Inhomogeneous seismic velocity structure was clearly imaged in the Hokkaido corner at depths of 0-120 km. A high-velocity anomaly of P- and S- waves with a volume of 20 km x 90 km x 35km was detected just beneath the main zone of the Hidaka metamorphic belt at depths of 0-35 km. This high-velocity anomaly is continuously distributed from the depths of the mantle wedge to the surface. The western edge of the anomaly exactly corresponds to the Hidaka main thrust (HMT) at the surface. The highest velocity value in the anomaly corresponds to those of the uppermost mantle material (e.g. peridotite). The location of them at depths of 0-35km is also consistent with that of the Horoman-Peridotite belt, which is located at the southwestern edge of the main zone of the Hidaka metamorphic belt.On the other hand, a low-velocity anomaly of P- and S- waves with a volume of 80 km x 100 km x 50 km is distributed to the west of the Hidaka metamorphic belt at depths of 35-90km. This low-velocity anomaly seems to be continuously distributed from the continental crust of the NE Japan forearc. The velocity values of this low-V anomaly correspond to those of crustal materials, which is consistent with results of the tomographic study of Kita et al. [2010, EPSL] and Takanami et al. [1982]. Comparison with the results of seismic reflection surveys of Ito [2000] shows that the boundary between anomalous high-velocity mantle materials and low-velocity continental crustal materials just beneath the Hidaka main thrust (HMT) presently obtained is exactly consistent with the locations of reflection planes of their study. Moreover, our study also suggests that the anomalous low-velocity crustal materials at the mantle wedge depth appears to belong to the NE Japan forearc crust, which does not support the expectation of the previous studies that the delaminated lower-crust materials of the Kuril forearc sliver descends into the mantle wedge due to the collision.

Aerodynamic drag reduction tests on a box-shaped vehicle

NASA Technical Reports Server (NTRS)

Peterson, R. L.; Sandlin, D. R.

1981-01-01

The intent of the present experiment is to define a near optimum value of drag coefficient for a high volume type of vehicle through the use of a boattail, on a vehicle already having rounded front corners and an underbody seal, or fairing. The results of these tests will constitute a baseline for later follow-on studies to evaluate candidate methods of obtaining afterbody drag coefficients approaching the boattail values, but without resorting to such impractical afterbody extensions. The current modifications to the box-shaped vehicle consisted of a full and truncated boattail in conjunction with the faired and sealed underbody. Drag results from these configurations are compared with corresponding wind tunnel results of a 1/10 scale model. Test velocities ranged up to 96.6 km/h (60 mph) and the corresponding Reynolds numbers ranged up to 1.3 x 10 to the 7th power based on the vehicles length which includes the boattail. A simple coast-down technique was used to define drag.

Extreme changes in the dayside ionosphere during a Carrington-type magnetic storm

NASA Astrophysics Data System (ADS)

Tsurutani, Bruce T.; Verkhoglyadova, Olga P.; Mannucci, Anthony J.; Lakhina, Gurbax S.; Huba, Joseph D.

2012-06-01

It is shown that during the 30 October 2003 superstorm, dayside O+ ions were uplifted to DMSP altitudes (~850 km). Peak densities were ~9 × 105 cm-3 during the magnetic storm main phase (peak Dst = -390 nT). By comparison the 1-2 September 1859 Carrington magnetic storm (peak Dst estimated at -1760 nT) was considerably stronger. We investigate the impact of this storm on the low- to mid-latitude ionosphere using a modified version of the NRL SAMI2 ionospheric code. It is found that the equatorial region (LAT = 0° ± 15°) is swept free of plasma within 15 min (or less) of storm onset. The plasma is swept to higher altitudes and higher latitudes due to E × B convection associated with the prompt penetration electric field. Equatorial Ionization Anomaly (EIA) O+ density enhancements are found to be located within the broad range of latitudes ~ ± (25°-40°) at ~500-900 km altitudes. Densities within these peaks are ~6 × 106 oxygen ions-cm-3 at ~700 km altitude, approximately +600% quiet time values. The oxygen ions at the top portions (850-1000 km) of uplifted EIAs will cause strong low-altitude satellite drag. Calculations are currently being performed on possible uplift of oxygen neutrals by ion-neutral coupling to understand if there might be further significant satellite drag forces present.

Eruptive history of Mount Katmai, Alaska

USGS Publications Warehouse

Hildreth, Edward; Fierstein, Judith

2012-01-01

Compositionally, products of Mount Katmai represent an ordinary medium-K arc array, both tholeiitic and calcalkaline, that extends from 51.6% to 72.3% SiO2. Values of 87Sr/86Sr range from 0.70335 to 0.70372, correlating loosely with fractionation indices. The 5–6 km3 of continuously zoned andesite-dacite magma (58%–68% SiO2) that erupted at Novarupta in 1912 was withdrawn from beneath Mount Katmai and bears close compositional affinity with products of that edifice, not with pre-1912 products of the adjacent Trident cluster. Evidence is presented that the 7–8 km3 of high-silica rhyolite (77% SiO2) released in 1912 is unlikely to have been stored under Novarupta or Trident. Pre-eruptive contiguity with the andesite-dacite reservoir is suggested by (1) eruption of ∼3 km3 of rhyolite magma first, followed by mutual mingling in fluctuating proportions; (2) thermal and redox continuity of the whole zoned sequence despite the wide compositional gap; (3) Nd, Sr, O isotopic, and rare earth element (REE) affinities of the whole array; (4) compositional continuity of the nearly aphyric rhyolite with the glass (melt) phase of the phenocryst-rich dacite; and (5) phase-equilibrium experiments that indicate similar shallow pre-eruptive storage depths (3–6 km) for rhyolite, dacite, and andesite.

Synthetic peptides and fluorogenic substrates related to the reactive site sequence of Kunitz-type inhibitors isolated from Bauhinia: interaction with human plasma kallikrein.

PubMed

Oliva, M L; Santomauro-Vaz, E M; Andrade, S A; Juliano, M A; Pott, V J; Sampaio, M U; Sampaio, C A

2001-01-01

We have previously described Kunitz-type serine proteinase inhibitors purified from Bauhinia seeds. Human plasma kallikrein shows different susceptibility to those inhibitors. In this communication, we describe the interaction of human plasma kallikrein with fluorogenic and non-fluorogenic peptides based on the Bauhinia inhibitors' reactive site. The hydrolysis of the substrate based on the B. variegata inhibitor reactive site sequence, Abz-VVISALPRSVFIQ-EDDnp (Km 1.42 microM, kcat 0.06 s(-1), and kcat/Km 4.23 x 10(4) M(-1) s(-1)), is more favorable than that of Abz-VMIAALPRTMFIQ-EDDnp, related to the B. ungulata sequence (Km 0.43 microM, kcat 0.00017 s(-1), and kcat/Km 3.9 x 10(2) M(-1) s(-1)). Human plasma kallikrein does not hydrolyze the substrates Abz-RPGLPVRFESPL-EDDnp and Abz-FESPLRINIIKE-EDDnp based on the B. bauhinioides inhibitor reactive site sequence, the most effective inhibitor of the enzyme. These peptides are competitive inhibitors with Ki values in the nM range. The synthetic peptide containing 19 amino acids based on the B. bauhinioides inhibitor reactive site (RPGLPVRFESPL) is poorly cleaved by kallikrein. The given substrates are highly specific for trypsin and chymotrypsin hydrolysis. Other serine proteinases such as factor Xa, factor XII, thrombin and plasmin do not hydrolyze B. bauhinioides inhibitor related substrates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halliday, M.E.; Cook, K.L.

Regional gravity data were collected in portions of the Pavant Range, Tushar Mountains, northern Sevier Plateau, the Antelope Range, and throughout Sevier Valley approximately between the towns of Richfield and Junction, Utah. Additionally, detailed gravity and ground magnetic data were collected in the vicinity of hot springs in both the Monroe and Joseph Known Geothermal Resource Areas (KGRA's) and subsurface geologic models were constructed. The regional gravity data were terrain corrected out to a distance of 167 km from the station and 948 gravity station values were compiled into a complete Bouguer gravity anomaly map of the survey area. Thismore » map shows a strong correlation with most structural features mapped in the survey area. Four regional gravity profiles were modeled using two-dimensional formerd and inverse algorithms.« less

Establish susceptibility and risk assessment models for rainfall-induced landslide: A case in Central Taiwan

NASA Astrophysics Data System (ADS)

Wu, Chunhung; Huang, Jyuntai

2017-04-01

Most of the landslide cases in Taiwan were triggered by rainfall or earthquake events. The heavy rainfall in the typhoon seasons, from June to October, causes the landslide hazard more serious. Renai Towhship is of the most large landslide cases after 2009 Typhoon Morakot (from Aug. 5 to Aug. 10, 2009) in Taiwan. Around 2,744 landslides cases with the total landslide area of 21.5 km2 (landslide ratio =1.8%), including 26 large landslide cases, induced after 2009 Typhoon Morakot in Renai Towhship. The area of each large landslides case is more than 0.1 km2, and the area of the largest case is around 0.96 km2. 58% of large landslide cases locate in the area with metamorphosed sandstone. The mean slope of 26 large landslide cases ranges from 15 degree to 56 degree, and the accumulated rainfall during 2009 Typhoon Morakot ranges from 530 mm to 937 mm. Three methods, including frequency ratio method (abbreviated as FR), weights of evidence method (abbreviated as WOE), and logistic regression method (abbreviated as LR), are used in this study to establish the landslides susceptibility in the Renai Township, Nantou County, Taiwan. Eight landslide related-factors, including elevation, slope, aspect, geology, land use, distance to drainage, distance to fault, accumulation rainfall during 2009 Typhoon Morakot, are used to establish the landslide susceptibility models in this study. The landslide inventory after 2009 Typhoon Morakot is also used to test the model performance in this study. The mean accumulated rainfall in Renai Township during 2009 typhoon Morakot was around 735 mm with the maximum 1-hr, 3-hrs, and 6-hrs rainfall intensity of 44 mm/1-hr, 106 mm/3-hrs and 204 mm/6-hrs, respectively. The range of original susceptibility values established by three methods are 4.0 to 20.9 for FR, -33.8 to -16.1 for WOE, and -41.7 to 5.7 for LR, and the mean landslide susceptibility value are 8.0, -24.6 and 0.38, respectively. The AUC values are 0.815 for FR, 0.816 for WOE, and 0.823 for LR. The study normalized the susceptibility value range of three landslide susceptibility models to 0 to 1 to deeply compare the model performance. The normalized landslide susceptibility value > 0.5 and ≦0.5 are regarded as predicted-landslide area and predicted-not-landslide area. The ratio of the area in the predicted-landslide area to the total area is 3.0% for FR, 71.4% for WOE, and 26.5% for LR. And the correct ratio is 65.5% for FR, 61.9% for WOE, 74.5% for LR. The study adopted 14 rainfall stations with more than 20 years daily rainfall data in Renai Township to estimate the 24 hrs accumulated rainfall with different RPYs. Landslide susceptibility map under 24 hrs accumulated rainfall distribution with different RPYs is used to estimate the landslide disaster location and scale. The landslide risk under different RPYs in Renai Township is calculated as 2.62 billion for 5 RPYs, 3.06 billion for 10 RPYs, 4.69 billion for 25 RPYs, 5.97 billion for 50 RPYs, 6.98 billion for 100 RPYs, and 8.23 billion for 200 RPYs, respectively.

Thermo-optical vacuum testing of IRNSS laser retroreflector array qualification model

NASA Astrophysics Data System (ADS)

Porcelli, L.; Boni, A.; Ciocci, E.; Contessa, S.; Dell'Agnello, S.; Delle Monache, G.; Intaglietta, N.; Martini, M.; Mondaini, C.; Patrizi, G.; Salvatori, L.; Tibuzzi, M.; Lops, C.; Cantone, C.; Tuscano, P.; Maiello, M.; Venkateswaran, R.; Chakraborty, P.; Ramana Reddy, C. V.; Sriram, K. V.

2017-09-01

We describe the activities performed by SCF_Lab (Satellite/lunar/GNSS laser ranging/altimetry and cube/microsat Characterization Facilities Laboratory) of INFN-LNF for the thermo-optical vacuum testing activity of a IRNSS (Indian Regional Navigation Satellite System) LRA (Laser Retroreflector Array), under contract for ISRO-LEOS. To our knowledge, this is the first publication on the characterization of the optical performance of an LRA operating at about 36,000 km altitude (typical of regional GNSS segments, namely QZSS, COMPASS-G) executed in fully representative, carefully lab-simulated space conditions. In particular, this is the only such publication concerning IRNSS. Since laser ranging to its altitude is more challenging than to GNSS altitudes (from about 19,100 km for GLONASS to about 23,200 km for Galileo), comparative measurements were long awaited by ILRS (International Laser Ranging Service) and we present measurements of the absolute laser return to ground stations of the ILRS in terms of lidar OCS (Optical Cross Section) at the IRNSS relevant value of velocity aberration, in turn derived from measurements of the full FFDP (Far Field Diffraction Pattern) over a very large range of velocity aberrations. These measurements were acquired: (i) on a full-size qualification model of a IRNSS CCR (Cube Corner Retroreflector) LRA that ISRO-LEOS provided to INFN-LNF; (ii) during the lab-simulation of a 1/4 orbit segment, in which the LRA CCRs are exposed to the perturbation of the sun heat at varying angles, from grazing incidence (90° with respect to the direction perpendicular to the plane of array), up to the perpendicular to the LRA, with a same time variation consistent with the actual space orbit. In this 1/4 orbit condition, the LRA experiences potentially large thermal degradations of the OCS, depending on the detailed thermal and mechanical design of the LRA. Since all GNSS constellations have different LRA designs or configurations, this is another reason of the interest in the laboratory optical performance of the IRNSS designs. In fact, we tested two different IRNSS LRA configurations, without and with an auxiliary cover. The latter of the configurations is designed to give a somewhat increased performance. We also measured FFDPs and OCS: (1) in-air isothermal conditions (thus obtaining the LRA nominal performance); (2) in space conditions at a low, stationary value of the LRA bulk temperature; (3) in space conditions at a high, stationary value of the LRA bulk temperature (Figs. S1-S18, available in the online supplementary material for this paper). In all these three cases, we measured FFDPs and OCS at the following laser incidence angles: (a) normal to the LRA plane; (b) +9° to the normal to the LRA plane; (c) -9° to the normal to the LRA plane. This is the first time, to our knowledge, that the measurements (not simulations) at ±9° (values requested by ISRO-LEOS) are published for GNSS LRAs. Finally, we point out that we measured full-FFDP and OCS of single CCRs, for maximum diagnostic value and performance validation at subelement level. For all these reasons, the articulate and variate set of tests of the IRNSS LRA reported in this paper is unique.

Field-aligned electrostatic potential differences on the Martian night side

NASA Astrophysics Data System (ADS)

Lillis, Rob; Collinson, Glyn; Mitchell, David

2017-04-01

Field-aligned electrostatic potential differences on the Martian night side above 170 km can be inferred with the aid of a kinetic electron transport model and in a statistical sense, by energy-dependent angular shifts in electron loss cones measured in Mars orbit. Potentials between 170 km and 400 km derived from pitch angle distributions measured by the Mars Global Surveyor (MGS) Magnetometer/ Electron Reflectometer experiment (MAG/ER) at 2 a.m. local time are typically small (-10 V to 10 V) but can reach magnitudes of >100 V. Geographically, the strongest negative potential differences (with mean values up to -50 V) are preferentially observed at the boundaries between open and closed strong magnetic field regions, while positive potential differences are preferentially observed further from open field lines. These characteristics may reflect current systems closing at high altitude through cross-tail currents and at low altitude in the conducting night side ionosphere. We will present a synthesis of potentials derived from pitch angle distributions measured by both MGS MAG/ER as mentioned above, and by the MAVEN Solar Wind Electron Analyzer (SWEA) collected at a range of local times and altitudes.

Collisionality and temperature dependence of the edge main-ion co-current rotation profile feature on DIII-D

NASA Astrophysics Data System (ADS)

Haskey, Shaun; Grierson, Brian; Ashourvan, Arash; Battaglia, Devon; Chrystal, Colin; Burrell, Keith; Groebner, Richard; Degrassie, John; Stagner, Luke; Stoltzfus-Dueck, Timothy; Pablant, Novimir

2017-10-01

A new edge main-ion (D+) CER system and upgraded edge impurity system are revealing clear differences between the main-ion and dominant impurity (C6+) toroidal rotation from the pedestal top to the scrape off layer on DIII-D with implications for intrinsic rotation studies. A peaked co-current edge toroidal rotation is observed for the main ion species near the outboard midplane separatrix with values up to 140 km/s for low collisionality QH modes. In lower power (PNBI = 0.8MW) H-modes the edge rotation is still present but reduced to 50km/s. D+ and C6+ toroidal rotation differences are presented for a variety of scenarios covering a significant range of edge collisionality and Ti. Observations are compared with predictions from several models including collisionless ion orbit loss calculations and more complete modeling using the XGC0 code, which also predicts 140km/s edge rotation for low collisionality QH mode cases. Work supported by the U.S. DOE under DE-AC02-09CH11466, No. DE-FC02-04ER54698, and DE-FC02-95ER54309.

Photographer : JPL Range : 5 million km. ( 3 million miles ) This photograph, shot from Voyager I,

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 5 million km. ( 3 million miles ) This photograph, shot from Voyager I, shows Jupiter's Great Red Spot, turbulent regions immediattely to the west, and, middle right, one of the several white ovals seen on Jupiter from Earth. This photograph represents much better resolution than ever seen by telescopic means to date. The Red Spot and Ovals both reveal intricate, involved structures, the smallest details of which, are estimated at 95 km. ( 55 miles ) across.

Schmidt-hammer exposure-age dating (SHD) of Lateglacial rock glacier systems near the eastern margin of the European Alps

NASA Astrophysics Data System (ADS)

Kellerer-Pirklbauer, Andreas

2016-04-01

Rock glaciers are widespread permafrost landforms in Austria. Various rock glacier inventories list more than 4500 rock glaciers in the country; some 30-40% of them are intact. Relict (permafrost free) and pseudo-relict rock glaciers (sporadic and isolated permafrost particularly near the root zone) prevail in number. Rock glaciers are commonly formed over a period of several ka. Dating such landforms helps to understand palaeoclimatic conditions. In this study three rock glaciers consisting of gneiss were dated applying the Schmidt-hammer exposure-age dating (SHD) method. The rock glaciers are located at three neighbouring cirques in the Seckauer Tauern Range named Reichart Rock Glacier (RRG, area 1.26 km², length 1800 m, elevation range 1520-1940 m a.s.l.), Schöneben Rock Glacier (SRG, 0.11 km², 750 m, 1715-1905 m a.s.l.), and Dürrtal Rock Glacier (DRG, 0.08 km², 850 m, 1750-1980 m a.s.l.). RRG is one of the largest rock glaciers in Austria. All three landforms are influenced by lenses of permafrost at present (as indicated by ERT). During the LGM the Seckauer Tauern were covered by valley glaciers and deglaciation occurred presumably already early in the Alpine Lateglacial period. An analogue N-type Schmidt-hammer (proceq) was used for measuring the surface strength of stable blocks at the rock glacier surface by recording a rebound value (R-value) of a spring-loaded bolt. The R-value gives a relative measure of the surface hardness and hence time since exposure to weathering. Eight (RRG) or six (SRG, DRG) Schmidt-hammer measurement sites (with 50-100 individual readings) aligned along longitudinal transects (=former central flow line) between a talus slope (with relatively fresh boulders) in the root zone and the frontal ridge were measured. Mean R-value differences of 30.5 at RRG, 25.1 at SRG, and 20.7 at DRG were revealed along the three transects. The differences between the lowest and the highest R-value at the rock glaciers itself were 19.0 at RRG, 15.2 at SRG, and 10.5 at DRG. The differences in R-values between the talus slopes and the uppermost Schmidt-hammer site at the rock glacier were 11.5 at RRG, 9.9 at SRG, and 10.2 at DRG. No high-quality age control points are available at the studied rock glacier. Therefore, an age-calibration curve cannot be established. An age-calibration curve for gneiss has been established previously for a rock glacier c.110 km west of the study area yielding a mean decrease of 1.46 R/1 ka. This allows the estimate that the rock glacier formation period in the study area stretched over a period of several ka. Not unlikely, the formation of the rock glaciers was initiated already during the Gschnitz stadial (Heinrich 1 ice rafting event) dated to 15.4 ka BP or even earlier. SRG is the oldest rock glacier possibly starting to form during the later part of the Lateglacial ice decay-phase. At least 7-8 ka ago the stabilisation of the uppermost part of the three rock glaciers was accomplished. This rather late stabilisation might be also related to the thermally inert response of coarse rock glacier systems.

Ground Motion in Lima: Pisco Earthquake of August 15, 2007 (Mw7.9)

NASA Astrophysics Data System (ADS)

Bernal, I.; Tavera, H.

2008-05-01

On 15 of August of 2007 at 06h 40min, local time, the central region of Peru was shooked by an earthquake magnitude Mw=7.9 with epicenter at 13.49°S and -76.85°W; this is, 74 km west of the city of Pisco. The earthquake was recorded by a total of fourteen accelerometers that operate in the city of Lima which show clearly the development of a complex process of rupture formed by two sources (R1 and R2) separated by 60-70 seconds. Maximum acceleration registered in the city of Lima was of 115.2 cm/seg² (0.12g) in the Urb. The Rinconada of the district the Molina located 155 km northwest from the epicenter. The periods associated to the maximum spectral acceleration appear to be between 0.1 to 0.4s in RIN and MOL, both located in the La Molina District; for ANC, CSM, MAY located in the Ancon, Rímac and Ate Vitarte district, are within the range of 0.1-0.6s; for CER, ANR, PUCP, CLD-CIP located in the San Borja, Santiago de Surco, San Miguel and San Isidro district the range is of 0.1-1.2s, and for CAL in Callao it is of 0.1-1.6s. The predominant periods have values close to 0.1s in the Molina and San Miguel distric, of 0.2s in Ate Vitarte and Rimac, of 0.3s in the Molina, Rimac, Ate Vitarte and Ancon, and of 0.5s in Santiago de Surco disctrict. In the Molina district, two acelerometric stations are located at less than 2 km away from each other, and present predominant periods next to 0.1s and 0.3s, which implies a strong variation of the physical properties of the ground at short distances. Shear wave velocity estimates, using the unidimensional method at stations MOL, MAY and ANC, give values of 80 m/s (with thicknesses less than 2 m), 200 m/s (with thicknesses less than 9 m) and of 690 m/s for the halfspace, values that suggest a compacted ground with respect to the rest of stations. Stations CAL and RIN show velocities of 60 of m/s (with thicknesses of 11 and 3 m respectively), a second layer of 140 m/s (with thicknesses of 12 and 7 m) over a halfspace of 450 m/s. These values are interpreted as representing less compacted grounds.

Monitoring diffuse degassing in monogentic volcanic field during a quiescent period: the case of Cumbre Vieja (La Palma,Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Burns, F.; Cole, M.; Vaccaro, W.; Alonso Cótchico, M.; Melián, G.; Asensio-Ramos, M.; Padron, E.; Hernandez Perez, P. A.; Perez, N. M.

2017-12-01

Volcanic activity at La Palma (Canary Islands) in the last 123 ka has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano, which is characterized by a main north-south rift zone 20 km long and up to 1950 m in elevation and covering an area of 220 km2 with vents located also at the northwest and northeast. Cumbre Vieja is the most active basaltic volcano in the Canaries with 7 historical eruptions being San Juan (1949) and Teneguía (1971) the most recent ones. Since no visible degassing (fumaroles, etc.) at Cumbre Vieja occurs, our geochemical program for the volcanic surveillance of Cumbre Vieja is mainly focused on diffuse degassing monitoring. Diffuse CO2 emission surveys are yearly performed in summer to minimize the influence of meteorological variations. About 570 sampling sites were selected for each survey to obtain a homogeneous distribution after taking into consideration the local geology, structure, and accessibility. Measurements of soil CO2 efflux were performed in situ by means of a portable non-dispersive infrared sensor following the accumulation chamber method. The soil CO2 efflux values of the 2017 survey ranged from non-detectable to 47.7 g m-2 d-1. Statistical-graphical analysis of the data show two different geocheleemical populations; background (B) and peak (P) represented by 98.2% and 1.8% of the total data, respectively. The geometric means of the B and P populations are 2.9 and 36.5 g m-2 d-1, respectively. Most of the area showed B values while the P values were mainly observed both flanks of the main N-S volcanic rift. To estimate the diffuse CO2 emission in metric tons per day released from Cumbre Vieja (220 km2) for the 2017 survey, we ran about 100 sGs simulations. The estimated 2017 diffuse CO2 output released to atmosphere by Cumbre Vieja was at 801 ± 27 t d-1, value relatively higher than the background average of CO2 emission estimated on 374 t d-1 and within the background range of 132 t d-1 (-1σ) and 1.254 t d-1 (+1σ) observed at Cumbre Vieja volcano during the period 2001-2013 (Padrón et al., 2015. Bull. Volcanol. 77:28). Monitoring the diffuse CO2 emission contributes to detect early warning signals of volcanic unrest at Cumbre Vieja volcano.

Assessing Controls on the Geometry and Dimensions of Modern Barrier Islands

NASA Astrophysics Data System (ADS)

Mulhern, J.; Johnson, C. L.; Martin, J. M.

2015-12-01

Barrier islands are highly ephemeral features, shaped by wave, tide, and storm energy. The processes that govern the size, shape, and motion of barrier islands are not well constrained, yet central to coastal dynamics. While the global distribution of barrier islands has been mapped and assessed, there is little consensus on the forces controlling barrier island formation, motion, or preservation. This study presents a new semi-global database of modern barrier islands to better understand their morphology and spatial distribution. We have mapped, in Google Earth, the subaerial extent of >350 barrier islands and spits, measuring spatial characteristic such as exposed area, perimeter, length, and width. These objects are cross-referenced with parameters that potentially control morphology, including tidal range, wave height, climate, distance from the continental shelf, proximity to fluvial output, and tectonic setting. This approach provides a more optimal framework to assess controls on coastal features, including barrier island morphology, and to investigate potential geometric scaling relationships. Preliminary analysis shows trends in the spatial characteristics of barrier islands. There is a strong linear relationship between the perimeter and length (y= -0.59 + 0.42x, R2=0.95). Linear trends also relate length to area when the data are separated by tidal range to wave height ratio. Assessment of barrier island shape supports the hypothesis of Hayes (1979) that barrier islands in wave-dominated settings are long and linear while those in mixed energy setting are more rounded. The barrier islands of the Texas Gulf of Mexico are larger than the global average for the database, with distinctly longer length values (41.16 km vs. 15.77 km respectively) and larger areas (103.81 km2 vs. 42.14 km2 respectively). Initial assessment shows that tidal range and wave height are primary controls barrier island dimensions. Future work will consider climate, latitude, fluvial input, and tectonic regime as additional factors. Assessing modern barrier islands will lend insight into potential paleomorphodynamic relationships and help determine how islands are transferred into the rock record, with implications for sequence stratigraphy, subsurface reservoirs, etc.

Influence of seasonality and vegetation on the attenuation of emerging contaminants in wastewater effluent-dominated streams. A preliminary study.

PubMed

Matamoros, Víctor; Rodríguez, Yolanda

2017-11-01

Treated wastewater from small communities is discharged into rivers or streams with a high biodiversity value. This is particularly important in Mediterranean countries, where most of the streams are dry almost all year round. This preliminary study assessed the occurrence and attenuation of 23 emerging contaminants (ECs) in 4 wastewater-dominated streams in which treated wastewater accounted for the entire stream flow. The concentration of ECs was monitored in the warm and cold seasons in the wastewater treatment plant (WWTP) effluent and at 6 downstream locations. The concentration of ECs in the WWTP effluents ranged from undetected to 12 μg L -1 . The attenuation of ECs 1 km downstream ranged from no removal to up to 80% (48% on average). The half-lives of ECs in the 4 streams ranged from 0.4 to 20 h (3.9 ± 3.5 h on average). Compounds such as benzodiazepine drugs and flame retardants were the most recalcitrant (half-lives >5 h). The highest attenuation of ECs and ammonia was observed in the stream completely covered by vegetation. The cumulative hazardous quotient 1 km downstream was reduced on average by more than 60%. Therefore, the results suggest that both seasonality and vegetation play an important role in in-stream attenuation of ECs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Petrogenesis of low-δ18O quartz porphyry dykes, Koegel Fontein complex, South Africa

NASA Astrophysics Data System (ADS)

Harris, Chris; Mulder, Kwenidyn; Sarkar, Saheli; Whitehead, Benjamin; Roopnarain, Sherissa

2018-04-01

This paper investigates the origin of low-δ18O quartz porphyry dykes associated with the 144-133 Ma Koegel Fontein Igneous Complex, which was intruded during the initial phase of breakup of Africa and South America. The 25-km diameter Rietpoort Granite is the largest and youngest phase of activity, and is roofed by a 10-km diameter pendant of gneiss. Quartz porphyry (QP) dykes, up to 15 m in width, strike NW-SE across the complex. The QP dykes that intruded outside the granite have similar quartz phenocryst δ18O values (average 8.0‰, ± 0.7, n = 33) to the granite (average 8.3 ± 1.0, n = 7). The QP dykes that intruded the roof pendant have quartz phenocrysts with more variable δ18O values (average 1.6‰, ± 2.1, n = 55). In some cases quartz phenocrysts have δ18O values as low as - 2.5‰. The variation in δ18O value within the quartz crystal population of individual dykes is small relative to the overall range, and core and rim material from individual quartz phenocrysts in three samples are identical within error. There is no evidence that quartz phenocryst δ18O values have been affected by fluid-rock interaction. Based on a Δquartz-magma value of 0.6‰, magma δ18O values must have been as low as - 3.1‰. Samples collected along the length of the two main QP dykes that traverse the roof pendant have quartz phenocryst δ18O values that range from + 1.1 to + 4.6‰, and - 2.3 to + 5.6‰, respectively. These δ18O values correlate negatively ( r = - 0.96) with initial 87Sr/86Sr, which can be explained by the event that lowered δ18O values of the source being older than the dykes. We suggest that the QP dykes were fed by magma produced by partial melting of gneiss, which had been variably altered at high temperature by 18O-depleted meteoric water during global glaciation at 550 Ma. The early melts had variable δ18O value but as melt pockets interconnected during melting, the δ18O values approached that of average gneiss. Variable quartz phenocryst δ18O values in the same dyke can be explained by vertical emplacement, at variable rates of ascent along the dyke. The lateral variation in quartz, and hence magma δ18O value at a particular point along a single dyke would depend on the rate of ascent of magma at that point along the dyke, and the `age' of the particular magma batch.

Investigations on the links between rain intensity or reflectivity structures estimated from radar and drop size distributions

NASA Astrophysics Data System (ADS)

Hachani, Sahar; Boudevillain, Brice; Bargaoui, Zoubeida; Delrieu, Guy

2015-04-01

During the first Special Observation Period (SOP) of the Hydrological cycle in the Mediterranean Experiment (HyMeX, www.hymex.org) held in fall 2012 in the Northwestern Mediterranean region, an observation network dedicated to rain studies was implemented in the Cévennes region, France. It was mainly constituted by weather radars, micro rain radars, disdrometers and rain gauges. Observations are performed by a network of 25 OTT Parsivel optical disdrometers distributed with inter-distances ranging from a few meters up to about one hundred kilometers. This presentation focuses on the comparison of one optical disdrometer observations located at Villeneuve-de-berg to observations using weather Météo-France / ARAMIS radar located at Bollène which is in a neighborhood of 60 km from the disdrometer.The period from September to November 2012 is studied. To analyze the structure of the rain observed by radar, a window of investigation centered on the disdrometer was selected and the mean spatial values, standard deviation, gradients, and intermittency of radar reflectivity or rainfall intensity were computed for a time step of 5 minutes.Four different windowsizes were analyzed: 1 km², 25 km², 100 km² and 400 km². On the other hand, the total concentration of drops Nt, the characteristic diameter of drops Dc, and a Gamma distribution shape parameter µ were estimated. Gamma distribution for the DSD related to disdrometer observations was estimated according to the modeling framework proposed by Yu et al. (2014). Correlation coefficient between intensity R obtained by the disdrometer and windowaverage R estimated using radar data is nearly 0.70 whatever the window. The highest value is found for the window 25 km² (0.74). Correlation coefficients between Dc and window average R vary from 0.35 for the window 1 km² to 0.4 for the window 400 km². So, they areweak and not sensitive to the choice of the window. Contrarily, formean radar reflectivityZ, correlation coefficients with Dc, Nt and µ vary to some extent from the window size 1 km² to the window size 100 km². The most sensitive is the correlation coefficient between Z and Nt. However it presents the smallest correlations while the highest correlations are found for Dc (respectively 0.80 and 0.74). The overall of relations between the rainfall structure variables and DSD parameters will be presented in the communication with a special attention to the weather and/or rainfall types (orographic, stratiform, and convective). References: Yu, N., Delrieu, G., Boudevillain, B., Hazenberg, P., and Uijlenhoet, R., 2014: Unified formulation of single and multi-moment normalizations of the raindrop size distribution based on the gamma probability density function. Journal of Applied Meteorology and Climatology, 53, pp 166-179.

Defining space use and movements of Canada lynx with global positioning system telemetry

USGS Publications Warehouse

Burdett, C.L.; Moen, R.A.; Niemi, G.J.; Mech, L.D.

2007-01-01

Space use and movements of Canada lynx (Lynx canadensis) are difficult to study with very-high-frequency radiocollars. We deployed global positioning system (GPS) collars on 11 lynx in Minnesota to study their seasonal space-use patterns. We estimated home ranges with minimum-convex-polygon and fixed-kernel methods and estimated core areas with area/probability curves. Fixed-kernel home ranges of males (range = 29-522 km2) were significantly larger than those of females (range = 5-95 km2) annually and during the denning season. Some male lynx increased movements during March, the month most influenced by breeding activity. Lynx core areas were predicted by the 60% fixed-kernel isopleth in most seasons. The mean core-area size of males (range = 6-190 km2) was significantly larger than that of females (range = 1-19 km2) annually and during denning. Most female lynx were reproductive animals with reduced movements, whereas males often ranged widely between Minnesota and Ontario. Sensitivity analyses examining the effect of location frequency on home-range size suggest that the home-range sizes of breeding females are less sensitive to sample size than those of males. Longer periods between locations decreased home-range and core-area overlap relative to the home range estimated from daily locations. GPS collars improve our understanding of space use and movements by lynx by increasing the spatial extent and temporal frequency of monitoring and allowing home ranges to be estimated over short periods that are relevant to life-history characteristics. ?? 2007 American Society of Mammalogists.

The life cycle assessment of alternative fuel chains for urban buses and trolleybuses.

PubMed

Kliucininkas, L; Matulevicius, J; Martuzevicius, D

2012-05-30

This paper describes a comparative analysis of public transport alternatives in the city of Kaunas, Lithuania. An LCA (Life Cycle Assessment) inventory analysis of fuel chains was undertaken using the midi urban bus and a similar type of trolleybus. The inventory analysis of fuel chains followed the guidelines provided by the ISO 14040 and ISO 14044 standards. The ReCiPe Life Cycle Impact Assessment (LCIA) methodology was used to quantify weighted damage originating from five alternative fuel chains. The compressed biogas fuel chain had the lowest weighted damage value, namely 45.7 mPt/km, whereas weighted damage values of the fuel chains based on electricity generation for trolleybuses were 60.6 mPt/km (for natural gas) and 78.9 mPt/km (for heavy fuel oil). The diesel and compressed natural gas fuel chains exhibited considerably higher damage values of 114.2 mPt/km and 132.6 mPt/km, respectively. The comparative life cycle assessment of fuel chains suggested that biogas-powered buses and electric trolleybuses can be considered as the best alternatives to use when modernizing the public transport fleet in Kaunas. Copyright © 2012 Elsevier Ltd. All rights reserved.

The granite problem as exposed in the southern Snake Range, Nevada

USGS Publications Warehouse

Lee, D.E.; Christiansen, E.H.

1983-01-01

A geochemically and mineralogically diverse group of granitoids is present within an area of 900 km2 in the southern Snake Range of eastern Nevada. The granitoids exposed range in age from Jurassic through Cretaceous to Oligocene and include two calcic intrusions, two different types of two-mica granites, and aplites. The younger intrusions appear to have been emplaced at progressively more shallow depths. All of these granitoid types are represented elsewhere in the eastern Great Basin, but the southern Snake Range is distinguished by the grouping of all these types within a relatively small area. The Jurassic calcic pluton of the Snake Creek-Williams Canyon area displays large and systematic chemical and mineralogical zonation over a horizontal distance of five km. Although major element variations in the pluton compare closely with Daly's average andesite-dacite-rhyolite over an SiO2 range of 63 to 76 percent, trace element (Rb, Sr, Ba) variations show that the zonation is the result of in situ fractional crystallization, with the formation of relatively mafic cumulates on at least one wall of the magma chamber. Models of trace element and isotopic data indicate that relatively little assimilation took place at the level of crystallization. Nonetheless, an initial 87Sr/86Sr value of 0.7071 and ??18O values of 10.2 to 12.2 permil suggest a lower crustal magma that was contaminated by upper crustal clastic sedimentary rocks before crystallization. The involvement of mantle-derived magmas in its genesis is difficult to rule out. Two other Jurassic plutons show isotopic and chemical similarities to the Snake Creek-Williams Canyon pluton. Cretaceous granites from eastern Nevada that contain phenocrystic muscovite are strongly peraluminous, and have high initial Sr-isotope ratios and other features characteristic of S-type granitoids. They were probably derived from Proterozoic metasediments and granite gneisses that comprise the middle crust of this region. Another group of granitoids (including the Tertiary aplites) show chemical, mineralogic, and isotopic characteristics intermediate between the first two groups and may have been derived by contamination of magmas from the lower crust by the midcrustal metasediments. ?? 1983 Springer-Verlag.

Seismic b-values and its correlation with seismic moment and Bouguer gravity anomaly over Indo-Burma ranges of northeast India: Tectonic implications

NASA Astrophysics Data System (ADS)

Bora, Dipok K.; Borah, Kajaljyoti; Mahanta, Rinku; Borgohain, Jayanta Madhab

2018-03-01

b-value is one of the most significant seismic parameters for describing the seismicity of a given region at a definite time window. In this study, high-resolution map of the Gutenberg-Richter b-value, seismic moment-release, Bouguer gravity anomaly and fault-plane solutions containing faulting styles are analyzed in the Indo-Burma ranges of northeast India using the unified and homogeneous part of the seismicity record in the region (January 1964-December 2016). The study region is subdivided into few square grids of geographical window size 1° × 1° and b-values are calculated in each square grid. Our goal is to explore the spatial correlations and anomalous patterns between the b-value and parameters like seismic moment release, Bouguer gravity anomaly and faulting styles that can help us to better understand the seismotectonics and the state of present-day crustal stress within the Indo-Burma region. Most of the areas show an inverse correlation between b-value and seismic moment release as well as convergence rates. While estimating the b-value as a function of depth, a sudden increase of b-value at a depth of 50-60 km was found out and the receiver function modeling confirms that this depth corresponds to the crust-mantle transition beneath the study region. The region is also associated with negative Bouguer gravity anomalies and an inverse relation is found between Gravity anomaly and b-value. Comparing b-values with different faulting styles, reveal that the areas containing low b-values show thrust mechanism, while the areas associated with intermediate b-values show strike-slip mechanism. Those areas, where the events show thrust mechanism but containing a strike-slip component has the highest b-value.

Volatile contents of magmas from the Deccan and Columbia River provinces: implications for atmospheric gas release from flood basalt eruptions

NASA Astrophysics Data System (ADS)

Self, S.; Blake, S.; Sharma, K.; Widdowson, M.

2008-12-01

Sulphur (S) and chlorine (Cl) contents of magmas from the Mesozoic Deccan basalt province have been measured directly on rare, preserved glass inclusions within crystals and on glassy selvages in these ancient lava flows (Self et al., 2008). Lava flows of the Deccan Traps, India, were emplaced around 66-65 Ma ago. S and Cl concentrations range from high values of ~ 1400 ppm S and 500 ppm Cl in inclusions down to a few hundred ppm in lava selvages. The data indicate that the basaltic magmas of certain (and by implication, many) Deccan eruptions would have emitted up to 0.15 wt % SO2 and up to 0.03 wt % HCl, using an approach that accounts for the variable degree of melt evolution. Such values imply atmospheric releases of ~ 4 Tg of SO2 (and 0.8 Tg HCl) per cubic kilometer (km) of basaltic lava erupted, with most of this being released above the vents. Although eruptive volumes of individual Deccan flood basalt lava fields are not known, the SO2 masses released are indicated to be around 4000 Tg for a 1000 cubic km eruption. Similar, to slightly higher, values for S and Cl have been recently obtained by the same method on two other lava flow fields besides the already-studied Roza lava (Thordarson and Self, 1996) from the 15 Ma Columbia River flood basalt province (CRB) in the Pacific NW of the USA. Volumes of individual eruptive units are known for the CRB (those studied are from 1300-2600 cubic km) and it can be shown that the studied eruptions released SO2 masses in the range 8,000 to 12000 Tg, depending upon flow-field volume. In some cases, the vent areas for these eruptions can be explored. Understanding the eruptive style indicated by proximal deposits will help in future modeling of the atmospheric behavior of the eruption columns, and in heights attained. These results provide a solid basis for interpretation and modeling of the environmental impact of gas releases from past flood basalt activity, which has long been assumed to have been severe. The significance of flood basalt volcanism is that the erupted volumes, and hence the potential environmental pollution caused by the gases released, were immense on a scale compared to smaller-scale historic and Quaternary basaltic eruptive activity.

Upper-Crustal Structure of the Møre Margin, Offshore-Norway

NASA Astrophysics Data System (ADS)

Moronfoye, A. T.; Ronen, S.; Klemperer, S. L.; Alves, G. C.

2016-12-01

The Møre Margin is a segment of the volcanic passive continental margin offshore mid Norway which formed as a result of the early-Cenozoic opening of the Norwegian-Greenland Sea. The Møre Margin has been interpreted as a `volcanic rifted margin', with voluminous basaltic lavas accompanied by a mafic underplate of velocities greater than 7 km/s. The Møre Margin is a region of interest for oil and gas exploration, and characterization of a layer with seismic velocities above 7 km/s could help understand the time-temperature history of its basin. However, seismic exploration of the Møre Margin is greatly complicated by the problems of sub-basalt imaging. We picked refraction arrivals from 2D seismic data acquired by Seabed Geosolutions using a common-receiver gather from a line of 179 4-component ocean-bottom nodes that spanned 85 km west to east. The source was an airgun of 4000 in3 and was fired at 100 m intervals to a maximum offset of 100 km. We used Seismic Unix to apply a linear-moveout reduction velocity, and estimated the velocities and thicknesses of the layers down to a prominent reflector believed to be either the basalt layer or the mafic underplate. The P-wave velocity, Vp, ranges from about 2 km/s at the seabed to 2.4 km/s above the prominent reflecting layer which has a velocity of 5 km/s. Using the horizontal component data, we identified a converted S wave refraction and used its travel time to estimate an average Vp/Vs ratio of just under 2 in the 2 km/s sedimentary layer, a value consistent with compacted sediments. Based on the seismic velocities calculated and an assessment of laboratory sonic-velocity measurements, we concluded that the primary reflector is likely weathered or vesicular basalt. We also generated synthetic travel-time curves from a velocity model that included a mafic underplate at a depth of about 20 km, as proposed in earlier studies. Our calculated refraction travel time curves suggest that our 85 km receiver line may be too short to identify a mafic underplate at such depth, even with a velocity greater than 7 km/s.

European VLBI Network imaging of 6.7 GHz methanol masers

NASA Astrophysics Data System (ADS)

Bartkiewicz, A.; Szymczak, M.; van Langevelde, H. J.

2016-03-01

Context. Methanol masers at 6.7 GHz are well known tracers of high-mass star-forming regions. However, their origin is still not clearly understood. Aims: We aimed to determine the morphology and velocity structure for a large sample of the maser emission with generally lower peak flux densities than those in previous surveys. Methods: Using the European VLBI Network (EVN) we imaged the remaining sources from a sample of sources that were selected from the unbiased survey using the Torun 32 m dish. In this paper we report the results for 17 targets. Together they form a database of a total of 63 source images with high sensitivity (3σrms = 15-30 mJy beam-1), milliarcsecond angular resolution (6-10 mas) and very good spectral resolution (0.09 km s-1 or 0.18 km s-1) for detailed studies. Results: We studied in detail the properties of the maser clouds and calculated the mean and median values of the projected size (17.4 ± 1.2 au and 5.5 au, respectively) as well as the FWHM of the line (0.373 ± 0.011 km s-1 and 0.315 km s-1 for the mean and median values, respectively), testing whether it was consistent with Gaussian profile. We also found maser clouds with velocity gradients (71%) that ranged from 0.005 km s-1 au-1 to 0.210 km s-1 au-1. We tested the kinematic models to explain the observed structures of the 6.7 GHz emission. There were targets where the morphology supported the scenario of a rotating and expanding disk or a bipolar outflow. Comparing the interferometric and single-dish spectra we found that, typically, 50-70% of the flux was missing. This phenomena is not strongly related to the distance of the source. Conclusions: The EVN imaging reveals that in the complete sample of 63 sources the ring-like morphology appeared in 17% of sources, arcs were seen in a further 8%, and the structures were complex in 46% cases. The ultra-compact (UC) H II regions coincide in position in the sky for 13% of the sources. They are related both to extremely high and low luminosity masers from the sample. The catalogue of the complete sample is available via http://paulo.astro.uni.torun.pl/~pw/mmcat/

Scalloped margin domes: What are the processes responsible and how do they operate?

NASA Technical Reports Server (NTRS)

Bulmer, M. H.; Guest, J. E.; Michaels, G.; Saunders, S.

1993-01-01

Studies of scalloped margin domes (SMD) indicate the scallops are the result of slope failure. SMD's have similar but smaller average diameters (26.5 km) to unmodified domes (29.8 km), and the majority plot at altitudes ranging from 0.5-4.7 km, relative to the mean planetary diameter. A range of morphological types exist from those least modified to those that show heavy modification. Of the 200 SMD's examined, 33 have clearly discernible debris aprons. Examination and comparison of debris aprons with mass movement features on the Moon, Mars, and in sub-aerial and submarine environments on Earth using H/L against area (km(sup 2)), suggests there are three main types of failure; debris avalanche, slumps, and debris flow. The five examples representing the morphological range within the SMD's, show the different modified forms and the different types of slope failures that have occurred.

H0 from cosmic chronometers and Type Ia supernovae, with Gaussian Processes and the novel Weighted Polynomial Regression method

NASA Astrophysics Data System (ADS)

Gómez-Valent, Adrià; Amendola, Luca

2018-04-01

In this paper we present new constraints on the Hubble parameter H0 using: (i) the available data on H(z) obtained from cosmic chronometers (CCH); (ii) the Hubble rate data points extracted from the supernovae of Type Ia (SnIa) of the Pantheon compilation and the Hubble Space Telescope (HST) CANDELS and CLASH Multy-Cycle Treasury (MCT) programs; and (iii) the local HST measurement of H0 provided by Riess et al. (2018), H0HST=(73.45±1.66) km/s/Mpc. Various determinations of H0 using the Gaussian processes (GPs) method and the most updated list of CCH data have been recently provided by Yu, Ratra & Wang (2018). Using the Gaussian kernel they find H0=(67.42± 4.75) km/s/Mpc. Here we extend their analysis to also include the most released and complete set of SnIa data, which allows us to reduce the uncertainty by a factor ~ 3 with respect to the result found by only considering the CCH information. We obtain H0=(67.06± 1.68) km/s/Mpc, which favors again the lower range of values for H0 and is in tension with H0HST. The tension reaches the 2.71σ level. We round off the GPs determination too by taking also into account the error propagation of the kernel hyperparameters when the CCH with and without H0HST are used in the analysis. In addition, we present a novel method to reconstruct functions from data, which consists in a weighted sum of polynomial regressions (WPR). We apply it from a cosmographic perspective to reconstruct H(z) and estimate H0 from CCH and SnIa measurements. The result obtained with this method, H0=(68.90± 1.96) km/s/Mpc, is fully compatible with the GPs ones. Finally, a more conservative GPs+WPR value is also provided, H0=(68.45± 2.00) km/s/Mpc, which is still almost 2σ away from H0HST.

The effect of wind induced bottom shear stress and salinity on Zostera noltii replanting in a Mediterranean coastal lagoon

NASA Astrophysics Data System (ADS)

Alekseenko, E.; Roux, B.; Fougere, D.; Chen, P. G.

2017-03-01

The paper concerns the wind influence on bottom shear stress and salinity levels in a Mediterranean semi-enclosed coastal lagoon (Etang de Berre), with respect to a replanting program of Zostera noltii. The MARS3D numerical model is used to analyze the 3D current, salinity and temperature distribution induced by three meteorological, oceanic and anthropogenic forcings in this lagoon. The numerical model has been carefully validated by comparison with daily observations of the vertical salinity and temperature profiles at three mooring stations, for one year. Then, two modelling scenarios are considered. The first scenario (scen.#1), starting with a homogeneous salinity of S = 20 PSU and without wind forcing, studies a stratification process under the influence of a periodic seawater inflow and a strong freshwater inflow from a hydropower plant (250 m3/s). Then, in the second scenario (scen.#2), we study how a strong wind of 80 km/h can mix the haline stratification obtained at the end of scen.#1. The most interesting results concern four nearshore replanting areas; two are situated on the eastern side of EB and two on the western side. The results of scen.#2 show that all these areas are subject to a downwind coastal jet. Concerning bottom salinity, the destratification process is very beneficial; it always remains greater than 12 PSU for a N-NW wind of 80 km/h and an hydropower runoff of 250 m3/s. Special attention is devoted to the bottom shear stress (BSS) for different values of the bottom roughness parameter (for gravels, sands and silts), and to the bottom salinity. Concerning BSS, it presents a maximum near the shoreline and decreases along transects perpendicular to the shoreline. There exists a zone, parallel to the shoreline, where BSS presents a minimum (close to zero). When comparing the BSS value at the four replanting areas with the critical value, BSScr, at which the sediment mobility would occur, we see that for the smaller roughness values (ranging from z0 = 3.5 × 10-4 mm, to 3.5 × 10-2 mm) BSS largely surpasses this critical value. For a N-NW wind speed of 40 km/h (which is blowing for around 100 days per year), BSS still largely surpasses BSScr - at least for the silt sediments (ranging from z0 = 3.5 × 10-4 mm, to 3.5 × 10-3 mm). This confirms the possibility that the coastal jet could generate sediment mobility which could have a negative impact for SAV replanting.

Photochemistry of Triton's Atmosphere and Ionosphere

NASA Technical Reports Server (NTRS)

Krasnopolsky, Vladimir A.; Cruikshank, Dale P.

1995-01-01

The photochemistry of 32 neutral and 21 ion species in Triton's atmosphere is considered. Parent species N2, CH4, and CO (with a mixing ratio of 3 x 10(exp -4) in our basic model) sublime from the ice with rates of 40, 208, and 0.3 g/sq cm/b.y., respectively. Chemistry below 50 km is driven mostly by photolysis of methane by the solar and interstellar medium Lyman-alpha photons, producing hydrocarbons C2H4, C2H6, and C2H2 which form haze particles with precipitation rates of 135, 28, and 1.3 g/sq cm/b.y., respectively. Some processes are discussed which increase the production of HCN (by an order of magnitude to a value of 29 g/sq cm/b.y.) and involve indirect photolysis of N2 by neutrals. Reanalysis of the measured methane profiles gives an eddy diffusion coefficient K = 4 x 10(exp 3)sq cm/s above the tropopause and a more accurate methane number density near the surface, (3.1 +/- 0.8)x IO(exp 11)/cu cm. Chemistry above 200 km is driven by the solar EUV radiation (lambda less than 1000 A) and by precipitation of magnetospheric electrons with a total energy input of 10(exp 8) W (based on thermal balance calculations). The most abundant photochemical species are N, H2, H, 0, and C. They escape with the total rates of 7.7 x 10(exp 24)/ s, 4.5 x 10(exp 25)/s, 2.4 x 10(exp 25)/s, 4.4 x 10(exp 22)/s, and 1.1 x 10(exp 24), respectively. Atomic species are transported to a region of 50-200 km and drive the chemistry there. Ionospheric chemistry explains the formation of an E region at 150-240 km with HCO(+) as a major ion, and of an F region above 240 km with a peak at 320 km and C(+) as a major ion. The ionosphere above 500 km consists of almost equal densities of C(+) and N(+) ions. The model profiles agree with the measured atomic nitrogen and electron density profiles. A number of other models with varying rate coefficients of some reactions, differing properties of the haze particles (chemically passive or active), etc., were developed. These models show that there are four basic unknown values which have strong impacts on the composition and structure of the atmosphere and ionosphere. These values and their plausible ranges are the CO mixing ratio f(sub co) = 10(exp -4) - 10(exp -3), the magnetospheric electron energy input (1 +/- 0.5) x 10(exp 8) W, the rate coefficient of charge-exchange reaction N2(+) + C(kappa) = 10(exp -11) - 10(exp -10)cu cm/s, and the ion escape velocity upsilon(sub i) approx. equals 150 cm/s.

Alteration Mineralogy and Geochemical Characteristics of Porphyry Cu-Mo Mineralization in Domaniç (Kütahya) Area

NASA Astrophysics Data System (ADS)

Sariiz, K.; Sendir, H.

2012-04-01

The study area is located at 30 km northwest of Domaniç (Kütahya) and covers on approximately 250 square kilometers. The Devonian (Paleozoic) schists which are composed of gneiss, mica schist and chlorite schist is the oldest unit of the study area. This units are overlain unconformably by the Permian Allıkaya Marbles. Eocene granodioritic intrusives cut other rock series and located as a batholite. Magmatic units present porphyric and holocrystalline textures. Granodioritic intrusions are represented by tonalite, tonalite porphyr, granodiorite, granodiorite porphyr, granite, diorite, diorite porphyries. Potassic, phyllitic and prophyllitic hydrothermal alteration zones are determined in host rocks and wallrocks. Mineralizations are observed as disseminated, and stockwork types within the granodioritic rocks. Ore minerals are pyrotine, pyrite, chalcopyrite, molybdenite, rutile, bornite, sphalerite, marcasite and limonite. Geochemically, it is of sub-alkaline affinity, belongs to the high-K, calc-alkaline series and displays features of typical I-type affinity. They show enrichment in large-ion lithophile elements (LIL) and depletion Nb and Ti indicating a subduction zone related magmatic signature for their origin. δ18O (quartz) values range from 8,8 to 12,1 ‰. δ18O (biotite) and δD (biotite) values range from 2,6 to 6,1 ‰ and -87 - -125 (SMOW). These values indicate that mixture magmatic-meteoric of hydrothermal solutions origin which are potassic to propylitic zones. δ13C (calcite) values range from 1,9 to 3,3 ‰ (PDB). Calcite values within the marine carbonates in the study area.

Extreme-event geoelectric hazard maps

NASA Astrophysics Data System (ADS)

Love, J. J.; Bedrosian, P.

2017-12-01

Maps covering about half of the continental United States are presented of geoelectric field amplitude that will be exceeded, on average, once per century in response to extreme-intensity geomagnetic disturbance. These maps are constructed using an empirical parameterization of induction: convolving latitude-dependent statistical maps of extreme-value geomagnetic disturbance, obtained from decades of 1-minute magnetic observatory data, with local estimates of Earth-surface impedance, obtained at discrete geographic sites from magnetotelluric surveys. Geoelectric amplitudes are estimated for geomagnetic waveforms having 240-s (and 1200-s) sinusoidal period and amplitudes over 10 minutes (1-hr) that exceed a once-per-century threshold. As a result of the combination of geographic differences in geomagnetic variation and Earth-surface impedance, once-per-century geoelectric amplitudes span more than two orders of magnitude and are a highly granular function of location. Specifically: for north-south 240-s induction, once-per-century geoelectric amplitudes across large parts of the United States have a median value of 0.34 V/km; for east-west variation, they have a median value of 0.23 V/km. In Northern Minnesota, amplitudes exceed 14.00 V/km for north-south geomagnetic variation (23.34 V/km for east-west variation), while just over 100 km away, amplitudes are only 0.08 V/km (0.02 V/km). At some sites in the Northern Central United States, once-per-century geoelectric amplitudes exceed the 2 V/km realized in Quebec during the March 1989 storm. These hazard maps are incomplete over large parts of the United States, including major population centers in the southern United States, due to a lack of publically available impedance data.

Suitable Environmental Ranges for Potential Coral Reef Habitats in the Tropical Ocean

PubMed Central

Guan, Yi; Hohn, Sönke; Merico, Agostino

2015-01-01

Coral reefs are found within a limited range of environmental conditions or tolerance limits. Estimating these limits is a critical prerequisite for understanding the impacts of climate change on the biogeography of coral reefs. Here we used the diagnostic model ReefHab to determine the current environmental tolerance limits for coral reefs and the global distribution of potential coral reef habitats as a function of six factors: temperature, salinity, nitrate, phosphate, aragonite saturation state, and light. To determine these tolerance limits, we extracted maximum and minimum values of all environmental variables in corresponding locations where coral reefs are present. We found that the global, annually averaged tolerance limits for coral reefs are 21.7—29.6 °C for temperature, 28.7—40.4 psu for salinity, 4.51 μmol L-1 for nitrate, 0.63 μmol L-1 for phosphate, and 2.82 for aragonite saturation state. The averaged minimum light intensity in coral reefs is 450 μmol photons m-2 s-1. The global area of potential reef habitats calculated by the model is 330.5 × 103 km2. Compared with previous studies, the tolerance limits for temperature, salinity, and nutrients have not changed much, whereas the minimum value of aragonite saturation in coral reef waters has decreased from 3.28 to 2.82. The potential reef habitat area calculated with ReefHab is about 121×103 km2 larger than the area estimated from the charted reefs, suggesting that the growth potential of coral reefs is higher than currently observed. PMID:26030287

Thermal Intertias of Main-Belt Asteroids from Wise Thermal Infrared Data

NASA Astrophysics Data System (ADS)

Hanus, Josef; Delbo', Marco; Durech, Josef; Alí-Lagoa, Victor

2014-11-01

By means of a modified thermophysical model (TPM) that takes into account asteroid shape and pole uncertainties, we analyze the thermal infrared data acquired by the NASA's Wide-field Infrared Survey Explorer (WISE) of about 300 asteroids with derived convex shape models. We adopt convex shape models from the DAMIT database (Durech et al., 2010, A&A 513, A46) and present new determinations based on optical disk-integrated photometry and the lightcurve inversion method (Kaasalainen & Torppa, 2001, Icarus 153, 37). This work more than double the number of asteroids with determined thermophysical properties. We also discuss cases in which shape uncertainties prevent the determination of reliable thermophysical properties. This is per-se a novel result, as the effect of shape has been often neglected in thermophysical modeling of asteroids.We also present the main results of the statistical study of derived thermophysical parameters within the whole population of MBAs and within few asteroid families. The thermal inertia increases with decreasing size, but a large range of thermal inertia values is observed within the similar size ranges between 10-100 km. Surprisingly, we derive low (<20J m^{-2} s^{-1/2} K^{-1}) thermal inertia values for several asteroids with sizes D>10 km, indicating a very fine and mature regolith on these small bodies. The work of JH and MD was carried under the contract 11-BS56-008 (SHOCKS) of the French Agence National de la Recherche (ANR), and JD has been supported by the grant GACR P209/10/0537 of the Czech Science Foundation.

Suitable environmental ranges for potential coral reef habitats in the tropical ocean.

PubMed

Guan, Yi; Hohn, Sönke; Merico, Agostino

2015-01-01

Coral reefs are found within a limited range of environmental conditions or tolerance limits. Estimating these limits is a critical prerequisite for understanding the impacts of climate change on the biogeography of coral reefs. Here we used the diagnostic model ReefHab to determine the current environmental tolerance limits for coral reefs and the global distribution of potential coral reef habitats as a function of six factors: temperature, salinity, nitrate, phosphate, aragonite saturation state, and light. To determine these tolerance limits, we extracted maximum and minimum values of all environmental variables in corresponding locations where coral reefs are present. We found that the global, annually averaged tolerance limits for coral reefs are 21.7-29.6 °C for temperature, 28.7-40.4 psu for salinity, 4.51 μmol L-1 for nitrate, 0.63 μmol L-1 for phosphate, and 2.82 for aragonite saturation state. The averaged minimum light intensity in coral reefs is 450 μmol photons m-2 s-1. The global area of potential reef habitats calculated by the model is 330.5 × 103 km2. Compared with previous studies, the tolerance limits for temperature, salinity, and nutrients have not changed much, whereas the minimum value of aragonite saturation in coral reef waters has decreased from 3.28 to 2.82. The potential reef habitat area calculated with ReefHab is about 121×103 km2 larger than the area estimated from the charted reefs, suggesting that the growth potential of coral reefs is higher than currently observed.

Three-dimensional P-wave velocity structure derived from local earthquakes at the Katmai group of volcanoes, Alaska

USGS Publications Warehouse

Jolly, A.D.; Moran, S.C.; McNutt, S.R.; Stone, D.B.

2007-01-01

The three-dimensional P-wave velocity structure beneath the Katmai group of volcanoes is determined by inversion of more than 10,000 rays from over 1000 earthquakes recorded on a local 18 station short-period network between September 1996 and May 2001. The inversion is well constrained from sea level to about 6??km below sea level and encompasses all of the Katmai volcanoes; Martin, Mageik, Trident, Griggs, Novarupta, Snowy, and Katmai caldera. The inversion reduced the average RMS travel-time error from 0.22??s for locations from the standard one-dimensional model to 0.13??s for the best three-dimensional model. The final model, from the 6th inversion step, reveals a prominent low velocity zone (3.6-5.0??km/s) centered at Katmai Pass and extending from Mageik to Trident volcanoes. The anomaly has values about 20-25% slower than velocities outboard of the region (5.0-6.5??km/s). Moderately low velocities (4.5-6.0??km/s) are observed along the volcanic axis between Martin and Katmai Caldera. Griggs volcano, located about 10??km behind (northwest of) the volcanic axis, has unremarkable velocities (5.0-5.7??km/s) compared to non-volcanic regions. The highest velocities are observed between Snowy and Griggs volcanoes (5.5-6.5??km/s). Relocated hypocenters for the best 3-D model are shifted significantly relative to the standard model with clusters of seismicity at Martin volcano shifting systematically deeper by about 1??km to depths of 0 to 4??km below sea level. Hypocenters for the Katmai Caldera are more tightly clustered, relocating beneath the 1912 scarp walls. The relocated hypocenters allow us to compare spatial frequency-size distributions (b-values) using one-dimensional and three-dimensional models. We find that the distribution of b is significantly changed for Martin volcano, which was characterized by variable values (0.8 < b < 2.0) with standard locations and more uniform values (0.8 < b < 1.2) after relocation. Other seismic clusters at Mageik (1.2 < b < 2.2), Trident (0.5 < b < 1.5) and Katmai Caldera (0.8 < b < 1.8) had stable b-values indicating the robustness of the observations. The strong high b-value region at Mageik volcano is mainly associated with an earthquake swarm in October, 1996 that possibly indicates a shallow intrusion or influx of gas. The new velocity and spatial b-value results, in conjunction with prior gravity (Bouguer anomalies up to - 40??mgal) and interferometry (several cm uplift) data, provide strong evidence in favor of partially molten rock at shallow depths beneath the Mageik-Katmai-Novarupta region. Moderately low velocities beneath Martin and Katmai suggest that old, mostly solidified intrusions exist beneath these volcanoes. Higher relative velocities beneath the Griggs and Snowy vents suggest that no magma is resident in the shallow crust beneath these volcanoes. ?? 2006 Elsevier B.V.

Crustal structure of north Peru from analysis of teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Condori, Cristobal; França, George S.; Tavera, Hernando J.; Albuquerque, Diogo F.; Bishop, Brandon T.; Beck, Susan L.

2017-07-01

In this study, we present results from teleseismic receiver functions, in order to investigate the crustal thickness and Vp/Vs ratio beneath northern Peru. A total number of 981 receiver functions were analyzed, from data recorded by 28 broadband seismic stations from the Peruvian permanent seismic network, the regional temporary SisNort network and one CTBTO station. The Moho depth and average crustal Vp/Vs ratio were determined at each station using the H-k stacking technique to identify the arrival times of primary P to S conversion and crustal reverberations (PpPms, PpSs + PsPms). The results show that the Moho depth correlates well with the surface topography and varies significantly from west to east, showing a shallow depth of around 25 km near the coast, a maximum depth of 55-60 km beneath the Andean Cordillera, and a depth of 35-40 km further to the east in the Amazonian Basin. The bulk crustal Vp/Vs ratio ranges between 1.60 and 1.88 with the mean of 1.75. Higher values between 1.75 and 1.88 are found beneath the Eastern and Western Cordilleras, consistent with a mafic composition in the lower crust. In contrast values vary from 1.60 to 1.75 in the extreme flanks of the Eastern and Western Cordillera indicating a felsic composition. We find a positive relationship between crustal thickness, Vp/Vs ratio, the Bouguer anomaly, and topography. These results are consistent with previous studies in other parts of Peru (central and southern regions) and provide the first crustal thickness estimates for the high cordillera in northern Peru.

[Leukemia mortality and incidence of infantile leukemia near the Vatican Radio Station of Rome].

PubMed

Michelozzi, P; Kirchmayer, U; Capon, A; Forastiere, F; Biggeri, A; Barca, A; Ancona, C; Fusco, D; Sperati, A; Papini, P; Pierangelini, A; Rondelli, R; Perucci, C A

2001-01-01

Some recent epidemiological studies suggest an association between lymphatic and haematopoietic cancers and residential exposure to high frequency electromagnetic fields (100 kHz-300 GHz) generated by radio and television transmitters. Vatican Radio, a very powerful radio station transmitting all over the world (up to 600 kW) is located in Santa Maria di Galeria, in the northern suburbs of the city of Rome. Electric field measurements in the proximity of the radio station ranged between 1.5 and 25 V/m. In the 10 km area around the station, with 60.182 residents (1999), leukaemia mortality among adults (> 14 years, 40 cases) in the period 1987-98 and childhood leukaemia incidence in the period 1987-99 (8 cases) were evaluated. The analysis (Stone's conditional test) was performed computing observed and expected cases (reference: population of Rome) in 5 bands of increasing radius (2 km width). The risk of childhood leukaemia was higher than expected within 6 km from the station (Standardized Incidence Ratio = 217; 95% Confidence Interval 99-405). Stone's test showed a significant decrease in risk with increasing distance both for male adult mortality (p-value = 0.03) and for childhood incidence (p-value = 0.04). A Score test, showed a significant decrease in risk of childhood incidence as function of the distance. The main limitations of this study are the small number of observed cases and the use of distance as a proxy for RF exposure. Further research will require a systematic campaign of electromagnetic field measurements to allow better assessment of the population exposure.

Lithospheric-Mantle Structure of the Kaapvaal Craton, South Africa, Derived From Thermodynamically Self-Consistent Modelling of Seismic Surface-Wave and S-wave Receiver Function, Heat-flow, Elevation, Xenolith and Magnetotelluric Observations

NASA Astrophysics Data System (ADS)

Muller, M. R.; Fullea, J.; Jones, A. G.; Adam, J.; Lebedev, S.; Piana Agostinetti, N.

2012-12-01

Results from recent geophysical and mantle-xenolith geochemistry studies of the Kaapvaal Craton appear, at times, to provide disparate views of the physical, chemical and thermal structure of the lithosphere. Models from our recent SAMTEX magnetotelluric (MT) surveys across the Kaapvaal Craton indicate a resistive, 220-240 km thick lithosphere for the central core of the craton. One published S-wave receiver function (SRF) study and other surface-wave studies suggest a thinner lithosphere characterised by a ~160 km thick high-velocity "lid" underlain by a low-velocity zone (LVZ) of between 65-150 km in thickness. Other seismic studies suggest that the (high-velocity) lithosphere is thicker, in excess of 220 km. Mantle xenolith pressure-temperature arrays from Mesozoic kimberlites require that the base of the "thermal" lithosphere (i.e., the depth above which a conductive geotherm is maintained) is at least 220 km deep, to account for mantle geotherms in the range 35-38 mWm-2. Richly diamondiferous kimberlites across the Kaapvaal Craton require a lithospheric thickness substantially greater than 160 km - the depth of the top of the diamond stability field. In this paper we use the recently developed LitMod software code to derive, thermodynamically consistently, a range of 1-D seismic velocity, density, electrical resistivity and temperature models from layered geochemical models of the lithosphere based on mantle xenolith compositions. In our work, the "petrological" lithosphere-asthenosphere boundary (pLAB) (i.e., the top of the fertile asthenospheric-mantle) and the "thermal" LAB (tLAB as defined above) are coincident. Lithospheric-mantle models are found simultaneously satisfying all geophysical observables: new surface-wave dispersion data, published SRFs, MT responses, surface elevation and heat-flow. Our results show: 1. All lithospheric-mantle models are characterised by a seismic LVZ with a minimum velocity at the depth of the petrological/thermal LAB. The top of the LVZ does not correspond with the LAB. 2. Thin (~160 km-thick) lithospheric-mantle models are consistent with surface elevation and heat-flow observations only for unreasonably low average crustal heat production values (~0.4 μWm-3). However, such models are inconsistent both with the surface-wave dispersion data and youngest (Group I) palaeo-geotherms defined by xenolith P-T arrays. 3. A three-layered geochemical model (consistent with mantle xenoliths), with lithospheric thickness in excess of 220 km, is required to match all geophysical constraints. 4. The chemical transition from a depleted harzburgitic composition (above) to a refertilised high-T lherzolitic composition (below) at 160 km depth produces a sharp onset of the seismic LVZ and a sharp increase in density. Synthetic SRFs will assess whether this chemical transition may account for the reported S-to-P conversion event at 160 km depth. However, in this this instance the SRF conversion event would not represent the petrological/thermal LAB.

Project WILAS: Seismic imaging of crustal and upper mantle structures beneath the western Iberian Peninsula by means of the receiver-function technique

NASA Astrophysics Data System (ADS)

Dündar, Süleyman; Dias, Nuno A.; Silveira, Graça; Vinnik, Lev; Haberland, Christian

2013-04-01

An accurate knowledge of the structure of the earth's interior is of great importance to our understanding of tectonic processes. The WILAS-project (REF: PTDC/CTE-GIX/097946/2008) is a three-year collaborative project developed to study the subsurface structure of the western Iberian Peninsula, putting the main emphases on the lithosphere-asthenosphere system beneath the mainland of Portugal. The tectonic evolution of the target area has been driven by major plate-tectonic processes such as the historical opening of the Central Atlantic and the subsequent African-Eurasian convergence. Still, very little is known about the spatial structure of the continental collision. Within the framework of this research, a temporary network of 30 broadband three-component digital stations was operated between 2010 and 2012 in the target area. To carry out a large-scale structural analysis and facilitate a dense station-coverage for the area under investigation, the permanent Global Seismic Network stations, and temporary broadband stations deployed within the scope of the several seismic experiments (e.g. Doctar Network, Portuguese National Seismic Network), were included in the research analysis. In doing so, an unprecedented volume of high-quality data of a ca. 60X60 km density along with a combined network of 65 temporary and permanent broadband seismic stations are currently available for research purposes. One of the tasks of the WILAS research project has been a study of seismic velocity discontinuities beneath the western Iberian Peninsula region, up to a depth range of 700 km, utilizing the P- and S-receiver function techniques (PRF, SRF). Both techniques are based mainly on mode conversion of the elastic body-waves at an interface dividing the layers with different elastic properties. In the first phase of the project, PRF analysis was conducted in order to image the crust-mantle interface (Moho) and the mantle-transition-zone discontinuities at a depth of 410 km and 660 km beneath the area under investigation. While applying the common data processing steps (e.g., rotation, deconvolution and moveout-correction) to the selected data-set, we were able to create approximately 4.500 PRFs. The signals from the Moho, 410-km and 660-km discontinuities are clearly visible in many PRF stacks. The Moho depth range is from 26 to 34 km, with an average value of 29 km. No significant lateral variations in the depths of the "410-km" and "660-km" discontinuities have been identified so far. In the second phase of this project, the S-receiver-function technique will be applied in order to map the thickness of the underlying mantle lithosphere. Additionally, joint inversion of PRFs and waveforms of SKS will be used to investigate depth-localized azimuthal anisotropy and the related past and present mantle flows.

Dynamic and Thermodynamic Characteristics of a Microburst-Producing Storm in Colorado Determined from JAWS (Joint Airport Weather Studies) Dual-Doppler Data.

DTIC Science & Technology

1986-01-01

amplitude gain function G, based 189 on the theoretical formulas derived by Testud and Chong (1983). GI is the amplitude gain for n = I (first order...theoretical formulas derived by Testud and Chong (1983). Values of kt, and AL are 0.1584 km and 0.0251 km respectively. For comparison, values of D...from Barnes (1973) scheme (D’) with Y=0.3 and R=2.5 km and theo:etical formulas derived by Testud and Chong (1983) for n=l (GI) and n=2 (G2). Fig. BI

National Centers for Environmental Prediction

Science.gov Websites

OPERATIONAL 00Z, .... 12Z ... EXPERIMENTAL Daily Comparisons between GFS/GEFS control & ECMWF/ECMWF control 00Z T382/38km GFS, 00Z T190/70km GEFS control 12Z T1279/16km ECMWF, 12Z T639/30km ECMWF ensemble control Daily Values of 500 hPa Height AC, RMS, Talagrand & Outliers Mean of 14 GFS, 10 ECMWF and 16

Internal friction quality-factor Q under confining pressure. [of lunar rocks

NASA Technical Reports Server (NTRS)

Tittmann, B. R.; Ahlberg, L.; Nadler, H.; Curnow, J.; Smith, T.; Cohen, E. R.

1977-01-01

It has been found in previous studies that small amounts of adsorbed volatiles can have a profound effect on the internal friction quality-factor Q of rocks and other porous media. Pandit and Tozer (1970) have suggested that the laboratory-measured Q of volatile-free rocks should be similar to the in situ seismic Q values of near-surface lunar rocks which according to Latham et al. (1970) are in the range of 3000-5000. Observations of dramatic increases in Q with outgassing up to values approaching 2000 in the seismic frequency range confirm this supposition. Measurements under confining pressures with the sample encapsulated under hard vacuum are reported to aid in the interpretation of seismic data obtained below the lunar surface. It has been possible to achieve in the experiments Q values just under 2000 at about 1 kbar for a terrestrial analog of lunar basalt. It was found that a well-outgassed sample maintains a high Q whereas one exposed to moisture maintains a low Q as the confining pressure is raised to 2.5 kbar. This result suggests that volatiles can indeed affect Q when cracks are partially closed and the high lunar seismic Q values reported are concomitant with very dry rock down to depths of at least 50 km.

Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica

NASA Astrophysics Data System (ADS)

Aitken, Alan R. A.; Wilson, Gary S.; Jordan, Thomas; Tinto, Kirsty; Blakemore, Hamish

2012-01-01

The basins of southern McMurdo Sound have evolved under the influence of lithospheric flexure induced by the loads of the Erebus Volcanic Province. To characterise these basins, it is important to investigate the lithosphere's flexural properties, and estimate their influence on basin architecture and evolution. Seismic and gravity data are used to constrain 3D forward modelling of the progressive development of accommodation space within the flexural basins. Elastic plate flexure was calculated for a range of effective elastic thicknesses (T e) from 0.5 to 25 km using a spectral method. Models with low, but nonzero, T e values (2 km < T e < 5 km) produce the best fit to the gravity data, although uncertainty is high due to inaccuracies in the Digital Elevation Model. The slopes of flexural horizons revealed in seismic reflection lines are consistent with this, indicating a T e of 2 km to 5 km, although the depths to these horizons are not consistent, perhaps due to a northwards slope, or step, in the pre-flexural surface. These results indicate that the lithospheric strength of southern McMurdo Sound is significantly less than estimates of the regional average (T e ~ 20 km). This low strength may reflect the weakening effects of the Terror Rift, and perhaps also the Discovery Accommodation Zone, a region of major transverse faulting. A low T e model (T e = 3) for southern McMurdo Sound predicts the development of two discrete flexural depressions, each 2-2.5 km deep. The predicted stratigraphy of the northern basin reflects flexure due to Ross Island, predominantly erupted since ca. 1.8 Ma. The predicted stratigraphy of the southern basin reflects more gradual flexure from ca. 10 Ma to ca. 2 Ma, due to the more dispersed volcanoes of the Discovery subprovince. Collectively, these two basins have the potential to preserve a remarkable stratigraphic record of Antarctic climate change through the late Neogene.

Reprint of: Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica

NASA Astrophysics Data System (ADS)

Aitken, Alan R. A.; Wilson, Gary S.; Jordan, Tom; Tinto, Kirsty; Blakemore, Hamish

2012-10-01

The basins of southern McMurdo Sound have evolved under the influence of lithospheric flexure induced by the loads of the Erebus Volcanic Province. To characterise these basins, it is important to investigate the lithosphere's flexural properties, and estimate their influence on basin architecture and evolution. Seismic and gravity data are used to constrain 3D forward modelling of the progressive development of accommodation space within the flexural basins. Elastic plate flexure was calculated for a range of effective elastic thicknesses (Te) from 0.5 to 25 km using a spectral method. Models with low, but nonzero, Te values (2 km < Te < 5 km) produce the best fit to the gravity data, although uncertainty is high due to inaccuracies in the Digital Elevation Model. The slopes of flexural horizons revealed in seismic reflection lines are consistent with this, indicating a Te of 2 km to 5 km, although the depths to these horizons are not consistent, perhaps due to a northwards slope, or step, in the pre-flexural surface. These results indicate that the lithospheric strength of southern McMurdo Sound is significantly less than estimates of the regional average (Te ~ 20 km). This low strength may reflect the weakening effects of the Terror Rift, and perhaps also the Discovery Accommodation Zone, a region of major transverse faulting. A low Te model (Te = 3) for southern McMurdo Sound predicts the development of two discrete flexural depressions, each 2-2.5 km deep. The predicted stratigraphy of the northern basin reflects flexure due to Ross Island, predominantly erupted since ca. 1.8 Ma. The predicted stratigraphy of the southern basin reflects more gradual flexure from ca. 10 Ma to ca. 2 Ma, due to the more dispersed volcanoes of the Discovery subprovince. Collectively, these two basins have the potential to preserve a remarkable stratigraphic record of Antarctic climate change through the late Neogene.

Source Parameters of the 8 October, 2005 Mw7.6 Kashmir Earthquake

NASA Astrophysics Data System (ADS)

Mandal, Prantik; Chadha, R. K.; Kumar, N.; Raju, I. P.; Satyamurty, C.

2007-12-01

During the last six years, the National Geophysical Research Institute, Hyderabad has established a semi-permanent seismological network of 5 broadband seismographs and 10 accelerographs in the Kachchh seismic zone, Gujarat, with the prime objective to monitor the continued aftershock activity of the 2001 Mw7.7 Bhuj mainshock. The reliable and accurate broadband data for the Mw 7.6 (8 Oct., 2005) Kashmir earthquake and its aftershocks from this network, as well as from the Hyderabad Geoscope station, enabled us to estimate the group velocity dispersion characteristics and the one-dimensional regional shear-velocity structure of peninsular India. Firstly, we measure Rayleigh- and Love-wave group velocity dispersion curves in the range of 8 to 35 sec and invert these curves to estimate the crustal and upper mantle structure below the western part of peninsular India. Our best model suggests a two-layered crust: The upper crust is 13.8-km thick with a shear velocity (Vs) of 3.2 km/s; the corresponding values for the lower crust are 24.9 km and 3.7 km/sec. The shear velocity for the upper mantle is found to be 4.65 km/sec. Based on this structure, we perform a moment tensor (MT) inversion of the bandpass (0.05 0.02 Hz) filtered seismograms of the Kashmir earthquake. The best fit is obtained for a source located at a depth of 30 km, with a seismic moment, Mo, of 1.6 × 1027 dyne-cm, and a focal mechanism with strike 19.5°, dip 42°, and rake 167°. The long-period magnitude (MA ~ Mw) of this earthquake is estimated to be 7.31. An analysis of well-developed sPn and sSn regional crustal phases from the bandpassed (0.02 0.25 Hz) seismograms of this earthquake at four stations in Kachchh suggests a focal depth of 30.8 km.

Three-dimensional flexure modelling of seamounts near the Ogasawara Fracture Zone in the western Pacific

NASA Astrophysics Data System (ADS)

Lee, Tae-Gook; Moon, Jai-Woon; Jung, Mee-Sook

2009-04-01

The geophysical data were obtained in 2000-2003 during a survey of seamounts near the Ogasawara Fracture Zone (OFZ) to the northwest of the Marshall Islands in the western Pacific. The OFZ is unique in that it is a wide rift zone showing 600-km-long right-lateral movement between the Pigafetta Basin (PB) and East Mariana Basin (EMB), and contains many seamounts (e.g. the Magellan Seamounts and the seamounts on the Dutton Ridge). Most seamounts in this study are newly mapped using modern multibeam echosounder (Seabeam 2000) and denoted sequentially by Korea Ocean Research and Development Institute (KORDI). OSM2, OSM4, OSM7, OSM8-1 and OSM8-2 seamounts of the study area are located in the OFZ which formed by the spreading ridge between the Izanagi and Pacific plates, and OSM5-1, Seascan, OSM6-1 and OSM6-2 seamounts in the PB which is a part of the oldest oceanic crust in the Pacific. In this study, the densities of seamounts and the elastic thickness values of lithosphere are estimated by using 3-D flexure and gravity modelling by considering several boundary conditions and a constant sediment layer. The infinite model with two different elastic thickness values is the best-fitting model and it indicates that the OFZ was mechanically coupled with plate of different elastic thickness values, probably after the reorganization of Izanagi-Pacific spreading zone. Very low elastic thickness values (5-10 km), relatively young seamounts, and old lithosphere in the east study area suggest the possibility of the rejuvenation of the lithosphere by widespread volcanism pulses, whereas higher elastic thickness values (15-20 km), relatively younger lithosphere, and old seamounts of the west study area are comparable with a simple cooling plate model. It implies that the west study area is outside the rejuvenation range of the lithosphere. In the flexure and gravity modelling, the different residual pattern of OSM6-1 and OSM6-2, which are joined, suggests that they have different load densities or elastic thickness values. OSM2 and OSM7 may be close to a basaltic volcano with low viscosity because they have high densities and ratios of the basal diameter to the height, whereas OSM4, OSM5-1 and Seascan may be close to an andesitic volcano.

Determination of Ionospheric Total Electron Content Derived from Gnss Measurements

NASA Astrophysics Data System (ADS)

Inyurt, S.; Mekik, C.; Yildirim, O.

2014-12-01

Global Navigation Satellite System (GNSS) has been used in numerous fields especially related to satellite- based radio navigation system for a long time. Ionosphere, one of the upper atmosphere layers ranges from 60 km to 1500 km, is a dispersive medium and it includes a number of free electrons and ions. The ionization is mainly subject to the sun and its activity. Ionospheric activity depends also on seasonal, diurnal variations and geographical location. Total Electron Content (TEC), which is also called Slant Total Electron Content (STEC), is a parameter that changes according to ionospheric conditions and has highly variable structure. Furthermore, Vertical TEC (VTEC) can be explained as TEC value in the direction of zenith. Thanks to VTEC, TEC values can be modelled. TEC is measured in units of TECU and 1TECU= 1016 electrons/m2. Ionospheric modelling has a great importance for improving the accuracies of positioning and understanding the ionosphere. Thus, various models have been developed to detect TEC value in the last years. Single Layer Model (SLM) which provides determining TEC value and GPS positioning in the ionosphere accurately is one of the most commonly used models. SLM assumes that all free electrons are concentrated in a shell of infinitesimal thickness. In this paper SLM model was used to derive TEC values by means of Bernese 5.0 program developed by the University of Bern, Sweden. In this study, we have used regional ionosphere model to derive TEC value. First of all, GPS data have been collected from 10 stations in Turkey and 13 IGS stations for 7 days from 06.03.2010 to 12.03.2010. Then, Regional Ionosphere Model (RIM) is created with the reference of the GPS data. At the end of the process, the result files are stored as IONEX format. TEC results for those days are obtained with two hours interval. TEC variation related to the research area ranges from nearly 6 TECU to approximately 20 TECU. The obtained results show that TEC values start increasing until mid-days and reach peak value at 12:00 UT. After 12:00 UT it begins decreasing gradually towards night because of recombination of the ions. As a result, SLM is an effective model for mapping TEC values and determination of TEC variation can be used to identify many studies such as precursor of earthquakes, volcanic eruptions and launching site determination etc.

Moho topography, ranges and folds of Tibet by analysis of global gravity models and GOCE data

PubMed Central

Shin, Young Hong; Shum, C.K.; Braitenberg, Carla; Lee, Sang Mook; Na, Sung -Ho; Choi, Kwang Sun; Hsu, Houtse; Park, Young-Sue; Lim, Mutaek

2015-01-01

The determination of the crustal structure is essential in geophysics, as it gives insight into the geohistory, tectonic environment, geohazard mitigation, etc. Here we present the latest advance on three-dimensional modeling representing the Tibetan Mohorovičić discontinuity (topography and ranges) and its deformation (fold), revealed by analyzing gravity data from GOCE mission. Our study shows noticeable advances in estimated Tibetan Moho model which is superior to the results using the earlier gravity models prior to GOCE. The higher quality gravity field of GOCE is reflected in the Moho solution: we find that the Moho is deeper than 65 km, which is twice the normal continental crust beneath most of the Qinghai-Tibetan plateau, while the deepest Moho, up to 82 km, is located in western Tibet. The amplitude of the Moho fold is estimated to be ranging from −9 km to 9 km with a standard deviation of ~2 km. The improved GOCE gravity derived Moho signals reveal a clear directionality of the Moho ranges and Moho fold structure, orthogonal to deformation rates observed by GPS. This geophysical feature, clearly more evident than the ones estimated using earlier gravity models, reveals that it is the result of the large compressional tectonic process. PMID:26114224

Seismic properties of Leg 195 serpentinites and their geophysical implications

USGS Publications Warehouse

Courtier, Anna M.; Hart, David J.; Christensen, Nikolas I.; Shinohara, Masanao; Salisbury, Matthew H.; Richter, Carl

2006-01-01

Knowledge of seismic velocities is necessary to constrain the lithologies encountered in seismic studies. We measured the seismic velocities, both compressional and shear wave, of clasts recovered during Ocean Drilling Program Leg 195 from a serpentine mud volcano, the South Chamorro Seamount. The compressional wave velocities of these clasts vary from a lower value of 5.5 km/s to an upper value of 6.1 km/s at a confining stress of 200 MPa. The shear wave velocities vary from a lower value of 2.8 km/s to an upper value of 3.3 km/s at a confining stress of 200 MPa. The densities of the samples vary from 2548 to 2701 kg/m3. These velocities and densities are representative of the highly serpentinized harzburgite and dunite mineralogy of the clasts. Velocities from a seismic study of the Izu-Bonin forearc wedge were used to calculate the degree of serpentinization in the forearc wedge. The seismic velocities of the forearc wedge are higher than the velocities of the clasts recovered from the South Chamorro Seamount, suggesting that the clasts are more serpentinized than the forearc wedge.

A GRASS GIS Semi-Stochastic Model for Evaluating the Probability of Landslides Impacting Road Networks in Collazzone, Central Italy

NASA Astrophysics Data System (ADS)

Taylor, Faith E.; Santangelo, Michele; Marchesini, Ivan; Malamud, Bruce D.

2013-04-01

During a landslide triggering event, the tens to thousands of landslides resulting from the trigger (e.g., earthquake, heavy rainfall) may block a number of sections of the road network, posing a risk to rescue efforts, logistics and accessibility to a region. Here, we present initial results from a semi-stochastic model we are developing to evaluate the probability of landslides intersecting a road network and the network-accessibility implications of this across a region. This was performed in the open source GRASS GIS software, where we took 'model' landslides and dropped them on a 79 km2 test area region in Collazzone, Umbria, Central Italy, with a given road network (major and minor roads, 404 km in length) and already determined landslide susceptibilities. Landslide areas (AL) were randomly selected from a three-parameter inverse gamma probability density function, consisting of a power-law decay of about -2.4 for medium and large values of AL and an exponential rollover for small values of AL; the rollover (maximum probability) occurs at about AL = 400 m.2 The number of landslide areas selected for each triggered event iteration was chosen to have an average density of 1 landslide km-2, i.e. 79 landslide areas chosen randomly for each iteration. Landslides were then 'dropped' over the region semi-stochastically: (i) random points were generated across the study region; (ii) based on the landslide susceptibility map, points were accepted/rejected based on the probability of a landslide occurring at that location. After a point was accepted, it was assigned a landslide area (AL) and length to width ratio. Landslide intersections with roads were then assessed and indices such as the location, number and size of road blockage recorded. The GRASS-GIS model was performed 1000 times in a Monte-Carlo type simulation. Initial results show that for a landslide triggering event of 1 landslide km-2 over a 79 km2 region with 404 km of road, the number of road blockages ranges from 6 to 17, resulting in one road blockage every 24-67 km of roads. The average length of road blocked was 33 m. As we progress with model development and more sophisticated network analysis, we believe this semi-stochastic modelling approach will aid civil protection agencies to get a rough idea for the probability of road network potential damage (road block number and extent) as the result of different magnitude landslide triggering event scenarios.

Strike-slip earthquakes in the oceanic lithosphere: Observations of exceptionally high apparent stress

USGS Publications Warehouse

Choy, George; McGarr, A.

2002-01-01

The radiated energies, ES, and seismic moments, M0, for 942 globally distributed earthquakes that occurred between 1987 to 1998 are examined to find the earthquakes with the highest apparent stresses (τa=μES/M0, where μ is the modulus of rigidity). The globally averaged τa for shallow earthquakes in all tectonic environments and seismic regions is 0.3 MPa. However, the subset of 49 earthquakes with the highest apparent stresses (τa greater than about 5.0 MPa) is dominated almost exclusively by strike-slip earthquakes that occur in oceanic environments. These earthquakes are all located in the depth range 7–29 km in the upper mantle of the young oceanic lithosphere. Many of these events occur near plate-boundary triple junctions where there appear to be high rates of intraplate deformation. Indeed, the small rapidly deforming Gorda Plate accounts for 10 of the 49 high-τa events. The depth distribution of τa, which shows peak values somewhat greater than 25 MPa in the depth range 20–25 km, suggests that upper bounds on this parameter are a result of the strength of the oceanic lithosphere. A recently proposed envelope for apparent stress, derived by taking 6 per cent of the strength inferred from laboratory experiments for young (less than 30 Ma) deforming oceanic lithosphere, agrees well with the upper-bound envelope of apparent stresses over the depth range 5–30 km. The corresponding depth-dependent shear strength for young oceanic lithosphere attains a peak value of about 575 MPa at a depth of 21 km and then diminishes rapidly as the depth increases. In addition to their high apparent stresses, which suggest that the strength of the young oceanic lithosphere is highest in the depth range 10–30 km, our set of high-τa earthquakes show other features that constrain the nature of the forces that cause interplate motion. First, our set of events is divided roughly equally between intraplate and transform faulting with similar depth distributions of τa for the two types. Secondly, many of the intraplate events have focal mechanisms with the T-axes that are normal to the nearest ridge crest or subduction zone and P-axes that are normal to the proximate transform fault. These observations suggest that forces associated with the reorganization of plate boundaries play an important role in causing high-τa earthquakes inside oceanic plates. Extant transform boundaries may be misaligned with current plate motion. To accommodate current plate motion, the pre-existing plate boundaries would have to be subjected to large horizontal transform push forces. A notable example of this is the triple junction near which the second large aftershock of the 1992 April Cape Mendocino, California, sequence occurred. Alternatively, subduction zone resistance may be enhanced by the collision of a buoyant lithosphere, a process that also markedly increases the horizontal stress. A notable example of this is the Aleutian Trench near which large events occurred in the Gulf of Alaska in late 1987 and the 1998 March Balleny Sea M= 8.2 earthquake within the Antarctic Plate.

Seasonal variations of NO and O3 at altitudes of 18.3 and 21.3 km

NASA Technical Reports Server (NTRS)

Loewenstein, M.; Savage, H. F.; Whitten, R. C.

1975-01-01

Nitric oxide and ozone concentrations have been measured in situ from a high-altitude research aircraft. Data which show the variations of NO and O3 with the time of year are presented for altitudes of 18.3 and 21.3 km. The extreme values of the observed NO concentrations at 21.3 km are 1.2 billion per cu cm in summer and 0.2 billion per cu cm in winter. At 18.3 km the extreme values are 1.6 billion per cu cm in summer and 0.1 billion per cu cm in winter. The smoothed NO seasonal data show a variation of about a factor of 2.5 at 21.3 km and a factor of 4 at 18.3 km. The ozone data show the generally expected magnitude and seasonal variation. We have used a photochemical model employing the measured ozone concentrations, the mean solar zenith angle, and seasonal HNO3 data reported by others to predict the seasonal NO variation at 20 km. The result is a summer-to-winter NO ratio of 2.5 which is in fair agreement with the observed ratios.

Longitudinal Stream Profile Morphology and Patterns of Knickpoint Propagation in the Bighorn Range

NASA Astrophysics Data System (ADS)

Safran, E. B.; Anderson, R. S.; Riihimaki, C. A.; Armstrong, J.

2005-12-01

The northern U. S. Rocky Mountains and the adjacent sedimentary basins are in a transient state of response to regional, Late Cenozoic exhumation. Assembling the history of landscape change there requires interpreting the morphology and genesis of transient landforms such as knickpoints in longitudinal stream profiles. We used concavity and normalized channel steepness indices to quantify the longitudinal profile morphology of >75 streams draining the east side of the Bighorn Range and the adjacent Powder River Basin. Our analyses show that individual units in the range-margin sedimentary cover rock exert a strong influence on longitudinal profile morphology. In the Tongue River and Crazy Woman Creek drainages, more than 50% of the streams examined had knickpoints localized within a resistant, siliceous dolomite. Knickpoints on most streams with drainage areas greater than ~100 km2 at the range front have migrated headward into the gneissic and plutonic core of the range. In the Clear Creek drainage, where the lateral extent of sedimentary cover rock is more restricted than in the adjacent drainages, knickpoints do not align with any particular unit. River profiles in the Powder River Basin beyond 10-20 km from the range front exhibit concavities of ~0.3-0.6 and normalized channel steepness indices of 40-60 (using 0.45 as a reference concavity). All profiles analyzed that extend into the mountain range exhibit at least one reach with exceptionally high (>2) concavity and relatively high (100-600) normalized channel steepness index, highlighting zones of transient adjustment to local base-level drop in the basin. Headwater reaches of range-draining streams exhibit variable but moderate values of concavity (0.15-0.9) and normalized channel steepness index (20-100). The varied morphology of these reaches reflects their passage across a relict surface of low relief but also the effects of glaciation and/or the signature of the narrow summit spine that caps the range.

Estimation of ground motion for Bhuj (26 January 2001; Mw 7.6 and for future earthquakes in India

USGS Publications Warehouse

Singh, S.K.; Bansal, B.K.; Bhattacharya, S.N.; Pacheco, J.F.; Dattatrayam, R.S.; Ordaz, M.; Suresh, G.; ,; Hough, S.E.

2003-01-01

Only five moderate and large earthquakes (Mw ???5.7) in India-three in the Indian shield region and two in the Himalayan arc region-have given rise to multiple strong ground-motion recordings. Near-source data are available for only two of these events. The Bhuj earthquake (Mw 7.6), which occurred in the shield region, gave rise to useful recordings at distances exceeding 550 km. Because of the scarcity of the data, we use the stochastic method to estimate ground motions. We assume that (1) S waves dominate at R < 100 km and Lg waves at R ??? 100 km, (2) Q = 508f0.48 is valid for the Indian shield as well as the Himalayan arc region, (3) the effective duration is given by fc-1 + 0.05R, where fc is the corner frequency, and R is the hypocentral distance in kilometer, and (4) the acceleration spectra are sharply cut off beyond 35 Hz. We use two finite-source stochastic models. One is an approximate model that reduces to the ??2-source model at distances greater that about twice the source dimension. This model has the advantage that the ground motion is controlled by the familiar stress parameter, ????. In the other finite-source model, which is more reliable for near-source ground-motion estimation, the high-frequency radiation is controlled by the strength factor, sfact, a quantity that is physically related to the maximum slip rate on the fault. We estimate ???? needed to fit the observed Amax and Vmax data of each earthquake (which are mostly in the far field). The corresponding sfact is obtained by requiring that the predicted curves from the two models match each other in the far field up to a distance of about 500 km. The results show: (1) The ???? that explains Amax data for shield events may be a function of depth, increasing from ???50 bars at 10 km to ???400 bars at 36 km. The corresponding sfact values range from 1.0-2.0. The ???? values for the two Himalayan arc events are 75 and 150 bars (sfact = 1.0 and 1.4). (2) The ???? required to explain Vmax data is, roughly, half the corresponding value for Amax, while the same sfact explains both sets of data. (3) The available far-field Amax and Vmax data for the Bhuj mainshock are well explained by ???? = 200 and 100 bars, respectively, or, equivalently, by sfact = 1.4. The predicted Amax and Vmax in the epicentral region of this earthquake are 0.80 to 0.95 g and 40 to 55 cm/sec, respectively.

The long-range shelling of Paris and physical chemistry problems of extremely long-range firing

NASA Astrophysics Data System (ADS)

Stettbacher, A.

1986-04-01

The 128-km long-range artillery shelling of Paris is discussed considering its physical and chemical make-up from the vantage point of the technology in 1919. It compares this shelling with a hypothetical 240-km shelling and concludes that the most important influence on shelling range distance to be air resistance. The amount of air resistance and the resulting velocity deceleration depend on the air's density and the shell's velocity and configuration.

Inhibition of purified enolases from oral bacteria by fluoride.

PubMed

Guha-Chowdhury, N; Clark, A G; Sissons, C H

1997-04-01

Enolase activity in strains of oral streptococci previously has been found to be inhibited by 50% (Ki) by fluoride concentrations ranging from 50 to 300 microM or more in the presence of 0.5 to 1.0 mM inorganic phosphate ions. In this study, enolase was extracted and partly purified by a two-step process from five oral bacterial species and the effect of fluoride on the kinetics of enolase examined. The molecular weight of the putative enolase proteins was 46-48 kDa. The Vmax values ranged from 20 to 323 IU/mg and K(m) for glycerate-2-phosphate from 0.22 to 0.74 mM. Enolase activity was inhibited competitively by fluoride, with Ki values ranging from 16 to 54 microM in the presence of 5 mM inorganic phosphate ions. Ki values for phosphate ranged from 2 to 8 mM. The enolase from Streptococcus sanguis ATCC 10556 was more sensitive to fluoride (Ki = 16 +/- 2) than was enolase from Streptococcus salivarius ATCC 10575 (Ki = 19 +/- 2) or Streptococcus mutans NCTC 10449 (Ki = 40 +/- 4) and all three streptococcal strains were more sensitive to fluoride than either Actinomyces naeslundii WVU 627 (Ki = 46 +/- 6) or Lactobacillus rhamnosus ATCC 7469 (Ki = 54 +/- 6) enolases. The levels of fluoride found to inhibit the streptococcal enolases in this study are much lower than previously reported and are likely to be present in plaque, especially during acidogenesis, and could exert an anti-glycolytic effect.

Burial and exhumation of the Eisenhower Range, Transantarctic Mountains, based on thermochronological, sedimentary rock maturity and petrographic constraints

NASA Astrophysics Data System (ADS)

Prenzel, J.; Lisker, F.; Elsner, M.; Schöner, R.; Balestrieri, M. L.; Läufer, A. L.; Berner, U.; Spiegel, C.

2014-09-01

The Eisenhower Range is a N-S trending mountain range in the Transantarctic Mountains (TAM) adjacent to the NW Ross Sea Embayment. New AFT and apatite (U-Th-Sm)/He (AHe) data from vertical basement profiles supplemented by paleotemperature and pressure estimates derived from Beacon sandstones provide new quantitative results on regional burial evolution and first regional constraints on basin inversion and exhumation processes. AFT ages between 32 ± 2 and 259 ± 18 Ma and AHe ages of 37 ± 3-173 ± 16 Ma correlate positively with sample elevations. Thermal history modeling of these data and complementary thermal indications detect heating of the paleosurface on the Eisenhower Range to temperatures ≥ 80 °C subsequent to Ferrar magmatism, and constrain Late Eocene rapid cooling. Regression of modeled paleotemperatures against sample elevations refers to a high Jurassic (~ 45 °C/km) and a moderate Cretaceous-Eocene (28 ± 8 °C/km) geothermal gradient. The texture of Beacon sandstones supports strong mechanical compaction that requires a higher overburden than preserved in the stratigraphic record. Modeled paleotemperatures and pressures suggest basement burial that increases from Late Jurassic (0.7-1.1 km) to Eocene (1.8-2.1 km). The overburden comprises 0.7-1.1 km cumulative Beacon/Ferrar rocks and 0.7-1.4 km of post-Ferrar sediments. Rapid cooling of the whole sample suite between ~ 35 and 30 Ma implies fast erosion of the post-Ferrar sediments and (re-) exposure of underlying magmatic rocks. Subsequent differential sample cooling to present-day surface temperature infers ongoing exhumation by glacial incision enhanced by isostatic response to basin inversion. Decreasing amounts of exhumation from the coast (> 3 km) toward the interior (1.5-2.2 km) point to backstepping incision along the fault controlled Priestley Glacier. Substantial exhumation of the Eisenhower Range since the Late Eocene is hence triggered by both tectonic and climatic factors, superimposed by considerable lithological influence during the initial exhumation stage.

Urban sewage lipids in the suspended particulate matter of a coral reef under river influence in the South West Gulf of Mexico.

PubMed

Carreón-Palau, Laura; Parrish, Christopher C; Pérez-España, Horacio

2017-10-15

Nutritional quality of suspended particulate matter (SPM) and the degree of human fecal pollution in the largest coral reef system in the southwest Gulf of Mexico were evaluated using lipid classes, fatty acids (FA) and sterols in the dry and rainy seasons. High proportions of triacylglycerols and saturated and monounsaturated FA were detected in the SPM however it was considered poor quality because it had low proportions of highly unsaturated FA which can be used to determine production of marine biogenic material of dietary value to pelagic and benthic organisms. Urban sewage organic carbon was traced with coprostanol. The reference value of coprostanol from the point source of pollution was set using two samples from a sewage treatment plant processing waste from >140,000 people near the coral reef system, and it was contrasted with one river station and nine marine stations including six coral reefs. The concentration of coprostanol in the SPM was 3621 ± 98 ng L -1 comprising 26% of total sterols. During the dry season, the river was contaminated upstream with human feces as evidenced by coprostanol at 1823 ng L -1 , the 5β-coprostanol: cholesterol ratio at 0.5, and 5β-coprostanol: [5α-cholestanol+5β-coprostanol] at 0.7. In contrast, marine stations had concentrations of coprostanol lower than a suggested regulation limit for tropical marine coastal waters (30 ng L -1 ), ranging between 6 and 28 ng L -1 . During the rainy season a dilution effect was detected in the river, however significantly higher concentrations of coprostanol in the marine stations were detected ranging between 15 and 215 ng L -1 , higher than the tentative tropical regulation range (30-100 ng L -1 ). Among the reefs, the nearshore one, 14.3 km from the treatment plant, was more exposed to human-fecal pollution, and offshore reefs, >17.3 km from the plant, had a lower degree of contamination. Finally, only three stations were clearly uncontaminated during both seasons including two reefs in the south located 21.8 and 35.6 km from the plant, with no presence of coprostanol. Contamination in the rainy season likely comes from a village with untreated sewage located 9.3-32 km from the reefs, and from the second largest Mexican river flowing into the Gulf of Mexico which has a watershed covering three states with lower than average sewage treatment. Inclusion of coprostanol monitoring could be a key factor in the management of this coral reef system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quaternary extrusion rates of the Cascade Range, northwestern United States and southern British Columbia

NASA Astrophysics Data System (ADS)

Sherrod, David R.; Smith, James G.

1990-11-01

Quaternary (2-0 Ma) extrusion rates change significantly along the Cascade Range volcanic arc. The extrusion rate north of Mount Rainier is about 0.21 km3 km-1 m.y.-1; the rate in southern Washington and northern Oregon south to Mount Hood is about 1.6 km3 km-1 m.y.-1; in central Oregon the rate is 3-6 km3 km-1 m.y.-1; and in northern California, the rate is 3.2 km3 km-1 m.y.-1. Eruption style also changes along the arc but at latitudes different from rate changes. At the ends of the arc, volcanism is focused at isolated intermediate to silicic composite volcanoes. The composite volcanoes represent ˜30% of the total volume of the arc. Mafic volcanic fields partly ring some composite volcanoes, especially in the south. In contrast, volcanism is diffused in the middle of the arc, where numerous overlapping mafic shields and a few composite volcanoes have built a broad ridge. Contrasting eruption style may signify diffuse versus focused heat sources or may reflect changes in permeability to ascending magma along the arc.

Crustal structure in the western United States; study of seismic propagation paths and regional traveltimes in the California-Nevada region

USGS Publications Warehouse

Roller, J.C.; Jackson, W.H.; Cooper, J.F.; Martina, B.A.

1963-01-01

The U.S. Geological Survey, with the assistance of United ElectroDynamics, Inc., completed ten weeks of seismic-refraction field work during the summer of 1962 in the southwestern part of the United States. This work was a continuation of a program initiated in 1961 to study traveltimes and seismic propagation paths in the earth?s crust and upper mantle in the western United States. A total of 761 seismograms were recorded along 10 profiles from 86 explosions at 18 shotpoints. Analysis of the data is continuing, but a few conclusions can be made from a preliminary study: (1) Variations in traveltimes in the Basin and Range province are large but measurable, and perhaps predictable. (2) Traveltimes of seismic waves in adjacent geologic provinces are usually significantly different. (3) The velocity of Pg along all of the profiles recorded in 1962 ranges from 5.0 to 6.5 km/sec, and averages 6.0 km/sec. (4) The average velocity of Pg in extreme northern Nevada and southern Idaho is 5.6 km/sec, and it is 6.1 km/sec in most of Nevada and California. (5) The average velocity of Pn is 7–9 km/ sec and ranges from 7.85 to 7.95 km/sec on reversed profiles where the true Pn velocity could be computed. (6) A shallow "intermediate" layer with a velocity of approximately 6.8 km/sec was found in the Snake River Plain. (7) Refraction arrivals from the mantle (Pn) were recorded in the Sierra Nevada. They indicate that the thickness of the crust in the Sierra Nevada is much greater than that in the Basin and Range province. (8) Many refinements in field techniques were made during the 1962 field season.

A statistical spatial power spectrum of the Earth's lithospheric magnetic field

NASA Astrophysics Data System (ADS)

Thébault, E.; Vervelidou, F.

2015-05-01

The magnetic field of the Earth's lithosphere arises from rock magnetization contrasts that were shaped over geological times. The field can be described mathematically in spherical harmonics or with distributions of magnetization. We exploit this dual representation and assume that the lithospheric field is induced by spatially varying susceptibility values within a shell of constant thickness. By introducing a statistical assumption about the power spectrum of the susceptibility, we then derive a statistical expression for the spatial power spectrum of the crustal magnetic field for the spatial scales ranging from 60 to 2500 km. This expression depends on the mean induced magnetization, the thickness of the shell, and a power law exponent for the power spectrum of the susceptibility. We test the relevance of this form with a misfit analysis to the observational NGDC-720 lithospheric magnetic field model power spectrum. This allows us to estimate a mean global apparent induced magnetization value between 0.3 and 0.6 A m-1, a mean magnetic crustal thickness value between 23 and 30 km, and a root mean square for the field value between 190 and 205 nT at 95 per cent. These estimates are in good agreement with independent models of the crustal magnetization and of the seismic crustal thickness. We carry out the same analysis in the continental and oceanic domains separately. We complement the misfit analyses with a Kolmogorov-Smirnov goodness-of-fit test and we conclude that the observed power spectrum can be each time a sample of the statistical one.

Transient kinetic studies of pH-dependent hydrolyses by exo-type carboxypeptidase P on a 27-MHz quartz crystal microbalance.

PubMed

Furusawa, Hiroyuki; Takano, Hiroki; Okahata, Yoshio

2008-02-15

pH-Dependent kinetic parameters (k(on), k(off), and k(cat)) of protein (myoglobin) hydrolyses catalyzed by exo-enzyme (carboxypeptidase P, CPP) were obtained by using a protein-immobilized quartz crystal microbalance (QCM) in acidic aqueous solutions. The formation of the enzyme-substrate (ES) complex (k(on)), the decay of the ES complex (k(off)), and the formation of the product (k(cat)) could be analyzed by transient kinetics as mass changes on the QCM plate. The Kd (k(off)/k(on)) value was different from the Michaelis constant Km calculated from (k(off) + k(cat))/k(on) due to k(cat) > k(off). The rate-determining step was the binding step (k(on), and the catalytic rate k(cat) was faster than other k(on) and k(off) values. In the range of pH 2.5-5.0, values of k(on) gradually increased with decreasing pH showing a maximum at pH 3.7, values of k(off) were independent of pH, and k(cat) increased gradually with decreasing pH. As a result, the apparent rate constant (k(cat)/Km) showed a maximum at pH 3.7 and gradually increased with decreasing pH. The optimum pH at 3.7 of k(on) is explained by the optimum binding ability of CPP to the COOH terminus of the substrate with hydrogen bonds. The increase of k(cat) at the lower pH correlated with the decrease of alpha-helix contents of the myoglobin substrate on the QCM.

A magnetic and gravity investigation of the Liberia Basin, West Africa

NASA Astrophysics Data System (ADS)

Morris Cooper, S.; Liu, Tianyou

2011-02-01

Gravity and magnetic analysis provide an opportunity to deduce and understand to a large extent the stratigraphy, structure and shape of the substructure. Euler deconvolution is a useful tool for providing estimates of the localities and depth of magnetic and gravity sources. Wavelet analysis is an interesting tool for filtering and improving geophysical data. The application of these two methods to gravity and magnetic data of the Liberia Basin enable the definition of the geometry and depth of the subsurface geologic structures. The study reveals the basin is sub-divided and the depth to basement of the basin structure ranges from about 5 km at its North West end to 10 km at its broadest section eastward. Magnetic data analysis indicates shallow intrusives ranging from a depth of 0.09 km to 0.42 km with an average depth of 0.25 km along the margin. Other intrusives can be found at average depths of 0.6 km and 1.7 km respectively within the confines of the basin. An analysis of the gravity data indicated deep faults intersecting the transform zone.

NGC 1058: Gas motions in an extended, quiescent spiral disk

NASA Technical Reports Server (NTRS)

Hanson, Margaret Murray; Dickey, John M.; Helou, George

1990-01-01

Researchers investigate in detail the motion of gas in the galaxy NGC 1058 using the very large array (VLA) to map the emission in the 21-cm line. This galaxy is so nearly face-on that the contribution to the line width due to the variation of the rotational velocity across the D-array beam is small compared with the random z-motion of the gas. Researchers confirm results of earlier studies (Lewis 1987, A. and A. Suppl., 63, 515; van der Kruit and Shostak 1984, A. and A., 134, 258) of the galaxy's total neutral hydrogen (HI) and kinematics, including the fact that the rotation curve drops faster than Keplerian at the outer edge of the disk, which is interpreted as a fortuitous twist of the plane of rotation in the outer disk. However, their very high velocity resolution (2.58 km s(exp -1) after Hanning smoothing) coupled with good spatial resolution, allows researchers to measure more accurately the line width, and even to some extent its shape, throughout the disk. One of the most interesting results of this study is the remarkable constancy of the line width in the outer disk. From radius 90 to 210 seconds the Gaussian velocity dispersion (sigma sub nu) of the 21-cm line has a mean value of 5.7 km s(exp -1) (after correcting for the spectral resolution) with a dispersion of less than 0.9 km s(exp -1) (after correcting for the spectral resolution) with a dispersion of less than 0.9 km s(exp -1). Translating this directly into a kinetic temperature (Doppler temperature): T sub Dopp equals 121K (sigma sub mu exp 2/(km s(exp -1) (exp 2) gives 4000 K, with a dispersion of less than 1500 K over the outer disk. This constancy is observed even when comparing the spiral arms versus inter-arm regions, which in the radius range from 100 to 150 seconds the surface density modulates (defined as the ratio N sub peak -N sub trough/N sub peak + N sub trough) from 0.5 to 0.25 in the range 150 to 200 seconds.

Substrate Specificity and Inhibitor Sensitivity of Plant UDP-Sugar Producing Pyrophosphorylases

PubMed Central

Decker, Daniel; Kleczkowski, Leszek A.

2017-01-01

UDP-sugars are essential precursors for glycosylation reactions producing cell wall polysaccharides, sucrose, glycoproteins, glycolipids, etc. Primary mechanisms of UDP sugar formation involve the action of at least three distinct pyrophosphorylases using UTP and sugar-1-P as substrates. Here, substrate specificities of barley and Arabidopsis (two isozymes) UDP-glucose pyrophosphorylases (UGPase), Arabidopsis UDP-sugar pyrophosphorylase (USPase) and Arabidopsis UDP-N-acetyl glucosamine pyrophosphorylase2 (UAGPase2) were investigated using a range of sugar-1-phosphates and nucleoside-triphosphates as substrates. Whereas all the enzymes preferentially used UTP as nucleotide donor, they differed in their specificity for sugar-1-P. UGPases had high activity with D-Glc-1-P, but could also react with Fru-1-P and Fru-2-P (Km values over 10 mM). Contrary to an earlier report, their activity with Gal-1-P was extremely low. USPase reacted with a range of sugar-1-phosphates, including D-Glc-1-P, D-Gal-1-P, D-GalA-1-P (Km of 1.3 mM), β-L-Ara-1-P and α-D-Fuc-1-P (Km of 3.4 mM), but not β-L-Fuc-1-P. In contrast, UAGPase2 reacted only with D-GlcNAc-1-P, D-GalNAc-1-P (Km of 1 mM) and, to some extent, D-Glc-1-P (Km of 3.2 mM). Generally, different conformations/substituents at C2, C4, and C5 of the pyranose ring of a sugar were crucial determinants of substrate specificity of a given pyrophosphorylase. Homology models of UDP-sugar binding to UGPase, USPase and UAGPase2 revealed more common amino acids for UDP binding than for sugar binding, reflecting differences in substrate specificity of these proteins. UAGPase2 was inhibited by a salicylate derivative that was earlier shown to affect UGPase and USPase activities, consistent with a common structural architecture of the three pyrophosphorylases. The results are discussed with respect to the role of the pyrophosphorylases in sugar activation for glycosylated end-products. PMID:28970843

The Maupin, Oregon Earthquake Swarm

NASA Astrophysics Data System (ADS)

Braunmiller, J.; Williams, M.; Trehu, A. M.; Nabelek, J.

2008-12-01

The area near Maupin, Oregon has experienced over 300 earthquakes since December 2006. The events, located by the Pacific Northwest Seismic Network (PNSN), occurred ~10 km SE of the town in central Oregon and ~50 km E-SE of Mount Hood. The temporal event pattern and lack of a distinct main shock are characteristic of an earthquake swarm with the event-size distribution indicating a low b-value similar to other non-volcanic swarms. Locations show a NW-SE trending, ~4x3 km cluster at apparent depths of 12-24 km. The largest events (Mw=3.8 and 3.9) on March 1, 2007 and July 14, 2008 occurred more than one year apart; 11 other events had a magnitude of 3 or greater. The larger events were felt locally. During the first 14 months EarthScope USArray seismic stations surrounded the swarm, providing a unique high-quality dataset. Waveform similarity at the closest USArray site G06A indicates hypocenters are much tighter than suggested by the PNSN distribution. Moment tensor inversion reveals nearly identical double- couple strike-slip mechanisms on a plane striking ~15° NW for the three largest 2007 events and the July 2008 event. The April 2008 Mw=3.3 event is rotated ~10° clockwise consistent with slight changes of G06A three-component waveforms relative to the other events. Preferred centroid depths are in the 15-20 km range. Historically, seismicity in the Pacific Northwest east of the Cascades is characterized by sporadic bursts of clustered seismicity with occasional M=6 earthquakes. The largest instrumentally recorded earthquake near Maupin (Mw=4.6) occurred 1976. An earlier swarm was observed 1987, but since then only ~2 events/yr occurred until the current swarm. In spite of recurrent seismicity, exposed surface rocks near Maupin are undeformed lava flows of the Columbia River Basalt Group and older John Day volcanics. The geologic map of Oregon shows a NW-trending dip slip fault near the epicenter area, inconsistent with moment tensor solutions. The cause for the swarm is currently unknown with hypotheses ranging from magmatic or fluid motion in the crust to tectonic activity along a weakly coupled microplate boundary.

Kelvin waves: a comparison study between SABER and normal mode analysis of ECMWF data

NASA Astrophysics Data System (ADS)

Blaauw, Marten; Garcia, Rolando; Zagar, Nedjeljka; Tribbia, Joe

2014-05-01

Equatorial Kelvin waves spectra are sensitive to the multi-scale variability of their source of tropical convective forcing. Moreover, Kelvin wave spectra are modified upward by changes in the background winds and stability. Recent high resolution data from observations as well as analyses are capable of resolving the slower Kelvin waves with shorter vertical wavelength near the tropical tropopause. In this presentation, results from a quantitive comparison study of stratospheric Kelvin waves in satellite data (SABER) and analysis data from the ECMWF operational archive will be shown. Temperature data from SABER is extracted over a six year period (2007-2012) with an effective vertical resolution of 2 km. Spectral power of stratospheric Kelvin waves in SABER data is isolated by selecting symmetric and eastward spectral components in the 8-20 days range. Global data from ECMWF operational analysis is extracted for the same six years on 91 model levels (top level at 0.01 hPa) and 25 km horizontal resolution. Using three-dimensional orthogonal normal-mode expansions, the input mass and wind data from ECMWF is projected onto balanced rotational modes and unbalanced inertia-gravity modes, including spectral data for pure Kelvin waves. The results show good agreement between Kelvin waves in SABER and ECMWF analyses data for: (i) the frequency shift of Kelvin wave variance with height and (ii) vertical wavelengths. Variability with respect to QBO will also be discussed. In a previous study, discrepancies in the upper stratosphere were found to be 60% and are found here to be 10% (8-20 day averaged value), which can be explained by the better stratosphere representation in the 91 model level version of the ECMWF operational model. New discrepancies in Kelvin wave variance are found in the lower stratosphere at 20 km. Averaged spectral power over the 8-20 day range is found to be 35% higher in ECMWF compared to SABER data. We compared results at 20 km with additional satellite data from HIRDLS (1 km eff. resolution) and conclude preliminary that SABER data does not represent the shortest 20 day Kelvin waves as well as HIRDLS and ECMWF operational analysis.

Shear heating and metamorphism in subduction zones, 2. The seismic-aseismic transition at c. 50 km depth.

NASA Astrophysics Data System (ADS)

Castro, A. E.; Spear, F. S.; Kohn, M. J.

2017-12-01

Recent work demonstrates that shear heating, which is required for explaining fore-arc heat flow, reconciles thermal models with pressure-temperature (P-T) conditions determined from exhumed metamorphic rocks, i.e. exhumed rocks are representative of normal subduction. However, the range of subduction conditions on Earth (age, angle and rate of subducting plate, character of overriding plate, coefficient of friction, etc.) implies a ≥250 °C range of corresponding temperatures at the depth of the seismic-aseismic transition (SAT), which is consistently observed at 40-60 km in subduction zones worldwide. Here we show that the predicted rheologies and mineral stabilities for 3 common rock types fail to explain the global consistency of the SAT depth, and we propose that mechanical removal of the weakest rocks is required. Using either realistic thermal models, or P-T conditions recorded by exhumed metamorphic rocks, a substantial subset of depths corresponding with any single petrologic or rheological process falls outside the relatively restricted 40-60 km depth of the SAT. For example, a thermal weakening mechanism (the brittle-ductile transition) implies a wide range of depths, regardless of proposed T (e.g. 20-30 km (300 °C), 25-60 km (400 °C), 35 to >85 km (500 °C), etc). Similarly, individual dehydration reactions span a larger range of depths than observed for the SAT; for example, chlorite-out (metapelites: 35 to >85 km; metabasalts: 40 to >85 km), brucite-out (35-75 km) and serpentine/talc-out (50 to >80 km). The failure of a single petrologic and rheological trigger for these characteristic rocks to produce a consistent SAT depth implies that these rocks do not control the SAT, and consequently must not be abundant at depths below the SAT. That is, these hydrated, weak, and buoyant rocks must be squeezed out of the subduction system, although subduction of discontinuous blobs or lenses to greater depth, e.g. to feed arc volcanoes, may occur. The SAT instead may represent progressive strengthening of the subduction interface through mechanical exclusion of weak rocks and formation of stiffer minerals with increasing temperature and depth. Ultimately, as the strengths of the slab and mantle wedge converge at c. 80 km depth, mechanical coupling occurs, driving mantle wedge convection.

Ab initio calculation of infrared intensities for hydrogen peroxide

NASA Technical Reports Server (NTRS)

Rogers, J. D.; Hillman, J. J.

1982-01-01

Results of an ab initio SCF quantum mechanical study are used to derive estimates for the infrared intensities of the fundamental vibrations of hydrogen peroxide. Atomic polar tensors (APTs) were calculated on the basis of a 4-31G basis set, and used to derive absolute intensities for the vibrational transitions. Comparison of the APTs calculated for H2O2 with those previously obtained for H2O and CH3OH, and of the absolute intensities derived from the H2O2 APTs with those derived from APTs transferred from H2O and CH3OH, reveals the sets of values to differ by no more than a factor of two, supporting the validity of the theoretical calculation. Values of the infrared intensities obtained correspond to A1 = 14.5 km/mol, A2 = 0.91 km/mol, A3 = 0.058 km/mol, A4 = 123 km/mol, A5 = 46.2 km/mol, and A6 = 101 km/mol. Charge, charge flux and overlap contributions to the dipole moment derivatives are also computed.

Ab initio calculation of infrared intensities for hydrogen peroxide

NASA Astrophysics Data System (ADS)

Rogers, J. D.; Hillman, J. J.

1982-04-01

Results of an ab initio SCF quantum mechanical study are used to derive estimates for the infrared intensities of the fundamental vibrations of hydrogen peroxide. Atomic polar tensors (APTs) were calculated on the basis of a 4-31G basis set, and used to derive absolute intensities for the vibrational transitions. Comparison of the APTs calculated for H2O2 with those previously obtained for H2O and CH3OH, and of the absolute intensities derived from the H2O2 APTs with those derived from APTs transferred from H2O and CH3OH, reveals the sets of values to differ by no more than a factor of two, supporting the validity of the theoretical calculation. Values of the infrared intensities obtained correspond to A1 = 14.5 km/mol, A2 = 0.91 km/mol, A3 = 0.058 km/mol, A4 = 123 km/mol, A5 = 46.2 km/mol, and A6 = 101 km/mol. Charge, charge flux and overlap contributions to the dipole moment derivatives are also computed.

Hydrogeological delineation of groundwater potential zones in the Nabogo basin, Ghana

NASA Astrophysics Data System (ADS)

Nsiah, Emmanuel; Appiah-Adjei, Emmanuel K.; Adjei, Kwaku A.

2018-07-01

This study has delineated groundwater potential zones of the Nabogo basin and categorized the northern and eastern parts, representing about 35% of the total basin, as the most suitable areas for groundwater prospecting. The inhabitants of the basin depend on rainfall and small surface reservoirs for their various water supply needs, which become very scarce and unsustainable in the dry seasons due to the arid to semi-arid conditions of the basin. Thus, groundwater is increasingly being exploited to supplement the water needs of the populace. However, groundwater development in the basin is sometimes hindered by relatively low success rate of boreholes. Therefore, this study was aimed at delineating the groundwater potential zones of the basin to improve on development of the resource for supply to the populace. The methodology used involved acquisition of data on well-distributed boreholes in the basin, computation of transmissivity and specific capacity values from the data, and delineation of potential groundwater zones through integration of borehole yields, regolith thickness, static water level and transmissivity using the weighted overlay technique in a GIS environment. The study results indicate that transmissivity ranges from 0.1 to 535 m2/day with a mean of 19.7 m2/day while the specific capacity ranges from 0.25 to 170.88 m3/day/m with a mean of 13.42 m3/day/m. A groundwater potential map generated categorizes the basin into poor, moderate and high zones covering 652.52 km2, 1250.45 km2 and 1002.23 km2 respectively, which would be very useful for groundwater development.

Heat-flow data and their relation to observed geothermal phenomena near Klamath Falls, Oregon

USGS Publications Warehouse

Sass, J.H.; Sammel, Edward A.

1976-01-01

Two holes were drilled to depths of about 180 m in the Lower Klamath Lake basin south of Klamath Falls, Oregon, to obtain heat flow data and to provide estimates of the thermal conductivity of the valley fill. Twenty-nine thermal conductivity determinations on eight cores give a mean conductivity of 1.82 mcal/cm s °C (0.75 W/m °K). Curvature in the upper 50 m of both terriperature profiles indicates a decrease in surface temperature of about 1.8°C, presumably resulting frorn reclamation of what was marshland in the early part of this century. A surprisingly low heat flow of 0.3 HFU (1 HFU = 10−6 cal/cm2 s = 41.8 mW/m2) was measured at site LS near the center of the basin. At site OC-1, 7 km east of LS and 2 km from the Klamath Hills geothermal zone, the heat flow was 1.44 HFU, also a low value in this setting. Temperature profiles in 15 unused water wells in the area had linear gradients ranging from 47° to 170°C/km. The corresponding lower limits of heat flow (conductivities measured at the two heat flow sites being used) range from 0.8 to 3.1 HFU. These variations in heat flow evidently are caused by temperature variations in a convecting system within the near-surface volcanic rocks and do not provide firm constraints on the nature of heat sources at depth.

Evolution of the stratospheric aerosol in the northern hemisphere following the June 1991 volcanic eruption of Mount Pinatubo: Role of tropospheric-stratospheric exchange and transport

NASA Astrophysics Data System (ADS)

Jónsson, Hafliòi H.; Wilson, James C.; Brock, Charles A.; Dye, J. E.; Ferry, G. V.; Chan, K. R.

1996-01-01

Since the eruption of Mount Pinatubo in June, 1991, measurements of particle size and concentration have intermittently been carried out from an ER-2 aircraft at altitudes of up to 21 km at midlatitudes and high latitudes in the northern hemisphere. They show the evolution and purge of the volcanic aerosol to be due to an interaction of aerosol mechanics with tropospheric-stratospheric exchange processes, transport, and mixing. During the first 5 months after the eruption the volcanic plume spread to higher latitudes in laminae and filaments, producing steep spatial gradients in the properties of the stratospheric aerosol. At the same time the concentration of newly formed particles in the plume rapidly decreased toward background values as a result of coagulation while particle size and aerosol surface area continued to increase. By December 1991, the particle number mixing ratios and aerosol surface area mixing ratios had become spatially uniform over a wide range of latitudes above 18 km. The surface area mixing ratios peaked in this region of the stratosphere at ˜35 times their background values in the winter of 1992. The corresponding condensed mass mixing ratio enhancement was by a factor of ˜200. After the winter of 1992, a gradual removal of the volcanic mass began and initially was dominated by sedimentation above 18 km. The aerosol surface area mixing ratio thus decreased by an order of magnitude over 2.5 years, and the aerosol volume, or condensed mass, mixing ratio decayed by an order of magnitude over approximately 1.7 years. Below 18 km, the purging of the Pinatubo aerosol at mid-latitudes appeared sporadic and disorderly and was strongly influenced by episodal rapid quasi-isentropic transport and dilution by tropical air of tropospheric origin having high condensation nuclei mixing ratios but low mixing ratios of aerosol surface area or condensed mass compared to the volcanic aerosol.

Shear velocity and intrinsic Q structure of the shallow crust in southeastern New England from Rg wave dispersion

NASA Astrophysics Data System (ADS)

Saikia, Chandan K.; Kafka, Alan L.; Gnewuch, Scott C.; McTigue, John W.

1990-06-01

In this study, we analyzed 0.5-2.0 s period Rayleigh waves (Rg) generated by quarry and construction blasting in southern New England (CNE). We investigated group velocity dispersion and attenuation of the observed Rg waves. The paths crossing the Hartford Rift basin (HRB) show an obvious correlation between geology and Rg dispersion. The entire region in the southeastern New England comprising a wide range of geological structures and rock types from the Bronson Hill Anticlinorium to the Avalonian Terrane can be represented as one dispersion region. Therefore the relationship between lateral changes in geologic structures mapped on the surface and Rg dispersion is not as straightforward as might be expected for a best fitting flat-layered model of the shallow crust. The shear wave velocities appear to vary between 2.55 and 3.63 km/s within the upper 2.5 km except for the central HRB where the variation is between 2.12 and 2.7 km/s. Intrinsic Q structure is considered to be the primary means for the loss of energy in the shallow crust and was analyzed by modelling the waveforms of several of the observed seismograms. For this aspect of our study, we used a modal summation of Rayleigh waves assuming a far-field radiation approximation. The observed seismograms were dominated primarily by contributions from the fundamental mode, but higher modes were also included in the synthesis of the waveform. We were unable to model the absolute amplitudes of the waveforms because of the problems with the instrument calibration. It is clear, however, that to predict correct waveforms, the shear wave Q values in the upper few tenths of a kilometer of the crust must be about an order of magnitude smaller than Q values at the depth of 1-3 km which is of order of 100-250.

A large-area, spatially continuous assessment of land cover map error and its impact on downstream analyses.

PubMed

Estes, Lyndon; Chen, Peng; Debats, Stephanie; Evans, Tom; Ferreira, Stefanus; Kuemmerle, Tobias; Ragazzo, Gabrielle; Sheffield, Justin; Wolf, Adam; Wood, Eric; Caylor, Kelly

2018-01-01

Land cover maps increasingly underlie research into socioeconomic and environmental patterns and processes, including global change. It is known that map errors impact our understanding of these phenomena, but quantifying these impacts is difficult because many areas lack adequate reference data. We used a highly accurate, high-resolution map of South African cropland to assess (1) the magnitude of error in several current generation land cover maps, and (2) how these errors propagate in downstream studies. We first quantified pixel-wise errors in the cropland classes of four widely used land cover maps at resolutions ranging from 1 to 100 km, and then calculated errors in several representative "downstream" (map-based) analyses, including assessments of vegetative carbon stocks, evapotranspiration, crop production, and household food security. We also evaluated maps' spatial accuracy based on how precisely they could be used to locate specific landscape features. We found that cropland maps can have substantial biases and poor accuracy at all resolutions (e.g., at 1 km resolution, up to ∼45% underestimates of cropland (bias) and nearly 50% mean absolute error (MAE, describing accuracy); at 100 km, up to 15% underestimates and nearly 20% MAE). National-scale maps derived from higher-resolution imagery were most accurate, followed by multi-map fusion products. Constraining mapped values to match survey statistics may be effective at minimizing bias (provided the statistics are accurate). Errors in downstream analyses could be substantially amplified or muted, depending on the values ascribed to cropland-adjacent covers (e.g., with forest as adjacent cover, carbon map error was 200%-500% greater than in input cropland maps, but ∼40% less for sparse cover types). The average locational error was 6 km (600%). These findings provide deeper insight into the causes and potential consequences of land cover map error, and suggest several recommendations for land cover map users. © 2017 John Wiley & Sons Ltd.