Science.gov

Sample records for ground observations potential

  1. Ground potential rise monitor

    DOEpatents

    Allen, Zachery Warren; Zevenbergen, Gary Allen

    2012-07-17

    A device and method for detecting ground potential rise (GPR) comprising a first electrode, a second electrode, and a voltage attenuator. The first electrode and the second electrode are both electrically connected to the voltage attenuator. A means for determining the presence of a dangerous ground potential is connected to the voltage attenuator. The device and method further comprises a means for enabling one or more alarms upon the detection of the dangerous ground potential. Preferably, a first transmitter/receiver is connected to the means for enabling one or more alarms. Preferably, a second transmitter/receiver, comprising a button, is electromagnetically connected to the first transmitter/receiver. Preferably, the means for determining the presence of a dangerous ground potential comprises a means for determining the true RMS voltage at the output of the voltage attenuator, a transient detector connected to the output of the voltage attenuator, or a combination thereof.

  2. Orbit of potentially hazardous asteroids using Gaia and ground-based observations

    NASA Astrophysics Data System (ADS)

    Bancelin, D.; Hestroffer, D.; Thuillot, W.

    2011-12-01

    Potentially Hazardous Asteroids (PHAs) are Near Earth Asteroids characterized by a Minimum Orbital Intersection Distance (MOID) with Earth less to 0,05 A.U and an absolute magnitude H<22. Those objects have sometimes a so significant close approach with Earth that they can be put on a chaotic orbit. This kind of orbit is very sensitive for exemple to the initial conditions, to the planetary theory used (for instance JPL's model versus IMCCE's model) or even to the numerical integrator used (Lie Series, Bulirsch-Stoer or Radau). New observations (optical, radar, flyby or satellite mission) can improve those orbits and reduce the uncertainties on the Keplerian elements.

  3. Multiscale ground aurora observations

    NASA Astrophysics Data System (ADS)

    Kozelov, Boris

    Aurora is the most impressive phenomenon that initially motivates people's interest in the study of near-Earth space. Now auroral observations provide unique information about the processes occurring in the magnetosphere-ionosphere plasma: this is the only type of observations that gives detailed two-dimensional spatial distribution with sufficient temporal resolution. Fractal power-law distributions that are typical for aurora indicate the passing transients in near-Earth plasma. Spatio-temporal dynamics of active auroral forms on the night side is showing signs of turbulence and self-organized criticality at huge range of scales. Pulsing auroral forms are usually associated with the wave-particle interaction. The report describes the current state of the ground-based optical observations of aurorae at different scales and methods of analysis of their results.

  4. Ground potential rise monitor

    SciTech Connect

    Allen, Zachery W.; Zevenbergen, Gary A.

    2012-04-03

    A device and method for detecting ground potential rise (GPR) comprising positioning a first electrode and a second electrode at a distance from each other into the earth. The voltage of the first electrode and second electrode is attenuated by an attenuation factor creating an attenuated voltage. The true RMS voltage of the attenuated voltage is determined creating an attenuated true RMS voltage. The attenuated true RMS voltage is then multiplied by the attenuation factor creating a calculated true RMS voltage. If the calculated true RMS voltage is greater than a first predetermined voltage threshold, a first alarm is enabled at a local location. If user input is received at a remote location acknowledging the first alarm, a first alarm acknowledgment signal is transmitted. The first alarm acknowledgment signal is then received at which time the first alarm is disabled.

  5. Simulation of polar atmospheric microwave and sub-millimetre spectra for characterizing potential new ground-based observations

    NASA Astrophysics Data System (ADS)

    Newnham, David; Turner, Emma; Ford, George; Pumphrey, Hugh; Withington, Stafford

    2016-04-01

    Advanced detector technologies from the fields of astronomy and telecommunications are offering the potential to address key atmospheric science challenges with new instrumental methods. Adoption of these technologies in ground-based passive microwave and sub-millimetre radiometry could allow new measurements of chemical species and winds in the polar middle atmosphere for verifying meteorological data-sets and atmospheric models. A site study to assess the feasibility of new polar observations is performed by simulating the downwelling clear-sky submillimetre spectrum over 10-2000 GHz (30 mm to 150 microns) at two Arctic and two Antarctic locations under different seasonal and diurnal conditions. Vertical profiles for temperature, pressure and 28 atmospheric gases are constructed by combining radiosonde, meteorological reanalysis, and atmospheric chemistry model data. The sensitivity of the simulated spectra to the choice of water vapour continuum model and spectroscopic line database is explored. For the atmospheric trace species hypobromous acid (HOBr), hydrogen bromide (HBr), perhydroxyl radical (HO2) and nitrous oxide (N2O) the emission lines producing the largest change in brightness temperature are identified and minimum integration times and maximum receiver noise temperatures estimated. The optimal lines for all species are shown to vary significantly between location and scenario, strengthening the case for future hyperspectral instruments that measure over a broad frequency range. We also demonstrate the feasibility of measuring horizontal wind profiles above Halley station, Antarctica with time resolution as high as 0.5hr using simulated spectroradiometric observations of Doppler-shifted ozone (O3) and carbon monoxide (CO) lines in the 230-250 GHz region. The techniques presented provide a framework that can be applied to the retrieval of additional atmospheric parameters and be taken forward to simulate and guide the design of future microwave and sub

  6. Methods for Characterizing Fine Particulate Matter Using Satellite Remote-Sensing Data and Ground Observations: Potential Use for Environmental Public Health Surveillance

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad Z.; Crosson, William L.; Limaye, Ashutosh S.; Rickman, Douglas L.; Quattrochi, Dale A.; Estes, Maurice G.; Qualters, Judith R.; Niskar, Amanda S.; Sinclair, Amber H.; Tolsma, Dennis D.; Adeniyi, Kafayat A.

    2007-01-01

    This study describes and demonstrates different techniques for surfacing daily environmental / hazards data of particulate matter with aerodynamic diameter less than or equal to 2.5 micrometers (PM2.5) for the purpose of integrating respiratory health and environmental data for the Centers for Disease Control and Prevention (CDC s) pilot study of Health and Environment Linked for Information Exchange (HELIX)-Atlanta. It described a methodology for estimating ground-level continuous PM2.5 concentrations using B-Spline and inverse distance weighting (IDW) surfacing techniques and leveraging National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectrometer (MODIS) data to complement The Environmental Protection Agency (EPA) ground observation data. The study used measurements of ambient PM2.5 from the EPA database for the year 2003 as well as PM2.5 estimates derived from NASA s satellite data. Hazard data have been processed to derive the surrogate exposure PM2.5 estimates. The paper has shown that merging MODIS remote sensing data with surface observations of PM2.5 not only provides a more complete daily representation of PM2.5 than either data set alone would allow, but it also reduces the errors in the PM2.5 estimated surfaces. The results of this paper have shown that the daily IDW PM2.5 surfaces had smaller errors, with respect to observations, than those of the B-Spline surfaces in the year studied. However the IDW mean annual composite surface had more numerical artifacts, which could be due to the interpolating nature of the IDW that assumes that the maxima and minima can occur only at the observation points. Finally, the methods discussed in this paper improve temporal and spatial resolutions and establish a foundation for environmental public health linkage and association studies for which determining the concentrations of an environmental hazard such as PM2.5 with good accuracy levels is critical.

  7. Ground observations of kinetic Alfven waves

    SciTech Connect

    Kloecker, N.; Luehr, H.; Robert, P.; Korth, A.

    1985-01-01

    Ground-based observations with the EISCAT magnetometer of locally confined intense drifting current systems and Geos-2 measurements during four events in November and December 1982 are examined. In the ground-based measurements near the Harang discontinuity, the events are characterized by strong pulsations with amplitudes in the horizontal component up to 1000 nT and periods of about 300 s and longer. They occur in the evening hours adjacent to the poleward side of the discontinuity with the onset of a substorm; at the same time, the inner edge of the plasma sheet passes the Geos-2 position, magnetically conjugate to ground stations. It is shown that the events can be explained in terms of kinetic Alfven waves. 8 references.

  8. Assessing ground water development potential using landsat imagery.

    PubMed

    Mutiti, Samuel; Levy, Jonathan; Mutiti, Christine; Gaturu, Ndung'u S

    2010-01-01

    Seven villages in southeastern Kenya surround Mt. Kasigau and depend on the mountain's cloud forest for their water supply. Five of these villages have regularly experienced water shortages, and all village water supplies were contaminated with Escherichia coli bacteria. There is a need to economically find new sources of fresh ground water. Remote sensing offers a relatively quick and cost-effective way of identifying areas with high potential for ground water development. This study used spectral properties of features on Landsat remote sensing imagery to map linear features, soil types, surface moisture, and vegetation. Linear features represented geologic or geomorphologic features indicating either shallow ground water or areas of increased subsurface hydraulic conductivity. Regarding soil type, black soils were identified as potential indicators of shallow aquifers based on their relatively lower elevation and association with river valleys. A vegetation map was created using unsupervised classification, and three of the resulting vegetation classes were observed to be commonly associated with wet areas and/or ground water discharge. A wetness map, created using tasseled cap analysis, was used to identify all areas of high ground moisture, including those that corresponded to vegetated areas. The linear features, soil type, vegetation, and wetness maps were overlaid to produce a composite that highlighted areas with the highest potential for ground water development. Electrical resistivity surveys confirmed that areas highlighted by the composite image had relatively shallow depths to the water table. Some figures in this paper are available in color in the online version of the paper. PMID:19210559

  9. Challenges and Rewards in Ground-Based Observing

    NASA Astrophysics Data System (ADS)

    Reardon, Kevin P.

    2016-05-01

    DKIST will be largest ground-based project in solar physics, and will offer access and data to the whole community. In pursuit of exciting science, many users may have their first encounters with high-resolution, ground-based solar observations. New facilities, space or ground-based, all bring particular signatures in their data. While tools or processed datasets might serve to minimize such non-solar signatures, it is nonetheless important for users to understand the impacts on observation planning, the nature of the corrections applied, and any residual effects on their data.In this talk I will review some of the instrumental and atmospheric signatures that are important for ground-based observing, in particular in planning for the potential capabilities of the DKIST Data Center. These techniques include image warping, local PSF deconvolution, atmospheric dispersion correction, and scattered light removal. I will present examples of data sets afflicted by such problems as well as some of the algorithms used in characterizing and removing these contributions. This will demonstrate how even with the challenges of observing through a turbulent atmosphere, it is possible to achieve dramatic scientific results.

  10. Ground based observations of stratospheric nitrogen dioxide

    NASA Astrophysics Data System (ADS)

    Syed, M. Q.; Harrison, A. W.

    1980-06-01

    The results of ground based measurements of stratospheric NO2, using four different established methods based on twilight sky observations in the spectral region 437.0-451.0 nm and made at two locations: Primrose Lake and at Priddis, Alberta, Canada, during March and April 1979 are presented. It is shown that the four methods differ from one another on the basis of: (a) whether or not stratospheric ozone is taken into account, (b) whether a continuous NO2 absorption spectrum or just the absorption at a few discrete wavelengths is used for analysis, and (c) the assumed altitude distribution of NO2 concentration. Further, two different independently developed altitude distribution models are employed in obtaining the NO2 vertical column abundance and its effective altitude from a set of slant column abundances measured in the twilight sky at different solar zenith angles in the range of 85 to 96 deg. Finally, a comparison shows that the use of one or the other of these two models alone could introduce a difference of as much as 30% in the derived vertical column abundance.

  11. Observations of a possible ground signature of flux transfer events

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.; Nielsen, E.; Korth, A.; Haldoupis, C.; Hoeg, P.; Hayward, D.; Glassmeier, K. H.

    1985-01-01

    Questions regarding the mechanism by which the large-scale cross-tail electric field and associated convection in the magnetosphere is maintained have not yet been completely answered. According to Dungey (1961), the boundary layer (BL) inside the magnetopause (MP) in which the tailward transport of mass, momentum, and magnetic flux takes place can be produced by reconnection. Observations made with the aid of the ISEE spacecraft show that reconnection can occur both in a quasisteady form and in a more unsteady form known under the name 'flux transfer event' (FTE). The present investigation proposes observation of the ground signature of an FTE. It is pointed out that the STARE radar system has the potential for making observations pertinent to identifying and studying the ionospheric signatures of FTE's. An analysis is conducted of two periods during which the convective boundary (CB) moved into the STARE field of view. The significance of the observations is discussed.

  12. GROUND WATER CONTAMINATION POTENTIAL FROM STORMWATER INFILTRATION

    EPA Science Inventory

    Prior to urbanization, ground water recharge resulted from infiltration of precipitation through pervious surfaces, including grasslands and woods. This infiltration water was relatively uncontaminated. With urbanization, the permeable soil surface area through which recharge by...

  13. Ground observations of magnetospheric boundary layer phenomena

    NASA Technical Reports Server (NTRS)

    Mchenry, Mark A.; Clauer, C. Robert; Friis-Christensen, Eigil; Newell, Patrick T.; Kelly, J. D.

    1990-01-01

    Several classes of traveling vortices in the dayside ionosphere convection have been detected and tracked using the Greenland magnetometer chain (Friis-Christensen et al., 1988, McHenry et al., 1989). One class observed during quiet times consists of a continuous series of vortices moving generally antisunward for several hours at a time. The vortices' strength is seen to be approximately steady and neighboring vortices rotate in opposite directions. Sondrestrom radar observations show that the vortices are located at the ionospheric convection reversal boundary. Low altitude DMSP observations indicate the vortices are on field lines which map to the inner edge of the low latitude boundary layer. Because the vortices are conjugate to the boundary layer, repeat in a regular fashion and travel antisunward, it is argued that this class of vortices is caused by the Kelvin-Helmholtz instability of the inner edge of the magnetospheric boundary layer.

  14. Potential for satellite remote sensing of ground water.

    PubMed

    Becker, Matthew W

    2006-01-01

    Predicting hydrologic behavior at regional scales requires heterogeneous data that are often prohibitively expensive to acquire on the ground. As a result, satellite-based remote sensing has become a powerful tool for surface hydrology. Subsurface hydrology has yet to realize the benefits of remote sensing, even though surface expressions of ground water can be monitored from space. Remotely sensed indicators of ground water may provide important data where practical alternatives are not available. The potential for remote sensing of ground water is explored here in the context of active and planned satellite-based sensors. Satellite technology is reviewed with respect to its ability to measure ground water potential, storage, and fluxes. It is argued here that satellite data can be used if ancillary analysis is used to infer ground water behavior from surface expressions. Remotely sensed data are most useful where they are combined with numerical modeling, geographic information systems, and ground-based information.

  15. Challenges and Opportunities for Ground-based Helioseismic Observations

    NASA Astrophysics Data System (ADS)

    Chaplin, W. J.

    2013-12-01

    I summarize the current status of ground-based helioseismic observations, in particular the two operational networks GONG and BiSON. I then discuss requirements for continued and future ground-based observations based on key science drivers, finishing with a discussion of SPRING, a proposed future high-spatial-resolution network that would provide helioseismic data and a broad range of synoptic data products.

  16. Ground-based observation of near-Earth asteroids

    NASA Astrophysics Data System (ADS)

    Gaffey, Michael J.

    An increased ground-based observation program is an essential component of any serious attempt to assess the resource potential of near-Earth asteroids. A vigorous search and characterization program could lead to the discovery and description of about 400 to 500 near-Earth asteroids in the next 20 years. This program, in conjunction with meteorite studies, would provide the data base to ensure that the results of a small number of asteroid-rendezvous and sample-return missions could be extrapolated with confidence into a geological base map of the Aten, Apollo, and Amor asteroids. Ground-based spectral studies of nearly 30 members of the Aten/Apollo/Amor population provide good evidence that this class includes bodies composed of silicates, metal-silicates, and carbonaceous assemblages similar to those found in meteorites. The instruments that are being used or could be used to search for near-Earth asteroids are listed. Techniques useful in characterizing asteroids and the types of information obtainable using these techniques are listed.

  17. Ground-based observation of near-Earth asteroids

    NASA Technical Reports Server (NTRS)

    Gaffey, Michael J.

    1992-01-01

    An increased ground-based observation program is an essential component of any serious attempt to assess the resource potential of near-Earth asteroids. A vigorous search and characterization program could lead to the discovery and description of about 400 to 500 near-Earth asteroids in the next 20 years. This program, in conjunction with meteorite studies, would provide the data base to ensure that the results of a small number of asteroid-rendezvous and sample-return missions could be extrapolated with confidence into a geological base map of the Aten, Apollo, and Amor asteroids. Ground-based spectral studies of nearly 30 members of the Aten/Apollo/Amor population provide good evidence that this class includes bodies composed of silicates, metal-silicates, and carbonaceous assemblages similar to those found in meteorites. The instruments that are being used or could be used to search for near-Earth asteroids are listed. Techniques useful in characterizing asteroids and the types of information obtainable using these techniques are listed.

  18. Ground-based and satellite observations of substorm onset features

    NASA Astrophysics Data System (ADS)

    Chang, T.; Cheng, C. Z.; Chiang, C.; Tam, S. W.; Chen, A. B.; Hsu, R.; Su, H.

    2009-12-01

    We present the ground-based and satellite observations of substorm onset events. In the observations from Ground Based Observatories (GBO) and the ISUAL/FORMOSAT-2 satellite, we find structures which consist of periodic bright spots on the auroral arc prior to the substorm expansion phase onset. The intensity of arc grows exponentially before breakup with a linear growth rate of ~O(1-3)sec-1. Under the arc, the negative H-bay associated with the substorm is evident in the ground-based magnetometer data. From ISUAL observations, the first auroral brightening is identified roughly at the beginning of the negative H-bay. The auroral arc is breaks up before dispersionless particle injections are observed at geosynchronous orbit. Based on analysis of these observations, we suggest that this event can be a support of the scenario of substorm onset which is caused by a kinetic ballooning instability which is localized at ~ -10RE.

  19. Observing Tsunamis in the Ionosphere Using Ground Based GPS Measurements

    NASA Technical Reports Server (NTRS)

    Galvan, D. A.; Komjathy, A.; Song, Y. Tony; Stephens, P.; Hickey, M. P.; Foster, J.

    2011-01-01

    Ground-based Global Positioning System (GPS) measurements of ionospheric Total Electron Content (TEC) show variations consistent with atmospheric internal gravity waves caused by ocean tsunamis following recent seismic events, including the Tohoku tsunami of March 11, 2011. We observe fluctuations correlated in time, space, and wave properties with this tsunami in TEC estimates processed using JPL's Global Ionospheric Mapping Software. These TEC estimates were band-pass filtered to remove ionospheric TEC variations with periods outside the typical range of internal gravity waves caused by tsunamis. Observable variations in TEC appear correlated with the Tohoku tsunami near the epicenter, at Hawaii, and near the west coast of North America. Disturbance magnitudes are 1-10% of the background TEC value. Observations near the epicenter are compared to estimates of expected tsunami-driven TEC variations produced by Embry Riddle Aeronautical University's Spectral Full Wave Model, an atmosphere-ionosphere coupling model, and found to be in good agreement. The potential exists to apply these detection techniques to real-time GPS TEC data, providing estimates of tsunami speed and amplitude that may be useful for future early warning systems.

  20. Ground truth observations for TRMM. [Tropical Rainfall Measuring Mission

    NASA Technical Reports Server (NTRS)

    Thiele, Otto W.

    1989-01-01

    Plans to obtain ground truth data for the validation of the Tropical Rainfall Measuring Mission (TRMM) are examined. The experimental rainfall measuring techniques considered for the program are discussed, including optical and Doppler rain gages, satellite beacon attenuation, underwater hydrophones, profilers, microwave attenuation, multiple frequency/polarization radar, and scanning and airborne Doppler radar. The TRMM validation program is considered, noting observations to compare averaged TRMM rainfall data with similar ground truth data and to compare the rainfall and height distribution data from TRMM with instantaneous ground truth data.

  1. Recent Advances in Magnetoseismology Using Network Observations by Ground Magnetometers

    NASA Astrophysics Data System (ADS)

    Chi, P. J.; Russell, C. T.

    2011-12-01

    The rise of modern, synchronized networks of ground magnetometers in recent years has inspired and advanced research and development in magnetoseismology. Like the practice in other geophysical disciplines, magnetoseismology can infer the structure of the magnetosphere from the observations of normal-mode frequencies of the magnetic field. It can also time and locate impulsive events by measuring the signal arrival time at multiple ground stations. We highlight recent advances in using network observations by ground magnetometers for both types of magnetoseismic research. In the area of normal-mode magnetoseismology the increase in ground magnetometers has enabled ever more station pairs suitable for the gradient analysis. We demonstrate progress in automatic detection of field line resonance frequencies and the results that reveal longitudinal structure of the plasmasphere. As a relatively young research topic, travel-time magnetoseismology has shown its capability to time and locate sudden impulses and substorm onsets by using ground-based magnetometer observations. These initial successes in turn motivated detailed examination of MHD wave propagation in the magnetosphere. In the end we discuss how these magnetoseismic studies shed light on the regions in the world where future establishment of ground magnetometers is desirable.

  2. Ground states of stealthy hyperuniform potentials: I. Entropically favored configurations

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Stillinger, F. H.; Torquato, S.

    2015-08-01

    Systems of particles interacting with "stealthy" pair potentials have been shown to possess infinitely degenerate disordered hyperuniform classical ground states with novel physical properties. Previous attempts to sample the infinitely degenerate ground states used energy minimization techniques, introducing algorithmic dependence that is artificial in nature. Recently, an ensemble theory of stealthy hyperuniform ground states was formulated to predict the structure and thermodynamics that was shown to be in excellent agreement with corresponding computer simulation results in the canonical ensemble (in the zero-temperature limit). In this paper, we provide details and justifications of the simulation procedure, which involves performing molecular dynamics simulations at sufficiently low temperatures and minimizing the energy of the snapshots for both the high-density disordered regime, where the theory applies, as well as lower densities. We also use numerical simulations to extend our study to the lower-density regime. We report results for the pair correlation functions, structure factors, and Voronoi cell statistics. In the high-density regime, we verify the theoretical ansatz that stealthy disordered ground states behave like "pseudo" disordered equilibrium hard-sphere systems in Fourier space. The pair statistics obey certain exact integral conditions with very high accuracy. These results show that as the density decreases from the high-density limit, the disordered ground states in the canonical ensemble are characterized by an increasing degree of short-range order and eventually the system undergoes a phase transition to crystalline ground states. In the crystalline regime (low densities), there exist aperiodic structures that are part of the ground-state manifold but yet are not entropically favored. We also provide numerical evidence suggesting that different forms of stealthy pair potentials produce the same ground-state ensemble in the zero

  3. 7. BULLET GLASS OBSERVATION WINDOW AT GROUND LEVEL ON WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. BULLET GLASS OBSERVATION WINDOW AT GROUND LEVEL ON WEST REAR. - Edwards Air Force Base, South Base Sled Track, Firing & Control Blockhouse for 10,000-foot Track, South of Sled Track at midpoint of 20,000-foot track, Lancaster, Los Angeles County, CA

  4. Analysis of UV Satellite and Ground Observed data for Sardinia

    NASA Astrophysics Data System (ADS)

    Cervone, Guido; Manca, Germana; Johnson, Kathleen

    Ultraviolet (UV) radiation in the 280 to 400 nanometers range has been found to be one of the primary cause for skin cancer. The correlation between UV radiation and skin cancer prevention is of global concern. Satellite observations from Nimbus7 (1978-1993), EarthProbe (1996-2004) and OMI/AURA (2004-present) provide long term UV time-series that can be used to study and compute the risk associated with exposure to harmful radiation. Additionally, several ground installations exist to acquire UV radiation data that can be paired with satellite observations. The current work presents the data mining analysis of UV time series from 1978 to present for the Italian region of Sardinia. Satellite observations are paired with ground measurements to provide historical averages of UV radiation, and daily maps of current exposure. A Geographical Information System (GIS) is used to fuse UV data with ground characteristics. The use of GIS is fundamental to calculate the real value of UV on the ground. It is known that the incidence of solar radiation, and consequently of UV, is modified by topography and surface features. Topography plays a important rule, because it is a major factor that determines the spatial variability of insulation and UV being a part of direct insulation. variation in elevation orientation (slope and aspect), and shadow cast by topographical features, determine the UV insulation in a given area or point.

  5. Ground-based observations of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Snodgrass, C.

    2015-10-01

    I will described the campaign of observations from ground-based (and Earth orbiting) telescopes that supports the Rosetta mission. Rosetta gets closer to the nucleus than any previous mission, and returns wonderfully detailed measurements from the heart of the comet, but at the cost of not seeing the large scale coma and tails. The ground-based campaign fills in the missing part of the picture, studying the comet at #1000km resolution, and following how the overall activity of the comet varies. These data provide context information for Rosetta, so changes in the inner coma seen by the spacecraft can be correlated with the phenomena observable in comets. This not only helps to complete our understanding of the activity of 67P, but also allows us to compare it with other comets that are only observed from the ground, and in that way extend the results of the Rosetta mission to the wider population. The ground-based campaign includes observations with nearly all major facilities world-wide. In 2014 the majority of data came from the ESO VLT, as the comet was still relatively faint and in Southern skies, but as it returns to visibility from Earth in 2015 it will be considerably brighter, approaching its perihelion in August, and at Northern declinations. I will show results from the 2014 campaign, including visible wavelength photometry and spectroscopy, and the latest results from early 2015 observations. I will also describe the varied observations that will be included in the campaign post-perihelion, and how all of these results fit around what we are learning about 67P from Rosetta.

  6. Potential risk of microplastics transportation into ground water

    NASA Astrophysics Data System (ADS)

    Huerta, Esperanza; Gertsen, Hennie; Gooren, Harm; Peters, Piet; Salánki, Tamás; van der Ploeg, Martine; Besseling, Ellen; Koelmans, Albert A.; Geissen, Violette

    2016-04-01

    Microplastics, are plastics particles with a size smaller than 5mm. They are formed by the fragmentation of plastic wastes. They are present in the air, soil and water. But only in aquatic systems (ocean and rivers) are studies over their distribution, and the effect of microplastics on organisms. There is a lack of information of what is the distribution of microplastics in the soil, and in the ground water. This study tries to estimate the potential risk of microplastics transportation into the ground water by the activity of earthworms. Earthworms can produce burrows and/or galleries inside the soil, with the presence of earthworms some ecosystem services are enhanced, as infiltration. In this study we observed after 14 days with 5 treatments (0, 7, 28 and 60% w/w microplastics mixed with Populus nigra litter) and the anecic earthworm Lumbricus terrestris, in microcosms (3 replicas per treatment) that macroplastics are indeed deposit inside earthworms burrows, with 7% microplastics on the surface is possible to find 1.8 g.kg-1 microplastics inside the burrows, with a bioaumentation factor of 0.65. Burrows made by earthworms under 60% microplastics, are significant bigger (p<0.05) than the burrows of those earthworms without microplastics in their soil surface. The amount of litter that is deposit inside the burrows is significant higher (p<0.05) with the presence of microplastics on the surface than without microplastics. The microplastics size distribution is smaller inside the burrows than on the surface, with an abundance of particles under 63 μm.

  7. Potential of Sentinel-1a for Grounding Line Measurements

    NASA Astrophysics Data System (ADS)

    Scheuchl, B.; Mouginot, J.; Rignot, E. J.

    2015-12-01

    The grounding line, the boundary between grounded and floating ice plays a crucial role for mass balance assessment, ice sheet modeling and the analysis of ice shelf melting. Interferometric Synthetic Aperture Radar data are the most accurate means to data to determine the grounding line on a large scale. The analysis of InSAR data from 1996 and 2011 shows a significant retreat of the grounding line in the Amundsen Sea Sector of West Antarctica along a retrograde bed. A new generation of spaceborne SAR sensors (Sentinel-1a, ALOS2) was launched in 2014 and has begun operational data collection since. Sentinel-1a collects data over ice sheets in a novel TOPSAR mode to provide large area coverage at relatively high resolution. Working closely with the ice sheet science community, ESA has implemented a data acquisition plan that ensures at least one ice sheet wide coverage per year and ongoing coverage in key coastal regions. The new mode, however does lead to some challenges in data processing. With focus on glaciers in West Antarctica (in particular we look at Smith, Pope and Kohler Glaciers), we show the potential of Sentinel-1a for grounding line mapping. Combining data from several currently available missions, we provide a 2015 update for the grounding line in the region.

  8. Ground Observations of ULF Pulsations During Pulsating Aurora

    NASA Astrophysics Data System (ADS)

    Kim, H.; Lessard, M.; Jones, S.; Engebretson, M.

    2008-12-01

    The ROPA (Rocket Observations of Pulsating Aurora) sounding rocket was launched northward from Poker Flat, crossing the poleward boundary of a region of pulsating aurora. In association with ground support (incoherent scatter radar, ULF search-coil magnetometer, fluxgate magnetometer, and all sky imager), pulsating auroral signatures have been observed on the ground and in space. During or before the periods of pulsating aurora, the observations of ULF waves revealed two signatures. A narrow band signal, which exhibits an abrupt onset and a rising tone from 0.1 to 0.3 Hz over the course of an hour or two, precedes the pulsating aurora in 4 of 5 events studied but is not observed in the 5th event. Following the narrow band signature, or possibly beginning while the narrow band signal is still observed, broad band waves (characterized by noisy spectral structure) are observed that are strongly modulated (in all of the events) with a period on the order of 10 15 minutes. In this presentation, we discuss the nature of these waves such as polarization (predominantly right handed). Some of the events show double band spectral signatures where the upper ones rise and lower ones fall with periodic spectral signatures (4 - 5 min) and harmonic structures. It is also discussed how they are generated and what role they might play in pulsating aurora.

  9. Compositional Ground Truth of Diviner Lunar Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Greenhagen, B. T.; Thomas, I. R.; Bowles, N. E.; Allen, C. C.; Donaldson Hanna, K. L.; Foote, E. J.; Paige, D. A.

    2012-01-01

    The Moon affords us a unique opportunity to "ground truth" thermal infrared (i.e. 3 to 25 micron) observations of an airless body. The Moon is the most accessable member of the most abundant class of solar system bodies, which includes Mercury, astroids, and icy satellites. The Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. And the Diviner Lunar Radiometer (Diviner) is the first instrument to globally map the spectral thermal emission of an airless body. Here we compare Diviner observations of Apollo sites to compositional and spectral measurements of Apollo lunar soil samples in simulated lunar environment (SLE).

  10. Terrestrial Gamma Flashes Observed from Nearby Thunderstorms at Ground Level

    NASA Astrophysics Data System (ADS)

    Cherry, M. L.; Chason, N.; Granger, D.; Guzik, T. G.; Pleshinger, D.; Rodi, J.; Stacy, J. G.; Stewart, M.; Zimmer, N.

    2014-12-01

    The TGF and Energetic Thunderstorm Rooftop Array (TETRA) is an array of NaI scintillators located on the campus of Louisiana State University in Baton Rouge, Louisiana. Since July 2010, TETRA has detected 37 millisecond bursts of gamma rays at energies 50 keV - 2 MeV associated with nearby (< 8 km) thunderstorms. The ability to observe ground-level Terrestrial Gamma Flashes from close to the source allows a unique analysis of the storm cells producing these events. A description of the observations, the results of the analysis, and plans for future measurements will be presented.

  11. Space- and Ground-Based Observations of Exceptionally Young Asteroids

    NASA Astrophysics Data System (ADS)

    Tamblyn, P. M.; Merline, W. J.; Chapman, C. R.; Nesvorný, D.; Durda, D. D.

    2004-12-01

    We provide an overview and progress report on a suite of observations of very young asteroids. Three asteroid groups were previously identified through dynamical back integration as having arisen from very recent (<10 Myr) asteroid collisions (Nesvorný et al. 2002, Nature 417, 720; 2003 ApJ 591, 486). Hence these asteroid families provide an opportunity to probe the properties of the fragments of asteroid collisions before their characteristics have been masked by the aging and dynamical effects that dominate the observable properties of older asteroids. With a variety of observational programs, we aim to measure characteristics critical for comparison with hydrodynamical models of asteroid collisions. First, with a large Hubble Snapshot survey, we are testing if binaries are more prevalent among the young asteroids. This might be expected because ejection of mutually bound pairs is one mechanism for binary formation. Although our observed samples are small, we have discovered two new binaries among our control sample of old asteroids and none among the young asteroids sampled. We are extending the sample with ground-based Adaptive Optics at VLT, Gemini-N, Keck, and IRTF. In another ground-based experiment, we are measuring the lightcurve amplitudes and spin periods of these young asteroids for eventual comparison with simulations of asteroid breakup (e.g. Durda et al. 2004 Icarus 170, 243). Finally, with a Spitzer program, we are measuring the sizes and albedos of some of these young asteroids. This will immediately test if albedo is correlated with size or age, and provide the calibration for a ground-based determination of the size distribution. Together with the spin and shape information from lightcurves, these data will also further constrain the measurement of the Yarkovsky effect on main belt asteroids recently presented by Nesvorný & Bottke 2004 (Icarus, 170, 324).

  12. Ground motion observations of the 2014 South Napa earthquake

    USGS Publications Warehouse

    Baltay, Annemarie S.; Boatwright, John

    2015-01-01

    Using the ground‐motion data compiled and reported by ShakeMap (Wald et al., 2000), we examine the peak ground acceleration (PGA) and peak ground velocity (PGV), as well as the pseudospectral acceleration (PSA) at periods of 0.3, 1.0, and 3.0 s. At the higher frequencies, especially PGA, data recorded at close distances (within ∼20  km) are very consistent with the GMPEs, implying a stress drop for this event similar to the median for California, that is, 5 MPa (Baltay and Hanks, 2014). At all frequencies, the attenuation with distance is stronger than the GMPEs would predict, which suggests the attenuation in the Napa and San Francisco Bay delta region is stronger than the average attenuation in California. The spatial plot of the ground‐motion residuals is positive to the north, in both Napa and Sonoma Valleys, consistent with increases in amplitude expected from both the directivity and basin effects. More interestingly, perhaps, there is strong ground motion to the south in the along‐strike direction, particularly for PSA at 1.0 s. These strongly positive residuals align with an older, Quaternary fault structure associated with the Franklin or Southampton fault, potentially indicating a fault‐zone‐guided wave.

  13. Earth observation data payload ground segments at DLR for GMES

    NASA Astrophysics Data System (ADS)

    Schreier, Gunter; Dech, Stefan; Diedrich, Erhard; Maass, Holger; Mikusch, Eberhard

    2008-07-01

    The European Global Monitoring of Environment and Security (GMES) programme involves missions of the European Space Agency (ESA), EUMETSAT and also missions, originating from European national space agencies and private operators. These missions will be complemented by further missions from non-European operators to close gaps in data provision. The German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) is involved in national and private missions contributing to the fleet of GMES satellites. Apart from operating as one of the major Processing and Archiving Centers (PAC) for the ESA EO Missions, DFD is developing the data payload ground segment for the German national missions TerraSAR-X, TanDEM-X and EnMAP. DFD is also operations partner of European Space Imaging, receiving, processing and distributing submetric Ikonos data. Likewise, it is partner of EUROMAP, ensuring the European coverage for Indian Earth Observation satellites such as ResouceSat and CartoSat. A brief description of the missions, its ground segment and significance for GMES is given. Harmonizing the availability of data and products for European GMES users and managing the various data and information flows within a heterogeneous and distributed data payload ground segment is a challenging task.

  14. First Observation of Ground State Dineutron Decay: Be16

    NASA Astrophysics Data System (ADS)

    Spyrou, A.; Kohley, Z.; Baumann, T.; Bazin, D.; Brown, B. A.; Christian, G.; Deyoung, P. A.; Finck, J. E.; Frank, N.; Lunderberg, E.; Mosby, S.; Peters, W. A.; Schiller, A.; Smith, J. K.; Snyder, J.; Strongman, M. J.; Thoennessen, M.; Volya, A.

    2012-03-01

    We report on the first observation of dineutron emission in the decay of Be16. A single-proton knockout reaction from a 53MeV/u B17 beam was used to populate the ground state of Be16. Be16 is bound with respect to the emission of one neutron and unbound to two-neutron emission. The dineutron character of the decay is evidenced by a small emission angle between the two neutrons. The two-neutron separation energy of Be16 was measured to be 1.35(10) MeV, in good agreement with shell model calculations, using standard interactions for this mass region.

  15. The Need for Synoptic Solar Observations from the Ground

    NASA Astrophysics Data System (ADS)

    Pevtsov, A. A.

    2016-04-01

    Synoptic observations are indispensable in studies of long-term effects pertinent to variation in solar radiative output, space weather and space climate, as well as for understanding the physics of global processes taking place on our nearest star. Synoptic data also allow putting the Sun in the context of stellar evolution. Historically, the main-stay of such observations has been groundbased although the improving longevity of space-borne instruments puts some space missions into the category of synoptic facilities. Space- and groundbased (synoptic) observations are complementary to each other; neither is inferior or superior to the other. Groundbased facilities can have a long-term (50 years+) operations horizon, and in comparison with their spacebased counterparts, they are less expensive to operate and have fewer restrictions on international collaboration and data access. The instruments can be serviced, upgraded, and cross-calibrated to ensure the continuity and uniformity of long-term data series. New measurements could be added in response to changes in understanding the solar phenomena. Some drawbacks such as day-night cycle and the variable atmospheric seeing can be mitigated e.g., by creating global networks and by employing adaptive optics. Furthermore, the groundbased synoptic observations can serve as a backbone and a back-up to spacebased observations. Here I review some existing groundbased synoptic facilities, describe plans for future networks, and outline the current efforts in strengthening the international collaboration in synoptic solar observations from the ground.

  16. Predictions of Experimentally Observed Stochastic Ground Vibrations Induced by Blasting

    PubMed Central

    Kostić, Srđan; Perc, Matjaž; Vasović, Nebojša; Trajković, Slobodan

    2013-01-01

    In the present paper, we investigate the blast induced ground motion recorded at the limestone quarry “Suva Vrela” near Kosjerić, which is located in the western part of Serbia. We examine the recorded signals by means of surrogate data methods and a determinism test, in order to determine whether the recorded ground velocity is stochastic or deterministic in nature. Longitudinal, transversal and the vertical ground motion component are analyzed at three monitoring points that are located at different distances from the blasting source. The analysis reveals that the recordings belong to a class of stationary linear stochastic processes with Gaussian inputs, which could be distorted by a monotonic, instantaneous, time-independent nonlinear function. Low determinism factors obtained with the determinism test further confirm the stochastic nature of the recordings. Guided by the outcome of time series analysis, we propose an improved prediction model for the peak particle velocity based on a neural network. We show that, while conventional predictors fail to provide acceptable prediction accuracy, the neural network model with four main blast parameters as input, namely total charge, maximum charge per delay, distance from the blasting source to the measuring point, and hole depth, delivers significantly more accurate predictions that may be applicable on site. We also perform a sensitivity analysis, which reveals that the distance from the blasting source has the strongest influence on the final value of the peak particle velocity. This is in full agreement with previous observations and theory, thus additionally validating our methodology and main conclusions. PMID:24358140

  17. Canopy Cover Predictions using Ground Observations and Remotely Sensed Data

    NASA Technical Reports Server (NTRS)

    Dungan, Jennifer L.

    1999-01-01

    Maps of vegetation status are needed at many scales, from the field level to monitor ecosystem condition to the global level to understand the carbon cycle. Status is quantified by such variables as leaf area index, biomass, and fraction of canopy cover. Current methods of predicting vegetation variables use remote sensing data to provide a spatially exhaustive data source. In a study in western Montana, several hundred ground observations made by the US Forest Service on tenth-acre conifer plots were used to develop aspatial regression and geostatistical prediction models. Normalized Difference Vegetation Index (NDVI) values from Landsat Thematic Mapper images were used as ancillary data. These models were then used to predict canopy cover at unsampled locations in a 97 square kilometer region on the boundary of the Flathead National Forest and the Bob Marshall Wilderness. Independent data from two dates six years apart were used for validation. Given the assumption that actual canopy cover remained relatively unchanged within this time period, partial validation can be achieved by measuring the correspondence of the two maps. This criterion results in ranking the aspatial regression maps as less accurate than the geostatistically generated maps. The geostatistical approach emphasizes ground measurements more heavily than does aspatid regression. Geostatistical simulations of canopy cover also provide a means of describing uncertainty about the patterns of canopy cover.

  18. MODELING ATMOSPHERIC EMISSION FOR CMB GROUND-BASED OBSERVATIONS

    SciTech Connect

    Errard, J.; Borrill, J.; Ade, P. A. R.; Akiba, Y.; Chinone, Y.; Arnold, K.; Atlas, M.; Barron, D.; Elleflot, T.; Baccigalupi, C.; Fabbian, G.; Boettger, D.; Chapman, S.; Cukierman, A.; Delabrouille, J.; Ducout, A.; Feeney, S.; Feng, C.; and others

    2015-08-10

    Atmosphere is one of the most important noise sources for ground-based cosmic microwave background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3D-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive a new analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using an original numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the polarbear-i project first season data set. We derive a new 1.0% upper limit on the linear polarization fraction of atmospheric emission. We also compare our results to previous studies and weather station measurements. The proposed model can be used for realistic simulations of future ground-based CMB observations.

  19. Io's volcanic enhancement observed in mid-infrared from the ground

    NASA Astrophysics Data System (ADS)

    Yoneda, M.; Miyata, T.; Tang, C. C. C.; Sako, S.; Kamizuka, T.; Nakamura, T.; Asano, K.; Uchiyama, M.; Okada, K.; Yoshii, Y.; Sakanoi, S.; Kasaba, Y.; Okano, S.

    2014-04-01

    We present new ground-based observations of Io's volcanic activity made in 2011 and 2012 using a 1-m telescope, at mid-infrared wavelengths where Io's thermal radiation dominates solar reflected light seen at shorter wavelengths. The emitted power from Daedalus in 2011 was estimated to be ~1013 (W). This level of power has never been observed from Daedalus from previous observations, and is almost as powerful as the lava lake Loki Patera, the most powerful hotspot on Io. However, the angular separation between Loki and Daedalus is only 0.1 arcsec at most. This means most of the ground-based telescopes cannot observe these two hotspots individually at infrared wavelengths. The possibility that the power of Daedalus has been underestimated should be noted. Previous thermal measurements from ground-based observations of Loki might be overestimated, as they may also include the thermal emissions from Daedalus as well. The diffraction limit in the mid-infrared range using a 1-m diameter telescopes is significantly larger than the angular size of Io from the ground. However, this study successfully distinguished a hotspot on Io by focusing on light curves that show Io's radiance as a function of Io's central longitude. The potential of small telescopes with infrared detectors for observing Io's volcanic activity should also be noted.

  20. Tomography of ground water flow from self-potential data

    NASA Astrophysics Data System (ADS)

    Revil, A.; Jardani, A.

    2007-12-01

    An inversion algorithm is developed to interpret self-potential (SP) data in terms of distribution of the seepage velocity of the ground water. The model is based on the proportionality existing between the electrokinetic source current density and the seepage velocity of the water phase. As the inverse problem is underdetermined, we use a Tikhonov regularization method with a smoothness constraint based on the differential Laplacian operator to solve the inverse problem. The regularization parameter is determined by the L-shape method. The recovery of the distribution of the seepage velocity vector of the ground water flow depends on the localization and number of non-polarizing electrodes and information relative to the distribution of the electrical resistivity of the ground. The inversion method is tested on two 2D synthetic cases and on two real SP data. The first field test corresponds to the infiltration of water from a ditch. The second one corresponds to large flow at the Cerro Prieto geothermal field in Baja California.

  1. Ground-based observations of the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Thomas, N.

    A series of ground-based 1-D spatially resolved, high resolution spectra (in SII, SIII, and OII) of the Io plasma torus were acquired in October 1999, around the time of the Galileo I24 passage through the IPT. In a previous paper (Thomas et al., JGR, 106, 26277, 2001), we have presented the initial results from these observations. In this presentation, we will describe recent more detailed analysis which seems to be lending further insight into the structure of the IPT. In particular, we have used an "onion-peeling" technique to remove line of sight effects from the observations. The resulting profiles, show the so-called ribbon region (5.7 RJ) being clearly separated from the cold torus (5.3 RJ) by a region of lower SII emission. SIII emission is now shown to be almost completely absent in the cold torus. The ratio of these two species is seen to rise systematically and almost linearly with jovicentric distance from the cold torus through to the warm torus (beyond 6.0 RJ). Models can be used to interpret this behaviour in terms of changing electron temperature with distance. We compare our results with the only other measurement of this property which was based on Voyager 1 PLS observations. We further show that the peak of OII emission is not centred at the, what we now call, the sulphur ribbon. We attempt to derive the relative composition of the three major species in the torus as a function of jovicentric distance using our data.

  2. Ali Observatory in Tibet: a unique northern site for future CMB ground-based observations

    NASA Astrophysics Data System (ADS)

    Su, Meng

    2015-08-01

    Ground-based CMB observations have been performed at the South Pole and the Atacama desert in Chile. However, a significant fraction of the sky can not be observed from just these two sites. For a full sky coverage from the ground in the future, a northern site for CMB observation, in particular CMB polarization, is required. Besides the long-thought site in Greenland, the high altitude Tibet plateau provides another opportunity. I will describe the Ali Observatory in Tibet, located at N32°19', E80°01', as a potential site for ground-based CMB observations. The new site is located on almost 5100m mountain, near Gar town, where is an excellent site for both infrared and submillimeter observations. Study with the long-term database of ground weather stations and archival satellite data has been performed. The site has enough relative height on the plateau and is accessible by car. The Shiquanhe town is 40 mins away by driving, and a recently opened airport with 40 mins driving, the site also has road excess, electricity, and optical fiber with fast internet. Preliminary measurement of the Precipitable Water Vapor is ~one quarter less than 0.5mm per year and the long term monitoring is under development. In addition, surrounding higher sites are also available and could be further developed if necessary. Ali provides unique northern sky coverage and together with the South Pole and the Atacama desert, future CMB observations will be able to cover the full sky from ground.

  3. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering

    NASA Astrophysics Data System (ADS)

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S.; Techert, Simone; Strocov, Vladimir N.; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-01

    Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.

  4. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering

    PubMed Central

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S.; Techert, Simone; Strocov, Vladimir N.; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-01

    Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future. PMID:26821751

  5. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering.

    PubMed

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S; Techert, Simone; Strocov, Vladimir N; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-01

    Thermally driven chemistry as well as materials' functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.

  6. Phobos and Deimos. [ground based and spacecraft observations

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1977-01-01

    Ground-based and spacecraft observations of Phobos and Deimos are reviewed and the satellites' origin is discussed. The crater densities of both bodies are close to the saturation level. The largest impact events may have caused extensive fracturing of their surfaces. The surfaces are at least 1.5 billion years old and may date back to the early history of the solar system. The Martian satellites display large deviations from sphericity. As a result of tidal processes, they are in synchronous rotation. Several independent lines of evidence show that they have regoliths. Despite some provocative arguments, their internal strengths and the nature of their interior are poorly known at present. Photometric measurements suggest that they are made of either carbonaceous chondritic material or a basalt. Sinclair (1972), Born and Duxbury (1975) and Shor (1975) apparently have successfully determined Phobos' secular acceleration. Their value of approximately .001 deg/year/year implies that the interior of Mars has a low specific dissipation factor (about 100), may indicate that a portion of the Martian interior is experiencing partial melting. The low inclination of the satellites' orbits indicates that they were formed as part of the same process that resulted in Mars.

  7. Public Remote Observing of Potentially Hazardous Asteroids

    NASA Astrophysics Data System (ADS)

    Hammergren, M.

    2003-05-01

    Since the mid-1990.s, the Adler Planetarium has engaged in a program of public remote observing using the ARC 3.5-meter telescope at the Apache Point Observatory. The impact on regular science programs is minimized by scheduling the public observing during evening twilight on the first Friday of every month, when the Planetarium is open for extended hours. We have recently begun to observe faint, potentially hazardous near-Earth asteroids for which further astrometry is desired. The observations and initial analyses are performed and displayed in real-time in our CyberSpace electronic gallery before a live audience. Audience participation is useful and is actively encouraged. In particular, the asteroids often are first spotted in sequences of images by a member of the audience. Young children have recovered potentially hazardous asteroids. Further data reduction is accomplished with commercially available software. The program is straightforward in concept and execution, and is accessible to audiences of all ages. Since it unambiguously involves real science, it directly addresses the public understanding of research. We believe this program may be copied easily by other institutions that have remote observing assets.

  8. Linking Space-Borne and Ground-Based Observations Observed Around Substorm Onset to Magnetospheric Processes

    NASA Technical Reports Server (NTRS)

    Kepko, Larry; Spanswick, Emma; Angelopoulos, Vassilis; Donovan, Eric

    2011-01-01

    The combined THEMIS five spacecraft in-situ and ground magnetic and camera arrays have advanced considerably our understanding of the causal relationship between midtail plasma flows, transient ionospheric features, and ground magnetic signatures. In particular, recent work has shown a connection between equatorward moving visible ionospheric transients and substorm onset, in both 6300 nm and white-light emissions. Although both observations detail pre-onset auroral features the interpretations differ substantially. We first provide a brief summary of these observations, highlighting in particular areas where the two observations differ, and suggest reasons for the differences. We then detail how these observations relate to dynamical magnetospheric processes, and show how they constrain models of transient convection. Next, we pull together observations and models of Pi2 generation, substorm current wedge (SCW) initiation and dipolarization to present a self-consistent description of the dynamical processes and communicative pathways that occur just prior to and during substorm expansion onset. Finally, we present a summary of open questions and suggest a roadmap for future work.

  9. Potential Cislunar and Interplanetary Proving Ground Excursion Trajectory Concepts

    NASA Technical Reports Server (NTRS)

    McGuire, Melissa L.; Strange, Nathan J.; Burke, Laura M.; MacDonald, Mark A.; McElrath, Timothy P.; Landau, Damon F.; Lantoine, Gregory; Hack, Kurt J.; Lopez, Pedro

    2016-01-01

    NASA has been investigating potential translunar excursion concepts to take place in the 2020s that would be used to test and demonstrate long duration life support and other systems needed for eventual Mars missions in the 2030s. These potential trajectory concepts could be conducted in the proving ground, a region of cislunar and near-Earth interplanetary space where international space agencies could cooperate to develop the technologies needed for interplanetary spaceflight. Enabled by high power Solar Electric Propulsion (SEP) technologies, the excursion trajectory concepts studied are grouped into three classes of increasing distance from the Earth and increasing technical difficulty: the first class of excursion trajectory concepts would represent a 90-120 day round trip trajectory with abort to Earth options throughout the entire length, the second class would be a 180-210 day round trip trajectory with periods in which aborts would not be available, and the third would be a 300-400 day round trip trajectory without aborts for most of the length of the trip. This paper provides a top-level summary of the trajectory and mission design of representative example missions of these three classes of excursion trajectory concepts.

  10. Ice shelf flexure at Antarctic grounding lines observed by high resolution satellite and ground measurements

    NASA Astrophysics Data System (ADS)

    Rack, Wolfgang; Wild, Christian; Ryan, Michelle; Marsh, Oliver; McDonald, Adrian; King, Matt; Floricioiu, Dana; Wiesmann, Andreas; Price, Daniel

    2015-04-01

    Climate change is expected to impact Antarctic ice sheets primarily through changes in the oceans. This will be felt most strongly near the grounding line, where the ice sheet first comes into contact with ocean water and becomes an ice shelf. The primary objective of this work is to make use of satellite techniques for better monitoring and interpretation of the link between floating ice shelves and grounded ice. By measuring the flexure of ice due to tides we can obtain critical data to derive information on ice properties. Satellites can measure tidal bending over discrete time intervals and over large areas, whereas ground stations monitor ice dynamics continuously at discrete points. By the combination of the two we derive a complete picture of vertical ice displacement by tides for different grounding line geometries. Our field site is the Southern McMurdo Ice Shelf in the western Ross Sea region at which horizontal ice dynamics can be neglected which simplifies corresponding satellite data analysis. During a field survey in 2014/15, we acquired data of tidal flexure along a straight line perpendicular to the grounding line using 8 ground stations equipped with differential GPS receivers and high precision tiltmeters. The most landward station was located close to the grounding line, and the last station was placed 5 km away at a point which was assumed to be freely floating. Additional data acquired for the flexure analysis are ice thickness, snow and ice stratigraphy and basal ice properties using ground radar systems; as well as information of snow morphology from snow pits and ice cores. During the same period a series of TerraSAR-X 11-day repeat pass satellite data have been acquired to map tidal displacement using differential SAR interferometry (DInSAR). Before the onset of the melting season in December all interferograms show generally high coherence and are suitable for tidal flexure analysis. The ice shelf in the area is around 200m thick, and

  11. Self-potential observations during hydraulic fracturing

    SciTech Connect

    Moore, Jeffrey R.; Glaser, Steven D.

    2007-09-13

    The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of -200 mV/MPa. However for pressure drops >2 MPa, the magnitude of the Cc increases by 80% in an exponential trend. This increasing Cc is related to increasing permeability at high pore pressures caused by dilatancy of micro-cracks, and is explained by a decrease in the hydraulic tortuosity. Resistivity measurements reveal a decrease of 2% prior to hydraulic fracturing and a decrease of {approx}35% after fracturing. An asymmetric spatial SP response created by injectate diffusion into dilatant zones is observed prior to hydraulic fracturing, and in most cases this SP variation revealed the impending crack geometry seconds before failure. At rupture, injectate rushes into the new fracture area where the zeta potential is different than in the rock porosity, and an anomalous SP spike is observed. After fracturing, the spatial SP distribution reveals the direction of fracture propagation. Finally, during tensile cracking in a point load device with no water flow, a SP spike is observed that is caused by contact electrification. However, the time constant of this event is much less than that for transients observed during hydraulic fracturing, suggesting that SP created solely from material fracture does not contribute to the SP response during hydraulic fracturing.

  12. Estimates of Ground Temperature and Atmospheric Moisture from CERES Observations

    NASA Technical Reports Server (NTRS)

    Wu, Man Li C.; Schubert, Siegfried; Einaudi, Franco (Technical Monitor)

    2000-01-01

    A method is developed to retrieve surface ground temperature (Tg) and atmospheric moisture using clear sky fluxes (CSF) from CERES-TRMM observations. In general, the clear sky outgoing long-wave radiation (CLR) is sensitive to upper level moisture (q(sub h)) over wet regions and Tg over dry regions The clear sky window flux from 800 to 1200 /cm (RadWn) is sensitive to low level moisture (q(sub j)) and Tg. Combining these two measurements (CLR and RadWn), Tg and q(sub h) can be estimated over land, while q(sub h) and q(sub t) can be estimated over the oceans. The approach capitalizes on the availability of satellite estimates of CLR and RadWn and other auxiliary satellite data. The basic methodology employs off-line forward radiative transfer calculations to generate synthetic CSF data from two different global 4-dimensional data assimilation products. Simple linear regression is used to relate discrepancies in CSF to discrepancies in Tg, q(sub h) and q(sub t). The slopes of the regression lines define sensitivity parameters that can be exploited to help interpret mismatches between satellite observations and model-based estimates of CSF. For illustration, we analyze the discrepancies in the CSF between an early implementation of the Goddard Earth Observing System Data Assimilation System (GEOS-DAS) and a recent operational version of the European Center for Medium-Range Weather Prediction data assimilation system. In particular, our analysis of synthetic total and window region SCF differences (computed from two different assimilated data sets) shows that simple linear regression employing (Delta)Tg and broad layer (Delta)q(sub l) from 500 hPa to surface and (Delta)q(sub h) from 200 to 500 hPa provides a good approximation to the full radiative transfer calculations, typically explaining more than 90% of the 6-hourly variance in the flux differences. These simple regression relations can be inverted to "retrieve" the errors in the geophysical parameters

  13. Estimates of Ground Temperature and Atmospheric Moisture from CERES Observations

    NASA Technical Reports Server (NTRS)

    Wu, Man Li C.; Schubert, Siegfried; Einaudi, Franco (Technical Monitor)

    2000-01-01

    A method is developed to retrieve surface ground temperature (T(sub g)) and atmospheric moisture using clear sky fluxes (CSF) from CERES-TRMM observations. In general, the clear sky outgoing longwave radiation (CLR) is sensitive to upper level moisture (q(sub l)) over wet regions and (T(sub g)) over dry regions The clear sky window flux from 800 to 1200/cm (RadWn) is sensitive to low level moisture (q(sub t)) and T(sub g). Combining these two measurements (CLR and RadWn), Tg and q(sub h) can be estimated over land, while q(sub h) and q(sub l) can be estimated over the oceans. The approach capitalizes on the availability of satellite estimates of CLR and RadWn and other auxiliary satellite data. The basic methodology employs off-line forward radiative transfer calculations to generate synthetic CSF data from two different global 4-dimensional data assimilation products. Simple linear regression is used to relate discrepancies in CSF to discrepancies in T(sub g), q(sub h) and q(sub l). The slopes of the regression lines define sensitivity parameters that can be exploited to help interpret mismatches between satellite observations and model-based estimates of CSF. For illustration, we analyze the discrepancies in the CSF between an early implementation of the Goddard Earth Observing System Data Assimilation System (GEOS-DAS) and a recent operational version of the European Center for Medium-Range Weather Prediction data assimilation system. In particular, our analysis of synthetic total and window region SCF differences (computed from two different assimilated data sets) shows that simple linear regression employing Delta(T(sub g)) and broad layer Delta(q(sub l) from .500 hPa to surface and Delta(q(sub h)) from 200 to .300 hPa provides a good approximation to the full radiative transfer calculations. typically explaining more than 90% of the 6-hourly variance in the flux differences. These simple regression relations can be inverted to "retrieve" the errors in the

  14. Ground-Based Observations of Terrestrial Gamma-Ray Flashes

    NASA Astrophysics Data System (ADS)

    Ringuette, R. A.; Cannady, N.; Case, G. L.; Cherry, M. L.; Granger, D.; Isbert, J.; Stewart, M.

    2010-10-01

    First seen from space by the BATSE gamma ray telescope in the 1990s, Terrestrial Gamma ray Flashes (TGFs) consist of extremely fast bursts of high energy (up to 40 MeV) gamma rays correlated with intense lightning from thunderstorms. Spacecraft experiments are sensitive to very large events, but ground-based detectors closer to the thunderstorms may provide data on the intensity spectrum of smaller events. Four detectors consisting of NaI scintillators viewed by photomultipliers have been placed on rooftops at LSU's Baton Rouge campus to monitor TGFs. The setup and design of the ground-based experiment will be discussed.

  15. Processing electronic photos of Mercury produced by ground based observation

    NASA Astrophysics Data System (ADS)

    Ksanfomality, Leonid

    New images of Mercury have been obtained by processing of ground based observations that were carried out using the short exposure technique. The disk of the planet extendeds usually from 6 to 7 arc seconds, with the linear size of the image in a focal plane of the telescope about 0.3-0.5 mm on the average. Processing initial millisecond electronic photos of the planet is very labour-consuming. Some features of processing of initial millisecond electronic photos by methods of correlation stacking were considered in (Ksanfomality et al., 2005; Ksanfomality and Sprague, 2007). The method uses manual selection of good photos including a so-called pilot- file, the search for which usually must be done manually. The pilot-file is the most successful one, in opinion of the operator. It defines the future result of the stacking. To change pilot-files increases the labor of processing many times. Programs of processing analyze the contents of a sample, find in it any details, and search for recurrence of these almost imperceptible details in thousand of other stacking electronic pictures. If, proceeding from experience, the form and position of a pilot-file still can be estimated, the estimation of a reality of barely distinct details in it is somewhere in between the imaging and imagination. In 2006-07 some programs of automatic processing have been created. Unfortunately, the efficiency of all automatic programs is not as good as manual selection. Together with the selection, some other known methods are used. The point spread function (PSF) is described by a known mathematical function which in its central part decreases smoothly from the center. Usually the width of this function is accepted at a level 0.7 or 0.5 of the maxima. If many thousands of initial electronic pictures are acquired, it is possible during their processing to take advantage of known statistics of random variables and to choose the width of the function at a level, say, 0.9 maxima. Then the

  16. Identification of Potential Fishing Grounds Using Geospatial Technique

    NASA Astrophysics Data System (ADS)

    Abdullah, Muhammad

    2016-07-01

    Fishery resources surveys using actual sampling and data collection methods require extensive ship time and sampling time. Informative data from satellite plays a vital role in fisheries application. Satellite Remote Sensing techniques can be used to detect fish aggregation just like visual fish identification ultimately these techniques can be used to predict the potential fishing zones by measuring the parameters which affect the distribution of fishes. Remote sensing is a time saving technique to locate fishery resources along the coast. Pakistan has a continental shelf area of 50,270 km2 and coastline length of 1,120 km. The total maritime zone of Pakistan is over 30 percent of the land area. Fishery plays an important role in the national economy. The marine fisheries sector is the main component, contributing about 57 percent in terms of production. Fishery is the most important economic activity in the villages and towns along the coast, and in most of the coastal villages and settlements it is the sole source of employment and income generation. Fishing by fishermen is done on the sole basis of repeated experiments and collection of information from other fishermen. Often they are in doubt about the location of potential fishing zones. This leads to waste of time and money, adversely affecting fishermen incomes and over or under-exploitation of fishing zones. The main purpose of this study was to map potential fishing grounds by identifying various environmental parameters which impact fish aggregation along the Pakistan coastline. The primary reason of this study is the fact that the fishing communities of Pakistan's coastal regions are extremely poor and lack knowledge of the modern tools and techniques that may be incorporated to enhance their yield and thus, improve their livelihood. Using geospatial techniques in order to accurately map the potential fishing zones based on sea surface temperature (SST) and chlorophyll -a content, in conjunction with

  17. Identification of Potential Fishing Grounds Using Geospatial Technique

    NASA Astrophysics Data System (ADS)

    Abdullah, Muhammad

    2016-07-01

    Fishery resources surveys using actual sampling and data collection methods require extensive ship time and sampling time. Informative data from satellite plays a vital role in fisheries application. Satellite Remote Sensing techniques can be used to detect fish aggregation just like visual fish identification ultimately these techniques can be used to predict the potential fishing zones by measuring the parameters which affect the distribution of fishes. Remote sensing is a time saving technique to locate fishery resources along the coast. Pakistan has a continental shelf area of 50,270 km2 and coastline length of 1,120 km. The total maritime zone of Pakistan is over 30 percent of the land area. Fishery plays an important role in the national economy. The marine fisheries sector is the main component, contributing about 57 percent in terms of production. Fishery is the most important economic activity in the villages and towns along the coast, and in most of the coastal villages and settlements it is the sole source of employment and income generation. Fishing by fishermen is done on the sole basis of repeated experiments and collection of information from other fishermen. Often they are in doubt about the location of potential fishing zones. This leads to waste of time and money, adversely affecting fishermen incomes and over or under-exploitation of fishing zones. The main purpose of this study was to map potential fishing grounds by identifying various environmental parameters which impact fish aggregation along the Pakistan coastline. The primary reason of this study is the fact that the fishing communities of Pakistan's coastal regions are extremely poor and lack knowledge of the modern tools and techniques that may be incorporated to enhance their yield and thus, improve their livelihood. Using geospatial techniques in order to accurately map the potential fishing zones based on sea surface temperature (SST) and chlorophyll -a content, in conjunction with

  18. Features of positive ground flashes observed in Kathmandu Nepal

    NASA Astrophysics Data System (ADS)

    Adhikari, Pitri Bhakta; Sharma, Shriram; Baral, Kedarnath

    2016-07-01

    Lightning vertical electric fields pertinent to the subtropical thunderstorms occurring over the rugged terrain have been measured and recorded at a hilly station Kathmandu, Nepal. In the present work, waveforms of the positive ground flashes have been selected from all the records and were analyzed. To the best of our knowledge, this is the first time that fine structure of electric field signature pertinent to the positive return stroke; have been analyzed and presented from Nepal. One hundred and thirty three (133) of the total of four hundred twenty-five (425) flashes were selected from seven thunderstorm days and analyzed. Of the data recorded for seven days, 133 flashes (31.3%) were positive flashes and 276 flashes (64.9%) were cloud flashes. Majority of the positive ground flashes were found to be single stroke ones, whereas, the average number of strokes per flash is found to be 1.1 with a maximum value of 4. Majority of the positive ground flashes were found either lacking the initial breakdown process and the leader stage or these processes could not be detected. The return strokes are found to be succeeded by large in cloud activity in the continuing current portion of the flash. The average zero-crossing time of the positive return strokes was found to be 60.45 μs with a range of 447.81 μs and the average rise time was found to be 9.44 μs with a range of 42.56 μs.

  19. Students as Ground Observers for Satellite Cloud Retrieval Validation

    NASA Technical Reports Server (NTRS)

    Chambers, Lin H.; Costulis, P. Kay; Young, David F.; Rogerson, Tina M.

    2004-01-01

    The Students' Cloud Observations On-Line (S'COOL) Project was initiated in 1997 to obtain student observations of clouds coinciding with the overpass of the Clouds and the Earth's Radiant Energy System (CERES) instruments on NASA's Earth Observing System satellites. Over the past seven years we have accumulated more than 9,000 cases worldwide where student observations are available within 15 minutes of a CERES observation. This paper reports on comparisons between the student and satellite data as one facet of the validation of the CERES cloud retrievals. Available comparisons include cloud cover, cloud height, cloud layering, and cloud visual opacity. The large volume of comparisons allows some assessment of the impact of surface cover, such as snow and ice, reported by the students. The S'COOL observation database, accessible via the Internet at http://scool.larc.nasa.gov, contains over 32,000 student observations and is growing by over 700 observations each month. Some of these observations may be useful for assessment of other satellite cloud products. In particular, some observing sites have been making hourly observations of clouds during the school day to learn about the diurnal cycle of cloudiness.

  20. Cross-validation of spaceborne radar and ground polarimetric radar observations

    NASA Astrophysics Data System (ADS)

    Bolen, Steven Matthew

    There is great potential for spaceborne weather radar to make significant observations of the precipitating medium on global scales. The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall in the tropics from space using radar. The Precipitation Radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit at 350 km altitude and 35 degree inclination. The PR is a single frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant, which can be as high as 10--15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR returns. Direct inter-comparison of meteorological measurements between space and ground radar observations can be used to evaluate spaceborne processing algorithms. Though conceptually straightforward, this can be a challenging task. Differences in viewing aspects between space and earth point observations, propagation frequencies, resolution volume size and time synchronization mismatch between measurements can contribute to direct point-by-point inter-comparison errors. The problem is further complicated by spatial geometric distortions induced into the space-based observations caused by the movements and attitude perturbations of the spacecraft itself. A method is developed to align space and ground radar observations so that a point-by-point inter-comparison of measurements can be made. Ground-based polarimetric observations are used to estimate the attenuation of PR signal returns along individual PR beams, and a technique is formulated to determine the true PR return from GR measurements via theoretical modeling of specific attenuation (k) at PR wavelength with ground-based S-band radar observations. The statistical behavior of the parameters

  1. Ground-based Observation of Post-Hayabusa Mission Targets

    NASA Astrophysics Data System (ADS)

    Abe, M.; Kitazato, K.; Sarugaku, Y.; Kawakatsu, Y.; Kinoshita, D.

    2007-03-01

    In 2006, we have observed 14 near-Earth asteroids as the candidate object of the post-Hayabusa mission, using Kiso and Lulin Observatory. Including our previous observation, we found that five asteroids are classified in C-type Group.

  2. Influence of ground scattering on satellite auroral observations.

    PubMed

    Hays, P B; Anger, C D

    1978-06-15

    Satellite observations of the optical emission features in the aurora and nighttime airglow are usually contaminated by scattering from clouds and snow. It is shown here that this contamination can easily be removed when the emission layer is viewed against a surface of known albedo. The effect of the earth's curvature, parallax, and varying image angle are found to be significant but can be removed from the observation.

  3. Influence of ground scattering on satellite auroral observations

    NASA Technical Reports Server (NTRS)

    Hays, P. B.; Anger, C. D.

    1978-01-01

    Satellite observations of the optical emission features in the aurora and nighttime airglow are usually contaminated by scattering from clouds and snow. It is shown here that this contamination can easily be removed when the emission layer is viewed against a surface of known albedo. The effect of the earth's curvature, parallax, and varying image angle are found to be significant but can be removed from the observation.

  4. Ground observation of electromagnetic emissions related to clusters of earthquakes

    NASA Astrophysics Data System (ADS)

    Singh, Vikram; Singh, Birbal

    2010-05-01

    ULF-VLF data obtained from three ground based experiments working at Agra station (geograph. Lat. 27.20N, Long. 780E) in India namely measurement of ultra low frequency (ULF) magnetic field emissions using a 3-component search coil magnetometer, vertical component of very low frequency (VLF) electric field emissions with a borehole antenna, and phase and amplitude of fixed frequency VLF transmitter signals using AbsPAL receiver are analysed in search of possible precursors of two major seismic activities that occurred in Sumatra (Indonesia) during post-tsunami period between January and April, 2005. These two major seismic events occurred as clusters of earthquakes during 27-29 January and 28-30 March, 2005. The results show that barring borehole all the experiments showed precursors due to these clusters of earthquakes. Such precursors were not seen in the case of isolated large magnitude earthquakes. Further, the precursory duration was influenced by the magnetic storm which occurred about a week before the clusters. The mechanism of ULF propagation to long distances between Sumatra and Agra, and perturbations in the ionosphere before the clusters are discussed.

  5. Cloud cover retrieved from ground-base observation using Skyviewer : A validation with human observations

    NASA Astrophysics Data System (ADS)

    Kim, Bu-Yo; Jee, Joon-Bum; Zo, Il-Sung; Lee, Kyu-Tae

    2016-04-01

    Cloud cover is used in various fields of research in addition to weather forecasts; however, the ground observation of cloud cover is conducted by human observers, a method with low objectivity, temporal and spatial resolutions. Therefore, to address these problems, we have developed an improved algorithm to calculate cloud cover using sky image data obtained with Skyviewer equipment. The algorithm uses a variable threshold of the Red Blue Ratio (RBR) determined from the frequency distributions of the Green Blue Ratio (GBR) to calculate cloud cover more accurately than existing algorithms. To verify the accuracy of the algorithm, we conducted daily, monthly, seasonal and yearly statistical analysis on human observations of cloud cover obtained every hour from 0800 to 1700 LST for the entire year of 2012 at Gangwon Regional Meteorological Administration (GRMA), Korea. A daily case study compared the images of 1200 LST cases by season and pixel images of cloud cover calculated by the algorithm. The selected weekly cases yielded a high correlation of 0.93 with GRMA data. A monthly case study showed low RMSEs and high correlations for December (RMSE=1.64 tenths and r=0.92) and August (RMSE=1.43 tenths and r=0.91). In addition, seasonal cases yielded a high correlation of 0.9 and 87% consistency within ±2 tenths for winter and a correlation of 0.83 and 82% consistency for summer, when cases of cloud-free or overcast conditions are frequent. Annual analysis showed that the bias of GRMA and Skyviewer for the year of 2012 was -0.36 tenth, with cloud cover of the GRMA data being greater, whilst RMSE was 2.12 tenths. Considering the spatial inconsistency of the data used in the analysis, GRMA and Skyviewer showed a high correlation (0.87) and 80% consistency for cases with a difference in cloud cover of within ±2 tenths.

  6. Multisatellite and ground-based observations of transient ULF waves

    NASA Technical Reports Server (NTRS)

    Potemra, T. A.; Zanetti, L. J.; Takahashi, K.; Luehr, H.; Lepping, R. P.

    1989-01-01

    Transient ULF pulsations associated with variations in solar wind plasma density observed by the IMP 8 satellite are presently studied in light of observations obtained during a fortuitous alignment of the AMPTE and Viking satellites with respect to the EISCAT Magnetometer Cross. It is found that the isolated 10-min oscillation in solar wind plasma density produced magnetic field compression oscillations within the magnetosphere at the same frequency, thereby enhancing resonant oscillations at approximately twice the frequency which were already present. Support is seen for the periodic solar wind density variation's exciting of a tailward-traveling large-scale magnetosphere wave train which excites local field line resonant oscillations.

  7. On the submarine communication cable JASC ground self-potential stability

    NASA Astrophysics Data System (ADS)

    Starjinsky, S. S.; Nikiforov, V. M.

    2005-09-01

    This investigation was undertaken for searching the source of linear trends in JASC submarine cable data over the time interval of 6 years and estimating the electrode noise level. One of the reasons for a trend is probably the potential instability in the cable ground, which happened because the titanium electrodes of the ground were placed in sea water that is electrochemically active. To study this phenomenon, we have registered the voltage variations of three titanium JASC cable electrodes, which were closely spaced (~15 cm) and placed at a depth of ~15 m near the coast for 70 days, synchronously with JASC cable voltage observations. The electrode noise level and coherence between channels were estimated and linear trends in electrode pair voltage variation were revealed. The estimated linear trend magnitude is about 0.28 mV/day, which is comparable with 0.21 mV/day earlier observed in JASC submarine cable data. We concluded that the linear trend in JASC cable data is, at least partly, probably caused by the titanium electrodes potential variations. This linear trend should be registered simultaneously with JASC cable voltage observation, keeping in mind the possibility of finding a procedure for removing it, in order to enhance the signal/noise ratio in data.

  8. Satellite observations of ground water changes in New Mexico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2002 NASA launched the Gravity Recovery and Climate Experiment (GRACE) satellite mission. GRACE consists of two satellites with a separation of about 200 km.  By accurately measuring the separation between the twin satellites, the differences in the gravity field can be determined. Monthly observ...

  9. Ground and satellite observations of auroral fragmentation into patches

    NASA Astrophysics Data System (ADS)

    Shiokawa, Kazuo; Nishi, Katsuki

    2016-07-01

    We review characteristic auroral fragmentation which is the process by which uniform aurora is broken into several fragments to form auroral patches, based on the all-sky camera observations at Tromsoe, Norway and THEMIS chain in Canada. The auroral fragmentation occurs as finger-like structures developing predominantly in meridional direction with speeds of several tens m/s and scale sizes of several tens kilometers without any shearing motion. These features suggest that pressure-driven instability in the balance between the earthward magnetic-tension force and the tailward pressure gradient force in the magnetosphere is the main driving force of the auroral fragmentation. Thus, these observations indicate that auroral fragmentation associated with pressure-driven instability is a process that creates auroral patches. Auroral fragmentation is seen from midnight to dawn local time and usually appears at the beginning of the substorm recovery phase, near the low latitude boundary of the auroral region. One example of plasma and magnetic field observations by the THEMIS satellite in the conjugate magnetosphere shows diamagnetic anti-phase variations of magnetic and plasma pressures with time scales of several to tens minutes associated with the auroral fragmentation. This observation also supports the idea of pressure-driven instability to cause the auroral fragmentation into patches.

  10. "Sniffing" Jupiter's moon Europa through ground-based IR observations

    NASA Astrophysics Data System (ADS)

    Paganini, Lucas; Mumma, Michael J.; Hurford, Terry; Roth, Lorenz; Villanueva, Geronimo Luis

    2016-10-01

    The ability to sample possible plumes from the subsurface ocean in Europa represents a major step in our search for extraterrestrial life. If plumes exist, sampling the effluent material would provide insights into their chemistry and relevant information about the prospect that life could exist, or now exists, within the ocean. Most of the difficulties in detecting plumes come from the less frequent observational coverage of Europa, which contrasts strongly with the frequent Cassini flybys of Enceladus (Spencer & Nimmo 2013). Recent observations have been taken with HST/STIS in 2014/2015, but results have shown no evident confirmation of the 2012 plume detection (Roth et al. 2014, 2015). Future in situ observations (Europa Mission) will provide definitive insights, but not before the spacecraft's arrival in ~2025, thus an interim approach is needed to inform such space mission planning and to complement existing observations at other wavelengths.In 2015, we initiated a strong campaign to build a comprehensive survey of possible plumes on Europa through high-resolution IR spectroscopy with Keck/NIRSPEC. We were awarded 10 nights out of 15 total nights available for Key Strategic Mission Support projects for the 2016A, 2016B, 2017A, and 2017B semesters under NASA time with the Keck Observatory. In 2016A, we observed Europa during 10 half-nights and will continue to do so for another 10 half-nights in 2017A. We target a serendipitous search of gaseous activity from Europa to confirm and constrain the chemical composition of possible Europan plumes that can aid the investigation of physical processes underlying (or on) its surface. Ultimately, we seek to: (1) provide information that can inform planning for NASA's Europa mission, (2) further our current understanding of Europa's gas environment, and (3) complement studies that are currently underway with other facilities (like the Hubble Space Telescope). In this presentation, we will discuss preliminary results

  11. Electrical Potential Transfer Through Grounding and the Concern for Facility and Worker Safety

    SciTech Connect

    Konkel, Herbert

    1998-09-13

    Electrical grounding is probably the most over-looke~ ignored, and misunderstood part of electrical energy source circuits. A faulty ground circuit am have lethal potential to the worker, can damage electrical equipment" or components, and can lead to higher consequences. For example, if the green-wire ground return circuit (in a three-wire power circuit) is fhulty or is open (someone cut the prong, etc.) a person can receive an electrical shock by touching the conductive enclosure, and the result can be lethal. If high explosives are involved m the process, sneak electrical energy paths may cause electrical threats that lead to ignition, which results to higher damage consequences. Proper electrical grounding is essential to mitigate the electrical hazard and improve work place safety. A designer must ask the question, "What grounding is proper?" continuously through a process design and in its application. This question must be readdressed with any process change, including tiom layout, equipment, or procedure changes. Electrical grounding varies ilom local work area grounding to the multi-point grounding found in large industrial areas. These grounding methods become more complex when the designer adds bonding to the grounding schemes to mitigate electrostatic discharge (ESD) and surfkce potentials resulting from lightning currents flowing through the facility structure. Figure 1 shows a typical facility power distribution circuit and the current flow paths resulting ffom a lightning discharge to a facility. This paper discusses electrical grounding methods and their characteristics and identifies potential sneak paths into a process for hazardous electrical energy.

  12. Simultaneous ground- and satellite-based observation of MF/HF auroral radio emissions

    NASA Astrophysics Data System (ADS)

    Sato, Yuka; Kumamoto, Atsushi; Katoh, Yuto; Shinbori, Atsuki; Kadokura, Akira; Ogawa, Yasunobu

    2016-05-01

    We report on the first simultaneous measurements of medium-high frequency (MF/HF) auroral radio emissions (above 1 MHz) by ground- and satellite-based instruments. Observational data were obtained by the ground-based passive receivers in Iceland and Svalbard, and by the Plasma Waves and Sounder experiment (PWS) mounted on the Akebono satellite. We observed two simultaneous appearance events, during which the frequencies of the auroral roar and MF bursts detected at ground level were different from those of the terrestrial hectometric radiation (THR) observed by the Akebono satellite passing over the ground-based stations. This frequency difference confirms that auroral roar and THR are generated at different altitudes across the F peak. We did not observe any simultaneous observations that indicated an identical generation region of auroral roar and THR. In most cases, MF/HF auroral radio emissions were observed only by the ground-based detector, or by the satellite-based detector, even when the satellite was passing directly over the ground-based stations. A higher detection rate was observed from space than from ground level. This can primarily be explained in terms of the idea that the Akebono satellite can detect THR emissions coming from a wider region, and because a considerable portion of auroral radio emissions generated in the bottomside F region are masked by ionospheric absorption and screening in the D/E regions associated with ionization which results from auroral electrons and solar UV radiation.

  13. Ground-based VLBI observations of orbiters and landers.

    NASA Astrophysics Data System (ADS)

    Cimo, G.; Duev, D.; Molera Calves, G.; Bocanegra Bohamon, T.; Pogrebenko, S.; Gurvits, L.

    2015-10-01

    Phase referencing near-field VLBI observations and radial Doppler measurements of spacecraft provide ultra-precise estimates of spacecraft state vectors. These measurements can be used for a variety of scientific applications, both fundamental and applied, including planetary science, improvement of ephemerides, ultra-precise celestial mechanics of planetary systems, gravimetry, spacecraft orbit determination, and fundamental physics. Precise determination of the lateral position of spacecraft on the celestial sphere is the main deliverable of the Planetary Radio Interferometry and Doppler Experiment (PRIDE). This technique is complementary to radio science experiments and addresses those areas of spacecraft mission science objectives that require accurate estimation of spacecraft state vector.

  14. Observation of Ground-state Two-neutron Decay

    NASA Astrophysics Data System (ADS)

    Thoennessen, M.; Kohley, Z.; Spyrou, A.; Lunderberg, E.; DeYoung, P. A.; Attanayake, H.; Baumann, T.; Bazin, D.; Brown, B. A.; Christian, G.; Divaratne, D.; Grimes, S. M.; Haagsma, A.; Finck, J. E.; Frank, N.; Luther, B.; Mosby, S.; Nagi, T.; Peaslee, G. F.; Peters, W. A.; Schiller, A.; Smith, J. K.; Snyder, J.; Strongman, M.; Volya, A.

    Neutron decay spectroscopy has become a successful tool to explore nuclear properties of nuclei with the largest neutron-to-proton ratios. Resonances in nuclei located beyond the neutron dripline are accessible by kinematic reconstruction of the decay products. The development of two-neutron detection capabilities of the Modular Neutron Array (MoNA) at NSCL has opened up the possibility to search for unbound nuclei which decay by the emission of two neutrons. Specifically this exotic decay mode was observed in 16Be and 26O.

  15. An Overview of JAXA's Ground-Observation Activities for HAYABUSA Reentry

    NASA Astrophysics Data System (ADS)

    Fujita, Kazuhisa; Yamamoto, Masa-Yuki; Abe, Shinsuke; Ishihara, Yoshiaki; Iiyama, Ohmi; Kakinami, Yoshihiro; Hiramatsu, Yoshihiro; Furumoto, Muneyoshi; Takayanagi, Hiroki; Suzuki, Toshiyuki; Yanagisawa, Toshifumi; Kurosaki, Hirohisa; Shoemaker, Michael; Ueda, Masayoshi; Shiba, Yasuo; Suzuki, Masaharu

    2011-10-01

    On 2010 June 13, the HAYABUSA asteroid explorer returned to Earth and underwent a super-orbital atmospheric reentry. In order to recover the sample return capsule and to take ground-based measurements, the Japan Aerospace Exploration Agency organized a ground-observation team and performed optical tracking of the capsule, spectroscopy of the fireball, and measurements of infrasounds and shock waves generated by the fireball. In this article, an overview of the ground-based observation is presented, and an outline of the preliminary results derived from observations is reported.

  16. Hydrogeologic setting and potential for denitrification in ground water, coastal plain of southern Maryland

    USGS Publications Warehouse

    Krantz, David E.; Powars, David S.

    2000-01-01

    The types and distribution of Coastal Plain sediments in the Patuxent River Basin may contribute to relatively low concentrations of nitrate (typically less than 1 milligram per liter) in stream base flow because of the chemical reduction of dissolved nitrate (denitrification) in ground water. Water chemistry data from synoptic stream base-flow surveys in the Patuxent River Basin show higher dissolved nitrate concentrations in the Piedmont than in the Coastal Plain section of the watershed. Stream base flow reflects closely the chemistry of ground water discharging from the surficial (unconfined) aquifer to the stream. Because land use in the sampled subbasins is virtually the same in each section, differences in the physical and geochemical characteristics of the surficial aquifer may explain the observed differences in water chemistry. One possible cause of lower nitrate concentrations in the Coastal Plain is denitrification within marine sediments that contain chemically reduced compounds. During denitrification, the oxygen atoms on the nitrate (N03-) molecule are transferred to a reduced compound and N gas is produced. Organic carbon and ferrous iron (Fe2+), derived from the dissolution of minerals such as pyrite (FeS2) and glauconite (an iron aluminosilicate clay), can act as reducing substrates; these reduced chemical species are common in the marine and estuarine deposits in Southern Maryland. The spatial distribution of geologic units and their lithology (sediment type) has been used to create a map of the potential for denitrification of ground water in the surficial aquifer of the Coastal Plain in Southern Maryland.

  17. Generation Mechanism of Earth Potential Difference Signal during Seismic Wave Propagation and its Observation Condition

    NASA Astrophysics Data System (ADS)

    Okubo, Kan; Yamamoto, Keisuke; Takayama, Masakazu; Takeuchi, Nobunao

    We have observed the co-seismic electromagnetic phenomena such as earth potential difference (EPD) variation in many observation sites of both Miyagi and Akita Prefectures. So far, in any earthquakes we observed clear signals of the EPD variation. However, the amplitude of observed EPD signals are very different at each site. To explain this difference, firstly we assumed the EPD generation mechanism to be the streaming potential. Secondarily, the underground circumstance is modeled as the composer of groundwater table, capillary tubes and fine tubes. The model how EPD variation signals appear is postulated to explain the observed data. The relative position of the ground water table against the buried electrodes is examined to explain the observed data. The groundwater table may be very sensitive to the appearance of the EPD variation. If electrodes were buried a few meters below the ground surface, we could observe the EPD signals in the case of shallow groundwater table.

  18. Preliminary Space VLBI Requirements for Observing Time on Ground Radio Telescopes

    NASA Technical Reports Server (NTRS)

    Meier, David L.; Murphy, David W.; Preston, Robert A.

    1992-01-01

    An initial estimate has been made of the observing time required on ground radio telescopes by the space VLBI missions Radioastron and VSOP. Typical science programs have been adopted for both missions.

  19. The 26 January 2001 M 7.6 Bhuj, India, earthquake: Observed and predicted ground motions

    USGS Publications Warehouse

    Hough, S.E.; Martin, S.; Bilham, R.; Atkinson, G.M.

    2002-01-01

    Although local and regional instrumental recordings of the devastating 26, January 2001, Bhuj earthquake are sparse, the distribution of macroseismic effects can provide important constraints on the mainshock ground motions. We compiled available news accounts describing damage and other effects and interpreted them to obtain modified Mercalli intensities (MMIs) at >200 locations throughout the Indian subcontinent. These values are then used to map the intensity distribution throughout the subcontinent using a simple mathematical interpolation method. Although preliminary, the maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated toward the western edge of the inferred fault, consistent with western directivity. Significant sediment-induced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region, intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium, such as mudflats and salt pans. In addition, we use fault-rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard-rock ground-motion parameters to MMI by using a relationship (derived from Internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-3 units than those estimated from news accounts, although they do predict near-field ground motions of approximately 80%g and potentially damaging ground motions on hard-rock sites to distances of approximately 300 km. For the most part, this discrepancy is consistent with the expected effect of sediment response, but it could also reflect other factors, such as unusually high building vulnerability in the Bhuj region and a tendency for media accounts to focus on the most dramatic damage, rather than

  20. Potential effects of the Hawaii geothermal project on ground-water resources on the Island of Hawaii

    SciTech Connect

    Sorey, M.L.; Colvard, E.M.

    1994-07-01

    This report provides data and information on the quantity and quality of ground-water resources in and adjacent to proposed geothermal development areas on the Island of Hawaii Geothermal project for the development of as much as 500 MW of electric power from the geothermal system in the East Rift Zone of Kilauea Volcano. Data presented for about 31 wells and 8 springs describe the chemical, thermal, and hydraulic properties of the ground-water system in and adjacent to the East Rift Zone. On the basis of this information, potential effects of this geothermal development on drawdown of ground-water levels and contamination of ground-water resources are discussed. Significant differences in ground-water levels and in the salinity and temperature of ground water within the study area appear to be related to mixing of waters from different sources and varying degrees of ground-water impoundment by volcanic dikes. Near Pahoa and to the east, the ground-water system within the rift is highly transmissive and receives abundant recharge from precipitation; therefore, the relatively modest requirements for fresh water to support geothermal development in that part of the east rift zone would result in minimal effects on ground-water levels in and adjacent to the rift. To the southwest of Pahoa, dike impoundment reduces the transmissivity of the ground-water system to such an extent that wells might not be capable of supplying fresh water at rates sufficient to support geothermal operations. Water would have to be transported to such developments from supply systems located outside the rift or farther downrift. Contaminant migration resulting from well accidents could be rapid because of relatively high ground-water velocities in parts of the region. Hydrologic monitoring of observation wells needs to be continued throughout development of geothermal resources for the Hawaii Geothermal Project to enable the early detection of leakage and migration of geothermal fluids.

  1. Potential New Lidar Observations for Cloud Studies

    NASA Technical Reports Server (NTRS)

    Winker, Dave; Hu, Yong; Narir, Amin; Cai, Xia

    2015-01-01

    The response of clouds to global warming represents a major uncertainty in estimating climate sensitivity. These uncertainties have been tracked to shallow marine clouds in the tropics and subtropics. CALIOP observations have already been used extensively to evaluate model predictions of shallow cloud fraction and top height (Leahy et al. 2013; Nam et al 2012). Tools are needed to probe the lowest levels of the troposphere. The large footprint of satellite lidars gives large multiple scattering from clouds which presents new possibilities for cloud retrievals to constrain model predictions.

  2. Self potential observations during DNAPL dissolution

    NASA Astrophysics Data System (ADS)

    Ntarlagiannis, D.; Slater, L.; Kulessa, B.; Russell, C.; Kalin, R.; Ferguson, A.; Graber, J.

    2006-05-01

    Dense non aqueous phase liquids (DNAPLs) are a major environmental problem and are considered to be long term heavy contaminant sources in the subsurface. Accurate monitoring of DNAPL breakdown is required to monitor remediation efforts. We aim to evaluate the efficiency of geophysical methods to monitor DNAPL remediation. Toward this goal we performed self potential (SP) measurements on laboratory columns packed with DNAPL contaminated sand undergoing (a) biodegradation, and (b) abiotic DNAPL dissolution. Geochemical monitoring showed higher concentration of dissolved DNAPL byproducts in the abiotic columns; the use of HgCl2 as a biocide probably increased the rates of DNAPL dissolution in the abiotic columns. The concentration of DNAPL byproducts is significantly lower in the biotic columns due to microbial activity since DNAPL degrading bacteria within the column consume the breakdown products. SP responses are significantly higher (~ 90 mV) in the abiotic columns; in the microbial active columns SP values remain steady with a value ~ 10 mV. High SP signals (up to 110 mV) are associated with DNAPL byproduct concentration gradients within the abiotic columns and exhibit a temporal behavior that mimics total organic carbon concentrations. Although microbial activity in organic rich contaminated areas has been associated with strong negative SP anomalies our results show that positive SP anomalies can also be generated in contaminated areas in the absence of any microbial activity. We discuss a possible SP source mechanism and the implications in geophysical monitoring of DNAPL remedial processes.

  3. Ground-based Observations of the Solar Sources of Space Weather

    NASA Astrophysics Data System (ADS)

    Veronig, A. M.; Pötzi, W.

    2016-04-01

    Monitoring of the Sun and its activity is a task of growing importance in the frame of space weather research and awareness. Major space weather disturbances at Earth have their origin in energetic outbursts from the Sun: solar flares, coronal mass ejections and associated solar energetic particles. In this review we discuss the importance and complementarity of ground-based and space-based observations for space weather studies. The main focus is drawn on ground-based observations in the visible range of the spectrum, in particular in the diagnostically manifold Hα spectral line, which enables us to detect and study solar flares, filaments (prominences), filament (prominence) eruptions, and Moreton waves. Existing Hα networks such as the GONG and the Global High-Resolution Hα Network are discussed. As an example of solar observations from space weather research to operations, we present the system of real-time detection of Hα flares and filaments established at Kanzelhöhe Observatory (KSO; Austria) in the frame of the space weather segment of the ESA Space Situational Awareness programme (swe.ssa.esa.int). An evaluation of the system, which is continuously running since July 2013 is provided, covering an evaluation period of almost 2.5 years. During this period, KSO provided 3020 hours of real-time Hα observations at the ESA SWE portal. In total, 824 Hα flares were detected and classified by the real-time detection system, including 174 events of Hα importance class 1 and larger. For the total sample of events, 95 % of the automatically determined flare peak times lie within ±5 min of the values given in the official optical flares reports (by NOAA and KSO), and 76 % of the start times. The heliographic positions determined are better than ±5°. The probability of detection of flares of importance 1 or larger is 95 %, with a false alarm rate of 16 %. These numbers confirm the high potential of automatic flare detection and alerting from ground

  4. 14 CFR 121.561 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 121.561 Section 121.561... meteorological conditions and irregularities of ground facilities or navigation aids. (a) Whenever he...

  5. 14 CFR 121.561 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 121.561 Section 121.561... meteorological conditions and irregularities of ground facilities or navigation aids. (a) Whenever he...

  6. 14 CFR 121.561 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 121.561 Section 121.561... meteorological conditions and irregularities of ground facilities or navigation aids. (a) Whenever he...

  7. 14 CFR 121.561 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 121.561 Section 121.561... meteorological conditions and irregularities of ground facilities or navigation aids. (a) Whenever he...

  8. 14 CFR 121.561 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 121.561 Section 121.561... meteorological conditions and irregularities of ground facilities or navigation aids. (a) Whenever he...

  9. Satellite Cloud Data Validation through MAGIC Ground Observation and the S'COOL Project: Scientific Benefits grounded in Citizen Science

    NASA Astrophysics Data System (ADS)

    Crecelius, S.; Chambers, L. H.; Lewis, P. M.; Rogerson, T.

    2013-12-01

    The Students' Cloud Observation On-Line (S'COOL) Project was launched in 1997 as the Formal Education and Public Outreach arm of the Clouds and the Earth's Radiant Energy System (CERES) Mission. ROVER, the Citizen Scientist area of S'COOL, started in 2007 and allows participants to make 'roving' observations from any location as opposed to a fixed, registered classroom. The S'COOL Project aids the CERES Mission in trying to answer the research question: 'What is the Effect of Clouds on the Earth's Climate'. Participants from all 50 states, most U.S. Territories, and 63 countries have reported more than 100,500 observations to the S'COOL Project over the past 16 years. The Project is supported by an intuitive website that provides curriculum support and guidance through the observation steps; 1) Request satellite overpass schedule, 2) Observe clouds, and 3) Report cloud observations. The S'COOL Website also hosts a robust database housing all participants' observations as well as the matching satellite data. While the S'COOL observation parameters are based on the data collected by 5 satellite missions, ground observations provide a unique perspective to data validation. Specifically, low to mid level clouds can be obscured by overcast high-level clouds, or difficult to observe from a satellite's perspective due to surface cover or albedo. In these cases, ground observations play an important role in filling the data gaps and providing a better, global picture of our atmosphere and clouds. S'COOL participants, operating within the boundary layer, have an advantage when observing low-level clouds that affect the area we live in, regional weather patterns, and climate change. S'COOL's long-term data set provides a valuable resource to the scientific community in improving the "poorly characterized and poorly represented [clouds] in climate and weather prediction models'. The MAGIC Team contacted S'COOL in early 2012 about making cloud observations as part of the MAGIC

  10. Predicted Attenuation Relation and Observed Ground Motion of Gorkha Nepal Earthquake of 25 April 2015

    NASA Astrophysics Data System (ADS)

    Singh, R. P.; Ahmad, R.

    2015-12-01

    A comparison of recent observed ground motion parameters of recent Gorkha Nepal earthquake of 25 April 2015 (Mw 7.8) with the predicted ground motion parameters using exitsing attenuation relation of the Himalayan region will be presented. The recent earthquake took about 8000 lives and destroyed thousands of poor quality of buildings and the earthquake was felt by millions of people living in Nepal, China, India, Bangladesh, and Bhutan. The knowledge of ground parameters are very important in developing seismic code of seismic prone regions like Himalaya for better design of buildings. The ground parameters recorded in recent earthquake event and aftershocks are compared with attenuation relations for the Himalayan region, the predicted ground motion parameters show good correlation with the observed ground parameters. The results will be of great use to Civil engineers in updating existing building codes in the Himlayan and surrounding regions and also for the evaluation of seismic hazards. The results clearly show that the attenuation relation developed for the Himalayan region should be only used, other attenuation relations based on other regions fail to provide good estimate of observed ground motion parameters.

  11. Fuel models and fire potential from satellite and surface observations

    USGS Publications Warehouse

    Burgan, R.E.; Klaver, R.W.; Klarer, J.M.

    1998-01-01

    A national 1-km resolution fire danger fuel model map was derived through use of previously mapped land cover classes and ecoregions, and extensive ground sample data, then refined through review by fire managers familiar with various portions of the U.S. The fuel model map will be used in the next generation fire danger rating system for the U.S., but it also made possible immediate development of a satellite and ground based fire potential index map. The inputs and algorithm of the fire potential index are presented, along with a case study of the correlation between the fire potential index and fire occurrence in California and Nevada. Application of the fire potential index in the Mediterranean ecosystems of Spain, Chile, and Mexico will be tested.

  12. Potential effects of the Hawaii Geothermal Project on ground-water resources on the island of Hawaii

    USGS Publications Warehouse

    Sorey, M.L.; Colvard, E.M.

    1994-01-01

    In 1990, the State of Hawaii proposed the Hawaii Geothermal Project for the development of as much as 500 MW of electric power from the geothermal system in the East Rift Zone of Kilauea Volcano. This report uses data from 31 wells and 8 springs to describe the properties of the ground-water system in and adjacent to the East Rift Zone. Potential effects of this project on ground-water resources are also discussed. Data show differences in ground-water chemistry and heads within the study area that appear to be related to mixing of waters of different origins and ground-water impoundment by volcanic dikes. East of Pahoa, the ground-water system within the rift is highly transmissive and receives abundant recharge from precipitation; therefore, the pumping of freshwater to support geothermal development in that part of the rift zone would have a minimal effect on ground-water levels. To the southwest of Pahoa, dike impoundment reduces the transmissivity of the ground-water system to such an extent that wells might not be capable of supplying sufficient fresh water to support geothermal operations. Contamination of ground-water resources by accidental release of geothermal fluids into shallow aquifers is possible because of corrosive conditions in the geothermal wells, potential well blowouts, and high ground-water velocities in parts of the region. Hydrologic monitoring of water level, temperature, and chemistry in observation wells should continue throughout development of geothermal resources for the Hawaii Geothermal Project for early detection of leakage and migration of geothermal fluids within the groundwater system.

  13. Statistical study of propagation characteristics of Pc1 pearl structures using conjugate ground-satellite observations

    NASA Astrophysics Data System (ADS)

    Jun, C. W.; Shiokawa, K.; Takahashi, K.; Paulson, K. W.; Schofield, I.; Connors, M. G.; Poddelskiy, I.; Shevtsov, B.; Kletzing, C.; Wygant, J. R.

    2015-12-01

    We investigated statistical characteristics of pearl structures (amplitude modulation) of Pc1 pulsations using conjugate observations with the ground induction magnetometers located at Athabasca (ATH, L = 4.3) in Canada and Magadan (MGD, L = 2.7) in Russia and the Van Allen Probes (RBSP-A and B) satellites located in the inner magnetosphere for a 1-year period (August 2012 to August 2013). We consider a ground magnetometer and a satellite to be conjugate when the satellite footprint is located within 1000 km of the ground magnetometer. From a survey of data acquired during the conjunction periods, we found 42 pearl Pc1events. These events were classified into four categories: structured Pc1 waves observed at both locations (9 events), structured Pc1 waves observed only on the ground (22 events) or in space (0 events), and unstructured Pc1 waves at both locations (11 events). We describe the spatial and temporal distributions of Pc1 pearl structures and their dependence on geomagnetic conditions. We also compare the frequency, the power ratio between space and ground, and the polarization among the four categories of events. In addition, we verified the similarity of Pc1 pearl structures between ground and space observations in order to investigate propagation and polarization characteristics of Pc1 pearl structures from the magnetosphere to the ionosphere.

  14. The Earth Observing System (EOS) Ground System: Leveraging an Existing Operational Ground System Infrastructure to Support New Missions

    NASA Technical Reports Server (NTRS)

    Hardison, David; Medina, Johnny; Dell, Greg

    2016-01-01

    The Earth Observer System (EOS) was officially established in 1990 and went operational in December 1999 with the launch of its flagship spacecraft Terra. Aqua followed in 2002 and Aura in 2004. All three spacecraft are still operational and producing valuable scientific data. While all are beyond their original design lifetime, they are expected to remain viable well into the 2020s. The EOS Ground System is a multi-mission system based at NASA Goddard Space Flight Center that supports science and spacecraft operations for these three missions. Over its operational lifetime to date, the EOS Ground System has evolved as needed to accommodate mission requirements. With an eye towards the future, several updates are currently being deployed. Subsystem interconnects are being upgraded to reduce data latency and improve system performance. End-of-life hardware and operating systems are being replaced to mitigate security concerns and eliminate vendor support gaps. Subsystem hardware is being consolidated through the migration to Virtual Machine based platforms. While mission operations autonomy was not a design goal of the original system concept, there is an active effort to apply state-of-the-art products from the Goddard Mission Services Evolution Center (GMSEC) to facilitate automation where possible within the existing heritage architecture. This presentation will provide background information on the EOS ground system architecture and evolution, discuss latest improvements, and conclude with the results of a recent effort that investigated how the current system could accommodate a proposed new earth science mission.

  15. Comparing predicted and observed ground motions from subduction earthquakes in the Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Douglas, John; Mohais, Rosemarie

    2009-10-01

    This brief article presents a quantitative analysis of the ability of eight published empirical ground-motion prediction equations (GMPEs) for subduction earthquakes (interface and intraslab) to estimate observed earthquake ground motions on the islands of the Lesser Antilles (specifically Guadeloupe, Martinique, Trinidad, and Dominica). In total, over 300 records from 22 earthquakes from various seismic networks are used within the analysis. It is found that most of the GMPEs tested perform poorly, which is mainly due to a larger variability in the observed ground motions than predicted by the GMPEs, although two recent GMPEs derived using Japanese strong-motion data provide reasonably good predictions. Analyzing separately the interface and intraslab events does not significant modify the results. Therefore, it is concluded that seismic hazard assessments for this region should use a variety of GMPEs in order to capture this large epistemic uncertainty in earthquake ground-motion prediction for the Lesser Antilles.

  16. Observing ground surface change series at active volcanoes in Indonesia using backscattering intensity of SAR data

    NASA Astrophysics Data System (ADS)

    Saepuloh, Asep; Trianaputri, Mila Olivia

    2015-04-01

    Indonesia contains 27 active volcanoes passing the West through the East part. Therefore, Indonesia is the most hazard front due to the volcanic activities. To obtain the new precursory signals leading to the eruptions, we applied remote sensing technique to observe ground surface change series at the summit of Sinabung and Kelud volcanoes. Sinabung volcano is located at Karo Region, North Sumatra Province. This volcano is a strato volcano type which is re-activated in August 2010. The eruption continues to the later years by ejecting volcanic products such as lava, pyroclastic flow, and ash fall deposits. This study is targeted to observe ground surface change series at the summit of Sinabung volcano since 2007 to 2011. In addition, we also compared the summit ground surface changes after the eruptions of Kelud volcano in 2007. Kelud volcano is also strato volcano type which is located at East Java, Indonesia. The Synthetic Aperture Radar (SAR) remotely sensed technology makes possible to observe rapidly a wide ground surface changes related to ground surface roughness. Detection series were performed by extracting the backscattering intensity of the Phased Array type L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite (ALOS). The intensity values were then calculated using a Normalized Radar Cross-Section (NRCS). Based on surface roughness criterion at the summit of Sinabung volcano, we could observe the ground surface changes prior to the early eruption in August 2010. The continuous increment of NRCS values showed clearly at window size 3×3 pixel of the summit of Sinabung volcano. The same phenomenon was also detected at the summit of Kelud volcano after the 2007 eruptions. The detected ground surface changes were validated using optical Landsat-8, backscattering intensity ratio for volcanic products detection, and radial component of a tilt-meter data.

  17. Ground-based observations of uranus and neptune using CCD instruments

    SciTech Connect

    Smith, B.A.

    1985-07-01

    The author verifies that with the help of charge-coupled devices (CCD) great progress is being made in ground-based astronomical observations, including the study of the remote giant planets Uranus and Neptune. In reading the CCD the top row of pixels (potential wells) is moved into the sequential (shift) reading register; after this each row (line) of pixels moves its electrons upward (in each column) until the bottom row is cleared. This process is repeated for each row until the device is interrogated sequentially. The use of CCD detectors for purposes of image acquisition and spectroscopy has already found wide popularity at astronomical observatories, and soon it will spread to space research. The first known attempts to use CCD to obtain astronomical images was made by the author and his colleagues in April 1976. The result was the first observations of structure on the dark disk of Uranus. In general, the more refined the mathematical provision, the more information can be extracted from the images or spectra.

  18. Ground states of stealthy hyperuniform potentials. II. Stacked-slider phases

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Stillinger, F. H.; Torquato, S.

    2015-08-01

    Stealthy potentials, a family of long-range isotropic pair potentials, produce infinitely degenerate disordered ground states at high densities and crystalline ground states at low densities in d -dimensional Euclidean space Rd. In the previous paper in this series, we numerically studied the entropically favored ground states in the canonical ensemble in the zero-temperature limit across the first three Euclidean space dimensions. In this paper, we investigate using both numerical and theoretical techniques metastable stacked-slider phases, which are part of the ground-state manifold of stealthy potentials at densities in which crystal ground states are favored entropically. Our numerical results enable us to devise analytical models of this phase in two, three, and higher dimensions. Utilizing this model, we estimated the size of the feasible region in configuration space of the stacked-slider phase, finding it to be smaller than that of crystal structures in the infinite-system-size limit, which is consistent with our recent previous work. In two dimensions, we also determine exact expressions for the pair correlation function and structure factor of the analytical model of stacked-slider phases and analyze the connectedness of the ground-state manifold of stealthy potentials in this density regime. We demonstrate that stacked-slider phases are distinguishable states of matter; they are nonperiodic, statistically anisotropic structures that possess long-range orientational order but have zero shear modulus. We outline some possible future avenues of research to elucidate our understanding of this unusual phase of matter.

  19. The use of products from ground-based GNSS observations in meteorological nowcasting

    NASA Astrophysics Data System (ADS)

    Terradellas, E.; Callado, A.; Pascual, R.; Téllez, B.

    2009-09-01

    Heavy rainfall is often focalized in areas of moisture convergence. A close relationship between precipitation and fast variations of vertically-integrated water vapour (IWV) has been found in numerous cases. Furthermore, a latency of several tens of minutes of the precipitation relative to a rapid increase of the water vapour contents appears to be a common truth. Therefore, continuous monitoring of atmospheric humidity and its spatial distribution is crucial to the operational forecaster for a proper nowcasting of heavy rainfall events. Radiosonde releases yield measurements of atmospheric humidity, but they are very sparse and present a limited time resolution of 6 to 12 hours. The microwave signals continuously broadcasted by the Global Navigation Satellite System (GNSS) satellites are influenced by the water vapour as they travel through the atmosphere to ground-based receivers. The total zenith delay (ZTD) of these signals, a by-product of the geodetic processing, is already operationally assimilated into numerical weather prediction (NWP) models and has positive impact on the prediction of precipitation events, as it has been reported after the analysis of parallel runs. Estimates of IWV retrieved from ground-based GNSS observations may also constitute a source of information on the horizontal distribution and the time evolution of atmospheric humidity that can be presented to the forecaster. Several advantages can be attributed to the ground-based GNSS as a meteorological observing system. First, receiving networks can be built and maintained at a relatively low cost, which it can, additionally, be shared among different users. Second, the quality of the processed observations is insensitive to the weather conditions and, third, the temporal resolution of its products is very high. On the other hand, the current latency of the data disposal, ranging between one and two hours, is acceptable for the NWP community, but appears to be excessive for nowcasting

  20. Subtropical and Polar Cirrus Clouds Characterized by Ground-Based Lidars and CALIPSO/CALIOP Observations

    NASA Astrophysics Data System (ADS)

    Córdoba-Jabonero, Carmen; Lopes, Fabio J. S.; Landulfo, Eduardo; Ochoa, Héctor; Gil-Ojeda, Manuel

    2016-06-01

    Cirrus clouds are product of weather processes, and then their occurrence and macrophysical/optical properties can vary significantly over different regions of the world. Lidars can provide height-resolved measurements with a relatively good both vertical and temporal resolutions, making them the most suitable instrumentation for high-cloud observations. The aim of this work is to show the potential of lidar observations on Cirrus clouds detection in combination with a recently proposed methodology to retrieve the Cirrus clouds macrophysical and optical features. In this sense, a few case studies of cirrus clouds observed at both subtropical and polar latitudes are examined and compared to CALIPSO/CALIOP observations. Lidar measurements are carried out in two stations: the Metropolitan city of Sao Paulo (MSP, Brazil, 23.3°S 46.4°W), located at subtropical latitudes, and the Belgrano II base (BEL, Argentina, 78ºS 35ºW) in the Antarctic continent. Optical (COD-cloud optical depth and LR-Lidar Ratio) and macrophysical (top/base heights and thickness) properties of both the subtropical and polar cirrus clouds are reported. In general, subtropical Cirrus clouds present lower LR values and are found at higher altitudes than those detected at polar latitudes. In general, Cirrus clouds are detected at similar altitudes by CALIOP. However, a poor agreement is achieved in the LR retrieved between ground-based lidars and space-borne CALIOP measurements, likely due to the use of a fixed (or low-variable) LR value in CALIOP inversion procedures.

  1. Kilometric radio waves generated along auroral field lines observed by ground facilities - A theoretical model

    NASA Technical Reports Server (NTRS)

    Ziebell, L. F.; Wu, C. S.; Yoon, Peter H.

    1991-01-01

    A theory of generation of radio waves observed by ground-based facilities in the frequency range 150-700 kHz is discussed. This work is a continuation of an earlier discussion (Wu et al., 1989) in which it was proposed that the trapped electrons along the auroral field lines can lead to a cyclotron instability which amplifies the whistler waves observed at ground level. The objective of the present study is to investigate the propagation effect on the wave amplification and to examine whether the proposed mechanism is indeed viable.

  2. 14 CFR 135.67 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 135.67 Section 135.67... navigation aids. Whenever a pilot encounters a potentially hazardous meteorological condition or...

  3. 14 CFR 135.67 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 135.67 Section 135.67... navigation aids. Whenever a pilot encounters a potentially hazardous meteorological condition or...

  4. 14 CFR 135.67 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 135.67 Section 135.67... navigation aids. Whenever a pilot encounters a potentially hazardous meteorological condition or...

  5. 14 CFR 135.67 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 135.67 Section 135.67... navigation aids. Whenever a pilot encounters a potentially hazardous meteorological condition or...

  6. 14 CFR 135.67 - Reporting potentially hazardous meteorological conditions and irregularities of ground facilities...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids. 135.67 Section 135.67... navigation aids. Whenever a pilot encounters a potentially hazardous meteorological condition or...

  7. Analytic Perturbation Method for Estimating Ground Flash Fraction from Satellite Lightning Observations

    NASA Technical Reports Server (NTRS)

    Koshak, William; Solakiewicz, Richard

    2013-01-01

    An analytic perturbation method is introduced for estimating the lightning ground flash fraction in a set of N lightning flashes observed by a satellite lightning mapper. The value of N is large, typically in the thousands, and the observations consist of the maximum optical group area produced by each flash. The method is tested using simulated observations that are based on Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) data. National Lightning Detection NetworkTM (NLDN) data is used to determine the flash-type (ground or cloud) of the satellite-observed flashes, and provides the ground flash fraction truth for the simulation runs. It is found that the mean ground flash fraction retrieval errors are below 0.04 across the full range 0-1 under certain simulation conditions. In general, it is demonstrated that the retrieval errors depend on many factors (i.e., the number, N, of satellite observations, the magnitude of random and systematic measurement errors, and the number of samples used to form certain climate distributions employed in the model).

  8. Do aerosols impact ground observation of total cloud cover over the North China Plain?

    NASA Astrophysics Data System (ADS)

    Sun, Li; Xia, Xiangao; Wang, Pucai; Fei, Ye

    2015-04-01

    Ground observation of the total cloud cover (TCC) showed a significant downward trend during the past half century over the North China Plain (NCP). The objective of this paper is to examine whether aerosols have impacted the surface observations of TCC by human observers. TCC observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (TCCgrd) were firstly compared with ground observations (TCCsat) at 201 synoptic stations over the NCP. Results showed that both data sets were in good agreement. The correlation coefficient between TCCgrd and TCCsatranged from 0.80 in winter to 0.90 in summer. The relationship between TCCsat - TCCgrdand visibility was then analyzed, which showed no significant correlation. Finally, long-term trends of TCCgrd and visibility were not correlated. These results indicated that aerosols likely did not impact the long-term trend of TCCgrdover the NCP.

  9. Do aerosols impact ground observation of total cloud cover over the North China Plain?

    NASA Astrophysics Data System (ADS)

    Sun, L.; Xia, X.; Wang, P.; Fei, Y.

    2014-06-01

    Ground observation of the total cloud cover (TCC) showed a significant downward trend during the past half century over the North China Plain (NCP). The objective of this paper is to examine whether aerosols have impacted the surface observations of TCC by human observers. TCC observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (TCCsat) were firstly compared with ground observations (TCCgrd) at 201 synoptic stations over the NCP. Results showed that both data sets were in good agreement. The correlation coefficient between TCCgrd and TCCsat ranged from 0.80 in winter to 0.90 in summer. The relationship between TCCsat-TCCgrd and visibility was then analyzed, which showed no significant correlation. Finally, long-term trends of TCCgrd and visibility were not correlated. These results indicated that aerosols likely did not impact the long-term trend of TCCgrd over the NCP.

  10. Scope of Jovian lightning observation by ground-based and spacecraft instruments

    NASA Astrophysics Data System (ADS)

    Fukuhara, T.; Takahashi, Y.; Sato, M.; Nakajima, K.

    2009-12-01

    It is suggested by recent observational and theoretical studies that the thunderstorms, i.e., strong moist convective clouds in Jupiter’s atmosphere are very important not only as an essential ingredient of meteorology of Jupiter but also as a potentially very useful “probe” of the water abundance of the deep atmosphere, which is crucial to constrain the behavior of volatiles in early solar system. We would propose the lightning observation with properly designed optical device onboard Jovian system orbiter and with the ground-based telescope. Based on detailed analysis of cloud motions by Galileo orbiter, Gierasch et al. proposed that the thunderstorms can produce the small scale eddies and ultimately drive the belt/zone structure. Moreover, the belt zone structure helps the development of thunderstorms in the belt region in accordance with observation; the belt/zone structure and thunderstorms may be in a symbiotic relation. This framework is a refined version of shallow origin theory, but, although it is a very fantastic idea, quantitative verification remains to be done. Most recent numerical modeling by our group calculated all three types of cloud, i.e., H2O, NH3, and, NH4SH. One of the most important findings is the existence of distinct, quasi-periodic temporal variation of the convective cloud activity; explosion of cloud activity extending all over the computational domain occurs separated by quiet period of order of 10 days. Another surprising finding is that the period of the active/break cycle is roughly proportional to the amount of condensable component in the sub-cloud layer. This strong correspondence between the deep volatile abundance and temporal variability of cloud convection implies a new method to probe the deep atmosphere. We believe JGO with other optical equipments especially for atmospheric spectral imaging is the ideal platform for the lightning detector. Comparing quantitative lightning activity with ambient cloud motion and

  11. RTTOV-gb - adapting the fast radiative transfer model RTTOV for the assimilation of ground-based microwave radiometer observations

    NASA Astrophysics Data System (ADS)

    De Angelis, Francesco; Cimini, Domenico; Hocking, James; Martinet, Pauline; Kneifel, Stefan

    2016-08-01

    Ground-based microwave radiometers (MWRs) offer a new capability to provide continuous observations of the atmospheric thermodynamic state in the planetary boundary layer. Thus, they are potential candidates to supplement radiosonde network and satellite data to improve numerical weather prediction (NWP) models through a variational assimilation of their data. However in order to assimilate MWR observations, a fast radiative transfer model is required and such a model is not currently available. This is necessary for going from the model state vector space to the observation space at every observation point. The fast radiative transfer model RTTOV is well accepted in the NWP community, though it was developed to simulate satellite observations only. In this work, the RTTOV code has been modified to allow for simulations of ground-based upward-looking microwave sensors. In addition, the tangent linear, adjoint, and K-modules of RTTOV have been adapted to provide Jacobians (i.e., the sensitivity of observations to the atmospheric thermodynamical state) for ground-based geometry. These modules are necessary for the fast minimization of the cost function in a variational assimilation scheme. The proposed ground-based version of RTTOV, called RTTOV-gb, has been validated against accurate and less time-efficient line-by-line radiative transfer models. In the frequency range commonly used for temperature and humidity profiling (22-60 GHz), root-mean-square brightness temperature differences are smaller than typical MWR uncertainties (˜ 0.5 K) at all channels used in this analysis. Brightness temperatures (TBs) computed with RTTOV-gb from radiosonde profiles have been compared with nearly simultaneous and co-located ground-based MWR observations. Differences between simulated and measured TBs are below 0.5 K for all channels except for the water vapor band, where most of the uncertainty comes from instrumental errors. The Jacobians calculated with the K-module of RTTOV

  12. Linkage between Grounding Line Dynamics and Geological Observations in the Weddell Sea Sector of Antarctica

    NASA Astrophysics Data System (ADS)

    Huybers, K. M.; Roe, G.; Conway, H.; Balco, G.; Todd, C. E.

    2012-12-01

    Surface-exposure dating is a potentially a powerful technique to constrain Antarctic ice-sheet thinning from the Last Glacial Maximum to its present state. Erratics recently collected near the grounding line of the Foundation Ice Stream in Antarctica's Weddell Sea sector detail thickness maxima and exposure rates along local nunatak elevation transects. These points in space and time constrain the local thickness and rate of thinning—however, what can they tell us about the history of the elevation profile of the interior ice stream? The elevation profile of the interior ice is strongly controlled by the position of the grounding line, which in turn depends on sea level, accumulation, and the ice stream/shelf's physical characteristics. We use to an idealized flowline model to assess the relative importance of factors used to model ice stream thickness profiles. We divide these factors into two general categories: model physics, and environmental factors. Model physics includes choices about the ice rheology, the sliding law, and the calculated flux at the grounding line, where the ice transitions from grounded stream to floating shelf. Environmental factors include climate, basal topography, sliding parameterization, sea level, ice softness, and lateral shelf stresses. In our simplified model, we ignore the potentially important effects of isostatic rebound and the gravitational pull of the ice on ocean water. Preliminary findings indicate that the position of the grounding line controls the elevation at the exposure sites; and that sub-glacial and sub-marine basal topography, together with the assumed form of the grounding-line flux, dominates the grounding-line sensitivity to change. This suggests that the surface elevation predominantly reflects regional-scale ice sheet behavior rather than the climate local to the ice-stream catchment.

  13. Software for inference of dynamic ground strains and rotations and their errors from short baseline array observations of ground motions

    USGS Publications Warehouse

    Spudich, P.; Fletcher, Joe B.

    2009-01-01

    In two previous articles we presented a formulation for inferring the strains and rotations of the ground beneath a seismic array having a finite footprint. In this article we derive expressions for the error covariance matrices of the inferred strains and rotations, and we present software for the calculation of ground strains, rotations, and their variances from short baseline array ground-motion data.

  14. Estimating the Radiative Forcing of Carbonaceous Aerosols over California based on Satellite and Ground Observations

    SciTech Connect

    Xu, Yangyang; Bahadur, R.; Zhao, Chun; Leung, Lai-Yung R.

    2013-10-04

    Carbonaceous aerosols have the potential to impact climate both through directly absorbing incoming solar radiation, and by indirectly affecting the cloud layer. To quantify this impact recent modeling studies have made great efforts to simulate both the spatial and temporal distribution of carbonaceous aerosols and their associated radiative forcing. This study makes the first observationally constrained assessment of the direct radiative forcing of carbonaceous aerosols at a regional scale over California. By exploiting multiple observations (including ground sites and satellites), we constructed the distribution of aerosol optical depths and aerosol absorption optical depths over California for a ten-year period (2000-2010). The total solar absorption was then partitioned into contributions from elemental carbon (EC), organic carbon (OC) and dust aerosols using a newly developed scheme. Aerosol absorption optical depth due to carbonaceous aerosols (EC and OC) at 440 nm is 50%-200% larger than natural dust, with EC contributing the bulk (70%-90%). Observationally constrained EC absorption agrees reasonably well with estimates from regional transport models, but the model underestimates the OC AAOD by at least 50%. We estimate that the TOA warming from carbonaceous aerosols is 0.7 W/m2 and the TOA forcing due to OC is close to zero. The atmospheric heating of carbonaceous aerosols is 2.2-2.9 W/m2, of which EC contributed about 80-90%. The atmospheric heating due to OC is estimated to be 0.1 to 0.4 W/m2, larger than model simulations. The surface brightening due to EC reduction over the last two decades is estimated to be 1.5-3.5 W/m2.

  15. Space Borne and Ground-Based Observations of Transient Processes Occurring Around Substorm Onset

    NASA Technical Reports Server (NTRS)

    Kepko, L.; Spanswick, E.; Angelopoulos, V.; Donovan, E.

    2010-01-01

    The combined THEMIS five spacecraft in-situ and ground magnetic and visible camera arrays have advanced considerably our understanding of the causal relationship between midtail plasma flows, transient ionospheric features, and ground magnetic signatures. In particular recent work has shown a connection between equatorward moving visible ionospheric transients and substorm onset, in both white-light and 6300 nm emissions. These observations, together with THEMIS in-situ measurements of bulk flows, provides strict constraints on the sequence of events leading to substorm auroral onset.We first provide a brief summary of these observations, highlighting in particular areas where the two observations differ, and suggest reasons for the differences. Next, by combining the observed correlation of flow and Pi2 waveform with a unified model of global Pi2 generation and substorm current wedge initiation we present a self-consistent description of the dynamical processes and communicative pathways that occur just prior to and during substorm expansion onset.

  16. Potential effects of climate change on ground water in Lansing, Michigan

    USGS Publications Warehouse

    Croley, T.E.; Luukkonen, C.L.

    2003-01-01

    Computer simulations involving general circulation models, a hydrologic modeling system, and a ground water flow model indicate potential impacts of selected climate change projections on ground water levels in the Lansing, Michigan, area. General circulation models developed by the Canadian Climate Centre and the Hadley Centre generated meteorology estimates for 1961 through 1990 (as a reference condition) and for the 20 years centered on 2030 (as a changed climate condition). Using these meteorology estimates, the Great Lakes Environmental Research Laboratory's hydrologic modeling system produced corresponding period streamflow simulations. Ground water recharge was estimated from the streamflow simulations and from variables derived from the general circulation models. The U.S. Geological Survey developed a numerical ground water flow model of the Saginaw and glacial aquifers in the Tri-County region surrounding Lansing, Michigan. Model simulations, using the ground water recharge estimates, indicate changes in ground water levels. Within the Lansing area, simulated ground water levels in the Saginaw aquifer declined under the Canadian predictions and increased under the Hadley.

  17. The interaction potential of NO-H2 in ground and A Rydberg state

    NASA Astrophysics Data System (ADS)

    Pajón-Suárez, Pedro; Valentín-Rodríguez, Mónica; Hernández-Lamoneda, Ramón

    2016-08-01

    The interaction potential for the ground and A Rydberg state of NO-H2 has been calculated using high level ab initio methods. The complex is very floppy in nature and large amplitude motions are expected to characterize its dynamics. The ground state is characterized by two very close-lying states which exhibit crossings. By analogy with other complexes the Rydberg state is characterized by much smaller well depth and larger intermolecular distance. We compare with model potentials used in previous molecular dynamics simulations of photoexcitation and relaxation and conclude on the importance of performing new studies.

  18. Ozone column content variability at the Kishinev site from satellite retrievals and ground observations

    NASA Astrophysics Data System (ADS)

    Aculinin, Alexandr; Smicov, Vladimir

    2010-05-01

    It is analyzed variability of the total ozone content (TOC) in column of atmosphere by using ozone retrievals from satellite platform and from direct ground observations at the Kishinev site, Moldova (47.00N; 28.56E). Direct ground observations of the TOC are regular carried out by Atmospheric Research Group (ARG), Institute of Applied Physics at the ground-based solar radiation monitoring station, Kishinev site, by using of hand-held ozonemeter MICROTOPS II. TOC measurements started since 2003. Data of ozone observations are presented at the research group web-site http://arg.phys.asm.md. Satellite TOC dataset at specific coordinates of Kishinev site was derived by using linear interpolation of the parent gridded databases from TOMS (1979-2004) and OMI (2005-2008) observations. It was established that relative difference of TOC between periods from 1979 to 1983 and from 2004 to 2008 was -5.16 %. Data were processed by applying of 5-year averaging "window". For a period from 1979 to 2008 statistical estimation of linear trend of the TOC was -2.08% per decade. Climatic norm of TOC for this period was equal to 335 DU. Variation of ozone column content at Kishinev site shows it seasonal character with maximum of the order of ~378 DU (in March and April) and with minimum of the order of ~289 DU (in October). The largest and lowest range of oscillations of monthly means of the TOC retrieved for Kishinev site from TOMS and OMI observations in the course of the period from 1979 to 2008 were ~ 102 DU (in February) and ~29 DU (in October). Extremely low and high values of the TOC ever registered for Kishinev site from TOMS and OMI observations were ~ 209 DU (on December 1, 1999) and ~ 532 DU (on March 3, 1988). It was shown that ARG ground observations give overestimated TOC values in comparison with the TOMS and OMI observations from satellite platforms. Relative differences or biases (in %) between satellite and ARG ground observations of the TOC at Kishinev site were

  19. Snow Never Falls on Satellite Radiometers: A Compelling Alternative to Ground Observations

    NASA Astrophysics Data System (ADS)

    Hinkelman, L. M.; Lapo, K. E.; Cristea, N. C.; Lundquist, J. D.

    2014-12-01

    Snowmelt is an important source of surface water for ecosystems, river flow, drinking water, and production of hydroelectric power. Thus accurate modeling of snow accumulation and melt is needed to improve our understanding of the impact of climate change on mountain snowpack and for use in water resource forecasting and management decisions. One of the largest potential sources of uncertainty in modeling mountain snow is the net radiative flux. This is because while net irradiance makes up the majority of the surface energy balance, it is one of the most difficult forcings to measure at remote mountain locations. Here we investigate the use of irradiances derived from satellite measurements in the place of surface observations. NASA's Clouds and the Earth's Radiant Energy System (CERES) SYN satellite product provides longwave and shortwave irradiances at the ground on three-hourly temporal and one degree spatial resolution.Although the low resolution of these data is a drawback, their availability over the entire globe for the full period of March 2000 through December 2010 (and beyond, as processing continues) makes them an attractive option for use in modeling. We first assessed the accuracy of the SYN downwelling solar and longwave fluxes by comparison to measurements at NOAA's Surface Radiation Network (SURFRAD) reference stations and at remote mountain stations. The performance of several snow models of varying complexity when using SYN irradiances as forcing data was then evaluated. Simulated snow water equivalent and runoff from cases using SYN data fell in the range of those from simulations forced with irradiances from higher quality surface observations or more highly-regarded empirical methods. We therefore judge the SYN irradiances to be suitable for use in snowmelt modeling and preferable to in situ measurements of questionable quality.

  20. (21) Lutetia spectrophotometry from Rosetta-OSIRIS images and comparison to ground-based observations

    NASA Astrophysics Data System (ADS)

    Magrin, S.; La Forgia, F.; Pajola, M.; Lazzarin, M.; Massironi, M.; Ferri, F.; da Deppo, V.; Barbieri, C.; Sierks, H.; Osiris Team

    2012-06-01

    Here we present some preliminary results on surface variegation found on (21) Lutetia from ROSETTA-OSIRIS images acquired on 2010-07-10. The spectrophotometry obtained by means of the two cameras NAC and WAC (Narrow and Wide Angle Cameras) is consistent with ground based observations, and does not show surface diversity above the data error bars. The blue and UV images (shortward 500 nm) may, however, indicate a variegation of the optical properties of the asteroid surface on the Baetica region (Sierks et al., 2011). We also speculate on the contribution due to different illumination and to different ground properties (composition or, more probably, grain size diversity). In particular a correlation with geologic units independently defined by Massironi et al. (2012) is evident, suggesting that the variegation of the ground optical properties is likely to be real.

  1. Observation-well network for collection of ground-water level data in Massachusetts

    USGS Publications Warehouse

    Socolow, Roy S.

    1994-01-01

    Aquifers--water-bearing deposits of sand and gravel, glacial till, and fractured bedrock--provide an extensive and readily accessible ground-water supply in Massachusetts. Ground water affects our everyday lives, not just in terms of how much water is available, but also in terms of the position of ground-water levels in relation to land surface. Knowledge of ground-water levels is needed by Federal, State, and local agencies to help plan, manage, and protect ground-water supplies, and by private construction companies for site planning and evaluation. A primary part of the mission of the U.S. Geological Survey (USGS), Water Resources Division, is the systematic collection of ground-water, surface-water, and water-quality data. These data are needed to manage and protect the nation's water resources. The Massachusetts-Rhode Island District of the USGS, in cooperation with the Massachusetts Department of Environmental Management (DEM), Office of Water Resources, and county and town environmental agencies, has maintained a network of observation wells throughout the Commonwealth since the mid 1930's. The purpose of this network is to monitor seasonal and long-term changes in groundwater storage in different lithologic, topographic, and geographic settings. These data are analyzed to provide a monthly index of ground-water conditions to aid in water-resources management and planning, and to define long-term changes in water levels resulting from manmade stresses (such as pumping and construction-site drainage) and natural stresses (such as floods and droughts).

  2. A theory of electron cyclotron waves generated along auroral field lines observed by ground facilities

    NASA Technical Reports Server (NTRS)

    Wu, C. S.; Yoon, Peter H.; Freund, H. P.

    1989-01-01

    A generation mechanism for radio waves in the frequency range 150 - 700 kHz observed by ground facilities is suggested in terms of an electromagnetic electron cyclotron instability driven by auroral electrons. The excited waves can propagate downward along the ambient magnetic field lines and are thus observable with ground facilities. The trapped auroral electrons are supposed to play an important role in the generation process, because they give rise to a thermal anisotropy which consequently leads to the instability. The present work is a natural extension of the theory proposed earlier by Wu et al. (1983) which was discussed in a different context but may be used to explain the observed waves originated at low altitudes. This paper presents a possible wave generation mechanism valid in the entire auroral field-line region of interest.

  3. On the estimability of geodetic parameters with space-ground and space-space SVLBI observations

    NASA Astrophysics Data System (ADS)

    Wei, Erhu; Liu, Jingnan; Yan, Wei; Shi, Chuang

    2008-12-01

    Space Very Long Baseline Interferometry (SVLBI) is the unique space technique that can directly interconnect the main three reference systems for geodesy and geodynamics. However, the estimable sequence of geodetic parameters including nutation parameters within SVLBI mathematical model has not been determined yet. In this paper, using the mathematical model of space-ground SVLBI observations including the nutation parameters derived by WEI Erhu et al.(2008), the estimable parameter sequence is determined. And the same study is done with space-space SVLBI Observations. To study the standard deviation of nutation parameters estimated with space-ground SVLBI observations, the model of variance propagation is derived, with which some numerical tests are done. Finally, the results are present.

  4. Thunderstorms and ground-based radio noise as observed by radio astronomy Explorer 1

    NASA Technical Reports Server (NTRS)

    Caruso, J. A.; Herman, J. R.

    1973-01-01

    Radio Astronomy Explorer (RAE) data were analyzed to determine the frequency dependence of HF terrestrial radio noise power. RAE observations of individual thunderstorms, mid-ocean areas, and specific geographic regions for which concommitant ground based measurements are available indicate that noise power is a monotonically decreasing function of frequency which conforms to expectations over the geographic locations and time periods investigated. In all cases investigated, active thunderstorm regions emit slightly higher power as contrasted to RAE observations of the region during meteorologically quiet periods. Noise levels are some 15 db higher than predicted values over mid-ocean, while in locations where ground based measurements are available a maximum deviation of 5 db occurs. Worldwide contour mapping of the noise power at 6000 km for five individual months and four observing frequencies, examples of which are given, indicate high noise levels over continental land masses with corresponding lower levels over ocean regions.

  5. Evaluating the Accuracy of Plasmasphere Data Assimilation from Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Jorgensen, A. M.; Lichtenberger, J.; Friedel, R. H.; Clilverd, M.; Heilig, B.; Vellante, M.; Raita, T.; Rodger, C. J.; Reda, J.; Collier, A.; Holzworth, R. H.; Ober, D. M.; Boudouridis, A.; Zesta, E.; Chi, P. J.

    2013-05-01

    VLF and magnetometer observations can be used to remotely sense the plasmasphere. VLF whistler waves can be used to measure the electron density and magnetic Field Line Resonance (FLR) measurements can be used to measure the mass density. In principle it is then possible to remotely map the plasmasphere with a network of ground-based stations which are also less expensive and more permanent than satellites. The PLASMON project, funded by the EU FP-7 program, is in the process of doing just this. A large number of ground-based observations will be input into a data assimilative framework which models the plasmasphere structure and dynamics. The data assimilation framework combines the Ensemble Kalman Filter with the Dynamic Global Core Plasma Model. Here we simulate the observations from these networks, with appropriate uncertainties, and use them to drive the data assimilation framework to recover the plasmaspheric configuration. We will discuss the level of accuracy that can be achieved.

  6. Evaluating the Accuracy of Plasmasphere Data Assimilation from Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Jorgensen, A. M.; Lichtenberger, J.; Duffy, J.; Friedel, R. H.; Clilverd, M.; Heilig, B.; Vallante, M.; Manninen, J. K.; Rodger, C. J.; Collier, A.; Reda, J.; Holzworth, R. H.; Ober, D. M.; Boudouridis, A.; Zesta, E.; Chi, P. J.

    2012-12-01

    VLF and magnetometer observations can be used to remotely sense the plasmasphere. VLF whistler waves can be used to measure the electron density and magnetic Field Line Resonance (FLR) measurements can be used to measure the mass density. In principle it is then possible to remotely map the plasmasphere with a network of ground-based stations which are also less expensive and more permanent than satellites. The PLASMON project, funded by the EU FP-7 program, is in the process of doing just this. A large number of ground-based observations will be input into a data assimilative framework which models the plasmasphere structure and dynamics. The data assimilation framework combines the Ensemble Kalman Filter with the Dynamic Global Core Plasma Model. Here we simulate the observations from these networks, with appropriate uncertainties, and use them to drive the data assimilation framework to recover the plasmaspheric configuration. We will discuss the level of accuracy that can be achieved.

  7. Evaluating the Accuracy of Plasmasphere Data Assimilation from Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Jorgensen, Anders M.; Lichtenberger, Janos; Duffy, Jared; Friedel, Reiner; Clilverd, Mark; Heilig, Balazs; Vellante, Massimo; Raita, Tero; Rodger, Craig; Collier, Andrew; Reda, Jan; Holzworth, Robert; Ober, Daniel; Boudouridis, Athanasios; Zesta, Eftyhia; Chi, Peter J.

    2013-04-01

    VLF and magnetometer observations can be used to remotely sense the plasmasphere. VLF whistler waves can be used to measure the electron density and magnetic Field Line Resonance (FLR) measurements can be used to measure the mass density. In principle it is then possible to remotely map the plasmasphere with a network of ground-based stations which are also less expensive and more permanent than satellites. The PLASMON project, funded by the EU FP-7 program, is in the process of doing just this. A large number of ground-based observations will be input into a data assimilative framework which models the plasmasphere structure and dynamics. The data assimilation framework combines the Ensemble Kalman Filter with the Dynamic Global Core Plasma Model. Here we simulate the observations from these networks, with appropriate uncertainties, and use them to drive the data assimilation framework to recover the plasmaspheric configuration. We will discuss the level of accuracy that can be achieved.

  8. Measurement of energetic radiation caused by thunderstorm activities by a sounding balloon and ground observation

    NASA Astrophysics Data System (ADS)

    Torii, T.

    2015-12-01

    Energetic radiation caused by thunderstorm activity is observed at various places, such as the ground, high mountain areas, and artificial satellites. In order to investigate the radiation source and its energy distribution, we measured energetic radiation by a sounding balloon, and the ground observation. On the measurement inside/above the thundercloud, we conducted a sounding observation using a radiosonde mounted two GM tubes (for gamma-rays, and for beta/gamma-rays), in addition to meteorological instruments. The balloon passed through a region of strong echoes in a thundercloud shown by radar image, at which time an increase in counting rate of the GM tube about 2 orders of magnitude occurred at the altitude from 5 km to 7.5 km. Furthermore, the counting rate of two GM tubes indicated the tendency different depending on movement of a balloon. This result suggests that the ratio for the gamma-rays (energetic photons) of the beta-rays (energetic electrons) varies according to the place in the thundercloud. Furthermore, we carried out a ground observation of the energetic gamma rays during winter thunderstorm at a coastal area facing the Sea of Japan. Two types of the energetic radiation have been observed at this time. We report the outline of these measurements and analysis in the session of the AGU meeting.

  9. Observations of high ground flash densities of positive lightning in summertime thunderstorms

    SciTech Connect

    Stolzenburg, M.

    1994-08-01

    Observations of summertime thunderstorms indicate that positive polarity cloud-to-ground lightning activity can occur with rates as high as 67 flashes in 5 min and spatial densities up to 0.60 flashes per square kilometer per hour. All ground flashes in a storm may be positive for substantial periods. Using data from a nationwide network of magnetic direction finders, 24 storms with high ground flash densities of positive lightning were found on 11 days in June and July 1989 in the Great Plains of the United States. The periods of high-density positive lightning persisted an average of 4 h, longer than the lifetime of a typical single thunderstorm cell. In most cases, they occurred at or near the beginning of the storms` cloud-to-ground lightning activity. Supporting data suggest that the production of high rate and high percentage of positive ground flashes may be associated with exceptionally tall storms that exhibit a stage of early, rapid increase in radar echo-top height and produce large hail.

  10. Extended field observations of cirrus clouds using a ground-based cloud observing system

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.

    1994-01-01

    The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

  11. Determination of the plasmapause boundary using ground magnetometer field line resonances, satellite observations, and modeling

    NASA Astrophysics Data System (ADS)

    Zesta, E.; Boudouridis, A.; Jorgensen, A. M.; Yizengaw, E.; Chi, P. J.; Moldwin, M.; Carranza, T.; Mann, I. R.; Johnston, W. R.; Wilson, G. R.

    2012-12-01

    The plasmapause boundary layer (PBL) separates the cold and dense plasmaspheric plasma from the more tenuous and hot plasma sheet plasma and organizes the spatial distribution of ULF and VLF waves that can contribute to acceleration or loss processes of radiation belt particles through wave-particle interactions. The PBL has been traditionally determined by in situ observations and can be given by empirical models. Recent work has shown that a mid-latitude chain of well-spaced ground magnetometers can also determine the PBL boundary location. Spectral properties, like the cross-phase reversal between two stations closely aligned in latitude, have been shown to indicate the presence of a sharp PBL. We show here an example of such a PBL identification during the moderate storm of Nov 9-12, 2006. We combine observations from the SAMBA (South American Meridional B-field Array), MEASURE (Magnetometers along the Eastern Atlantic Seaboard for Undergraduate Research and Education), McMAC (Mid-continent Magnetoseismic Chain), and CARISMA ground magnetometer chains covering L values from L=2 to L=5 to statistically determine how commonly the PBL is determined from ground magnetometers. In our initial study we examine observations from June to December, 2006. We compare our PBL determinations with the determination of the same boundary from the Defense Meteorological Satellite Program (DMSP) satellites, based on the H+ density observations, which have been shown to accurately identify the PBL from a low-Earth orbiting satellite. We also compare our PBL identification with those determined from a global GPS TEC map and GPS TEC tomography technique used by a chain of ground GPS receivers. Finally, we compare our observations with results from the Dynamic Global Core Plasma Model (DGCPM), as well as existing empirical models based on in situ observations.

  12. Prevalence and Characterization of Salmonella in Bovine Lymph Nodes Potentially Destined for Use in Ground Beef

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A potential source of pathogenic bacteria in ground beef is the lymphatic system, specifically the lymph nodes. There are several reports of bacteria isolated from the lymph nodes of cattle at slaughter; however, most of the studies have dealt with mesenteric lymph nodes that are not normally incor...

  13. Evaluation of GOCE satellite gravimetry using BGI ground gravity observations over Africa, Asia and South America

    NASA Astrophysics Data System (ADS)

    Rexer, M. J.; Hirt, C.; Bonvalot, S.; Bruinsma, S.; Pail, R.; Kuhn, M.

    2013-12-01

    Launched in 2009, GOCE ('Gravity and Steady-state Ocean Circulation Explorer') satellite's gravity gradiometer gathered gravity observations which resulted in unprecedented global models of the Earth's gravity field at spatial scales up to 80 km. In remote regions and countries with sparsely distributed ground gravity observations the largest benefit through homogeneous GOCE observations is to be expected. This study deals with the evaluation of GOCE satellite data in those rather poorly surveyed areas with ground gravity data sets provided by the Bureau Gravimétrique International (BGI). We evaluate up-to-date GOCE gravity models at over 60,000 stations over parts of Africa, South America, Central and South-East Asia, and are able to give absolute accuracy estimates for GOCE models in respective areas and quantify the improvement due to GOCE with respect to current global gravity models containing terrestrial information (e.g. EGM2008). Our analysis is based on the spectral enhancement method (Hirt et al, 2011) where satellite data is augmented with terrestrial and forward-modelled gravity from topography prior to the comparisons with observed ground gravity.

  14. Report on the ground-based observation campaign of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Jehin, Emmanuel

    2015-11-01

    Rosetta gets closer to the nucleus than any previous mission, and returns wonderfully detailed measurements from the heart of the comet, but at the cost of not seeing the large scale coma and tails. The ground-based campaign fills in the missing part of the picture, studying the comet at about 1000 km resolution, and following how the overall activity of the comet varies. These data provide context information for Rosetta, so changes in the inner coma seen by the spacecraft can be correlated with the phenomena observable in comets. This will not only help to complete our understanding of the activity of 67P, but also to allow us to compare it with other comets that are only observed from the ground.The ground-based campaign includes observations with nearly all major facilities world-wide. In 2014 the majority of data came from the ESO VLT, as the comet was still relatively faint and in Southern skies, but as it returns to visibility from Earth in 2015 it is considerably brighter, approaching its perihelion in August, and at Northern declinations. I will present results from the 2014 campaign, including visible wavelength photometry and spectroscopy, and the latest results from 2015 observations.

  15. Ground-level observation of a terrestrial gamma ray flash initiated by a triggered lightning

    NASA Astrophysics Data System (ADS)

    Hare, B. M.; Uman, M. A.; Dwyer, J. R.; Jordan, D. M.; Biggerstaff, M. I.; Caicedo, J. A.; Carvalho, F. L.; Wilkes, R. A.; Kotovsky, D. A.; Gamerota, W. R.; Pilkey, J. T.; Ngin, T. K.; Moore, R. C.; Rassoul, H. K.; Cummer, S. A.; Grove, J. E.; Nag, A.; Betten, D. P.; Bozarth, A.

    2016-06-01

    We report on a terrestrial gamma ray flash (TGF) that occurred on 15 August 2014 coincident with an altitude-triggered lightning at the International Center for Lightning Research and Testing (ICLRT) in North Central Florida. The TGF was observed by a ground-level network of gamma ray, close electric field, distant magnetic field, Lightning Mapping Array (LMA), optical, and radar measurements. Simultaneous gamma ray and LMA data indicate that the upward positive leader of the triggered lightning flash induced relativistic runaway electron avalanches when the leader tip was at about 3.5 km altitude, resulting in the observed TGF. Channel luminosity and electric field data show that there was an initial continuous current (ICC) pulse in the lightning channel to ground during the time of the TGF. Modeling of the observed ICC pulse electric fields measured at close range (100-200 m) indicates that the ICC pulse current had both a slow and fast component (full widths at half maximum of 235 μs and 59 μs) and that the fast component was more or less coincident with the TGF, suggesting a physical association between the relativistic runaway electron avalanches and the ICC pulse observed at ground. Our ICC pulse model reproduces moderately well the measured close electric fields at the ICLRT as well as three independent magnetic field measurements made about 250 km away. Radar and LMA data suggest that there was negative charge near the region in which the TGF was initiated.

  16. Synchronized observations by using the STEREO and the largest ground-based decametre radio telescope

    NASA Astrophysics Data System (ADS)

    Konovalenko, A. A.; Stanislavsky, A. A.; Rucker, H. O.; Lecacheux, A.; Mann, G.; Bougeret, J.-L.; Kaiser, M. L.; Briand, C.; Zarka, P.; Abranin, E. P.; Dorovsky, V. V.; Koval, A. A.; Mel'nik, V. N.; Mukha, D. V.; Panchenko, M.

    2013-08-01

    We consider the approach to simultaneous (synchronous) solar observations of radio emission by using the STEREO-WAVES instruments (frequency range 0.125-16 MHz) and the largest ground-based low-frequency radio telescope. We illustrate it by the UTR-2 radio telescope implementation (10-30 MHz). The antenna system of the radio telescope is a T-shape-like array of broadband dipoles and is located near the village Grakovo in the Kharkiv region (Ukraine). The third observation point on the ground in addition to two space-based ones improves the space-mission performance capabilities for the determination of radio-emission source directivity. The observational results from the high sensitivity antenna UTR-2 are particularly useful for analysis of STEREO data in the condition of weak event appearances during solar activity minima. In order to improve the accuracy of flux density measurements, we also provide simultaneous observations with a large part of the UTR-2 radio telescope array and its single dipole close to the STEREO-WAVES antennas in sensitivity. This concept has been studied by comparing the STEREO data with ground-based records from 2007-2011 and shown to be effective. The capabilities will be useful in the implementation of new instruments (LOFAR, LWA, MWA, etc.) and during the future Solar Orbiter mission.

  17. Comparison of Ground-Based 3-Dimensional Lightning Mapping Observation with Satellite-Based LIS Observations in Oklahoma

    NASA Technical Reports Server (NTRS)

    Thomas, Ronald J.; Krehbiel, Paul R.; Rison, William; Hamlin, Timothy; Boccippio, Dennis J.; Goodman, Steven J.; Christian, Hugh J.

    1999-01-01

    3-dimensional lightning mapping observations were obtained in central Oklahoma during June 1998, using New Mexico Tech's Lightning Mapping Array (LMA). The results have been compared with observations of the discharges from space obtained by NASA's Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) spacecraft. Excellent spatial and temporal correlations were obtained between the two sets of observations. All discharges seen by LIS were mapped by the LMA. Most of the detected optical events were associated with lightning channels that extended into the upper part of the storm. Cloud-to-ground discharges that were confined to mid- and lower-altitudes tended to be detected by LIS at the time of late-stage return strokes. Extensive illumination tended to occur in impulsive bursts toward the end or part way through intracloud discharges and appeared to be produced by energetic K-changes that typically occur at these times.

  18. Classification of ground-water recharge potential in three parts of Santa Cruz County, California

    USGS Publications Warehouse

    Muir, K.S.; Johnson, Michael J.

    1979-01-01

    Ground-water recharge potential was classified in the Santa Cruz coastal area, North-central area, and Soquel-Aptos area in Santa Cruz County, Calif., for three data elements that affect recharge; slope, soils, and geology. Separate numerical maps for each element were composited into a single numerical map using a classification system that ranked the numbers into areas of good , fair, and poor recharge potential. Most of the Santa Cruz coastal area and the Norht-central area have a poor recharge potential, and much of the Soquel-Aptos area has a good to fair recharge potential. (Kosco-USGS)

  19. Coupling of ground biosensor networks for water monitoring with satellite observations in assessing Leptospirosis

    NASA Astrophysics Data System (ADS)

    Skouloudis, A. N.; Rickerby, D. G.

    2012-12-01

    mapping is reliant on the identification of location where such networks could be of use. Systematic monitoring from satellite images are utilized for increasing the potential areas of application, for assessing the geographical representativeness on the measurements of the sensors and proposing the methodology on assessing the environmental conditions that are associated with outbreaks of leptospirosis. Unfortunately, several combined deployments of earth observations with ground sensors are required before for the understanding of the connections between hydrology and the human health. Ultimately this will lead to the establishment of early warning system that might investigate the effectiveness of key control measures, including vaccine (when they will become available) and affront the water decontamination, and animal control issues.

  20. Modelling Ground Based X- and Ku-Band Observations of Tundra Snow

    NASA Astrophysics Data System (ADS)

    Kasurak, A.; King, J. M.; Kelly, R. E.

    2012-12-01

    As part of a radar-based remote sensing field experiment in Churchill, Manitoba ground based Ku- and X-band scatterometers were deployed to observe changing tundra snowpack conditions from November 2010 to March 2011. The research is part of the validation effort for the Cold Regions Hydrology High-resolution Observatory (CoReH2O) mission, a candidate in the European Space Agency's Earth Explorer program. This paper focuses on the local validation of the semi-empirical radiative transfer (sRT) model proposed for use in snow property retrievals as part of the CoReH2O mission. In this validation experiment, sRT was executed in the forward mode, simulating backscatter to assess the ability of the model. This is a necessary precursor to any inversion attempt. Two experiments are considered, both conducted in a hummocky tundra environment with shallow snow cover. In both cases, scatterometer observations were acquired over a field of view of approximately 10 by 20 meters. In the first experiment, radar observations were made of a snow field and then repeated after the snow had been removed. A ground-based scanning LiDAR system was used to characterize the spatial variability of snow depth through measurements of the snow and ground surface. Snow properties were determined in the field of view from two snow pits, 12 density core measurements, and Magnaprobe snow depth measurements. In the second experiment, a site was non-destructively observed from November through March, with snow properties measured out-of-scene, to characterize the snow evolution response. The model results from sRT fit the form of the observations from the two scatterometer field experiments but do not capture the backscatter magnitude. A constant offset for the season of 5 dB for X-band co- and cross-polarization response was required to match observations, in addition to a 3 dB X- and Ku-band co-polarization offset after the 6th of December. To explain these offsets, it is recognized that the two

  1. DEMETER observations of bursty MF emissions and their relation to ground-level auroral MF burst

    NASA Astrophysics Data System (ADS)

    Broughton, M. C.; LaBelle, J.; Parrot, M.

    2014-12-01

    A survey of medium frequency (MF) electric field data from selected orbits of the Detection of Electro-Magnetic Emissions Transmitted from Earthquakes (DEMETER) spacecraft reveals 68 examples of a new type of bursty MF emissions occurring at high latitudes associated with auroral phenomena. These resemble auroral MF burst, a natural radio emission observed at ground level near local substorm onsets. Similar to MF burst, the bursty MF waves observed by DEMETER have broadband, impulsive frequency structure covering 1.5-3.0 MHz, amplitudes of 50-100 μV/m, an overall occurrence rate of ˜0.76% with higher occurrence during active times, and strong correlation with auroral hiss. The magnetic local time distribution of the MF waves observed by DEMETER shows peak occurrence rate near 18 MLT, somewhat earlier than the equivalent peak in the occurrence rate of ground level MF burst, though propagation effects and differences in the latitudes sampled by the two techniques may explain this discrepancy. Analysis of solar wind and SuperMAG data suggests that while the bursty MF waves observed by DEMETER are associated with enhanced auroral activity, their coincidence with substorm onset may not be as exact as that of ground level MF burst. One conjunction occurs in which MF burst is observed at Churchill, Manitoba, within 8 min of MF emissions detected by DEMETER on field lines approximately 1000 km southeast of Churchill. These observations may plausibly be associated with the same auroral event detected by ground level magnetometers at several Canadian observatories. Although it is uncertain, the balance of the evidence suggests that the bursty MF waves observed with DEMETER are the same phenomenon as the ground level MF burst. Hence, theories of MF burst generation in the ionosphere, such as beam-generated Langmuir waves excited over a range of altitudes or strong Langmuir turbulence generating a range of frequencies within a narrow altitude range, need to be revisited to

  2. Ground Truth Observations of the Interior of a Rockglacier as Validation for Geophysical Monitoring Data Sets

    NASA Astrophysics Data System (ADS)

    Hilbich, C.; Roer, I.; Hauck, C.

    2007-12-01

    Monitoring the permafrost evolution in mountain regions is currently one of the important tasks in cryospheric studies as little data on past and present changes of the ground thermal regime and its material properties are available. In addition to recently established borehole temperature monitoring networks, techniques to determine and monitor the ground ice content have to be developed. A reliable quantification of ground ice is especially important for modelling the thermal evolution of frozen ground and for assessing the hazard potential due to thawing permafrost induced slope instability. Near surface geophysical methods are increasingly applied to detect and monitor ground ice occurrences in permafrost areas. Commonly, characteristic values of electrical resistivity and seismic velocity are used as indicators for the presence of frozen material. However, validation of the correct interpretation of the geophysical parameters can only be obtained through boreholes, and only regarding vertical temperature profiles. Ground truth of the internal structure and the ice content is usually not available. In this contribution we will present a unique data set from a recently excavated rockglacier near Zermatt/Valais in the Swiss Alps, where an approximately 5 m deep trench was cut across the rockglacier body for the construction of a ski track. Longitudinal electrical resistivity tomography (ERT) and refraction seismic tomography profiles were conducted prior to the excavation, yielding data sets for cross validation of commonly applied geophysical interpretation approaches in the context of ground ice detection. A recently developed 4-phase model was applied to calculate ice-, air- and unfrozen water contents from the geophysical data sets, which were compared to the ground truth data from the excavated trench. The obtained data sets will be discussed in the context of currently established geophysical monitoring networks in permafrost areas. In addition to the

  3. OBSERVATIONAL EVIDENCE FOR DARK MATTER INTERACTING THROUGH A YUKAWA POTENTIAL

    SciTech Connect

    Chan, M. H.

    2013-05-20

    Recent observations in galaxies and clusters indicate that dark matter density profiles exhibit core-like structures which contradict the numerical simulation results of collisionless cold dark matter (CDM). On the other hand, it has been shown that CDM particles interacting through a Yukawa potential could naturally explain the cores in dwarf galaxies. In this Letter, I use the Yukawa potential interacting dark matter model to derive two simple scaling relations on the galactic and cluster scales, respectively, which give excellent agreements with observations. Also, in our model, the masses of the force carrier and dark matter particle can be constrained by the observational data.

  4. Morningside Pi2 Pulsation Observed in Space and on the Ground

    NASA Astrophysics Data System (ADS)

    Ghamry, Essam

    2015-12-01

    In this study, we examined a morningside Pi2 pulsation, with a non-substorm signature, that occurred in very quiet geomagnetic conditions (Kp = 0) at 05:38 UT on December 8, 2012, using data obtained by Van Allen Probes A and B (VAP-A and VAP-B, respectively) and at a ground station. Using 1 sec resolution vector magnetic field data, we measured the X-component of the pulsation from the Abu Simbel ground station (L = 1.07, LT = UT +2 hr, where LT represents local time) in Egypt. At the time of the Pi2 event, Abu Simbel and VAP-A (L = 3.3) were in the morning sector (07:38 LT and 07:59 MLT, respectively, where MLT represents magnetic local time), and VAP-B was in the postmidnight sector (04:18 MLT and L = 5.7). VAP-A and VAP-B observed oscillations in the compressional magnetic field component (Bz), which were in close agreement with the X-component measurements of the Pi2 pulsation that were made at Abu Simbel. The oscillations observed by the satellites and on the ground were in phase. Thus, we concluded that the observed morningside Pi2 pulsation was caused by the cavity resonance mode rather than by ionospheric current systems.

  5. TETRA observation of gamma-rays at ground level associated with nearby thunderstorms

    PubMed Central

    Ringuette, Rebecca; Case, Gary L; Cherry, Michael L; Granger, Douglas; Guzik, T Gregory; Stewart, Michael; Wefel, John P

    2013-01-01

    [1] Terrestrial gamma-ray flashes (TGFs)—very short, intense bursts of electrons, positrons, and energetic photons originating from terrestrial thunderstorms—have been detected with satellite instruments. TGF and Energetic Thunderstorm Rooftop Array (TETRA), an array of NaI(Tl) scintillators at Louisiana State University, has now been used to detect similar bursts of 50 keV to over 2 MeV gamma-rays at ground level. After 2.6 years of observation, 24 events with durations 0.02–4.2 ms have been detected associated with nearby lightning, three of them coincident events observed by detectors separated by ∼1000 m. Nine of the events occurred within 6 ms and 5 km of negative polarity cloud-to-ground lightning strokes with measured currents in excess of 20 kA. The events reported here constitute the first catalog of TGFs observed at ground level in close proximity to the acceleration site. PMID:26167428

  6. Magnetospheric Response to Interplanetary Field Enhancements: Coordinated Space-based and Ground-based Observations

    NASA Astrophysics Data System (ADS)

    Chi, Peter; Russell, Christopher; Lai, Hairong

    2014-05-01

    In general, asteroids, meteoroids and dust do not interact with the plasma structures in the solar system, but after a collision between fast moving bodies the debris cloud contains nanoscale dust particles that are charged and behave like heavy ions. Dusty magnetic clouds are then accelerated to the solar wind speed. While they pose no threat to spacecraft because of the particle size, the coherency imposed by the magnetization of the cloud allows the cloud to interact with the Earth's magnetosphere as well as the plasma in the immediate vicinity of the cloud. We call these clouds Interplanetary Field Enhancements (IFEs). These IFEs are a unique class of interplanetary field structures that feature cusp-shaped increases and decreases in the interplanetary magnetic field and a thin current sheet. The occurrence of IFEs is attributed to the interaction between the solar wind and dust particles produced in inter-bolide collisions. Previous spacecraft observations have confirmed that IFEs move with the solar wind. When IFEs strike the magnetosphere, they may distort the magnetosphere in several possible ways, such as producing a small indentation, a large scale compression, or a glancing blow. In any event if the IFE is slowed by the magnetosphere, the compression of the Earth's field should be seen in the ground-based magnetic records that are continuously recorded. Thus it is important to understand the magnetospheric response to IFE arrival. In this study, we investigate the IFE structure observed by spacecraft upstream of the magnetosphere and the induced magnetic field perturbations observed by networks of ground magnetometers, including the THEMIS, CARISMA, McMAC arrays in North America and the IMAGE array in Europe. We find that, in a well-observed IFE event on December 24, 2006, all ground magnetometer stations observed an impulse at approximately 1217 UT when the IFE was expected to arrive at the Earth's magnetopause. These ground stations spread across many

  7. Towards a critical design of an operational ground segment for an Earth observation mission

    NASA Astrophysics Data System (ADS)

    Storch, Tobias; Habermeyer, Martin; Eberle, Sabrina; Mühle, Helmut; Müller, Rupert

    2013-01-01

    The ground segment for the future remote sensing mission Environmental Mapping and Analysis Program (EnMAP; www.enmap.org) is developed by the Earth Observation Center and the German Space Operations Center at the German Aerospace Center. The launch is scheduled for 2017. An operational satellite ground segment is a highly complex heterogeneous system which has to cope with different levels of criticality, novelty, specificity, and to be operated for many years. It consists of equipment, hard- and software as well as operators with their procedures. The strengths of the global coherence of the segment-wide approach bringing these aspects together is examined and not on the local details of segment-specific issues. However, the effects on two software-based elements of the ground segment are considered in more detail, namely the product library and the level 2geo processor. The development methodology and how the critical design of the complete ground segment finished its detailed design phase successfully was achieved is analyzed. As a measure of the maturity of the design, its stability across the project phases is proposed.

  8. Proving Ground Potential Mission and Flight Test Objectives and Near Term Architectures

    NASA Technical Reports Server (NTRS)

    Smith, R. Marshall; Craig, Douglas A.; Lopez, Pedro Jr.

    2016-01-01

    NASA is developing a Pioneering Space Strategy to expand human and robotic presence further into the solar system, not just to explore and visit, but to stay. NASA's strategy is designed to meet technical and non-technical challenges, leverage current and near-term activities, and lead to a future where humans can work, learn, operate, and thrive safely in space for an extended, and eventually indefinite, period of time. An important aspect of this strategy is the implementation of proving ground activities needed to ensure confidence in both Mars systems and deep space operations prior to embarking on the journey to the Mars. As part of the proving ground development, NASA is assessing potential mission concepts that could validate the required capabilities needed to expand human presence into the solar system. The first step identified in the proving ground is to establish human presence in the cis-lunar vicinity to enable development and testing of systems and operations required to land humans on Mars and to reach other deep space destinations. These capabilities may also be leveraged to support potential commercial and international objectives for Lunar Surface missions. This paper will discuss a series of potential proving ground mission and flight test objectives that support NASA's journey to Mars and can be leveraged for commercial and international goals. The paper will discuss how early missions will begin to satisfy these objectives, including extensibility and applicability to Mars. The initial capability provided by the launch vehicle will be described as well as planned upgrades required to support longer and more complex missions. Potential architectures and mission concepts will be examined as options to satisfy proving ground objectives. In addition, these architectures will be assessed on commercial and international participation opportunities and on how well they develop capabilities and operations applicable to Mars vicinity missions.

  9. Ground-based Transit Observations of the Super-Earth 55 Cnc e

    NASA Astrophysics Data System (ADS)

    de Mooij, E. J. W.; López-Morales, M.; Karjalainen, R.; Hrudkova, M.; Jayawardhana, Ray

    2014-12-01

    We report the first ground-based detections of the shallow transit of the super-Earth exoplanet 55 Cnc e using a 2 m class telescope. Using differential spectrophotometry, we observed one transit in 2013 and another in 2014, with average spectral resolutions of ~700 and ~250, spanning the Johnson BVR photometric bands. We find a white light planet-to-star radius ratio of 0.0190-0.0027+0.0023 from the 2013 observations and 0.0200-0.0018+0.0017 from the 2014 observations. The two data sets combined result in a radius ratio of 0.0198-0.0014+0.0013. These values are all in agreement with previous space-based results. Scintillation noise in the data prevents us from placing strong constraints on the presence of an extended hydrogen-rich atmosphere. Nevertheless, our detections of 55 Cnc e in transit demonstrate that moderate-sized telescopes on the ground will be capable of routine follow-up observations of super-Earth candidates discovered by the Transiting Exoplanet Survey Satellite around bright stars. We expect it also will be possible to place constraints on the atmospheric characteristics of those planets by devising observational strategies to minimize scintillation noise.

  10. GROUND-BASED TRANSIT OBSERVATIONS OF THE SUPER-EARTH 55 Cnc e

    SciTech Connect

    De Mooij, E. J. W.; López-Morales, M.; Karjalainen, R.; Hrudkova, M.; Jayawardhana, Ray

    2014-12-20

    We report the first ground-based detections of the shallow transit of the super-Earth exoplanet 55 Cnc e using a 2 m class telescope. Using differential spectrophotometry, we observed one transit in 2013 and another in 2014, with average spectral resolutions of ∼700 and ∼250, spanning the Johnson BVR photometric bands. We find a white light planet-to-star radius ratio of 0.0190{sub −0.0027}{sup +0.0023} from the 2013 observations and 0.0200{sub −0.0018}{sup +0.0017} from the 2014 observations. The two data sets combined result in a radius ratio of 0.0198{sub −0.0014}{sup +0.0013}. These values are all in agreement with previous space-based results. Scintillation noise in the data prevents us from placing strong constraints on the presence of an extended hydrogen-rich atmosphere. Nevertheless, our detections of 55 Cnc e in transit demonstrate that moderate-sized telescopes on the ground will be capable of routine follow-up observations of super-Earth candidates discovered by the Transiting Exoplanet Survey Satellite around bright stars. We expect it also will be possible to place constraints on the atmospheric characteristics of those planets by devising observational strategies to minimize scintillation noise.

  11. Validation of SCIAMACHY Radiances and Ozone Products Using Ground and Space Observations

    NASA Technical Reports Server (NTRS)

    Hilsenrath, E.; Bhartia, P. K.; Bojkov, B. R.; Kowalewski, M.; Labow, G.; Ahmad, Z.

    2004-01-01

    Validation of SCIAMACHY data products are is key element for the detecting a stratospheric ozone recovery, which is a high priority for environmental research and environmental policy. Models predict an ozone recovery at a much lower rate than the measured depletion rate observed to date. Therefore improved precision of the satellite and ground ozone observing systems are required over the long term to verify its recovery. We show that validation of satellite radiances from space and from the ground can be an effective means for correcting long term drifts of backscatter type satellite measurements such as SCIAMACHY and can be used to cross calibrate all BUV instruments in orbit (TOMS, SBUV/2, GOME, OMI, GOME-2, OMPS). This method bypasses the retrieval algorithms used for both satellite and ground based measurements that are normally used to validate and correct the satellite data. This approach however requires well calibrated instruments and an accurate radiative transfer model that accounts for aerosols. In addition to comparing radiances, validation of SCIAMACHY ozone products will conducted by comparing total and profile ozone with TOMS and SBUV/2.

  12. Comparisons of CH4 ground-based FTIR measurements near Saint Petersburg with GOSAT observations

    NASA Astrophysics Data System (ADS)

    Gavrilov, N. M.; Makarova, M. V.; Poberovskii, A. V.; Timofeyev, Yu. M.

    2014-04-01

    Atmospheric column-average methane mole fractions measured with ground-based Fourier-transform spectroscopy near Saint Petersburg, Russia (59.9° N, 29.8° E, 20 m a.s.l.) are compared with similar data obtained with the Japanese GOSAT (Greenhouse gases Observing SATellite) in the years 2009-2012. Average CH4 mole fractions for the GOSAT data version V01.xx are -15.0 ± 5.4 ppb less than the corresponding values obtained from ground-based measurements (with the standard deviations of biases at 13.0 ± 4.2 ppb). For the GOSAT data version V02.xx, the average values of the differences are -1.9 ± 1.8 ppb with standard deviations of 14.5 ± 1.3 ppb. This verifies that FTIR (Fourier transform infrared) spectroscopic observations near Saint Petersburg have similar biases with GOSAT satellite data as FTIR measurements at other ground-based networks and aircraft CH4 estimations.

  13. Tropospheric nitrogen dioxide column retrieval from ground-based zenith-sky DOAS observations

    NASA Astrophysics Data System (ADS)

    Tack, F.; Hendrick, F.; Goutail, F.; Fayt, C.; Merlaud, A.; Pinardi, G.; Hermans, C.; Pommereau, J.-P.; Van Roozendael, M.

    2015-06-01

    We present an algorithm for retrieving tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) from ground-based zenith-sky (ZS) measurements of scattered sunlight. The method is based on a four-step approach consisting of (1) the differential optical absorption spectroscopy (DOAS) analysis of ZS radiance spectra using a fixed reference spectrum corresponding to low NO2 absorption, (2) the determination of the residual amount in the reference spectrum using a Langley-plot-type method, (3) the removal of the stratospheric content from the daytime total measured slant column based on stratospheric VCDs measured at sunrise and sunset, and simulation of the rapid NO2 diurnal variation, (4) the retrieval of tropospheric VCDs by dividing the resulting tropospheric slant columns by appropriate air mass factors (AMFs). These steps are fully characterized and recommendations are given for each of them. The retrieval algorithm is applied on a ZS data set acquired with a multi-axis (MAX-) DOAS instrument during the Cabauw (51.97° N, 4.93° E, sea level) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI) held from 10 June to 21 July 2009 in the Netherlands. A median value of 7.9 × 1015 molec cm-2 is found for the retrieved tropospheric NO2 VCDs, with maxima up to 6.0 × 1016 molec cm-2. The error budget assessment indicates that the overall error σTVCD on the column values is less than 28%. In the case of low tropospheric contribution, σTVCD is estimated to be around 39% and is dominated by uncertainties in the determination of the residual amount in the reference spectrum. For strong tropospheric pollution events, σTVCD drops to approximately 22% with the largest uncertainties on the determination of the stratospheric NO2 abundance and tropospheric AMFs. The tropospheric VCD amounts derived from ZS observations are compared to VCDs retrieved from off-axis and direct-sun measurements of the same MAX-DOAS instrument as well as to data

  14. Tropospheric nitrogen dioxide column retrieval from ground-based zenith-sky DOAS observations

    NASA Astrophysics Data System (ADS)

    Tack, F.; Hendrick, F.; Goutail, F.; Fayt, C.; Merlaud, A.; Pinardi, G.; Hermans, C.; Pommereau, J.-P.; Van Roozendael, M.

    2015-01-01

    We present an algorithm for retrieving tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) from ground-based zenith-sky (ZS) measurements of scattered sunlight. The method is based on a four-step approach consisting of (1) the Differential Optical Absorption Spectroscopy (DOAS) analysis of ZS radiance spectra using a fixed reference spectrum corresponding to low NO2 absorption, (2) the determination of the residual amount in the reference spectrum using a Langley-plot-type method, (3) the removal of the stratospheric content from the daytime total measured slant column based on stratospheric VCDs measured at sunrise and sunset, and simulation of the rapid NO2 diurnal variation, (4) the retrieval of tropospheric VCDs by dividing the resulting tropospheric slant columns by appropriate air mass factors (AMFs). These steps are fully characterized and recommendations are given for each of them. The retrieval algorithm is applied on a ZS dataset acquired with a Multi-AXis (MAX-) DOAS instrument during the Cabauw (51.97° N, 4.93° E, sea level) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI) held from the 10 June to the 21 July 2009 in the Netherlands. A median value of 7.9 × 1015 molec cm-2 is found for the retrieved tropospheric NO2 VCDs, with maxima up to 6.0 × 1016 molec cm-2. The error budget assessment indicates that the overall error σTVCD on the column values is less than 28%. In case of low tropospheric contribution, σTVCD is estimated to be around 39% and is dominated by uncertainties in the determination of the residual amount in the reference spectrum. For strong tropospheric pollution events, σTVCD drops to approximately 22% with the largest uncertainties on the determination of the stratospheric NO2 abundance and tropospheric AMFs. The tropospheric VCD amounts derived from ZS observations are compared to VCDs retrieved from off-axis and direct-sun measurements of the same MAX-DOAS instrument as well as to

  15. Grounded or submerged bulk carrier: the potential for leaching of coal trace elements to seawater.

    PubMed

    Lucas, Steven Andrew; Planner, John

    2012-05-01

    This study investigates the potential for leaching of coal trace elements to seawater from a grounded bulk carrier. The coal type and ecological scenario was based on the grounding of the "Shen Neng" (April 2010) at Douglas Shoal located within the Great Barrier Reef (Queensland, Australia). The area is of high ecological value and the Queensland Water Quality Guidelines (2009) provided threshold limits to interpret potential impacts. Coal contains many trace elements that are of major and moderate concern to human health and the environment although many of these concerns are only realised when coal is combusted. However, "unburnt" coal contains trace elements that may be leached to natural waterways and few studies have investigated the potential ecological impact of such an occurrence. For example, coal maritime transport has increased by almost 35% over the last five reported years (Jaffrennou et al., 2007) and as a result there is an increased inherent risk of bulk carrier accidents. Upon grounding or becoming submerged, coal within a bulk carrier may become saturated with seawater and potentially leach trace elements to the environment and impact on water quality and ecological resilience. The worst case scenario is the breakup of a bulk carrier and dispersal of cargo to the seafloor. PMID:22417390

  16. Locating potential biosignatures on Europa from surface geology observations.

    PubMed

    Figueredo, Patricio H; Greeley, Ronald; Neuer, Susanne; Irwin, Louis; Schulze-Makuch, Dirk

    2003-01-01

    We evaluated the astrobiological potential of the major classes of geologic units on Europa with respect to possible biosignatures preservation on the basis of surface geology observations. These observations are independent of any formational model and therefore provide an objective, though preliminary, evaluation. The assessment criteria include high mobility of material, surface concentration of non-ice components, relative youth, textural roughness, and environmental stability. Our review determined that, as feature classes, low-albedo smooth plains, smooth bands, and chaos hold the highest potential, primarily because of their relative young age, the emplacement of low-viscosity material, and indications of material exchange with the subsurface. Some lineaments and impact craters may be promising sites for closer study despite the comparatively lower astrobiological potential of their classes. This assessment will be expanded by multidisciplinary examination of the potential for habitability of specific features.

  17. Combined Characterisation of GOME and TOMS Total Ozone Using Ground-Based Observations from the NDSC

    NASA Technical Reports Server (NTRS)

    Lambert, J.-C.; VanRoozendael, M.; Simon, P. C.; Pommereau, J.-P.; Goutail, F.; Andersen, S. B.; Arlander, D. W.; BuiVan, N. A.; Claude, H.; deLaNoee, J.; DeMaziere, M.; Dorokhov, V.; Eriksen, P.; Gleason, J. F.; Tornkvist, K. Karlsen; Hoiskar, B. A. Kastad; Kyroe, E.; Leveau, J.; Merienne, M.-F.; Milinevsky, G.

    1998-01-01

    Several years of total ozone measured from space by the ERS-2 GOME, the Earth Probe Total Ozone Mapping Spectrometer (TOMS), and the ADEOS TOMS, are compared with high-quality ground-based observations associated with the Network for the Detection of Stratospheric Change (NDSC), over an extended latitude range and a variety of geophysical conditions. The comparisons with each spaceborne sensor are combined altogether for investigating their respective solar zenith angle (SZA) dependence, dispersion, and difference of sensitivity. The space- and ground-based data are found to agree within a few percent on average. However, the analysis highlights for both Global Ozone Monitoring Experiment (GOME) and TOMS several sources of discrepancies, including a dependence on the SZA at high latitudes and internal inconsistencies.

  18. The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets.

    PubMed

    Cooper, Scott T; Richters, Karl E; Melin, Travis E; Liu, Zhi-jian; Hordyk, Peter J; Benrud, Ryan R; Geiser, Lauren R; Cash, Steve E; Simon Shelley, C; Howard, David R; Ereth, Mark H; Sola-Visner, Martha C

    2012-05-15

    Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.

  19. GROUND-BASED MULTISITE OBSERVATIONS OF TWO TRANSITS OF HD 80606b

    SciTech Connect

    Shporer, A.; Winn, J. N.; Dreizler, S.; Colon, K. D.; Wood-Vasey, W. M.; Cerutti, S.; Coban, L.; Costello, K.; Choi, P. I.; Morley, C.; Adams, E.; Moutou, C.; Welsh, W. F.; Pollaco, D.; Barros, S. C. C.; Starkey, D.; Bouchy, F.; DIaz, R. F.; Cabrera-Lavers, A.; Deeg, H.

    2010-10-10

    We present ground-based optical observations of the 2009 September and 2010 January transits of HD 80606b. Based on three partial light curves of the 2009 September event, we derive a midtransit time of T{sub c} [HJD] = 2455099.196 {+-} 0.026, which is about 1{sigma} away from the previously predicted time. We observed the 2010 January event from nine different locations, with most phases of the transit being observed by at least three different teams. We determine a midtransit time of T{sub c} [HJD] = 2455210.6502 {+-} 0.0064, which is within 1.3{sigma} of the time derived from a Spitzer observation of the same event.

  20. Observations and Modeling of Grounding Line Basal Crevasses: Connections between Surface Speed, Topography and Crevasse Morphology

    NASA Astrophysics Data System (ADS)

    Logan, L.; Catania, G.; Lavier, L. L.

    2011-12-01

    We analyze several lines of ground-penetrating radar acquired across the grounding line in the Siple Coast region of Antarctica (Catania et al., 2006) which reveal characteristic diffraction hyperbolae commonly believed to be bottom-crevasses. We show that bottom-crevasses forming in different ice thicknesses and with different material in-fill produce almost identical diffraction hyperbolae. That is, diffraction hyperbolae seen in our profiles likely result from a geometrically non-unique set of bottom-crevasses at the groundling lines of Kamb (KIS) and Whillans Ice Streams (WIS), and Siple Dome (SDM). Further, we observe a Poisson-type distribution in crevasse spacing with mean crevasse spacing for SDM, KIS, and WIS of 363 m, 488 m, and 1387 m, respectively. These measurements correlate positively with ice speed. There is no obvious relationship between crevasse height and ice velocity. There is a weak negative correlation between crevasse penetration height and distance from the grounding line. Finally, we note the presence of undulating topographic features aligned with the bottom crevasses of KIS, and suggest their connection to the formation of corresponding bottom crevasses. We use these observations to model the formation of a single bottom crevasse at the grounding line in a finite-difference Lagrangian mesh with viscoplastic rheology (FLAC). We show that the modeled bottom crevasse provides sufficient material weakening in our viscoplastic ice to account for the accompanying topographic depression. Thus we attribute the topographic features seen on KIS to plastic necking as modeled in FLAC, and suggest that their entire expression results from an unknown non-linear interaction between fracture and associated plastic yielding in ice.

  1. Ground Truthing Orbital Clay Mineral Observations with the APXS Onboard Mars Exploration Rover Opportunity

    NASA Technical Reports Server (NTRS)

    Schroeder, C.; Gellert, R.; VanBommel, S.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. S.; Yen, A. S.

    2016-01-01

    NASA's Mars Exploration Rover Opportunity has been exploring approximately 22 km diameter Endeavour crater since 2011. Its rim segments predate the Hesperian-age Burns formation and expose Noachian-age material, which is associated with orbital Fe3+-Mg-rich clay mineral observations [1,2]. Moving to an orders of magnitude smaller instrumental field of view on the ground, the clay minerals were challenging to pinpoint on the basis of geochemical data because they appear to be the result of near-isochemical weathering of the local bedrock [3,4]. However, the APXS revealed a more complex mineral story as fracture fills and so-called red zones appear to contain more Al-rich clay minerals [5,6], which had not been observed from orbit. These observations are important to constrain clay mineral formation processes. More detail will be added as Opportunity is heading into her 10th extended mission, during which she will investigate Noachian bedrock that predates Endeavour crater, study sedimentary rocks inside Endeavour crater, and explore a fluid-carved gully. ESA's ExoMars rover will land on Noachian-age Oxia Planum where abundant Fe3+-Mg-rich clay minerals have been observed from orbit, but the story will undoubtedly become more complex once seen from the ground.

  2. Understanding the Longitudinal Variability of Equatorial Electrodynamics using integrated Ground- and Space-based Observations

    NASA Astrophysics Data System (ADS)

    Yizengaw, E.; Moldwin, M.; Zesta, E.

    2015-12-01

    The currently funded African Meridian B-Field Education and Research (AMBER) magnetometer array comprises more than thirteen magnetometers stationed globally in the vicinity of geomagnetic equator. One of the main objectives of AMBER network is to understand the longitudinal variability of equatorial electrodynamics as function of local time, magnetic activity, and season. While providing complete meridian observation in the region and filling the largest land-based gap in global magnetometer coverage, the AMBER array addresses two fundamental areas of space physics: first, the processes governing electrodynamics of the equatorial ionosphere as a function of latitude (or L-shell), local time, longitude, magnetic activity, and season, and second, ULF pulsation strength at low/mid-latitude regions and its connection with equatorial electrojet and density fluctuation. The global AMBER network can also be used to augment observations from space-based instruments, such us the triplet SWARM mission and the upcoming ICON missions. Thus, in coordination with space-based and other ground-based observations, the AMBER magnetometer network provides a great opportunity to understand the electrodynamics that governs equatorial ionosphere motions. In this paper we present the longitudinal variability of the equatorial electrodynamics using the combination of instruments onboard SWARM and C/NOFS satellites and ground-based AMBER network. Both ground- and pace-based observations show stronger dayside and evening sector equatorial electrodynamics in the American and Asian sectors compared to the African sector. On the other hand, the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This raises the question if the evening sector equatorial electrodynamics (vertical drift), which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the

  3. Ground-Based Observational Support for Spacecraft Exploration of the Outer Planets

    NASA Astrophysics Data System (ADS)

    Orton, Glenn S.

    2009-09-01

    This report presents both a retrospective of ground-based support for spacecraft missions to the outer solar system and a perspective of support for future missions. Past support is reviewed in a series of case studies involving the author. The most basic support is essential, providing the mission with information without which the planned science would not have been accomplished. Another is critical, without which science would have been returned, but missing a key element in its understanding. Some observations are enabling by accomplishing one aspect of an experiment which would otherwise not have been possible. Other observations provide a perspective of the planet as a whole which is not available to instruments with narrow fields of view and limited spatial coverage, sometimes motivating a re-prioritizing of experiment objectives. Ground-based support is also capable of providing spectral coverage not present in the complement of spacecraft instruments. Earth-based observations also have the capability of filling in gaps of spacecraft coverage of atmospheric phenomena, as well as providing surveillance of longer-term behavior than the coverage available to the mission. Future missions benefiting from ground-based support would include the Juno mission to Jupiter in the next decade, a flagship-class mission to the Jupiter or to the Saturn systems currently under consideration, and possible intermediate-class missions which might be proposed in NASA’s New Frontiers category. One of the principal benefits of future 30 m-class giant telescopes would be to improve the spatial resolution of maps of temperature and composition which are derived from observations of thermal emission at mid-infrared and longer wavelengths. In many situations, this spatial resolution is competitive with those of the relevant instruments on the spacecraft themselves.

  4. Ground-Based Network and Supersite Observations to Complement and Enrich EOS Research

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee; Holben, Brent N.; Welton, Ellsworth J.

    2011-01-01

    Since 1997 NASA has been successfully launching a series of satellites - the Earth Observing System (EOS) - to intensively study, and gain a better understanding of, the Earth as an integrated system. Space-borne remote sensing observations, however, are often plagued by contamination of surface signatures. Thus, ground-based in-situ and remote-sensing measurements, where signals come directly from atmospheric constituents, the sun, and/or the Earth-atmosphere interactions, provide additional information content for comparisons that confirm quantitatively the usefulness of the integrated surface, aircraft, and satellite datasets. Through numerous participations, particularly but not limited to the EOS remote-sensing/retrieval and validation projects over the years, NASA/GSFC has developed and continuously refined ground-based networks and mobile observatories that proved to be vital in providing high temporal measurements, which complement and enrich the satellite observations. These are: the AERO NET (AErosol RObotic NETwork) a federation of ground-based globally distributed network of spectral sun-sky photometers; the MPLNET (Micro-Pulse Lidar NETwork, a similarly organized network of micro-pulse lidar systems measuring aerosol and cloud vertical structure continuously; and the SMART-COMMIT (Surface-sensing Measurements for Atmospheric Radiative Transfer - Chemical, Optical & Microphysical Measurements of In-situ Troposphere, mobile observatories, a suite of spectral radiometers and in-situ probes acquiring supersite measurements. Most MPLNET sites are collocated with those of AERONET, and both networks always support the deployment of SMART-COMMIT worldwide. These data products follow the data structure of EOS conventions: Level-0, instrument archived raw data; Level-1 (or 1.5), real-time data with no (or limited) quality assurance; Level-2, not real high temporal and spectral resolutions. In this talk, we will present NASA/GSFC groundbased facilities, serving

  5. Comparison of Thermal Structure Results from Venus Express and Ground Based Observations since Vira

    NASA Astrophysics Data System (ADS)

    Limaye, Sanjay

    2016-07-01

    An international team was formed in 2013 through the International Space Studies Institute (Bern, Switzerland) to compare recent results of the Venus atmospheric thermal structure from spacecraft and ground based observations made since the Venus International Reference Atmosphere (VIRA) was developed (Kliore et al., 1985, Keating et al., 1985). Five experiments on European Space Agency's Venus Express orbiter mission have yielded results on the atmospheric structure during is operational life (April 2006 - November 2014). Three of these were from occultation methods: at near infrared wavelengths from solar occultations, (SOIR, 70 - 170 km), at ultraviolet wavelengths from stellar occultations (SPICAV, 90-140 km), and occultation of the VEx-Earth radio signal (VeRa, 40-90 km). In-situ drag measurements from three different techniques (accelerometry, torque, and radio tracking, 130 - 200 km) were also obtained using the spacecraft itself while passive infrared remote sensing was used by the VIRTIS experiment (70 - 120 km). The only new data in the -40-70 km altitude range are from radio occultation, as no new profiles of the deep atmosphere have been obtained since the VeGa 2 lander measurements in 1985 (not included in VIRA). Some selected ground based results available to the team were also considered by team in the inter comparisons. The temperature structure in the lower thermosphere from disk resolved ground based observations (except for one ground based investigation), is generally consistent with the Venus Express results. These experiments sampled at different periods, at different locations and at different local times and have different vertical and horizontal resolution and coverage. The data were therefore binned in latitude and local time bins and compared, ignoring temporal variations over the life time of the Venus Express mission and assumed north-south symmetry. Alternating warm and cooler layers are present in the 120-160 altitude range in results

  6. The response of a ground-based antenna to variations of ionospheric potential

    NASA Astrophysics Data System (ADS)

    Tammet, Kh. F.

    Analytical and numerical models are used to study the response of a ground-based atmospheric electric antenna to ionospheric potential variations. The three-term Schweidler-Gish formula is used to describe the vertical profile of conductivity. It is shown that the different inertia of the volume discharge redistribution in the vertical column can lead to a phase shift between the two antenna signals.

  7. Coupling between tsunamis and ionosphere: ground-based and space-based observation opportunities

    NASA Astrophysics Data System (ADS)

    Coisson, Pierdavide; Makela, Jonathan J.; Occhipinti, Giovanni; Astafyeva, Elvira; alam Kherani, Esfhan; Lognonne, Philippe

    2012-07-01

    Large scale phenomena as tsunamis propagating through the ocean excite gravity waves that can reach ionospheric heights. The coupling between the ground/ocean and the atmosphere up to the ionosphere opens the possibility to observe in the upper atmosphere the effects of the propagation of tsunamis. During all recent major tsunami events ionospheric waves have been observed by ground GPS networks, satellite altimeters and, recently, also by an airglow imager. During the tsunami event of 11 March 2011 an all-sky camera in Hawaii observes the Internal Gravity Waves (IGW) during about one-and-a-half hours before the arrival of the, while it was crossing the Pacific Ocean in that region. Collocated ionospheric measurements were also done with GNSS sounding and Jason satellite. We present results of assessment studies of ground-based and space-based ionospheric remote sensing for tsunami propagation monitoring. We analyze the cases of airglow imager, Over-The-Horizon (OTH) radar, GPS, radio occultation and GNSS reflectometry. We describe modeling results of IGW excited by a realistic tsunami propagation model through the ocean near Hawaii. The model includes the propagation of the gravity wave in the atmosphere, the coupling between neutral and charged particles in the ionosphere and the production of the airglow emission at 630.0 nm. Synthetic all-sky images are calculated by integration of the emission along rays from the camera location to though the airglow layer. Additional ground-based observations could be provided by (OTH) radars, which operate in High Frequency (HF) band and can be used to monitor the bottomside ionosphere. Synthetic radar measurements computed using HF numerical ray-tracing confirm the possibility to detect IGW excited by tsunamis. The large coverage of OTH radar and its sensitivity to low-altitude plasma anomalies provides a wide range of observation. Additionally, we analyze the capabilities of space-based radio occultation and GNSS

  8. Coordinated Ground-Based Observations and the New Horizons Fly-by of Pluto

    NASA Astrophysics Data System (ADS)

    Young, Eliot; Young, Leslie; Parker, Joel; Binzel, Richard

    2015-04-01

    The New Horizons (NH) spacecraft is scheduled to make its closest approach to Pluto on July 14, 2015. NH carries seven scientific instruments, including separate UV and Visible-IR spectrographs, a long-focal-length imager, two plasma-sensing instruments and a dust counter. There are three arenas in particular in which ground-based observations should augment the NH instrument suite in synergistic ways: IR spectra at wavelengths longer than 2.5 µm (i.e., longer than the NH Ralph spectrograph), stellar occultation observations near the time of the fly-by, and thermal surface maps and atmospheric CO abundances based on ALMA observations - we discuss the first two of these. IR spectra in the 3 - 5 µm range cover the CH4 absorption band near 3.3 µm. This band can be an important constraint on the state and areal extent of nitrogen frost on Pluto's surface. If this band depth is close to zero (as was observed by Olkin et al. 2007), it limits the area of nitrogen frost, which is bright at that wavelength. Combined with the NH observations of nitrogen frost at 2.15 µm, the ground-based spectra will determine how much nitrogen frost is diluted with methane, which is a basic constraint on the seasonal cycle of sublimation and condensation that takes place on Pluto (and similar objects like Triton and Eris). There is a fortuitous stellar occultation by Pluto on 29-JUN-2015, only two weeks before the NH closest approach. The occulted star will be the brightest ever observed in a Pluto event, about 2 magnitudes brighter than Pluto itself. The track of the event is predicted to cover parts of Australia and New Zealand. Thanks to HST and ground based campaigns to find a TNO target reachable by NH, the position of the shadow path will be known at the +/-100 km level, allowing SOFIA and mobile ground-based observers to reliably cover the central flash region. Ground-based & SOFIA observations in visible and IR wavelengths will characterize the haze opacity and vertical

  9. The dynamics of the plasmasphere boundary layer as determined by ground magnetometers, satellite observations, and modeling

    NASA Astrophysics Data System (ADS)

    Zesta, E.; Boudouridis, A.; Yizengaw, E.; Jorgensen, A. M.; Carranza-fulmer, T. L.; Moldwin, M.; Mann, I. R.; Chi, P. J.

    2013-12-01

    The plasmasphere boundary layer (PBL) separates the cold and dense plasmaspheric plasma from the more tenuous and hot plasma sheet plasma and organizes the spatial distribution of ULF and VLF waves that can contribute to acceleration or loss processes of radiation belt particles through wave-particle interactions. The PBL has been traditionally determined by in situ observations and can be given by empirical models. Recent work has shown that a mid-latitude chain of well-spaced ground magnetometers can also determine the PBL location. Spectral properties, like the cross-phase reversal in the standard field-line resonance (FLR) determination between two stations closely aligned in latitude, have been shown to indicate the presence of a sharp PBL. We merge data from many ground magnetometer pairs from the SAMBA (South American Meridional B-field Array), McMAC (Mid continent Magnetoseismic Chain), and CARISMA (Canadian Array for Realtime Investigations of Magnetic Activity) chains to provide the best available spatial coverage in L values spanning the plasmasphere and PBL, for a range of dynamic states (L=1.6 to greater than 5). The PBL location is identified as the L value of the station pair for which a reverse phase difference is observed in the standard FLR determination. We compare the FLR determined PBL with the trough boundary determined by GPS Total Electron Content (TEC) analysis and with model PBL. Initial results demonstrate that the PBL as identified by the reverse phase differences is in general agreement with TEC identifications and reasonable agreement with models. Reverse Phase Differences are regularly observed at the L range of 2.7 to 3.7 and are highly correlated with Dst and Kp, as determined by daily correlations. We further examine the more detailed time sequence of the PBL dynamics by focusing on key periods around storms preceded by quiet periods, and by using the full L range of the ground magnetometer pairs.

  10. Multi-wavelength Solar Flare Observations with Ground- and Space-based Observatories

    NASA Astrophysics Data System (ADS)

    Kleint, Lucia

    2016-07-01

    Solar flares affect a wide range of atmospheric heights from the corona to the photosphere. Solar instruments are generally designed for high-resolution observations in limited spectral windows and therefore only capture part of the flare. To obtain a more complete flare picture from coronal reconnection to the atmospheric response of the chromosphere and photosphere, it is necessary to combine data from multiple instruments. I will review multi-wavelength flare observations with ground- and space-based observatories. By taking the X1 flare on March 29, 2014 as an example, which was observed with an unprecedented number of telescopes, I will demonstrate how to investigate the origin of the flare by looking at a filament eruption, the chromospheric evaporation by means of spectroscopy, the flare heating by analyzing continuum emission, and the changes of chromospheric magnetic fields using polarimetric data.

  11. Hydrogen production rates from ground-based Fabry-Perot observations of comet Kohoutek

    NASA Technical Reports Server (NTRS)

    Scherb, F.

    1981-01-01

    The only ground-based observations of a cometary hydrogen corona that have been obtained up to the present were carried out during the appearance of comet Kohoutek (1973 XII). Hydrogen Balmer alpha (H-alpha) emission from the gas cloud surrounding the comet was detected using a Fabry-Perot spectrometer at Kitt Peak National Observatory. These observations have been reexamined using (1) recently obtained solar full-disk Lyman beta emission line profiles, (2) a new calibration of the absolute sensitivity of the Fabry-Perot spectrometer based on comparison of NGC 7000 with standard stars and the planetary nebula NGC 7662, and (3) corrections for atmospheric extinction instead of the geocoronal H-alpha comparison method used previously to obtain comet H-alpha intensities. The new values for hydrogen production rates are in good agreement with results obtained from Lyman alpha observations of comet Kohoutek.

  12. Space-born and ground-based observations of a solar active region and a flare

    NASA Astrophysics Data System (ADS)

    Chiuderi Drago, F.

    Observational data of the active solar region AR 2490 are discussed with an eye to underlying physical processes. Ground- and spaceborne measurements were made by radio, optical, and XUV instrumentation. A double structure observed at 6 and 20 cm wavelengths was overlying a sunspot group which displayed north polarity. The 6 cm emission was attributed to free-free emission, while the 20 cm feature was thought to be caused by gyroresonance absorption. An analytical formulation was developed which described the thermal component for maximum X ray intensities. A flare observed on June 10, 1980 was detected on H-alpha and C IV spectrographic bands. The origin of the emissions was fixed at the two feet of the X ray loop, with a radio emission coming from the top of the loop.

  13. First Ground-based Observation of Transient Luminous Events over Southern Africa

    NASA Astrophysics Data System (ADS)

    Nnadih, Ogechukwu; Kosch, Michael; Martinez, Peter

    2016-07-01

    We present the first ground-based observations in southern Africa of Transient Luminous Events (TLEs) in the summer of 2015/16 over convective thunderstorms. For the months of December to February, South Africa has one of the highest lightning stroke rates in the world. This was part of the AfriSprite campaign initiated by the South African National Space Agency. These observations show a variety of fine structures such as tree-like shaped, carrot, angel and jellyfish-shaped sprites. The South African Weather Service array of VLF receivers is used to locate and quantify the magnitude and polarity of the lightning strikes associated with TLEs. We plan to make bi-static as well as multi-wavelength observations in future.

  14. Central role of the observable electric potential in transport equations.

    PubMed

    Garrido, J; Compañ, V; López, M L

    2001-07-01

    Nonequilibrium systems are usually studied in the framework of transport equations that involve the true electric potential (TEP), a nonobservable variable. Nevertheless another electric potential, the observable electric potential (OEP), may be defined to construct a useful set of transport equations. In this paper several basic characteristics of the OEP are deduced and emphasized: (i) the OEP distribution depends on thermodynamic state of the solution, (ii) the observable equations have a reference value for all other transport equations, (iii) the bridge that connects the OEP with a certain TEP is usually defined by the ion activity coefficient, (iv) the electric charge density is a nonobservable variable, and (v) the OEP formulation constitutes a natural model for studying the fluxes in membrane systems. PMID:11461346

  15. Central role of the observable electric potential in transport equations.

    PubMed

    Garrido, J; Compañ, V; López, M L

    2001-07-01

    Nonequilibrium systems are usually studied in the framework of transport equations that involve the true electric potential (TEP), a nonobservable variable. Nevertheless another electric potential, the observable electric potential (OEP), may be defined to construct a useful set of transport equations. In this paper several basic characteristics of the OEP are deduced and emphasized: (i) the OEP distribution depends on thermodynamic state of the solution, (ii) the observable equations have a reference value for all other transport equations, (iii) the bridge that connects the OEP with a certain TEP is usually defined by the ion activity coefficient, (iv) the electric charge density is a nonobservable variable, and (v) the OEP formulation constitutes a natural model for studying the fluxes in membrane systems.

  16. Comprehensive ground-based and in situ observations of substorm expansion phase onset

    NASA Astrophysics Data System (ADS)

    Walsh, A. P.; Rae, J.; Fazakerley, A. N.; Murphy, K. R.; Mann, I. R.; Watt, C. E.; Volwerk, M.; Forsyth, C.; Singer, H. J.; Donovan, E. F.; Zhang, T.

    2010-12-01

    We present comprehensive ground-based and space-based in situ geosynchronous observations of a substorm expansion phase onset on 1 October 2005. The Double Star TC2 and GOES12 spacecraft were both located within the substorm current wedge during the substorm expansion phase onset, which occurred over the Canadian sector. We find that an onset of ULF waves in space was observed after onset on the ground by extending the AWESOME timing algorithm into space. Furthermore a population of low energy field-aligned electrons was detected by the TC2 PEACE instrument contemporaneous with the ULF waves in space. These electrons appear to be associated with an enhancement of field-aligned Poynting flux into the ionosphere which is large enough to power visible auroral displays. The observations are most consistent with a near-Earth initiation of substorm expansion phase onset, such as the Near Geosynchronous Onset (NGO) substorm scenario. A lack of data from further downtail, however, means other mechanisms cannot be ruled out.

  17. Comprehensive ground-based and in situ observations of substorm expansion phase onset

    NASA Astrophysics Data System (ADS)

    Walsh, A. P.; Rae, I. J.; Fazakerley, A. N.; Murphy, K. R.; Mann, I. R.; Watt, C. E. J.; Volwerk, M.; Forsyth, C.; Singer, H. J.; Donovan, E. F.; Zhang, T. L.

    2010-12-01

    In this paper, we present comprehensive ground-based and space-based in situ geosynchronous observations of a substorm expansion phase onset on 1 October 2005. The Double Star TC-2 and GOES-12 spacecraft were both located within the substorm current wedge during the substorm expansion phase onset, which occurred over the Canadian sector. We find that an onset of ULF waves in space was observed after onset on the ground by extending the AWESOME timing algorithm into space. Furthermore, a population of low-energy field-aligned electrons was detected by the TC-2 PEACE instrument contemporaneous with the ULF waves in space. These electrons appear to be associated with an enhancement of field-aligned Poynting flux into the ionosphere which is large enough to power visible auroral displays. The observations are most consistent with a near-Earth initiation of substorm expansion phase onset, such as the Near-Geosynchronous Onset (NGO) substorm scenario. A lack of data from further downtail, however, means other mechanisms cannot be ruled out.

  18. Ground-based Observations of Water Vapor in Planet-forming Regions

    NASA Astrophysics Data System (ADS)

    Salyk, Colette; Zhang, K.; Pontoppidan, K.; Blake, G. A.

    2014-01-01

    Spitzer-IRS spectroscopy has shown that protoplanetary disks around low-mass young stars are generally blanketed in the mid-IR with strong molecular emission lines. Observations of these emission lines are allowing us, for the first time, to investigate disk chemistry in planet-forming regions, and to test our understanding of planet formation processes, such as the condensation sequence. However, at the spectral resolution of the IRS, the emission lines are unresolved and blended, making their interpretation difficult, even in the context of sophisticated radiative transfer disk modeling. In addition, with Spitzer alone, we are primarily sensitive to the few-AU region of protoplanetary disks, but do not get a complete picture of the water chemistry throughout the disk. Therefore, we have been pursuing a campaign of ground-based observing of water vapor in protoplanetary disks, utilizing a range of high-resolution spectrographs probing near- through mid-infrared wavelengths. I will present an update on our ground-based observing program and discuss implications for disk chemistry and planet formation.

  19. Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Gould, Andrew; Beichman, Charles; Calchi Novati, Sebastiano; Carey, Sean; Gaudi, B. Scott; Henderson, Calen B.; Penny, Matthew; Shvartzvald, Yossi; Yee, Jennifer C.; Udalski, A.; Poleski, R.; Skowron, J.; Kozłowski, S.; Mróz, P.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Ling, H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Rattenbury, N.; Wakiyama, Y.; Yonehara, A.; MOA Collaboration; Maoz, D.; Kaspi, S.; Friedmann, M.; The Wise Group

    2015-12-01

    To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity, and therefore probability, for detecting planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.

  20. Comparing satellite- to ground-based automated and manual cloud coverage observations - a case study

    NASA Astrophysics Data System (ADS)

    Werkmeister, A.; Lockhoff, M.; Schrempf, M.; Tohsing, K.; Liley, B.; Seckmeyer, G.

    2015-05-01

    In this case study we compare cloud fractional cover measured by radiometers on polar satellites (AVHRR) and on one geostationary satellite (SEVIRI) to ground-based manual (SYNOP) and automated observations by a cloud camera (Hemispherical Sky Imager, HSI). These observations took place in Hannover, Germany, and in Lauder, New Zealand, over time frames of 3 and 2 months, respectively. Daily mean comparisons between satellite derivations and the ground-based HSI found the deviation to be 6 ± 14% for AVHRR and 8 ± 16% for SEVIRI, which can be considered satisfactory. AVHRR's instantaneous differences are smaller (2 ± 22%) than instantaneous SEVIRI cloud fraction estimates (8 ± 29%) when compared to HSI due to resolution and scenery effect issues. All spaceborne observations show a very good skill in detecting completely overcast skies (cloud cover ≥ 6 oktas) with probabilities between 92 and 94% and false alarm rates between 21 and 29% for AVHRR and SEVIRI in Hannover, Germany. In the case of a clear sky (cloud cover lower than 3 oktas) we find good skill with detection probabilities between 72 and 76%. We find poor skill, however, whenever broken clouds occur (probability of detection is 32% for AVHRR and 12% for SEVIRI in Hannover, Germany). In order to better understand these discrepancies we analyze the influence of algorithm features on the satellite-based data. We find that the differences between SEVIRI and HSI cloud fractional cover (CFC) decrease (from a bias of 8 to almost 0%) with decreasing number of spatially averaged pixels and decreasing index which determines the cloud coverage in each "cloud-contaminated" pixel of the binary map. We conclude that window size and index need to be adjusted in order to improve instantaneous SEVIRI and AVHRR estimates. Due to its automated operation and its spatial, temporal and spectral resolution, we recommend as well that more automated ground-based instruments in the form of cloud cameras should be installed

  1. Coordinated satellite and ground observations of global monochromatic Pc5 oscillations on the morning side

    NASA Astrophysics Data System (ADS)

    Motoba, T.; Takahashi, K.; Gjerloev, J. W.; Ohtani, S.

    2012-12-01

    Strong Pc5 activity on the morning side was observed by the CARISMA ground magnetometer array on 7 December 2002, for several hours under moderately high solar wind speed (~580 km/s). In this study, we focus on the 30-min time interval from 1245 to 1315 UT, when a narrow-band Pc5 oscillation (~4.0 mHz) was clearly visible near 6 MLT over a wide range of L, 4-11. During this interval, the Cluster spacecraft was crossing L shells in the MLT sector covered by the CARISMA array. On the ground the X component of the magnetic field indicated the classical field line resonance signatures, latitudinal localization in amplitude (peaking at 300 nT at the Gillam station, L=6.6) and 180-degree phase shift. The ground Pc5 propagated tailward at a low azimuthal number of 3~5, suggesting that the ground Pc5 was caused by an external source. In the magnetosphere there were toroidal oscillations, which had a constant (i.e., global) frequency of ~4.0 mHz over the L shells 3.8-6.2 covered by the Custer spacecraft. Consistent with the ground observations, the toroidal wave amplitude in space was large at Cluster 3, which was moving from L= 6.2 to L= 4.8, and small at the other three Cluster spacecraft located at L= 4.0-4.5. The toroidal magnetic and electric field components at each Cluster spacecraft were approximately 90 degrees out of phase, as expected for a standing Alfven wave. In addition, the toroidal oscillations at the Cluster were accompanied by a significant compressional component with the same frequency, and by periodic modulations in oxygen ions of 1-38 keV and energetic electrons of 30-120 keV. We discuss possible mechanisms for the excitation of the global 4 mHz oscillations and for the modulation of such particle fluxes.

  2. Geographical and Temporal Differences in NOAA Observed Ground-Level Ozone in the Arctic

    NASA Astrophysics Data System (ADS)

    McClure-Begley, Audra; Petropavlovskikh, Irina; Andrews, Betsy; Hageman, Derek; Oltmans, Samuel; Uttal, Taneil

    2016-04-01

    The Arctic region is rapidly gaining interest and support for scientific studies to help understand and characterize the processes, sources, and chemical composition of the Arctic environment. In order to understand the Arctic climate system and the changes that are occurring, it is imperative to know the behavior and impact of atmospheric constituents. Surface level ozone in the Arctic is variable in both time and space and plays an essential role on the oxidation capacity of the atmosphere. NOAA Global Monitoring Division (NOAA/GMD) maintains continuous measurements and long-term records of ground-level ozone from Barrow, Alaska (since 1973) and Summit, Greenland (since 2000). Measurements taken by Thermo-Scientific ozone monitors are collected and examined with the NOAA/GMD Aerosol LiveCPD acquisition and software. These quality controlled data are used to develop seasonal climatologies, understand diurnal variation, and analyze differences in stations specifics by addressing spatial variability in the Arctic. Once typical ozone behavior is characterized, anomalies in the record are defined and investigated. Increased ozone events associated with transported pollution and photochemical production of ozone, and ozone depletion episodes related to sea-ice halogen release and chemical destruction of ozone are the primary processes which lead to deviations from typical ground-level ozone conditions. The measurements taken from Barrow and Summit are a critical portion of the IASOA network of observations of ground-level ozone and are investigated to ensure proper data management and quality control, as well as provide the fundamental understanding of ground-level ozone behavior in the Arctic.

  3. Calculated ground state potential surface and excitation energies for the copper trimer

    NASA Technical Reports Server (NTRS)

    Walch, S. P.; Laskowski, B. C.

    1986-01-01

    In the context of their relevance to catalysis and to materials science problems, transition metals and transition metal (TM) compounds are currently of considerable interest, and studies have been conducted of the copper trimer, Cu3. The present investigation is concerned with a study of the ground state surface and several groups of excited states in order to improve the understanding of the spectroscopy of Cu3. Differences of the current study from previous investigations are related to an employment of larger basis sets and a more extensive electron correlation. This was done with the objective to obtain a more accurate definition of the ground state surface. Features of the bonding in the copper dimer are considered to obtain a basis for an understanding of the copper trimer. Attention is given to calculational details, the ground state surface, and calculated vertical excitation energies. The results of SCF/SDCI calculations are reported for portions of the ground surface, for two groups of excited states, and for the ionization potential of Cu3.

  4. Observations of coupled seismicity and ground deformation at El Hierro Island (2011-2014)

    NASA Astrophysics Data System (ADS)

    Gonzalez, P. J.

    2015-12-01

    New insights into the magma storage and evolution at oceanic island volcanoes are now being achieved using remotely sensed space geodetic techniques, namely satellite radar interferometry. Differential radar interferometry is a technique tracking, at high spatial resolution, changes in the travel-time (distance) from the satellites to the ground surface, having wide applications in Earth sciences. Volcanic activity usually is accompanied by surface ground deformation. In many instances, modelling of surface deformation has the great advantage to estimate the magma volume change, a particularly interesting parameter prior to eruptions. Jointly interpreted with petrology, degassing and seismicity, it helps to understand the crustal magmatic systems as a whole. Current (and near-future) radar satellite missions will reduce the revisit time over global sub-aerial volcanoes to a sub-weekly basis, which will increase the potential for its operational use. Time series and filtering processing techniques of such streaming data would allow to track subsurface magma migration with high precision, and frequently update over vast areas (volcanic arcs, large caldera systems, etc.). As an example for the future potential monitoring scenario, we analyze multiple satellite radar data over El Hierro Island (Canary Islands, Spain) to measure and model surface ground deformation. El Hierro has been active for more than 3 years (2011 to 2014). Initial phases of the unrest culminated in a submarine eruption (late 2011 - early 2012). However, after the submarine eruption ended, its magmatic system still active and affected by pseudo-regular energetic seismic swarms, accompanied by surface deformation without resumed eruptions. Such example is a great opportunity to understand the crustal magmatic systems in low magma supply-rate oceanic island volcanoes. This new approach to measure surface deformation processes is yielding an ever richer level of information from volcanology to

  5. A new two-parameter family of potentials with a tunable ground state

    NASA Astrophysics Data System (ADS)

    Fellows, Jonathan M.; Smith, Robert A.

    2011-08-01

    In a previous paper (Fellows and Smith 2009 J. Phys. A: Math. Theor. 42 335303) we solved a countably infinite family of one-dimensional Schrödinger equations by showing that they were supersymmetric partner potentials of the standard quantum harmonic oscillator. In this work we extend these results to find the complete set of real partner potentials of the harmonic oscillator, showing that these depend upon two continuous parameters. Their spectra are identical to that of the harmonic oscillator, except that the ground state energy becomes a tunable parameter. We finally use these potentials to analyse the physical problem of Bose-Einstein condensation in an atomic gas trapped in a dimple potential.

  6. The early ELF signals of the gigantic jets captured by the Taiwan ground observation network

    NASA Astrophysics Data System (ADS)

    Chen, A. B. C.; Huang, P. H.; Su, H. T.; Hsu, R. R.

    2015-12-01

    The in-cloud ignition process of gigantic jets and blue jets receives attentions and discussions in the past years. The polarity and the position of their breakdown were proposed by Krehbiel et al. [2008] but no concrete observational evidence to support it directly. ELF spectrogram is a good tool to explore the electric activities, but traditional spectrograms are generated by a Fourier transform which obtain the frequency information through an integration operation. However the integration greatly limits the lowest frequency revealed by spectrogram and buries the important transient features. In this study, we applied a new but widely-used method, the Hilbert-Huang transform (HHT), to explore the spectrogram. Instead of the integration, HHT obtains the frequency information by differentiating on the phase angle, and become a powerful tool to reveal the fast frequency variation associated with transient luminous events. More than 100 transient luminous events including 25 gigantic jets observed by Taiwan ground optical observation network were analyzed. The results indicate that approximately 70% of gigantic jets can identify a rapid frequency variation in the interval of 300-600 milliseconds before main surge discharge, and this early feature can not find a clear corresponding amplitude variation in its sferic. Since this early signal can not be identified from the traditional Fourier spectrogram, but clear in-cloud lightning was registered correspondingly by the ground optical observation. In contrast to gigantic jets, this feature of early frequency change can be seen only in less than 30% of sprites and elves. These observational evidences are able to provide new constraints on the early discharge process of gigantic jets in clouds.

  7. Spatial Localization and Ducting of EMIC Waves: Van Allen Probes and Ground-based Observations

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Usanova, Maria; Murphy, Kyle; Robertson, Matthew; Milling, David; Kale, Andy; Kletzing, Craig; Wygant, John; Thaller, Scott; Raita, Tero

    2014-05-01

    On 11th October 2012, during the recovery phase of a moderate geomagnetic storm, an extended interval (> 18 hours) of continuous EMIC waves was observed by CARISMA and STEP induction coil magnetometers in North America. At around 14:15 UT, both Van Allen Probes B and A (65 degrees magnetic longitude apart) in conjunction with the ground array observed very narrow (Delta L~0.1-0.4) left-hand polarized EMIC emission confined to regions of mass density gradients at the outer edge of the plasmasphere at L~4. EMIC waves were seen with complex polarization patterns on the ground, in good agreement with model results from Woodroffe and Lysak [2012] and consistent with Earth's rotation sweeping magnetometer stations across multiple polarization reversals in the fields in the Earth-ionosphere duct. The narrow L-widths explain the relative rarity of space-based EMIC occurrence, ground-based measurements providing better estimates of global EMIC wave occurrence for input into radiation belt dynamical models. EMIC wave impacts on the radiation belts during this interval are also presented. This work is supported in part by participation in the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization) consortium. MAARBLE has received funding from the European Community's Seventh Framework Programme (FP7-SPACE-2010-1, SP1 Cooperation, Collaborative project) under grant agreement n° 284520. This paper reflects only the authors' views and the European Union is not liable for any use that may be made of the information contained herein.

  8. Urea for SCR-based NOx Control Systems and Potential Impacts to Ground Water Resources

    SciTech Connect

    Layton, D.

    2002-01-03

    One of the key challenges facing manufacturers of diesel engines for light- and heavy-duty vehicles is the development of technologies for controlling emissions of nitrogen oxides, In this regard, selective catalytic reduction (SCR) systems represent control technology that can potentially achieve the NOx removal efficiencies required to meet new U.S. EPA standards. SCR systems rely on a bleed stream of urea solution into exhaust gases prior to catalytic reduction. While urea's role in this emission control technology is beneficial, in that it supports reduced NOx emissions, it can also be an environmental threat to ground water quality. This would occur if it is accidentally released to soils because once in that environmental medium, urea is subsequently converted to nitrate--which is regulated under the U.S. EPA's primary drinking water standards. Unfortunately, nitrate contamination of ground waters is already a significant problem across the U.S. Historically, the primary sources of nitrate in ground waters have been septic tanks and fertilizer applications. The basic concern over nitrate contamination is the potential health effects associated with drinking water containing elevated levels of nitrate. Specifically, consumption of nitrate-contaminated water can cause a blood disorder in infants known as methemoglobinemia.

  9. Combination of space- and ground-based astrometric observations to create astrometric catalogs

    NASA Astrophysics Data System (ADS)

    Vondrák, J.; Štefka, V.

    2008-09-01

    Modern space-based astrometric observations made by Hipparcos satellite yielded two principal catalogs in optical wavelength: Hipparcos and Tycho. These catalogs, that recently celebrated ten years of existence, contain star positions with unprecedented accuracy. However, their proper motions are, due to a relatively short interval of Hipparcos mission, quite often not as good as their formal standard errors indicate. This deficiency is especially significant for about twenty per cent of double or multiple stars contained in these catalogs. The combination with ground-based astrometric observations that have much longer history is therefore very important for improving the Hipparcos proper motions. Significant improvement in this respect was achieved during the past years by creating combined catalogs, such as Tycho-2, FK6, GC+HIP, TYC2+HIP, or ARIHIP. Yet a large and important group of astrometric observations of latitude/universal time variations, made in the programs of monitoring Earth orientation, stood apart from these activities. Recently we started to use these observations, covering almost the whole 20th century, to create astrometric catalogs EOC-1, EOC-2, EOC-3 and most recently EOC-4. To construct them, we used the Earth orientation observations in combination with the above mentioned catalogs. The latter two, EOC-3 and EOC-4, contain not only the ``classical'' linear proper motions, but also periodic changes due to orbital motions, for a substantial portion of the observed stars.

  10. Urban flood modelling combining top-view LiDAR data with ground-view SfM observations

    NASA Astrophysics Data System (ADS)

    Meesuk, Vorawit; Vojinovic, Zoran; Mynett, Arthur E.; Abdullah, Ahmad F.

    2015-01-01

    small urban feature. Overall, the new multi-view approach of combining top-view LiDAR data with ground-view SfM observations shows a good potential for creating an accurate digital terrain map which can be then used as an input for a numerical urban flood model.

  11. Modeling analysis of ground water recharge potential on alluvial fans using limited data.

    PubMed

    Munévar, A; Mariño, M A

    1999-01-01

    A modeling approach is developed to evaluate the potential for artificial recharge on alluvial fans in the Salinas Valley, California, using limited data of soil texture, soil hydraulic properties, and interwell stratigraphy. Promising areas for surface recharge are identified and mapped on a broad-scale using soil surveys, geologic investigations, permeability tests, and seasonal ground water response to rainfall and runoff. Two-dimensional representations of the vadose zone at selected sites are then constructed from drillers'logs and soil material types are estimated. Next, hydraulic properties are assigned to each soil material type by comparing them to laboratory-tested cores of similar soils taken from one site. Finally, water flow through the vadose zone is modeled in two dimensions at seven sites using a transient, finite-difference, variably saturated flow model. Average infiltration rates range from 0.84 to 1.54 cm/hr and recharge efficiency, the percentage of infiltrated water that reaches the water table, varies from 51% to 79%. Infiltration rates and recharge efficiency are found to be relatively insensitive to recharge basin ponding depth due to the thickness of the vadose zones modeled (31 to 84 m). The impact of artificial recharge on the Salinas Valley ground water basin is investigated by simulating the regional ground water response to surface spreading and streamflow augmentation with a recently calibrated, finite-element, ground water-surface water model for the basin. It was determined that a combined approach of surface recharge and streamflow augmentation significantly reduces the state of ground water overdraft and, to a lesser extent, reduces the rate of sea water intrusion. PMID:19125917

  12. Modeling analysis of ground water recharge potential on alluvial fans using limited data.

    PubMed

    Munévar, A; Mariño, M A

    1999-01-01

    A modeling approach is developed to evaluate the potential for artificial recharge on alluvial fans in the Salinas Valley, California, using limited data of soil texture, soil hydraulic properties, and interwell stratigraphy. Promising areas for surface recharge are identified and mapped on a broad-scale using soil surveys, geologic investigations, permeability tests, and seasonal ground water response to rainfall and runoff. Two-dimensional representations of the vadose zone at selected sites are then constructed from drillers'logs and soil material types are estimated. Next, hydraulic properties are assigned to each soil material type by comparing them to laboratory-tested cores of similar soils taken from one site. Finally, water flow through the vadose zone is modeled in two dimensions at seven sites using a transient, finite-difference, variably saturated flow model. Average infiltration rates range from 0.84 to 1.54 cm/hr and recharge efficiency, the percentage of infiltrated water that reaches the water table, varies from 51% to 79%. Infiltration rates and recharge efficiency are found to be relatively insensitive to recharge basin ponding depth due to the thickness of the vadose zones modeled (31 to 84 m). The impact of artificial recharge on the Salinas Valley ground water basin is investigated by simulating the regional ground water response to surface spreading and streamflow augmentation with a recently calibrated, finite-element, ground water-surface water model for the basin. It was determined that a combined approach of surface recharge and streamflow augmentation significantly reduces the state of ground water overdraft and, to a lesser extent, reduces the rate of sea water intrusion.

  13. An Intense Terrestrial Gamma-ray Flash Observed at Ground Level

    NASA Astrophysics Data System (ADS)

    Grove, J. E.; Phlips, B. F.; Wulf, E. A.; Hutcheson, A. L.; Mitchell, L. J.; Woolf, R. S.; Johnson, W. N.; Schaal, M.; Uman, M. A.; Jordan, D.; Hare, B.; Rassoul, H.; Bozarth, A.

    2015-12-01

    We report on an intense gamma-ray flash observed at ground level in August 2014 at the International Center for Lightning Research and Testing, Camp Blanding, Florida, that occurred 13 ms after the initiation of the first stroke of an altitude-triggered lightning discharge. The measurements were made with an array of 78 plastic, liquid, and fast inorganic scintillators for robust spectroscopy of high-rate transients. The gamma-ray spectrum, time-intensity profile, and luminosity at the putative source altitude are consistent with those of a Terrestrial Gamma-ray Flash (TGF). The fluence of >100 keV gamma rays at ground level in the ~200 μs flash was in excess of 10 photons / cm2, an order of magnitude brighter than typical TGFs observed from low-Earth orbit. The proximity of the TGF to our large scintillator array allows these to be the most detailed gamma-ray measurements ever made of a TGF. Work at NRL was sponsored by the Chief of Naval Research.

  14. Ground-satellite conjugate observations of low-latitude travelling ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Ceren Moral, Aysegul; Shiokawa, Kazuo; Otsuka, Yuichi; Suzuki, Shin; Liu, Huixin; Yatini, Clara

    2016-07-01

    Equatorial travelling ionospheric disturbances (TIDs) are studied by using three CHAMP satellite overpasses on ground-based 630-nm airglow images. The airglow images are obtained from Kototabang (KTB), Indonesia (geographic coordinates: 0.2S, 100.3E, geomagnetic latitude: 10.6S). From 7-year data from October 2002 to October 2009, April 30, 2006 (event 1), September 28, 2006 (event 2) and April 12, 2004 (event 3) are the only TID events found in both ground and satellite measurements. They show southward-moving structures in 630-nm airglow images. The events 1 and 2 are single pulse with horizontal scales of ~500-1000 km and event 3 show three wave fronts with horizontal scale sizes of 500-700 km. For events 1 and 3, the neutral density in CHAMP shows out-of-phase variations with the airglow intensity, while event 2 is in-phase. For event 1, the relation between electron density and airglow intensity is out of phase, while relationships of event 2 and 3 are unclear. These unclear relationships suggest that ionospheric plasma variation is not the cause of the TIDs. In the case if gravity waves in the thermosphere is the source of the observed TIDs, in-phase and out-of-phase relationships of neutral density and airglow intensity can be explained by different vertical wavelengths of the gravity wave. We estimate possible vertical wavelengths for those events using observed wave parameters and modeled neutral winds.

  15. Observations of ULF waves on the ground and ionospheric Doppler shifts during storm sudden commencement

    NASA Astrophysics Data System (ADS)

    Ouyang, Xinyan; Liu, Wenlong; Xiao, Zuo; Hao, Yongqiang

    2016-04-01

    Using data from ground-based magnetometers and HF Doppler sounder, we study ultralow frequency (ULF) waves excited during the storm sudden commencement (SSC) on 8 March 2012 and find possible evidence on the link between ULF waves and ionospheric Doppler shifts. Pc1-Pc2 ULF waves are observed from 11:04 to 11:27 UT after the SSC by ground stations of L shell ranging from 1.06 to 2.31, mapping to the topside ionosphere. There are weak responses in this frequency range in the power spectra of ionospheric Doppler shift. From 11:19 to 11:23 UT, oscillations of magnetic field in a lower frequency range of Pc3-Pc4 are observed and are well correlated with the trace of Doppler shift. It is thus suggested that ionospheric Doppler shift can response to ULF oscillations in magnetic field in various frequency ranges, especially in the frequency range of Pc3-Pc4 and below. This paper demonstrates a new mechanism of magnetosphere-ionosphere coupling.

  16. Simultaneous ground-satellite observations of meso-scale auroral arc undulations

    NASA Astrophysics Data System (ADS)

    Motoba, T.; Hosokawa, K.; Ogawa, Y.; Sato, N.; Kadokura, A.; Milan, S. E.; Lester, M.

    2012-06-01

    We present simultaneous ground-based and in situ measurements of a train of meso-scale (about 100-300 km) auroral arc undulations, occurring in the postmidnight sector (˜1 MLT) between 0040 UT and 0054 UT on September 21, 2009. The undulations appeared at the auroral poleward boundary, and then moved eastward with a speed of 0.9-2.2 km s-1. Dynamic behaviors of the associated meso-scale ionospheric plasma flows and current systems were also detected with the ground-based magnetometer and radar measurements within the all-sky camera field-of-view. During the interval of interest, simultaneous Cluster observations in the central near tail region (11-14 RE down tail) were available, and especially the ionospheric footprint of Cluster 2 (CL2) was close to the optical auroral forms. CL2 observed strong fluctuations in the in situ magnetic field with amplitude of 5-10 nT whenever a bright arc area, and its trailing adjacent area, of the auroral undulations passed its ionospheric footprint. Such in situ magnetic field changes at CL2 could be considered as a manifestation of localized upward and downward field-aligned current sheets moving eastward at the central near-Earth tail boundary, linked to the meso-scale auroral undulation structures.

  17. Ground-coupled airwaves at Pavlof Volcano, Alaska, and their potential for eruption monitoring

    NASA Astrophysics Data System (ADS)

    Smith, Cassandra M.; McNutt, Stephen R.; Thompson, Glenn

    2016-07-01

    An abnormally high number of explosion quakes were noted during the monitoring effort for the 2007 eruption of Pavlof Volcano on the Alaska Peninsula. In this study, we manually cataloged the explosion quakes from their characteristic ground-coupled airwaves. This study investigates how the ground-coupled airwaves might be used in a monitoring or analysis effort by estimating energy release and gas mass release. Over 3 × 104 quakes were recorded. The energy release from the explosions is approximated to be 3 × 1011 J, and the total gas mass (assuming 100 % water) released was 450 t. The tracking of explosion quakes has the potential to estimate relative eruption intensity as a function of time and is thus a useful component of a seismic monitoring program.

  18. Dynamic Electron Correlation Effects on the Ground State Potential Energy Surface of a Retinal Chromophore Model.

    PubMed

    Gozem, Samer; Huntress, Mark; Schapiro, Igor; Lindh, Roland; Granovsky, Alexander A; Angeli, Celestino; Olivucci, Massimo

    2012-11-13

    The ground state potential energy surface of the retinal chromophore of visual pigments (e.g., bovine rhodopsin) features a low-lying conical intersection surrounded by regions with variable charge-transfer and diradical electronic structures. This implies that dynamic electron correlation may have a large effect on the shape of the force fields driving its reactivity. To investigate this effect, we focus on mapping the potential energy for three paths located along the ground state CASSCF potential energy surface of the penta-2,4-dieniminium cation taken as a minimal model of the retinal chromophore. The first path spans the bond length alternation coordinate and intercepts a conical intersection point. The other two are minimum energy paths along two distinct but kinetically competitive thermal isomerization coordinates. We show that the effect of introducing the missing dynamic electron correlation variationally (with MRCISD) and perturbatively (with the CASPT2, NEVPT2, and XMCQDPT2 methods) leads, invariably, to a stabilization of the regions with charge transfer character and to a significant reshaping of the reference CASSCF potential energy surface and suggesting a change in the dominating isomerization mechanism. The possible impact of such a correction on the photoisomerization of the retinal chromophore is discussed. PMID:26605574

  19. Coordinated observations of chemical releases from the ground and from aircraft at high latitudes

    NASA Technical Reports Server (NTRS)

    Romick, G. J.

    1973-01-01

    The ground observations of the Na-Li trail released from a Nike-Apache rocket obtained by the Geophysical Institute are discussed. By using the nominal trajectory for a 60 pound payload and the particular rocket, a best fit trajectory was determined based on the Ester Dome photographic data, launch time and earth-sun geometrical shadow height. From these calculations, the height of obvious features along the trail were determined and their velocity estimated. A clockwise rotation of the velocity vector with increasing height was observed. Velocities deduced at various altitudes were then compared to meter radar data also obtained during this period. The comparisons of these two neutral wind measurements techniques are satisfactory.

  20. Noctilucent clouds: modern ground-based photographic observations by a digital camera network.

    PubMed

    Dubietis, Audrius; Dalin, Peter; Balčiūnas, Ričardas; Černis, Kazimieras; Pertsev, Nikolay; Sukhodoev, Vladimir; Perminov, Vladimir; Zalcik, Mark; Zadorozhny, Alexander; Connors, Martin; Schofield, Ian; McEwan, Tom; McEachran, Iain; Frandsen, Soeren; Hansen, Ole; Andersen, Holger; Grønne, Jesper; Melnikov, Dmitry; Manevich, Alexander; Romejko, Vitaly

    2011-10-01

    Noctilucent, or "night-shining," clouds (NLCs) are a spectacular optical nighttime phenomenon that is very often neglected in the context of atmospheric optics. This paper gives a brief overview of current understanding of NLCs by providing a simple physical picture of their formation, relevant observational characteristics, and scientific challenges of NLC research. Modern ground-based photographic NLC observations, carried out in the framework of automated digital camera networks around the globe, are outlined. In particular, the obtained results refer to studies of single quasi-stationary waves in the NLC field. These waves exhibit specific propagation properties--high localization, robustness, and long lifetime--that are the essential requisites of solitary waves.

  1. Simultaneous ground- and space-based observations of the plasmaspheric plume and reconnection.

    PubMed

    Walsh, B M; Foster, J C; Erickson, P J; Sibeck, D G

    2014-03-01

    Magnetic reconnection is the primary process through which energy couples from the solar wind into Earth's magnetosphere and ionosphere. Conditions both in the incident solar wind and in the magnetosphere are important in determining the efficiency of this energy transfer. In particular, the cold, dense plasmaspheric plume can substantially impact the coupling in the dayside reconnection region. Using ground-based total electron content (TEC) maps and measurements from the THEMIS spacecraft, we investigated simultaneous ionosphere and magnetosphere observations of the plasmaspheric plume and its involvement in an unsteady magnetic reconnection process. The observations show the full circulation pattern of the plasmaspheric plume and validate the connection between signatures of variability in the dense plume and reconnection at the magnetopause as measured in situ and through TEC measurements in the ionosphere. PMID:24604196

  2. Simultaneous Ground- and Space-Based Observations of the Plasmaspheric Plume and Reconnection

    NASA Technical Reports Server (NTRS)

    Walsh, B. M.; Foster, J. C.; Erickson, P. J.; Sibeck, D. G.

    2014-01-01

    Magnetic reconnection is the primary process through which energy couples from the solar wind into Earth's magnetosphere and ionosphere. Conditions both in the incident solar wind and in the magnetosphere are important in determining the efficiency of this energy transfer. In particular, the cold, dense plasmaspheric plume can substantially impact the coupling in the dayside reconnection region. Using ground-based total electron content (TEC) maps and measurements from the THEMIS spacecraft, we investigated simultaneous ionosphere and magnetosphere observations of the plasmaspheric plume and its involvement in an unsteady magnetic reconnection process. The observations show the full circulation pattern of the plasmaspheric plume and validate the connection between signatures of variability in the dense plume and reconnection at the magnetopause as measured in situ and through TEC measurements in the ionosphere.

  3. Simultaneous ground- and space-based observations of the plasmaspheric plume and reconnection.

    PubMed

    Walsh, B M; Foster, J C; Erickson, P J; Sibeck, D G

    2014-03-01

    Magnetic reconnection is the primary process through which energy couples from the solar wind into Earth's magnetosphere and ionosphere. Conditions both in the incident solar wind and in the magnetosphere are important in determining the efficiency of this energy transfer. In particular, the cold, dense plasmaspheric plume can substantially impact the coupling in the dayside reconnection region. Using ground-based total electron content (TEC) maps and measurements from the THEMIS spacecraft, we investigated simultaneous ionosphere and magnetosphere observations of the plasmaspheric plume and its involvement in an unsteady magnetic reconnection process. The observations show the full circulation pattern of the plasmaspheric plume and validate the connection between signatures of variability in the dense plume and reconnection at the magnetopause as measured in situ and through TEC measurements in the ionosphere.

  4. Mid-infrared observations of Io’s volcanism from the ground in 2011 and 2012

    NASA Astrophysics Data System (ADS)

    Yoneda, M.; Miyata, T.; Tsang, C. C. C.; Sako, S.; Kamizuka, T.; Nakamura, T.; Asano, T.; Uchiyama, M.; Okada, K.; Hayashi, Y.; Yoshii, Y.; Kagitani, M.; Sakanoi, T.; Kasaba, Y.; Okano, S.

    2014-07-01

    We report the latest volcanic activity on Io based on our ground-based observations made in 2011 and 2012 using just a 1-m telescope, at 8.9 μm where Io’s thermal radiation dominates solar reflected light seen at shorter wavelengths. A particular result from these observations is that the power we detected from a bright hotspot at the longitude of 282±18°, perhaps Daedalus Patera, was ∼1013 (W) which is comparable to that of Loki Patera, the most powerful volcanic hotspot on Io. We conclude this hotspot is one of the most powerful volcanic hotspots on Io, but its activation is not as frequent as Loki Patera.

  5. Precipitation of radiation belt electrons by EMIC waves, observed from ground and space

    SciTech Connect

    Jordanova, Vania K; Miyoski, Y; Sakaguchi, K; Shiokawa, K; Evans, D S; Albert, Jay; Connors, M

    2008-01-01

    We show evidence that left-hand polarised electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere. Our unique set of ground and satellite observations shows coincident precipitation of ions with energies of tens of keY and of relativistic electrons into an isolated proton aurora. The coincident precipitation was produced by wave-particle interactions with EMIC waves near the plasmapause. The estimation of pitch angle diffusion coefficients supports that the observed EMIC waves caused coincident precipitation ofboth ions and relativistic electrons. This study clarifies that ions with energies of tens of ke V affect the evolution of relativistic electrons in the radiation belts via cyclotron resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.

  6. Observation of Ground Level Muon at Bangi In 2008-2009

    NASA Astrophysics Data System (ADS)

    Zain, N. M.; Gopir, G.; Yatim, B.; Sanusi, H.; Husain, N. H.

    2010-07-01

    This study is carried out to observe muons coming from the zenith direction at ground level using a muon telescope based on Geiger-Muller (GM) tubes. Measurements were made for 16 sampling days from November 2008 to January 2009; simultaneously outside and inside the Physics Building of Universiti Kebangsaan Malaysia in Bangi (3.05edeg N, 101.68° E and 50 m asl), Malaysia. Daily sampling sessions of 30 minutes are sub-divided into six consecutive sub-sampling periods of five minutes and descriptive statistics is used to summarise the observed muon counts. Then, applying the inferential statistical methods of ANOVA and t-test indicate that the time variation of the muon count is not significant and the building roof does not significantly affect the muon count rate.

  7. Polar Stratospheric Clouds from ground-based lidar and CALIPSO observations and Chemistry Climate Models evaluation

    NASA Astrophysics Data System (ADS)

    Fierli, Federico; Di Liberto, Luca; Cairo, Francesco; Cagnazzo, Chiara; Snels, Marcel; Keckhut, Philippe; Jumelet, Julien; Pitts, Michael C.

    2014-05-01

    We evaluate the Antarctic PSC observational databases of CALIPSO and the ground-based lidars of NDACC (Network for Detection of Atmospheric Composition Changes) located in McMurdo and Dumont D'Urville stations and provide a process-oriented evaluation of PSC in a subset of CCMVAL-2 chemistry-climate models. Lidar observatories have a decadal coverage, albeit with discontinuities, spanning from 1992 to today hence offering a unique database. A clear issue is the representativeness of ground-based long-term data series of the Antarctic stratosphere conditions that may limit their value in climatological studies and model evaluation. The comparison with the CALIPSO observations with a global coverage is, hence, a key issue. In turn, models can have a biased representation of the stratospheric conditions and of the PSC microphysics leading to large discrepancies in PSC occurrence and composition. CALIPSO observations indicate a large longitudinal variability in PSC formation in the polar atmosphere and ground-based observations are hence representative of different cloud conditions. Point-to-point comparison is difficult due to sparseness of the database (or PSC appearance at the edge of the vortex) and to intrinsic differences in spatial distribution between models and observations. So the use of simple diagnostics that are independent from instrumental coverage is fundamental. Comparison between ground-based and satellite borne-lidar is overall satisfactory and differences may be attributed to differences in coverage. As expected, McMurdo site is dominated by a NAT-type regime that is a clear feature of the eastern part of polar vortex while Dumont D'Urville is largely influenced by the transition at the edge the polar vortex resulting, on average, in a much reduced PSC coverage with a partition between NAT and STS cloud types. Data from the 5 CCMs having provided PSC surface areas on daily basis have been evaluated using the same diagnostic type that may be derived

  8. Evaluation of neurotoxicity potential in rats: the functional observational battery.

    PubMed

    Boucard, Aurélie; Bétat, Anne-Marie; Forster, Roy; Simonnard, Alain; Froget, Guillaume

    2010-12-01

    This unit describes the functional observational battery (FOB), a behavioral screening procedure commonly used in safety pharmacology and toxicology studies to assess potentially adverse effects of test agents on the central nervous system. The battery includes general observations and the determination of reactivity to various stimuli. Also presented is the severity score index for analyzing individual measurements and evaluations over a range of endpoints. The severity score index can be used to identify, quantify, and describe the effects of compounds on neurological, autonomic, and behavioral functions.

  9. Ground-nesting marine birds and potential for human disturbance in Glacier Bay National Park

    USGS Publications Warehouse

    Arimitsu, M.L.; Romano, Marc D.; Piatt, J.F.; Piatt, J.F.; Gende, S.M.

    2004-01-01

    Glacier Bay National Park and Preserve contains a diverse assemblage of marine birds that use the area for nesting, foraging and molting. The abundance and diversity of marine bird species in Glacier Bay is unmatched in the region, due in part to the geomorphic and successional characteristics that result in a wide array of habitat types (Robards and others, 2003). The opportunity for proactive management of these species is unique in Glacier Bay National Park because much of the suitable marine bird nesting habitat occurs in areas designated as wilderness. Ground-nesting marine birds are vulnerable to human disturbance wherever visitors can access nest sites during the breeding season. Human disturbance of nest sites can be significant because intense parental care is required for egg and hatchling survival, and repeated disturbance can result in reduced productivity (Leseberg and others, 2000). Temporary nest desertion by breeding birds in disturbed areas can lead to increased predation on eggs and hatchlings by conspecifics or other predators (Bolduc and Guillemette, 2003). Human disturbance of ground-nesting birds may also affect incubation time and adult foraging success, which in turn can alter breeding success (Verhulst and others, 2001). Furthermore, human activity can potentially cause colony failure when disturbance prevents the initiation of nesting (Hatch, 2002). There is management concern about the susceptibility of breeding birds to disturbance from human activities, but little historical data has been collected on the distribution of ground-nesting marine birds in Glacier Bay. This report summarizes results obtained during two years of a three-year study to determine the distribution of ground-nesting marine birds in Glacier Bay, and the potential for human disturbance of those nesting birds.

  10. Density and crosswind from GOCE - comparisons with other satellite data, ground-based observations and models

    NASA Astrophysics Data System (ADS)

    Doornbos, E.; Bruinsma, S.; Conde, M.; Forbes, J. M.

    2013-12-01

    Observations made by the European Space Agency (ESA) Gravity field and Ocean Circulation Explorer (GOCE) satellite have enabled the production of a spin-off product of high resolution and high accuracy data on thermosphere density, derived from aerodynamic analysis of acceleration measurements. In this regard, the mission follows in the footsteps of the earlier accelerometer-carrying gravity missions CHAMP and GRACE. The extremely high accuracy and redundancy of the six accelerometers carried by GOCE in its gravity gradiometer instrument has provided new insights on the performance and calibration of these instruments. Housekeeping data on the activation of the GOCE drag free control thruster, made available by ESA has made the production of the thermosphere data possible. The long duration low altitude of GOCE, enabled by its drag free control system, has ensured the presence of very large aerodynamic accelerations throughout its lifetime. This has been beneficial for the accurate derivation of data on the wind speed encountered by the satellite. We have compared the GOCE density observations with data from CHAMP and GRACE. The crosswind data has been compared with CHAMP observations, as well as ground-based observations, made using Scanning Doppler Imagers in Alaska. Models of the thermosphere can provide a bigger, global picture, required as a background in the interpretation of the local space- and ground-based measurements. The comparison of these different sources of information on thermosphere density and wind, each with their own strengths and weaknesses, can provide scientific insight, as well as inputs for further refinement of the processing algorithms and models that are part of the various techniques. Density and crosswind data derived from GOCE (dusk-dawn) and CHAMP (midnight-noon) satellite accelerometer data, superimposed over HWM07 modelled horizontal wind vectors.

  11. Addressing sub-scan variability of tundra snow properties in ground-based Ku- and X-band scatterometer observations

    NASA Astrophysics Data System (ADS)

    King, J. M.; Kasurak, A.; Kelly, R. E.; Duguay, C. R.; Derksen, C.; Rutter, N.; Sandells, M.; Watts, T.

    2012-12-01

    During the winter of 2010-2011 ground-based Ku- (17.2 GHz) and X-band (9.6 GHz) scatterometers were deployed near Churchill, Manitoba, Canada to evaluate the potential for dual-frequency observation of tundra snow properties. Field-based scatterometer observations when combined with in-situ snowpack properties and physically based models, provide the means necessary to develop and evaluate local scale property retrievals. To form meaningful analysis of the observed physical interaction space, potential sources of bias and error in the observed backscatter must be identified and quantified. This paper explores variation in observed Ku- and X-band backscatter in relation to the physical complexities of shallow tundra snow whose properties evolve at scales smaller than the observing instrument. The University of Waterloo scatterometer (UW-Scat) integrates observations over wide azimuth sweeps, several meters in length, to minimize errors resulting from radar fade and poor signal-to-noise ratios. Under ideal conditions, an assumption is made that the observed snow target is homogeneous. Despite an often-outward appearance of homogeneity, topographic elements of the Canadian open tundra produce significant local scale variability in snow properties, including snow water equivalent (SWE). Snow at open tundra sites observed during this campaign was found to vary by as much as 20 cm in depth and 40 mm in SWE within the scatterometer field of view. Previous studies suggest that changes in snow properties on this order will produce significant variation in backscatter, potentially introducing bias into products used for analysis. To assess the influence of sub-scan variability, extensive snow surveys were completed within the scatterometer field of view immediately after each scan at 32 sites. A standardized sampling protocol captured a grid of geo-located measurements, characterizing the horizontal variability of bulk properties including depth, density, and SWE. Based upon

  12. Asteroid masses with Gaia from ground and space-based observations

    NASA Astrophysics Data System (ADS)

    Ivantsov, Anatoliy; Hestroffer, Daniel; Thuillot, William; Bancelin, David

    2013-04-01

    Determination of masses of large asteroids is one of the expected scientific outputs from the future Gaia astrometric space mission. With the exception of binary asteroids or fly-by with a space probe, the error in mass determination depends on the size of perturbation effect produced on the motion of small asteroids. Considering the 5 years nominal duration of the Gaia mission, there will be mutual close encounters between asteroids occurring either close to the beginning or to the end of the mission. So that the maximum of deflection angle pertained to the perturbation maxima will not be observed directly by Gaia. Since astrometric data of the perturbed body before and after the encounter are mandatory to derive a perturber mass, the precision of mass determinations based solely on the Gaia observations will deteriorate in such cases. The possible way out consists in acquiring ground-based observations of high astrometric precision in time either before or after the Gaia operations, as it was suggested in [1]. By adding such data, it is expected to increase the number of derived asteroids masses [2]. This paper updates earlier predictions of encounters of large asteroids with smaller ones, e.g. [3], in terms of newly discovered asteroids and available ground-based observations. The method used consists in the computation of the offsets in right ascension and declination between the unperturbed and perturbed solutions fitted to the available observations for each small (perturbed) asteroid. For the purpose of decreasing CPU time, a special filter was applied based on the solution of the two-body problem and systematical search for close encounters, e.g. less than 0.1 A.U., of all known asteroids with the large (perturber) ones. The obtained list of asteroids-candidates was used as the input file for the mentioned above accurate calculations. Such a procedure was used for a few asteroids in [2]. The maximum visible offset corresponds to the dates when the

  13. Heliospheric Modulation Potential from SOHO/EPHIN Observations of Protons

    NASA Astrophysics Data System (ADS)

    Gomez-Herrero, R.; del Peral, Luis; Rodriguez-Frias, M. Dolores, Gutierrez, Julio; Mueller-Mellin, Reinhold; Kunow, Horst

    2003-07-01

    We summarize observations of energetic H and He isotop es measured by EPHIN/SOHO instrument during 1996-97 solar minimum. modulated Anomalous and Galactic Cosmic Ray fluxes reach maximum values during this period, showing a simultaneous absolute maximum around September 1997. Using the force-field approximation to fit proton spectrum, we obtain a modulation potential of ˜544 MV for 1996 quiet time periods.

  14. Observing the inflation potential. [in models of cosmological inflation

    NASA Technical Reports Server (NTRS)

    Copeland, Edmund J.; Kolb, Edward W.; Liddle, Andrew R.; Lidsey, James E.

    1993-01-01

    We show how observations of the density perturbation (scalar) spectrum and the gravitational wave (tensor) spectrum allow a reconstruction of the potential responsible for cosmological inflation. A complete functional reconstruction or a perturbative approximation about a single scale are possible; the suitability of each approach depends on the data available. Consistency equations between the scalar and tensor spectra are derived, which provide a powerful signal of inflation.

  15. System-level view of geospace dynamics: Challenges for high-latitude ground-based observations

    NASA Astrophysics Data System (ADS)

    Donovan, E.

    2014-12-01

    Increasingly, research programs including GEM, CEDAR, GEMSIS, GO Canada, and others are focusing on how geospace works as a system. Coupling sits at the heart of system level dynamics. In all cases, coupling is accomplished via fundamental processes such as reconnection and plasma waves, and can be between regions, energy ranges, species, scales, and energy reservoirs. Three views of geospace are required to attack system level questions. First, we must observe the fundamental processes that accomplish the coupling. This "observatory view" requires in situ measurements by satellite-borne instruments or remote sensing from powerful well-instrumented ground-based observatories organized around, for example, Incoherent Scatter Radars. Second, we need to see how this coupling is controlled and what it accomplishes. This demands quantitative observations of the system elements that are being coupled. This "multi-scale view" is accomplished by networks of ground-based instruments, and by global imaging from space. Third, if we take geospace as a whole, the system is too complicated, so at the top level we need time series of simple quantities such as indices that capture important aspects of the system level dynamics. This requires a "key parameter view" that is typically provided through indices such as AE and DsT. With the launch of MMS, and ongoing missions such as THEMIS, Cluster, Swarm, RBSP, and ePOP, we are entering a-once-in-a-lifetime epoch with a remarkable fleet of satellites probing processes at key regions throughout geospace, so the observatory view is secure. With a few exceptions, our key parameter view provides what we need. The multi-scale view, however, is compromised by space/time scales that are important but under-sampled, combined extent of coverage and resolution that falls short of what we need, and inadequate conjugate observations. In this talk, I present an overview of what we need for taking system level research to its next level, and how

  16. New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations

    NASA Astrophysics Data System (ADS)

    Varotsos, C. A.; Melnikova, I. N.; Cracknell, A. P.; Tzanis, C.; Vasilyev, A. V.

    2013-06-01

    The airborne spectral observations of the upward and downward irradiances are revisited to investigate the dependence of the near-ground albedo as a function of wavelength in the entire solar spectrum for different surfaces (sand, water, snow) and in different conditions (clear or cloudy sky). The radiative upward and downward fluxes were determined by a diffraction spectrometer flown on a research aircraft that was performing multiple flight paths near ground. The results obtained show that the near-ground albedo does not generally increase with increasing wavelengths for all kinds of surfaces as is widely believed today. Particularly, in the case of water surfaces we found that the albedo in the ultraviolet region is more or less independent of the wavelength on a long-term basis. Interestingly, in the visible and near-infrared spectra the water albedo obeys an almost constant power-law relationship with wavelength. In the case of sand surfaces we found that the sand albedo is a quadratic function of wavelength, which becomes more accurate, if the ultraviolet wavelengths are neglected. Finally, we found that the spectral dependence of snow albedo behaves similarly to that of water, i.e. both decrease from the ultraviolet to the near-infrared wavelengths by 20-50%, despite of the fact that their values differ by one order of magnitude (water albedo being lower). In addition, the snow albedo versus ultraviolet wavelength is almost constant, while in the visible-near infrared spectrum the best simulation is achieved by a second-order polynomial, as in the case of sand, but with opposite slopes.

  17. How ground-based observations can support satellite greenhouse gas retrievals

    NASA Astrophysics Data System (ADS)

    Butler, J. H.; Tans, P. P.; Sweeney, C.; Dlugokencky, E. J.

    2012-04-01

    Global society will eventually accelerate efforts to reduce greenhouse gas emissions in a variety of ways. These would likely involve international treaties, national policies, and regional strategies that will affect a number of economic, social, and environmental sectors. Some strategies will work better than others and some will not work at all. Because trillions of dollars will be involved in pursuing greenhouse gas emission reductions - through realignment of energy production, improvement of efficiencies, institution of taxes, implementation of carbon trading markets, and use of offsets - it is imperative that society be given all the tools at its disposal to ensure the ultimate success of these efforts. Providing independent, globally coherent information on the success of these efforts will give considerable strength to treaties, policies, and strategies. Doing this will require greenhouse gas observations greatly expanded from what we have today. Satellite measurements may ultimately be indispensable in achieving global coverage, but the requirements for accuracy and continuity of measurements over time are demanding if the data are to be relevant. Issues such as those associated with sensor drift, aging electronics, and retrieval artifacts present challenges that can be addressed in part by close coordination with ground-based and in situ systems. This presentation identifies the information that ground-based systems provide very well, but it also looks at what would be deficient even in a greatly expanded surface system, where satellites can fill these gaps, and how on-going, ground and in situ measurements can aid in addressing issues associated with accuracy, long-term continuity, and retrieval artifacts.

  18. New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations

    NASA Astrophysics Data System (ADS)

    Varotsos, C. A.; Melnikova, I. N.; Cracknell, A. P.; Tzanis, C.; Vasilyev, A. V.

    2014-07-01

    The airborne spectral observations of the upward and downward irradiances are revisited to investigate the dependence of the near-ground albedo as a function of wavelength in the entire solar spectrum for different surfaces (sand, water, snow) and under different conditions (clear or cloudy sky). The radiative upward and downward fluxes were determined by a diffraction spectrometer flown on a research aircraft that was performing multiple flight paths near the ground. The results obtained show that the near-ground albedo does not generally increase with increasing wavelengths for all kinds of surfaces as is widely believed today. Particularly, in the case of water surfaces it was found that the albedo in the ultraviolet region is more or less independent of the wavelength on a long-term basis. Interestingly, in the visible and near-infrared spectra the water albedo obeys an almost constant power-law relationship with wavelength. In the case of sand surfaces it was found that the sand albedo is a quadratic function of wavelength, which becomes more accurate if the ultraviolet wavelengths are neglected. Finally, it was found that the spectral dependence of snow albedo behaves similarly to that of water, i.e. both decrease from the ultraviolet to the near-infrared wavelengths by 20-50%, despite the fact that their values differ by one order of magnitude (water albedo being lower). In addition, the snow albedo vs. ultraviolet wavelength is almost constant, while in the visible near-infrared spectrum the best simulation is achieved by a second-order polynomial, as in the case of sand, but with opposite slopes.

  19. Asteroid spins and shapes by combining Gaia and ground-based observations

    NASA Astrophysics Data System (ADS)

    Durech, J.

    2014-07-01

    The astrometric and photometric satellite Gaia of the European Space Agency, launched in 2013, will observe all point sources brighter than ˜ 20 mag during its five-year mission. Apart from its main goal --- accurate astrometry and photometry of billions of stars --- it will also observe minor planets in our Solar System. The estimated total number of asteroids observed by Gaia is ˜ 400,000, with typically 40--100 detections per object [1]. Gaia's sparse-in-time photometry will be used to derive asteroid spin-axis orientations and shapes by using triaxial ellipsoid models and a genetic algorithm for finding the best-fit model [2]. The expected number of successfully determined models is ˜ 10,000. Although Gaia photometry is accurate enough to enable us to obtain a unique solution from the Gaia data alone, the number of models can be dramatically increased if Gaia data are combined with photometry from other ground-based surveys and with dense lightcurves. Then the data will cover a longer time interval with changing geometry, and we can model asteroids as convex bodies using the lightcurve inversion method [3]. The problem of finding a unique solution of the inverse problem for photometry sparse in time is time consuming because the sidereal rotation period has to be found by scanning a wide interval of physically possible periods. This can be efficiently solved by splitting the period parameter space into small parts that are sent to computers of volunteers and processed in parallel. We will show how this approach of distributed computing works with currently available sparse photometry processed in the framework of project Asteroids@home. We will also demonstrate the importance of Gaia-complementary data on asteroid photometry from Hipparcos satellite combined with photometry from ground-based surveys.

  20. Observation of coastal fogs using a suite of ground based remote sensing instruments

    NASA Astrophysics Data System (ADS)

    Song, J. I.; Yum, S. S.; Kim, K. H.; Kim, Y. H.; Cho, C. H.; Oh, S. B.

    2014-12-01

    Fog is the cloud of which the base is at the earth surface. Because of severely reduced visibility when fog is present, on-road traffics, maritime transport and aircraft operations are often hampered by fog occurrence. Therefore, accurate prediction of fog has been of high priority in traffic safety. The first step towards the accurate prediction of fog would be to detect the fog formation and monitor the evolution of fog in a continuous manner so that we can better characterize the fog formation mechanism. However, observing the evolution of fog has been difficult due to its nature of local meteorological scale and the lack of proper measurement of such scale. In situ measurements can provide us the most accurate data, but these measurements are limited to a very small spatial coverage. Satellite remote sensing can cover a wider spatial scale but detailed structure cannot be detected, In contrast, ground based remote sensing has advantages in spatial and temporal coverages. Here we present the data measured using a suite of ground based remote sensing instruments at the National Center for Intensive Observation of severe weather (NCIO), located at a southern coastal rural town of Boseong, Korea (34.76 ̊ N, 127.16 ̊ E), which include a scanning Ka-band cloud radar, wind profiler, microwave radiometer, ceilometer and lidar. Analysis of these data will be complemented by the basic meteorological (temperature, relative humidity, wind speed and direction) data measured at 11 different altitudes on a 300m meteorological observation tower installed at NCIO. With the sea to the south, the hilly topographical setting to the north, and the ragged coastal line in between, fog formation mechanisms in this region are expected to be very complex. Our eventual goal is to obtain an insight on the formation mechanisms of the coastal fogs in this region through the analysis of these comprehensive dataset. Some preliminary results from this effort will be presented at the

  1. Ground-based observations of overshooting convection during the Tropical Warm Pool-International Cloud Experiment

    NASA Astrophysics Data System (ADS)

    Hassim, M. E. E.; Lane, T. P.; May, P. T.

    2014-01-01

    This study uses gridded radar data to investigate the properties of deep convective storms that penetrate the tropical tropopause layer (TTL) and overshoot the cold-point tropopause during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE). Overshooting convection during the observed break period is relatively more intense and exhibits lesser diurnal variability than severe monsoonal storms in terms of mean overshooting area in the TTL (as covered by >20 dBZ echoes). However, ground-based radar has geometrical constraints and sampling gaps at high altitude that lead to biases in the final radar product. Using synthetic observations derived from model-based data, ground-based radar is shown to underestimate the mean overshooting area in the TTL across both TWP-ICE regimes. Differences range from ˜180 km2 (˜100 km2) to ˜14 km2 (˜8 km2) between 14 and 18 km for the active (break) period. This implies that the radar is underestimating the transport of water and ice mass into the TTL by convective overshoots during TWP-ICE. The synthetic data is also used to correct profiles of the mean observed overshooting area. These are shown to differ only marginally between the two sampled regimes once the influence of a large mesoscale convective system, considered as a departure from normal monsoon behavior, was removed from the statistics. The results of our study provide a useful cross-validation comparison for satellite-based detections of overshooting top areas over Darwin, Australia.

  2. THE 2011 JUNE 23 STELLAR OCCULTATION BY PLUTO: AIRBORNE AND GROUND OBSERVATIONS

    SciTech Connect

    Person, M. J.; Bosh, A. S.; Levine, S. E.; Gulbis, A. A. S.; Zangari, A. M.; Zuluaga, C. A.; Sallum, S.; Dunham, E. W.; Collins, P.; Bida, T.; Bright, L.; Pasachoff, J. M.; Babcock, B. A.; Pandey, S.; Amrhein, D.; Tholen, D. J.; Taylor, B.; Wolf, J.; Pfueller, E.; Meyer, A.; and others

    2013-10-01

    On 2011 June 23, stellar occultations by both Pluto (this work) and Charon (future analysis) were observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 with the Kuiper Airborne Observatory resulted in the best occultation chords recorded for the event, in three visible wavelength bands. The data obtained from SOFIA are combined with chords obtained from the ground at the IRTF, the U.S. Naval Observatory Flagstaff Station, and Leeward Community College to give the detailed state of the Pluto-Charon system at the time of the event with a focus on Pluto's atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee or kink in the light curve separating them as was observed in 1988, rather than the smoothly transitioning bowl-shaped light curves of recent years. The upper atmosphere is analyzed by fitting a model to all of the light curves, resulting in a half-light radius of 1288 {+-} 1 km. The lower atmosphere is analyzed using two different methods to provide results under the differing assumptions of particulate haze and a strong thermal gradient as causes for the lower atmospheric diminution of flux. These results are compared with those from past occultations to provide a picture of Pluto's evolving atmosphere. Regardless of which lower atmospheric structure is assumed, results indicate that this part of the atmosphere evolves on short timescales with results changing the light curve structures between 1988 and 2006, and then reverting these changes in 2011 though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again except for the overall pressure changes. No evidence of onset of atmospheric collapse predicted by frost migration models is seen, and the atmosphere appears to be remaining at a stable pressure level, suggesting it should

  3. Calculation of Steady-state Evaporation for an Arbitrary Matrix Potential at Ground Surface

    NASA Astrophysics Data System (ADS)

    Liu, X.; Zhan, H.

    2014-12-01

    The water loss from soil by evaporation and the amount of ground water available to plants due to the upward movement of water from a water table is an important topic in many disciplines such as soil science, hydrology, and plant physiology. Although water evaporation in actual field setting is a highly complex process, a nearly steady upward flow from a water table to a bare soil surface may be established if the daily evaporative demand is reasonably uniform for a long period of time. While the maximum potential rate of evaporation from the ground surface depends on atmospheric conditions, the actual flux across the soil surface is limited by the ability of the porous medium for transmitting water from the unsaturated zone.The purpose of this study is to calculate the steady-state evaporation for an arbitrary matrix potential at bare soil surface above a shallow water table, while the unsaturated hydraulic conductivity is a nonlinear function of water content or matrix potential. The Haverkamp function and the Brooks-Corey function for the unsaturated hydraulic conductivity are used, and the study results are contrast among the solution developed from the two retention equation and HYDRUS simulation.

  4. Charactering the Surface Radiation Budget over the Tibetan Plateau Using Ground Observations, Reanalysis, and Satellite Datasets

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Liang, S.

    2013-12-01

    The importance of the surface radiation budget (SRB) over the Tibetan Plateau (TP) to impact not only the local climate but also the remote area (i.e., the drought and flood in China) attracts increasing attentions in the scientific communities. Observed evidences support a continuous dimming trend with predominant warming, wind stilling, and moistening trends since 1980s. Cautions, however, need to be exercised when using ground observations or satellite retrievals alone, which are limited with large errors and sparse distributions, respectively. This study aims to characterize the monthly SRB at 0.5° over the TP extending two decades by incorporating multiple datasets, including ground-measured datasets, reanalysis datasets, and satellite datasets. The fused SRB was first generated using a multiple linear regression method to synthesize reanalysis and satellite datasets with ground observations from 1984 to 2007, and was then applied not only to analyze the characteristics (spatial distribution, temporal variation, and trend) of the SRB but also to compare with selected atmospheric (cloud cover, precipitation, and water vapor) and surface (temperature, snow cover, and the Normalized Difference Vegetation Index (NDVI)) anomalies over the TP. The cross validation results suggested that the fused data lowered the root mean square errors (RMSEs) at the monthly scale (<19 W/m2) by constraining uncertainties from multiple sources (i.e., inputs, preprocessing, and data fusion). The major finding is that the interaction of solar dimming with changes of surface albedo has dominated the marked decrease of all-wave net radiation since the mid-1980s regardless of the increase of downward longwave radiation (that counteracts the increase of upward longwave radiation). Furthermore, the weakening and strengthening of the relationships between the components of SRB and the correlated variables of atmospheric or surface conditions exhibit a seasonal dependency over the TP, where

  5. Soil surface potentials induced by ITAIPU HVDC ground return current. Part I - Theoretical evaluation

    SciTech Connect

    Kovarsky, D.; Pinto, L.J.; Caroli, C.E.; Santos, N. )

    1988-07-01

    The methodology for the theoretical evaluation of the soil surface potentials induced in ground return mode, is presented. For each electrode, soil resistivity data acquisition is discussed, giving rise to soil models amenable to mathematical analysis. For one electrode, the soil model considers a slanting interface between the first two layers, empirically considering the influence of a third deeper layer. For the other, the model consists of four different soil layers with horizontal interfaces, for which a special numerical approach is used, that can be extended to the case of AC induction between parallel wires over multilayer soils.

  6. Ground-based very high energy gamma ray astronomy: Observational highlights

    NASA Technical Reports Server (NTRS)

    Turver, K. E.

    1986-01-01

    It is now more than 20 years since the first ground based gamma ray experiments involving atmospheric Cerenkov radiation were undertaken. The present highlights in observational ground-based very high energy (VHE) gamma ray astronomy and the optimism about an interesting future for the field follow progress in these areas: (1) the detection at increased levels of confidence of an enlarged number of sources so that at present claims were made for the detection, at the 4 to 5 sd level of significance, of 8 point sources; (2) the replication of the claimed detections with, for the first time, confirmation of the nature and detail of the emission; and (3) the extension of gamma ray astronomy to the ultra high energy (UHE) domain. The pattern, if any, to emerge from the list of sources claimed so far is that X-ray binary sources appear to be copious emitters of gamma rays over at least 4 decades of energy. These X-ray sources which behave as VHE and UHE gamma ray emitters are examined.

  7. Evaluations of Thin Cirrus Contamination and Screening in Ground Aerosol Observations Using Collocated Lidar Systems

    NASA Technical Reports Server (NTRS)

    Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Holben, Brent N.; Welton, Ellsworth J.; Smirnov, Alexander; Jeong, Myeong-Jae; Hansell, Richard A.; Berkoff, Timothy A.

    2012-01-01

    Cirrus clouds, particularly sub visual high thin cirrus with low optical thickness, are difficult to be screened in operational aerosol retrieval algorithms. Collocated aerosol and cirrus observations from ground measurements, such as the Aerosol Robotic Network (AERONET) and the Micro-Pulse Lidar Network (MPLNET), provide us with an unprecedented opportunity to examine the susceptibility of operational aerosol products to thin cirrus contamination. Quality assured aerosol optical thickness (AOT) measurements were also tested against the CALIPSO vertical feature mask (VFM) and the MODIS-derived thin cirrus screening parameters for the purpose of evaluating thin cirrus contamination. Key results of this study include: (1) Quantitative evaluations of data uncertainties in AERONET AOT retrievals are conducted. Although AERONET cirrus screening schemes are successful in removing most cirrus contamination, strong residuals displaying strong spatial and seasonal variability still exist, particularly over thin cirrus prevalent regions during cirrus peak seasons, (2) Challenges in matching up different data for analysis are highlighted and corresponding solutions proposed, and (3) Estimation of the relative contributions from cirrus contamination to aerosol retrievals are discussed. The results are valuable for better understanding and further improving ground aerosol measurements that are critical for aerosol-related climate research.

  8. Assimilation of humidity and temperature observations retrieved from ground-based microwave radiometers into a convective-scale NWP model

    NASA Astrophysics Data System (ADS)

    Caumont, Olivier; Vincendon, Béatrice; Cimini, Domenico; Löhnert, Ulrich; Alados-Arboledas, Lucas; Bleisch, René; Buffa, Franco; Enrico Ferrario, Massimo; Haefele, Alexander; Huet, Thierry; Madonna, Fabio; Pace, Giandomenico

    2016-04-01

    Temperature and humidity retrievals from an international network of ground-based microwave radiometers (MWR) have been collected to assess the potential of their assimilation into a convective-scale Numerical Weather Prediction (NWP) system. Thirteen stations over a domain encompassing the western Mediterranean basin were considered for a time period of forty-one days in autumn, when heavy-precipitation events most often plague this area. Prior to their assimilation, MWR data were compared to very-short-term forecasts. Observation-minus-background statistics revealed some biases, but standard deviations were comparable to that obtained with radiosondes. The MWR data were then assimilated in a three-dimensional variational (3DVar) data assimilation system through the use of a rapid update cycle. A set of sensitivity experiments allowed assessing extensively the impact of the assimilation of temperature and humidity profiles, both separately and jointly. The respective benefit of MWR data and radiosonde data on analyses and forecasts was also investigated.

  9. Ground-based observations of ion/neutral coupling at Thule and Qanaq, Greenland

    NASA Technical Reports Server (NTRS)

    Thayer, J. P.; Crowley, G.; Niciejewski, R. J.; Killeen, T. L.; Buchau, J.; Reinisch, B. W.

    1995-01-01

    During December 1988, 24 hours of darkness and clear sky conditions permitted continuous observations of the O I(6300 A) airglow by a Fabry-Perot interferometer located at Thule Air Base, Greenland. Thus a continuous record of the F region neutral winds was obtained for that month. During this same time period, a digital ionosonde located at Qanaq, Greenland (110 km north of Thule Air Base), was in operation measuring electron density profiles and F region ion drifts. This combination of ground-based observations allowed the investigation of ion/neutral coupling at a temporal resolution of about 15 min. Interplanetary magnetic field (IMF) data from the IMP 8 satellite were also available from December 16 to 24 and indicated intervals of B(sub z) northward IMF conditions during this period. Here we investigate the observed response of the neutral wind to convection changes in the ion drift inside the polar cap for southward and northward IMF B(sub z) conditions. In particular, we establish a control day illustrating the typical antisunward neutral wind and ion drift patterns observed for southward B(sub z) over Thule and Qanaq, and we compare it with observations made when the IMF B(sub z) is directed northward. The observations during periods of northward B(sub z) display sunward directed ion drifts over the polar cap accompanied by decreasing antisunward directed neutral winds. We investigate these times of northward B(sub z) further and demonstrate that the ion drag term alone cannot describe the observed response in the neutral wind during northward IMF.

  10. The potential of advanced ground-based gravitational wave detectors to detect generic deviations from general relativity

    NASA Astrophysics Data System (ADS)

    Narikawa, Tatsuya; Tagoshi, Hideyuki

    2016-09-01

    We discuss the potential of advanced ground-based gravitational wave detectors such as LIGO, Virgo, and KAGRA to detect generic deviations of gravitational waveforms from the predictions of general relativity. We use the parameterized post-Einsteinian formalism to characterize the deviations, and assess what magnitude of deviations are detectable by using an approximate decision scheme based on Bayesian statistics. We find that there exist detectable regions of the parameterized post-Einsteinian parameters for different binary masses from the observation of a single gravitational wave event. The regions are not excluded by currently existing binary pulsar observations for the parameterized post-Einsteinian parameters at higher post-Newtonian order. We also find that neglect of orbital eccentricity or tidal deformation effects do not cause a significant bias on the detectable region of generic deviations from general relativity.

  11. Observation of γ vibrations and alignments built on non-ground-state configurations in 156Dy

    NASA Astrophysics Data System (ADS)

    Majola, S. N. T.; Hartley, D. J.; Riedinger, L. L.; Sharpey-Schafer, J. F.; Allmond, J. M.; Beausang, C.; Carpenter, M. P.; Chiara, C. J.; Cooper, N.; Curien, D.; Gall, B. J. P.; Garrett, P. E.; Janssens, R. V. F.; Kondev, F. G.; Kulp, W. D.; Lauritsen, T.; McCutchan, E. A.; Miller, D.; Piot, J.; Redon, N.; Riley, M. A.; Simpson, J.; Stefanescu, I.; Werner, V.; Wang, X.; Wood, J. L.; Yu, C.-H.; Zhu, S.

    2015-03-01

    The exact nature of the lowest Kπ=2+ rotational bands in all deformed nuclei remains obscure. Traditionally they are assumed to be collective vibrations of the nuclear shape in the γ degree of freedom perpendicular to the nuclear symmetry axis. Very few such γ bands have been traced past the usual backbending rotational alignments of high-j nucleons. We have investigated the structure of positive-parity bands in the N =90 nucleus 156Dy , using the 148Nd(12C,4 n ) 156Dy reaction at 65 MeV, observing the resulting γ-ray transitions with the Gammasphere array. The even- and odd-spin members of the Kπ=2+ γ band are observed up to 32+ and 31+, respectively. This rotational band faithfully tracks the ground-state configuration to the highest spins. The members of a possible γ vibration built on the aligned yrast S band are observed up to spins 28+ and 27+. An even-spin positive-parity band, observed up to spin 24+, is a candidate for an aligned S band built on the seniority-zero configuration of the 02+ state at 676 keV. The crossing of this band with the 02+ band is at ℏ ωc=0.28 (1 ) MeV and is consistent with the configuration of the 02+ band not producing any blocking of the monopole pairing.

  12. Proposed observation-well network and ground-water level program for North Carolina

    USGS Publications Warehouse

    Winner, M.D.

    1981-01-01

    An initial system of 223 observation wells is proposed for monitoring ground-water levels in North Carolina. These wells are suggested to replace and upgrade nearly 650 observation wells currently measured in separate State and Federal programs, and are arranged in four groups or networks each having specific objectives. These groups are (1) a climatic-effects network, (2) a terrane-effects network, (3) a local-effects network, and (4) an areal-effects network. Recommendations are also made regarding additional observation-well coverage in some areas of the State. Records-review and network-review procedures constituted the largest amount of effort in this study and required a considerable amount of organization to keep track of well records and water-level data. These procedures are outlined in this report as a guide for those who are contemplating an observation-well program review. The report also contains suggested organizational contents of a data file, including procedures for records processing, and various forms used to document the review and data-collection efforts.

  13. Characterization of Activity at Loki from Galileo and Ground-based Observations

    NASA Technical Reports Server (NTRS)

    Howell, R. R.; Lopes, R. M.

    2004-01-01

    While Loki is the most active volcanic center on Io, major questions remain concerning the nature of that activity. Rathbun et al. showed that the activity was semi-periodic, and suggested it was due to a resurfacing wave which swept across a lava lake as the crust cooled and become unstable. However in 2001 new observations showed that an intermediate level, less periodic mode of activity had apparently begun. Galileo-NIMS observations of Loki clearly show that the highest temperatures are found near the edge of the patera, consistent with disruption of a lava lake at the margins. NIMS observations also show gradients in temperature across the patera which, when modeled in terms of lava cooling models, are generally consistent with ages expected for the resurfacing wave but may also be consistent with spreading flows. We present a further analysis of NIMS data from I24 and I32 which help define the nature of the temperature variations present in Loki patera, along with Galileo-SSI images from the G1-I32 flybys which show albedo changes apparently correlated with the "periodic" activity measured from ground-based observations.

  14. Pulsating aurora observed on the ground and in-situ by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Lessard, M.; Cohen, I. J.; Denton, R. E.; Engebretson, M. J.; Kletzing, C.; Wygant, J. R.; Bounds, S. R.; Smith, C. W.; MacDowall, R. J.; Kurth, W. S.

    2013-12-01

    Early observations and theory related to pulsating aurora suggested that the electrons that drive this aurora originate from the equatorial region of the magnetosphere and that a likely process that can scatter these electrons would involve chorus waves. Recent satellite observations during pulsating auroral events have provided important "firsts", including evidence of strong correlations between pulsating auroral patches and in-situ lower-band chorus (THEMIS), as well as correlations with energetic electron precipitation in the vicinity of geosynchronous orbit (GOES). These results provide important information regarding particle dynamics, leading to a question about how the chorus might be driven. We present observations of the Van Allen Probes in conjunction with a pulsating aurora event, as confirmed by observations on the ground. The in-situ data again show the presence of lower-band chorus. However, magnetic and electric field data also show that the wave bursts coincide with an apparent poloidal field-line resonance, begging the question of whether the resonance might be responsible for driving the VLF waves.

  15. Ground-water flow and the potential effects of remediation at Graces Quarters, Aberdeen Proving Ground, Maryland

    USGS Publications Warehouse

    Tenbus, F.J.; Fleck, W.B.

    1996-01-01

    Ground water in the east-central part of Graces Quarters, a former open-air chemical-agent test facility at Aberdeen Proving Ground, Maryland, is contaminated with chlorinated volatile organic compounds. The U.S. Geological Survey's finite- difference model was used to help understand ground-water flow and simulate the effects of alternative remedial actions to clean up the ground water. Scenarios to simulate unstressed conditions and three extraction well con- figurations were used to compare alternative remedial actions on the contaminant plume. The scenarios indicate that contaminants could migrate from their present location to wetland areas within 10 years under unstressed conditions. Pumping 7 gal/min (gallons per minute) from one well upgradient of the plume will not result in containment or removal of the highest contaminant concentrations. Pumping 7 gal/min from three wells along the central axis of the plume should result in containment and removal of dissolved contami- nants, as should pumping 7 gal/min from three wells at the leading edge of the plume while injecting 7 gal/min back into an upgradient well.

  16. Electrophysiological potentials reveal cortical mechanisms for mental imagery, mental simulation, and grounded (embodied) cognition.

    PubMed

    Schendan, Haline E; Ganis, Giorgio

    2012-01-01

    Grounded cognition theory proposes that cognition, including meaning, is grounded in sensorimotor processing. The mechanism for grounding cognition is mental simulation, which is a type of mental imagery that re-enacts modal processing. To reveal top-down, cortical mechanisms for mental simulation of shape, event-related potentials were recorded to face and object pictures preceded by mental imagery. Mental imagery of the identical face or object picture (congruous condition) facilitated not only categorical perception (VPP/N170) but also later visual knowledge [N3(00) complex] and linguistic knowledge (N400) for faces more than objects, and strategic semantic analysis (late positive complex) between 200 and 700 ms. The later effects resembled semantic congruity effects with pictures. Mental imagery also facilitated category decisions, as a P3 peaked earlier for congruous than incongruous (other category) pictures, resembling the case when identical pictures repeat immediately. Thus mental imagery mimics semantic congruity and immediate repetition priming processes with pictures. Perception control results showed the opposite for faces and were in the same direction for objects: Perceptual repetition adapts (and so impairs) processing of perceived faces from categorical perception onward, but primes processing of objects during categorical perception, visual knowledge processes, and strategic semantic analysis. For both imagery and perception, differences between faces and objects support domain-specificity and indicate that cognition is grounded in modal processing. Altogether, this direct neural evidence reveals that top-down processes of mental imagery sustain an imagistic representation that mimics perception well enough to prime subsequent perception and cognition. Findings also suggest that automatic mental simulation of the visual shape of faces and objects operates between 200 and 400 ms, and strategic mental simulation operates between 400 and 700

  17. Comparison of land surface temperatures derived from satellite observations with ground truth during FIFE

    NASA Technical Reports Server (NTRS)

    Sugita, M.; Brutsaert, W.

    1993-01-01

    Surface temperatures of the FIFE (First ISLSCP Field Experiment) experimental area derived from thermal infrared radiances recorded from different satellite platforms at different scales were compared with reference observations by means of infrared thermometers at ground stations distributed over the area. FIFE was conducted during late spring, summer and fall over an area of 15 km by 15 km in a hilly tall-grass prairie region in northeastern Kansas. The data available for this purpose were produced by AVHRR and TOVS instruments aboard NOAA-9 and NOAA-10, the TM instrument aboard Landsat-5, and VISSR instrument aboard GOES-7. The scales covered by these instruments span a wide range, namely between hundreds of meters (Landsat TM) and hundreds of kilometers (TOVS). The data are analyzed both with and without the application of an atmospheric correction.

  18. Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations

    NASA Astrophysics Data System (ADS)

    Palle, E.; Goode, P. R.; Montañés-Rodríguez, P.; Shumko, A.; Gonzalez-Merino, B.; Lombilla, C. Martinez; Jimenez-Ibarra, F.; Shumko, S.; Sanroma, E.; Hulist, A.; Miles-Paez, P.; Murgas, F.; Nowak, G.; Koonin, S. E.

    2016-05-01

    The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured not only from space platforms but also from the ground for 16 years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim of quantifying sustained monthly, annual, and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the 16 years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the Clouds and the Earth's Radiant Energy System instruments, although each method measures different slices of the Earth's Bond albedo.

  19. Studies of the dayside boundary layer processes based on ground observations in the Svalbard area

    NASA Astrophysics Data System (ADS)

    Egeland, A.; Holtet, J. A.; Sandholt, P. E.

    1994-01-01

    Based on extensive, diagnostic ground observations in the Svalbard area (mainly at Ny Alesund at 76 deg lambda) together with simultaneous, coordinated measurements from east Greenland, the EISCAT radars as well as DMSP satellite recordings, structures and dynamics of the dayside cleft and polar cap region have been obtained. This is an important prerequisite to the understanding of the physics of dayside boundary layers processes. Several papers have been published, many lectures given and a NATO Advanced Workshop related to this program arranged. Possible generation mechanisms of dayside cusp/cleft auroras including magnetic merging, external pressure pulses, Kelvin-Helmholtz-instabilities, and dynamo processes by intruding plasma elements are discussed. Characteristics of boundary layer process and their ionospheric effects are a major objective of these studies. The Fast Explorer project as well as the new EISCAT radar at Svalbard will give new dimension to our studies of temporal/spatial structures of dayside auroral processes.

  20. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

    2003-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine what are the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  1. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Dubovik, Oleg; Holben, Brent; Torres, Omar; Anderson, Tad; Quinn, Patricia; Ginoux, Paul

    2004-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET, satellite retrievals from the TOMS instrument, and field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption. and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  2. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Main; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

    2004-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  3. Research on a UAV path planning method for ground observation based on threat sources

    NASA Astrophysics Data System (ADS)

    Yan, Hao; Fan, Xing; Xia, Xuezhi; Lin, Linshu

    2008-12-01

    The path planning method is one of the main research directions in current UAV(unmanned aerial vehicle) technologies. In this paper we perform analyses on the adversarial environment which may be broken through during the UAV mission for ground observation, and carry out the grade classification according to the threat level. On the basis of genetic algorithm, the encoding method of dimension reduction and direct quantization is used to combine the threat value of each leg with the flight distance, so as to construct the fitness evaluation function based on the threat amount and design the algorithm. This method is proven to be able to converge effectively and quickly via the simulation experiments, which meet the threat restriction and applicability of UAV in route planning.

  4. Ground deformation model for Tenerife (Canary Islands, Spain) from TEGETEIDE GNSS stations observation

    NASA Astrophysics Data System (ADS)

    García, A.; Carmona, J.; Fernández-Ros, A.; Pérez-Peña, A.; Ortiz, R.; Berrocoso, M.

    2009-04-01

    TEGETEIDE GNSS network is composed of seven benchmarks distributed over Tenerife Island, two of them are permanent stations. The whole network has been observed periodically from 2005 at least twice a year. Processed data using Bernese 5.0 software indicates different vector displacement pattern, as in magnitude as in direction, which expected from the African plate movement, suggesting the activity of other geodynamic process in the Island. The TEGETEIDE ground deformation model suggest the action not only the tectonics, but also the volcanic activity in an island where during 2004 a reawakening of the Teide volcano was detected. In this sense, the use of precise space-geodetic techniques to study the present-day dynamics of Tenerife is essential for a better knowledge and forecasting of the volcanic evolution during periods of crises, in an island of one million inhabitants and 5 million tourists a year.

  5. Recent observations of the solar corona with a new ground-based Coronagraph in Argentina (MICA)

    NASA Astrophysics Data System (ADS)

    Stenborg, G.; Schwenn, R.; Srivastava, N.; Inhester, B.; Podlipnik, B.; Rovira, M.; Francile, C.

    1999-06-01

    As part of the new German-Argentinian Solar-Observatory in El Leoncito, San Juan, Argentina, a new ground-based solar telescope (MICA: Mirror Coronagraph for Argentina) began to operate in August 1997. MICA is an advanced mirror coronagraph, its design being an almost exact copy of the LASCO-C1 instrument. Since its installation, it has been imaging the inner solar corona (1.05 to 2.0 solar radii) in two spectral ranges, corresponding to the emission lines of the Fe XIV and Fe X ions. The instrument can image the corona as fast as every minute. Thus, it is ideally suited to study fast processes in the inner corona. In this way it is a good complement for the LASCO-C1 instrument. We present a brief review of the characteristics of the instrument, and some recent observations.

  6. Comparison of Forest and Tundra Ecosystems Npp with Remote Sensing and Ground Observation Data

    NASA Astrophysics Data System (ADS)

    Ivanova, Yuliya; Ovchinnikova, Nataly; Kryazhimskiy, Fedor; Maklakov, Kirill

    2012-07-01

    In this study we compared two models for NPP estimate: an estimate based on satellite data and an estimate based on biomass calculation for tundra in the Yamal Peninsula and for forest ecosystems at the West Sayan Mountains. Ground NPP estimates were done for the same study areas which made it possible to identify the most significant parameters, specific to each model, that affect the estimates. The main difficulty in NPP-related studies is that current NPP values in an ecosystem cannot be determined exactly. Estimates, however, are feasible, and they can be made using a variety of methods. Thus, it seems important to see the ways in which these methods are different from each other and to find out how close the resulting values are. If these are dissimilar, the parameters used to make NPP estimates should be compared in order to identify the stage that can give rise to defects and errors, and to under- and overestimates. In this study we estimated NPP using the following two approaches: NPP calculation based on ground-truth measurements, such as calculation of plant phytomass on the studied area based on morphometric measurements (height, stem diameter, crown volume, etc.) and variations in this phytomass over a certain time period. NPP calculation based on satellite remote sensing data, using the data of satellite spectral channels and the data on underlying terrain. In this study we used MODIS/TERRA 8-day composite images, namely MOD09A1 and MOD11A2, with the spatial resolution 500 m and 1 km, respectively, obtained from EOS Data Gateway. Different models evaluate NPP using different physical values, with dissimilar temporal and spatial distributions. The NPP values evaluated by two models differ inherently. We used both of the models: GLO-PEM end MODIS-NPP. The study area is situated in the south of the Krasnoyarskii Krai, at the West Sayan Mountains, where the Institute of Forest SB RAS has been conducting observations since 1960. In this area altitudinal

  7. Evaluation of satellite soil moisture products over Norway using ground-based observations

    NASA Astrophysics Data System (ADS)

    Griesfeller, A.; Lahoz, W. A.; Jeu, R. A. M. de; Dorigo, W.; Haugen, L. E.; Svendby, T. M.; Wagner, W.

    2016-03-01

    In this study we evaluate satellite soil moisture products from the advanced SCATterometer (ASCAT) and the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) over Norway using ground-based observations from the Norwegian water resources and energy directorate. The ASCAT data are produced using the change detection approach of Wagner et al. (1999), and the AMSR-E data are produced using the VUA-NASA algorithm (Owe et al., 2001, 2008). Although satellite and ground-based soil moisture data for Norway have been available for several years, hitherto, such an evaluation has not been performed. This is partly because satellite measurements of soil moisture over Norway are complicated owing to the presence of snow, ice, water bodies, orography, rocks, and a very high coastline-to-area ratio. This work extends the European areas over which satellite soil moisture is validated to the Nordic regions. Owing to the challenging conditions for soil moisture measurements over Norway, the work described in this paper provides a stringent test of the capabilities of satellite sensors to measure soil moisture remotely. We show that the satellite and in situ data agree well, with averaged correlation (R) values of 0.72 and 0.68 for ASCAT descending and ascending data vs in situ data, and 0.64 and 0.52 for AMSR-E descending and ascending data vs in situ data for the summer/autumn season (1 June-15 October), over a period of 3 years (2009-2011). This level of agreement indicates that, generally, the ASCAT and AMSR-E soil moisture products over Norway have high quality, and would be useful for various applications, including land surface monitoring, weather forecasting, hydrological modelling, and climate studies. The increasing emphasis on coupled approaches to study the earth system, including the interactions between the land surface and the atmosphere, will benefit from the availability of validated and improved soil moisture satellite datasets, including those

  8. Coincident observation of lightning using spaceborne spectrophotometer and ground-level electromagnetic sensors

    NASA Astrophysics Data System (ADS)

    Adachi, T.; Cohen, M.; Lu, G.; Cummer, S. A.; Blakeslee, R. J.; Marshall, T.; Stolzenburg, M.; Karunarathne, S.; Hsu, R.; Su, H.; Chen, A. B.; Takahashi, Y.; Mende, S. B.; Frey, H. U.

    2012-12-01

    The present study aims at assessing a new way to reveal properties of lightning flash, using the spectrophotometric data obtained by FORMOSAT-2/ISUAL which is the first spaceborne multicolor lightning detector. The ISUAL data was analyzed in conjunction with ground-based electromagnetic data obtained by Duke magnetic field sensors, NLDN, North Alabama Lightning Mapping Array (LMA), and University of Mississippi (UM) electric field change antennas operated around Kennedy Space Center. We first classified the observed events into cloud-to-ground (CG) and intra-cloud (IC) lightning based on the Duke and NLDN measurements and analyzed ISUAL data to clarify their optical characteristics. It was found that the ISUAL optical waveform of CG lightning was strongly correlated with the current moment waveform, suggesting that it is possible to evaluate the electrical properties of lightning from satellite optical measurement to some extent. The ISUAL data also indicated that the color of CG lightning turned to red at the time of return stroke while the color of IC pulses remained unchanged. Furthermore, in one CG event which was simultaneously detected by ISUAL and LMA, the observed optical emissions slowly turned red as the altitude of optical source gradually decreased. All of these results indicate that the color of lightning flash depends on the source altitude and suggest that spaceborne optical measurement could be a new tool to discriminate CG and IC lightning. In the presentation, we will also show results on the comparison between the ISUAL and UM electric field change data to clarify characteristics of each lightning process such as preliminary breakdown and return stroke.

  9. Coincident Observation of Lightning using Spaceborne Spectrophotometer and Ground-Level Electromagnetic Sensors

    NASA Technical Reports Server (NTRS)

    Adachi, Toru; Cohen, Morris; Li, Jingbo; Cummer, Steve; Blakeslee, Richard; Marshall, THomas; Stolzenberg, Maribeth; Karunarathne, Sumedhe; Hsu, Rue-Ron; Su, Han-Tzong; Chen, Alfred; Takahashi, Yukihiro; Frey, Harald; Mende, Stephen

    2012-01-01

    The present study aims at assessing a possible new way to reveal the properties of lightning flash, using spectrophotometric data obtained by FORMOSAT-2/ISUAL which is the first spaceborne multicolor lightning detector. The ISUAL data was analyzed in conjunction with ground ]based electromagnetic data obtained by Duke magnetic field sensors, NLDN, North Alabama Lightning Mapping Array (LMA), and Kennedy Space Center (KSC) electric field antennas. We first classified the observed events into cloud ]to ]ground (CG) and intra ]cloud (IC) lightning based on the Duke and NLDN measurements and analyzed ISUAL data to clarify their optical characteristics. It was found that the ISUAL optical waveform of CG lightning was strongly correlated with the current moment waveform, suggesting that it is possible to evaluate the electrical properties of lightning from satellite optical measurement to some extent. The ISUAL data also indicated that the color of CG lightning turned to red at the time of return stroke while the color of IC pulses remained unchanged. Furthermore, in one CG event which was simultaneously detected by ISUAL and LMA, the observed optical emissions slowly turned red as the altitude of optical source gradually decreased. All of these results indicate that the color of lightning flash depends on the source altitude and suggest that spaceborne optical measurement could be a new tool to discriminate CG and IC lightning. In the presentation, we will also show results on the comparison between the ISUAL and KSC electric field data to clarify characteristics of each lightning process such as preliminary breakdown, return stroke, and subsequent upward illumination.

  10. Empirical relationships between instrumental ground motions and observed intensities for two great Chilean subduction zone earthquakes

    NASA Astrophysics Data System (ADS)

    Cilia, M. G.; Baker, L. M.

    2015-12-01

    We determine empirical relationships between instrumental peak ground motions and observed intensities for two great Chilean subduction earthquakes: the 2010 Mw8.8 Maule earthquake and the 2014 Mw8.2 Iquique earthquake. Both occurred immediately offshore on the primary plate boundary interface between the Nazca and South America plates. They are among the largest earthquakes to be instrumentally recorded; the 2010 Maule event is the second largest earthquake to produce strong motion recordings. Ground motion to intensity conversion equations (GMICEs) are used to reconstruct the distribution of shaking for historical earthquakes by using intensities estimated from contemporary accounts. Most great (M>8) earthquakes, like these, occur within subduction zones, yet few GMICEs exist for subduction earthquakes. It is unclear whether GMICEs developed for active crustal regions, such as California, can be scaled up to the large M of subduction zone events, or if new data sets must be analyzed to develop separate subduction GMICEs. To address this question, we pair instrumental peak ground motions, both acceleration (PGA) and velocity (PGV), with intensities derived from onsite surveys of earthquake damage made in the weeks after the events and internet-derived felt reports. We fit a linear predictive equation between the geometric mean of the maximum PGA or PGV of the two horizontal components and intensity, using linear least squares. We use a weighting scheme to express the uncertainty of the pairings based on a station's proximity to the nearest intensity observation. The intensity data derived from the onsite surveys is a complete, high-quality investigation of the earthquake damage. We perform the computations using both the survey data and community decimal intensities (CDI) calculated from felt reports volunteered by citizens (USGS "Did You Feel It", DYFI) and compare the results. We compare the GMICEs we developed to the most widely used GMICEs from California and

  11. DoD energy vulnerabilities: potential problems and observations

    SciTech Connect

    Freiwald, D A; Berger, M E; Roach, J F

    1982-08-01

    The Department of Defense is almost entirely dependent on civilian energy supplies to meet its needs in both peacetime and periods of heightened conflict. There are a number of potential vulnerabilities to the continual and timely supply of energy to both the civilian and military sectors. These include denial of the energy resources themselves, disruption of critical transportation networks, destruction of storage facilities, and interruption of electrical power. This report briefly reviews the present situation for provision of energy from the civilian sector to the military. General vulnerabilities of the existing energy supply system are identified, along with the potential for armed aggression (including terrorist and sabotage activities) against the energy network. Conclusions and some tentative observations are made as to a proper response to the existing vulnerabilities.

  12. Retrieval of ammonia from ground-based FTIR measurements and its use for validation of satellite observations by IASI

    NASA Astrophysics Data System (ADS)

    Dammers, Enrico; Palm, Mathias; Warneke, Thorsten; Van Damme, Martin; Smale, Daniel; Vigouroux, Corinne; Mahieu, Emmanuel; Notholt, Justus; Willem Erisman, Jan

    2015-04-01

    Atmospheric Ammonia (NH3) has a major impact on human health and ecosystem services and plays a major role in the formation of aerosols [Erisman et al.,2013; Paulot and Jacob 2014]. NH3 concentrations are highly variable in space and time with overall short lifetime due to deposition and aerosol formation. The global atmospheric budget of nitrogen and in turn NH3 is still uncertain which asks for more ground-based and satellite observations around the world. Recent papers have described the possibility to measure NH3 with satellite infrared sounders which open up the way for calculations of global and regional nitrogen budgets [Clarisse et al 2009,Van Damme et al 2014a]. Validation of the satellite observations is essential to determine the uncertainty in the signal and its potential use. So far available surface layer observations of atmospheric NH3 concentrations have been used for comparisons with total columns retrieved from satellite observations [Van Damme 2014b]. We developed a retrieval for NH3 column density concentrations (molecules NH3/cm2) by fitting a set of spectral windows to ground-based solar absorption Fourier transform infrared (FTIR) measurements with the spectral fitting program SFIT4 [Hase et al., 2004]. The retrieval is then applied to FTIR measurements from a set of spectrometer sites from the Network for detection of Atmospheric Composition Change (NDACC) to retrieve NH3 columns for the sites located in Bremen, Germany; Lauder, New Zealand; Jungfraujoch, Switzerland; and the island of Reunion, France. Using eight years (2005-2013) of retrieved NH3 columns clear seasonal cycles are observed for each of the stations. Maximum concentrations can be related to NH3 emission sources, specific for the regions. A comparison between the retrieved NH3 columns and observations from the recent IASI- NH3 product [Van Damme et al, 2014a] using strict spatial and temporal criteria for the selection of observations showed a good correlation (R=0.82; slope=0

  13. Assessment of nitrification potential in ground water using short term, single-well injection experiments

    USGS Publications Warehouse

    Smith, R.L.; Baumgartner, L.K.; Miller, D.N.; Repert, D.A.; Böhlke, J.K.

    2006-01-01

    Nitrification was measured within a sand and gravel aquifer on Cape Cod, MA, using a series of single-well injection tests. The aquifer contained a wastewater-derived contaminant plume, the core of which was anoxic and contained ammonium. The study was conducted near the downgradient end of the ammonium zone, which was characterized by inversely trending vertical gradients of oxygen (270 to 0 ??M) and ammonium (19 to 625 ??M) and appeared to be a potentially active zone for nitrification. The tests were conducted by injecting a tracer solution (ambient ground water + added constituents) into selected locations within the gradients using multilevel samplers. After injection, the tracers moved by natural ground water flow and were sampled with time from the injection port. Rates of nitrification were determined from changes in nitrate and nitrite concentration relative to bromide. Initial tests were conducted with 15N-enriched ammonium; subsequent tests examined the effect of adding ammonium, nitrite, or oxygen above background concentrations and of adding difluoromethane, a nitrification inhibitor. In situ net nitrate production exceeded net nitrite production by 3- to 6- fold and production rates of both decreased in the presence of difluoromethane. Nitrification rates were 0.02-0.28 ??mol (L aquifer)-1 h-1 with in situ oxygen concentrations and up to 0.81 ??mol (L aquifer)-1 h-1 with non-limiting substrate concentrations. Geochemical considerations indicate that the rates derived from single-well injection tests yielded overestimates of in situ rates, possibly because the injections promoted small-scale mixing within a transport-limited reaction zone. Nonetheless, these tests were useful for characterizing ground water nitrification in situ and for comparing potential rates of activity when the tracer cloud included non-limiting ammonium and oxygen concentrations. ?? Springer Science+Business Media, Inc. 2005.

  14. Using Aoristic Analysis to Link Remote and Ground-Level Phenological Observations

    NASA Astrophysics Data System (ADS)

    Henebry, G. M.

    2013-12-01

    Phenology is about observing events in time and space. With the advent of publically accessible geospatial datastreams and easy to use mapping software, specifying where an event occurs is much less of a challenge than it was just two decades ago. In contrast, specifying when an event occurs remains a nontrivial function of a population of organismal responses, sampling interval, compositing period, and reporting precision. I explore how aoristic analysis can be used to analyzing spatiotemporal events for which the location is known to acceptable levels of precision but for which temporal coordinates are poorly specified or only partially bounded. Aoristic analysis was developed in the late 1990s in the field of quantitative criminology to leverage temporally imprecise geospatial data of crime reports. Here I demonstrate how aoristic analysis can be used to link remotely sensed observations of land surface phenology to ground-level observations of organismal phenophase transitions. Explicit representation of the windows of temporal uncertainty with aoristic weights enables cross-validation exercises and forecasting efforts to avoid false precision.

  15. The Effect of Pulsar Timing Noise and Glitches on Timing Analysis for Ground Based Telescopes Observation

    NASA Astrophysics Data System (ADS)

    Oña-Wilhelmi, E.; de Jager, O. C.; Contreras, J. L.; de los Reyes, R.; Fonseca, V.; López, M.; Lucarelli, F.; MAGIC Collaboration

    2003-07-01

    Pulsed emission from a number of gamma-ray pulsars is expected to be detectable with next generation ground-based gamma-ray telescopes such as MAGIC and possibly H.E.S.S. within a few hours of observations. The sensitivity is however not sufficient to enable a detection within a few seconds as reached by radio surveys. In some cases we may be fortunate to do a period search given a few hours' data, but if the signal is marginal, the correct period parameters must be known to allow a folding of the gamma-ray arrival times. The residual phases are then sub jected to a test for uniformity from which the significance of a signal can be assessed. If contemporary radio parameters are not available, we have to extrap olate archival radio parameters to the observation time in question. Such an extrap olation must then be accurate enough to avoid significant pulse smearing. The pulsar ephemerides from the archival data of HartRAO and Princeton (b etween 1989 and 1998) provide an excellent opportunity to study the accuracy of extrap olations of such ephemerides to the present moment, if an appropriate time shift is intro duced. The aim of this study is to investigate the smear in the gamma-ray pulse profile during a single night of observations.

  16. Multi-mode Observations of Cloud-to-Ground Lightning Strokes

    NASA Astrophysics Data System (ADS)

    Smith, M. W.; Smith, B. J.; Clemenson, M. D.; Zollweg, J. D.

    2015-12-01

    We present hyper-temporal and hyper-spectral data collected using a suite of three Phantom high-speed cameras configured to observe cloud-to-ground lightning strokes. The first camera functioned as a contextual imager to show the location and structure of the strokes. The other two cameras were operated as slit-less spectrometers, with resolutions of 0.2 to 1.0 nm. The imaging camera was operated at a readout rate of 48,000 frames per second and provided an image-based trigger mechanism for the spectrometers. Each spectrometer operated at a readout rate of 400,000 frames per second. The sensors were deployed on the southern edge of Albuquerque, New Mexico and collected data over a 4 week period during the thunderstorm season in the summer of 2015. Strikes observed by the sensor suite were correlated to specific strikes recorded by the National Lightning Data Network (NLDN) and thereby geo-located. Sensor calibration factors, distance to each strike, and calculated values of atmospheric transmission were used to estimate absolute radiometric intensities for the spectral-temporal data. The data that we present show the intensity and time evolution of broadband and line emission features for both leader and return strokes. We highlight several key features and overall statistics of the observations. A companion poster describes a lightning model that is being developed at Sandia National Laboratories.

  17. Multi-instrument observations of midlatitude summer nighttime anomaly from satellite and ground

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mamoru; Thampi, Smitha V.; Liu, Huixin; Lin, Charles

    "Midlatitude Summer Nighttime Anomaly (MSNA)" is a phenomenon that the nighttime elec-tron densities exceed the daytime values on almost all days in summer over latitudes of 33-34N of more. We recently found the MSNA over the northeast Asian region from multi-instrument observations. The observations include the tomography analysis based on the chain of digital beacon receivers at Shionomisaki (33.45N, 135.8E), Shigaraki (34.85N, 136.1E), and Fukui (36.06N,136E), the ionosonde network over Japan (especially data from Wakkanai (45.4N, 141.7E)), ground-based GPS TEC observations using the GEONET. Also from satellites, CHAMP in situ electron density measurements, and Formosat3/COSMIC (F3/C) occultation measurements are useful to confirm the presence of MSNA over this region. In the presen-tation we show detailed features of the MSNA based on these multi-instrument, and discuss importance of the neutral atmosphere as a driver of the phenomenon.

  18. Heavy precipitation retrieval from combined satellite observations and ground-based lightning measurements

    NASA Astrophysics Data System (ADS)

    Mugnai, A.; Dietrich, S.; Casella, D.; di Paola, F.; Formenton, M.; Sanò, P.

    2010-09-01

    We have developed a series of algorithms for the retrieval of precipitation (especially, heavy precipitation) over the Mediterranean area using satellite observations from the available microwave (MW) radiometers onboard low Earth orbit (LEO) satellites and from the visible-infrared (VIS-IR) SEVIRI radiometer onboard the European geosynchronous (GEO) satellite Meteosat Second Generation (MSG), in conjunction with lightning data from ground-based networks - such as ZEUS and LINET. These are: • A new approach for precipitation retrieval from space (which we call the Cloud Dynamics and Radiation Database approach, CDRD) that incorporates lightning and environmental/dynamical information in addition to the upwelling microwave brightness temperatures (TB’s) so as to reduce the retrieval uncertainty and improve the retrieval performance; • A new combined MW-IR technique for producing frequent precipitation retrievals from space (which we call PM-GCD technique), that uses passive-microwave (PM) retrievals in conjunction with lightning information and the Global Convection Detection (GCD) technique to discriminate deep convective clouds within the GEO observations; • A new morphing approach (which we call the Lightning-based Precipitation Evolving Technique, L-PET) that uses the available lightning measurements for propagating the rainfall estimates from satellite-borne MW radiometers to a much higher time resolution than the MW observations. We will present and discuss our combined MW/IR/lightning precipitation algorithms and analyses with special reference to some case studies over the western Mediterranean.

  19. Crevice Repassivation Potentials for Alloy 22 in Simulated Concentrated Ground Waters

    SciTech Connect

    Rebak, R B; Evans, K J; Ilevbare, G O

    2006-11-08

    The resistance of Alloy 22 (N06022) to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. However, the behavior of Alloy 22 in concentrated aqueous solutions that may simulate concentrated ground waters was not fully understood. Systematic electrochemical tests using cyclic potentiodynamic polarization as well as the Tsujikawa-Hisamatsu electrochemical method were performed to determine the crevice corrosion susceptibility of Alloy 22 in simulated concentrated water (SCW), simulated acidified water (SAW) and basic saturated water (BSW). Results show that Alloy 22 is immune to crevice corrosion in SCW and SAW but may suffer crevice corrosion initiation in BSW. Results also show that in a naturally aerated environment, the corrosion potential would never reach the critical potential for crevice corrosion initiation.

  20. Conjugate ground and multisatellite observations of compression-related EMIC Pc1 waves and associated proton precipitation

    NASA Astrophysics Data System (ADS)

    Usanova, M. E.; Mann, I. R.; Kale, Z. C.; Rae, I. J.; Sydora, R. D.; Sandanger, M.; Søraas, F.; Glassmeier, K.-H.; Fornacon, K.-H.; Matsui, H.; Puhl-Quinn, P. A.; Masson, A.; Vallières, X.

    2010-07-01

    We present coordinated ground satellite observations of solar wind compression-related dayside electromagnetic ion cyclotron (EMIC) waves from 25 September 2005. On the ground, dayside structured EMIC wave activity was observed by the CARISMA and STEP magnetometer arrays for several hours during the period of maximum compression. The EMIC waves were also registered by the Cluster satellites for half an hour, as they consecutively crossed the conjugate equatorial plasmasphere on their perigee passes at L ˜ 5. Simultaneously, conjugate to Cluster, NOAA 17 passed through field lines supporting EMIC wave activity and registered a localized enhancement of precipitating protons with energies >30 keV. Our observations suggest that generation of the EMIC waves and consequent loss of energetic protons may last for several hours while the magnetosphere remains compressed. The EMIC waves were confined to the outer plasmasphere region, just inside the plasmapause. Analysis of lower-frequency Pc5 waves observed both by the Cluster electron drift instrument (EDI) and fluxgate magnetometer (FGM) instruments and by the ground magnetometers show that the repetitive structure of EMIC wave packets observed on the ground cannot be explained by the ultra low frequency (ULF) wave modulation theory. However, the EMIC wave repetition period on the ground was close to the estimated field-aligned Alfvénic travel time. For a short interval of time, there was some evidence that EMIC wave packet repetition period in the source region was half of that on the ground, which further suggests bidirectional propagation of wave packets.

  1. Mars Aeolian Features and Processes Observed Concurrently From Orbit and the Ground

    NASA Astrophysics Data System (ADS)

    Greeley, R.; Arvidson, R.; Cabrol, N.; Christensen, P.; de Souza, P.; Geissler, P.; Goetz, W.; Landis, G.; Lemmon, M.; Malin, M.; McEwen, A.; Neukum, G.; Pendleton Hoffer, M.; Squyres, S.; Sullivan, R.; Waller, D.; Williams, D.

    2008-12-01

    The last four years have provided the opportunity to study Mars through the concurrent operation of orbiters and rovers to observe processes related to active winds. Data have been obtained on the characteristics of active sand and dust at the MER sites for comparisons with features and active processes seen from orbit. Combined with modeling, results give new insight into surface modification by windblown material. For example, the operation area of Spirit seen from orbit is criss-crossed with dark linear features thought to be tracks left by dust devils (DD). The rover traversed one track and obtained Microscopic Imager data showing that sand grains within the track are relatively clear of dust, while those outside the track are partly mantled with dust. Subsequent observations show that as active DD cross the plains (entraining dust into the atmosphere) they leave behind low-albedo tracks, which are later gradually obscured by settling of dust. The rate of deposition can be calculated from the solar panel output and appears to be continuous, proportional to optical depth τ, minus a constant. Dust removal from the panels is in discrete episodes. Observations of terrain and the atmosphere were made from the ground and from orbit: 1) before the dust devil "season" (τ = 0.578), 2) during active dust devil formation (τ = 0.918), 3) after active dust devil formation, but during active dust clouds (τ = 2.061), and 4) after clearing of dust from the atmosphere (τ = 0.487). Results were compared with temperatures derived from the Thermal Emission Spectrometer for the relevant seasons. Results suggest that spring heating of the surface enhances DD formation, but as atmospheric dust-loading progresses, active DD "shut-off," possibly because atmospheric conditions become thermally stable. In addition to dust activity, movement of coarser grains (i.e., "sand") has also been observed. For example, MOC, HiRISE, THEMIS, and HRSC images from orbit show abundant bedforms

  2. Observations on the potential across the rumen of the sheep.

    PubMed

    Ferreira, H G; Harrison, F A; Keynes, R D; Nauss, A H

    1966-12-01

    1. The electric potential difference between rumen contents and jugular venous blood was measured in anaesthetized sheep. In order to investigate the effect on the potential of changing the ionic concentrations within the rumen, the digesta were removed from the rumen and various salt solutions were substituted. The reticulo-rumen sac was isolated before the experiment by ligation of the oesophagus and the reticulo-omasal junction. 2. The observation of Dobson & Phillipson (1958) that the rumen contents are normally of the order of 30 mV negative to the blood was confirmed. 3. For potassium concentrations between 25 and 100 mM the potential at constant [Na+] varied linearly with log [K+]. With sulphate as the anion, the slope for a 10-fold concentration change was 39.7 +/- 3.0 mV when [Na+] was around 50 mM. The slope showed a tendency to increase when [Na+] was lowered, and to decrease when [Na+] was raised. 4. When chloride was substituted for sulphate, both the slope and the absolute size of the potential were slightly reduced. 5. When the sodium concentration was varied at constant [K+], the potential increased as an approximately linear function of [Na+]. At around 10 mM-K the mean slope was 0-32 +/- 0.07 mV/mM; at the highest potassium concentrations it fell to 0-13 +/- 0 05 mV/mM. 6. In most of these experiments isotonicity was maintained with sucrose. The results of a few tests in which Li+ was substituted for Na+ or K+ suggested that the rumen epithelium behaves in a relatively inert fashion towards this ion.

  3. The Potential of Small Space Telescopes for Exoplanet Observations

    NASA Technical Reports Server (NTRS)

    Serabyn, E.

    2010-01-01

    The imaging of faint exoplanets near bright stars requires the development of very high contrast detection techniques, including both precise wavefront control and deep starlight rejection. A system-level proof-of-principle experiment carried out at at the Palomar Observatory has recently demonstrated that exoplanets can be detected very near stars even with a fairly small (1.5 m diameter) telescope aperture, such as someday might be used by a first space-based exoplanet imaging mission. Using fine-scale wavefront correction across this small aperture, together with fine pointing and focus control, pre- and post-detection speckle reduction, and a vector vortex coronagraph, it has been possible to achieve extremely good starlight rejection within a small number of diffractions beams of the stellar position. This performance has recently allowed the imaging of the three HR8799 planets and the HD32297 disk, thus providing a first system-level validation of the steps needed to achieve high-contrast observations at very small angles. These results thus serve to highlight the potential of small space telescopes aiming at high-contrast exoplanet observations. Specifically, a small-angle coronagraph enables the use of smaller telescopes, thus potentially reducing mission cost significantly.

  4. Sensitivity of aerosol retrieval to geometrical configuration of ground-based sun/sky-radiometer observations

    NASA Astrophysics Data System (ADS)

    Torres, B.; Dubovik, O.; Toledano, C.; Berjon, A.; Cachorro, V. E.; Lapyonok, T.; Goloub, P.

    2013-03-01

    A sensitivity study of the aerosol optical properties retrieval to the geometrical configuration of the ground-based sky radiometer observations is carried out through the inversion tests. Specifically, the study is focused on the principal plane and almucantar observation, since these geometries are employed in Aeronet (AErosol RObotic NETwork). The following effects has been analyzed with simulated data for both geometries: sensitivity of the retrieval to variability of the observed scattering angle range, uncertainties in the assumptions of the aerosol vertical distribution and surface reflectance, possible instrument pointing errors and the effects of the finite field of view. The synthetic observations of radiometer in the tests were calculated using a previous climatology data of retrieved aerosol over three Aeronet sites: Mongu (Zambia) for biomass burning aerosol, Goddard Space Flight Center (Maryland-USA) for urban aerosol and Solar Village (Saudi Arabia) for desert dust aerosol. The results show that almucantar retrievals, in general, are more reliable than principal plane retrievals in presence of the analyzed error sources. This fact partially can be explained by to practical advantages of almucantar geometry: the symmetry between its left and right branches that helps to eliminate some observational uncertainties and the constant value of optical mass constant during the measurements that makes almucantar observations nearly independent on vertical variability of aerosol. Nevertheless, almucantar retrievals present instabilities at high sun observations due to the reduction of the scattering angle range coverage resulting in decrease of information content. The last part of the study is devoted to identification of possible differences between the aerosol retrieval results obtained from real Aeronet data using both geometries. In particular, we have compared Aeronet retrievals at three different key sites: Mongu (biomass burning), Beijing (urban) and

  5. Current Icing Potential: Algorithm Description and Comparison with Aircraft Observations.

    NASA Astrophysics Data System (ADS)

    Bernstein, Ben C.; McDonough, Frank; Politovich, Marcia K.; Brown, Barbara G.; Ratvasky, Thomas P.; Miller, Dean R.; Wolff, Cory A.; Cunning, Gary

    2005-07-01

    The “current icing potential” (CIP) algorithm combines satellite, radar, surface, lightning, and pilot-report observations with model output to create a detailed three-dimensional hourly diagnosis of the potential for the existence of icing and supercooled large droplets. It uses a physically based situational approach that is derived from basic and applied cloud physics, combined with forecaster and onboard flight experience from field programs. Both fuzzy logic and decision-tree logic are applied in this context. CIP determines the locations of clouds and precipitation and then estimates the potential for the presence of supercooled liquid water and supercooled large droplets within a given airspace. First developed in the winter of 1997/98, CIP became an operational National Weather Service and Federal Aviation Administration product in 2002, providing real-time diagnoses that allow users to make route-specific decisions to avoid potentially hazardous icing. The CIP algorithm, its individual components, and the logic behind them are described.

  6. GIANT GROUND LEVEL ENHANCEMENT OF RELATIVISTIC SOLAR PROTONS ON 2005 JANUARY 20. I. SPACESHIP EARTH OBSERVATIONS

    SciTech Connect

    Bieber, J. W.; Clem, J.; Evenson, P.; Pyle, R.; Saiz, A.; Ruffolo, D. E-mail: clem@bartol.udel.edu E-mail: pyle@bartol.udel.edu E-mail: david.ruf@mahidol.ac.th

    2013-07-10

    A ground level enhancement (GLE) is a solar event that accelerates ions (mostly protons) to GeV range energies in such great numbers that ground-based detectors, such as neutron monitors, observe their showers in Earth's atmosphere above the Galactic cosmic ray background. GLEs are of practical interest because an enhanced relativistic ion flux poses a hazard to astronauts, air crews, and aircraft electronics, and provides the earliest direct indication of an impending space radiation storm. The giant GLE of 2005 January 20 was the second largest on record (and largest since 1956), with up to 4200% count rate enhancement at sea level. We analyzed data from the Spaceship Earth network, supplemented to comprise 13 polar neutron monitor stations with distinct asymptotic viewing directions and Polar Bare neutron counters at South Pole, to determine the time evolution of the relativistic proton density, energy spectrum, and three-dimensional directional distribution. We identify two energy-dispersive peaks, indicating two solar injections. The relativistic solar protons were initially strongly beamed, with a peak maximum-to-minimum anisotropy ratio over 1000:1. The directional distribution is characterized by an axis of symmetry, determined independently for each minute of data, whose angle from the magnetic field slowly varied from about 60 Degree-Sign to low values and then rose to about 90 Degree-Sign . The extremely high relativistic proton flux from certain directions allowed 10 s tracking of count rates, revealing fluctuations of period {approx}> 2 minutes with up to 50% fractional changes, which we attribute to fluctuations in the axis of symmetry.

  7. Microwave signatures of ice hydrometeors from ground-based observations above Summit, Greenland

    NASA Astrophysics Data System (ADS)

    Pettersen, Claire; Bennartz, Ralf; Kulie, Mark S.; Merrelli, Aronne J.; Shupe, Matthew D.; Turner, David D.

    2016-04-01

    Multi-instrument, ground-based measurements provide unique and comprehensive data sets of the atmosphere for a specific location over long periods of time and resulting data compliment past and existing global satellite observations. This paper explores the effect of ice hydrometeors on ground-based, high-frequency passive microwave measurements and attempts to isolate an ice signature for summer seasons at Summit, Greenland, from 2010 to 2013. Data from a combination of passive microwave, cloud radar, radiosonde, and ceilometer were examined to isolate the ice signature at microwave wavelengths. By limiting the study to a cloud liquid water path of 40 g m-2 or less, the cloud radar can identify cases where the precipitation was dominated by ice. These cases were examined using liquid water and gas microwave absorption models, and brightness temperatures were calculated for the high-frequency microwave channels: 90, 150, and 225 GHz. By comparing the measured brightness temperatures from the microwave radiometers and the calculated brightness temperature using only gas and liquid contributions, any residual brightness temperature difference is due to emission and scattering of microwave radiation from the ice hydrometeors in the column. The ice signature in the 90, 150, and 225 GHz channels for the Summit Station summer months was isolated. This measured ice signature was then compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single-scattering properties for several ice habits. Initial model results compare well against the 4 years of summer season isolated ice signature in the high-frequency microwave channels.

  8. Giant Ground Level Enhancement of Relativistic Solar Protons on 2005 January 20. I. Spaceship Earth Observations

    NASA Astrophysics Data System (ADS)

    Bieber, J. W.; Clem, J.; Evenson, P.; Pyle, R.; Sáiz, A.; Ruffolo, D.

    2013-07-01

    A ground level enhancement (GLE) is a solar event that accelerates ions (mostly protons) to GeV range energies in such great numbers that ground-based detectors, such as neutron monitors, observe their showers in Earth's atmosphere above the Galactic cosmic ray background. GLEs are of practical interest because an enhanced relativistic ion flux poses a hazard to astronauts, air crews, and aircraft electronics, and provides the earliest direct indication of an impending space radiation storm. The giant GLE of 2005 January 20 was the second largest on record (and largest since 1956), with up to 4200% count rate enhancement at sea level. We analyzed data from the Spaceship Earth network, supplemented to comprise 13 polar neutron monitor stations with distinct asymptotic viewing directions and Polar Bare neutron counters at South Pole, to determine the time evolution of the relativistic proton density, energy spectrum, and three-dimensional directional distribution. We identify two energy-dispersive peaks, indicating two solar injections. The relativistic solar protons were initially strongly beamed, with a peak maximum-to-minimum anisotropy ratio over 1000:1. The directional distribution is characterized by an axis of symmetry, determined independently for each minute of data, whose angle from the magnetic field slowly varied from about 60° to low values and then rose to about 90°. The extremely high relativistic proton flux from certain directions allowed 10 s tracking of count rates, revealing fluctuations of period >~ 2 minutes with up to 50% fractional changes, which we attribute to fluctuations in the axis of symmetry.

  9. The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations

    NASA Astrophysics Data System (ADS)

    Heymans, Catherine; Van Waerbeke, Ludovic; Bacon, David; Berge, Joel; Bernstein, Gary; Bertin, Emmanuel; Bridle, Sarah; Brown, Michael L.; Clowe, Douglas; Dahle, Håkon; Erben, Thomas; Gray, Meghan; Hetterscheidt, Marco; Hoekstra, Henk; Hudelot, Patrick; Jarvis, Mike; Kuijken, Konrad; Margoniner, Vera; Massey, Richard; Mellier, Yannick; Nakajima, Reiko; Refregier, Alexandre; Rhodes, Jason; Schrabback, Tim; Wittman, David

    2006-05-01

    The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In this first STEP paper, we present the results of a blind analysis of simulated ground-based observations of relatively simple galaxy morphologies. The most successful methods are shown to achieve percent level accuracy. From the cosmic shear pipelines that have been used to constrain cosmology, we find weak lensing shear measured to an accuracy that is within the statistical errors of current weak lensing analyses, with shear measurements accurate to better than 7 per cent. The dominant source of measurement error is shown to arise from calibration uncertainties where the measured shear is over or underestimated by a constant multiplicative factor. This is of concern as calibration errors cannot be detected through standard diagnostic tests. The measured calibration errors appear to result from stellar contamination, false object detection, the shear measurement method itself, selection bias and/or the use of biased weights. Additive systematics (false detections of shear) resulting from residual point-spread function anisotropy are, in most cases, reduced to below an equivalent shear of 0.001, an order of magnitude below cosmic shear distortions on the scales probed by current surveys. Our results provide a snapshot view of the accuracy of current ground-based weak lensing methods and a benchmark upon which we can improve. To this end we provide descriptions of each method tested and include details of the eight different implementations of the commonly used Kaiser, Squires & Broadhurst method (KSB+) to aid the improvement of future KSB+ analyses.

  10. Epigenetic Dysregulation Observed in Monosomy Blastocysts Further Compromises Developmental Potential.

    PubMed

    Denomme, Michelle M; McCallie, Blair R; Parks, Jason C; Schoolcraft, William B; Katz-Jaffe, Mandy G

    2016-01-01

    Epigenetic mechanisms such as DNA methylation regulate genomic imprinting and account for the distinct non-equivalence of the parental genomes in the embryo. Chromosomal aneuploidy, a major cause of infertility, distorts this highly regulated disparity by the presence or absence of chromosomes. The implantation potential of monosomy embryos is negligible compared to their trisomy counterparts, yet the cause for this is unknown. This study investigated the impact of chromosomal aneuploidy on strict epigenetically regulated domains, specifically imprinting control regions present on aneuploid chromosomes. Donated cryopreserved human IVF blastocysts of transferable quality, including trisomy 15, trisomy 11, monosomy 15, monosomy 11, and donor oocyte control blastocysts were examined individually for DNA methylation profiles by bisulfite mutagenesis and sequencing analysis of two maternally methylated imprinting control regions (ICRs), SNRPN (15q11.2) and KCNQ1OT1 (11p15.5), and one paternally methylated imprinting control region, H19 (11p15.5). Imprinted genes within the regions were also evaluated for transcript abundance by RT-qPCR. Overall, statistically significant hypermethylated and hypomethylated ICRs were found in both the trisomy and monosomy blastocysts compared to controls, restricted only to the chromosome affected by the aneuploidy. Increased expression was observed for maternally-expressed imprinted genes in trisomy blastocysts, while a decreased expression was observed for both maternally- and paternally-expressed imprinted genes in monosomy blastocysts. This epigenetic dysregulation and altered monoallelic expression observed at imprinting control regions in aneuploid IVF embryos supports euploid embryo transfer during infertility treatments, and may specifically highlight an explanation for the compromised implantation potential in monosomy embryos. PMID:27271036

  11. Epigenetic Dysregulation Observed in Monosomy Blastocysts Further Compromises Developmental Potential

    PubMed Central

    Denomme, Michelle M.; McCallie, Blair R.; Parks, Jason C.; Schoolcraft, William B.; Katz-Jaffe, Mandy G.

    2016-01-01

    Epigenetic mechanisms such as DNA methylation regulate genomic imprinting and account for the distinct non-equivalence of the parental genomes in the embryo. Chromosomal aneuploidy, a major cause of infertility, distorts this highly regulated disparity by the presence or absence of chromosomes. The implantation potential of monosomy embryos is negligible compared to their trisomy counterparts, yet the cause for this is unknown. This study investigated the impact of chromosomal aneuploidy on strict epigenetically regulated domains, specifically imprinting control regions present on aneuploid chromosomes. Donated cryopreserved human IVF blastocysts of transferable quality, including trisomy 15, trisomy 11, monosomy 15, monosomy 11, and donor oocyte control blastocysts were examined individually for DNA methylation profiles by bisulfite mutagenesis and sequencing analysis of two maternally methylated imprinting control regions (ICRs), SNRPN (15q11.2) and KCNQ1OT1 (11p15.5), and one paternally methylated imprinting control region, H19 (11p15.5). Imprinted genes within the regions were also evaluated for transcript abundance by RT-qPCR. Overall, statistically significant hypermethylated and hypomethylated ICRs were found in both the trisomy and monosomy blastocysts compared to controls, restricted only to the chromosome affected by the aneuploidy. Increased expression was observed for maternally-expressed imprinted genes in trisomy blastocysts, while a decreased expression was observed for both maternally- and paternally-expressed imprinted genes in monosomy blastocysts. This epigenetic dysregulation and altered monoallelic expression observed at imprinting control regions in aneuploid IVF embryos supports euploid embryo transfer during infertility treatments, and may specifically highlight an explanation for the compromised implantation potential in monosomy embryos. PMID:27271036

  12. Conjugate Observations of Optical Aurora with POLAR Satellite and Ground Based Imagers in Antarctica

    NASA Technical Reports Server (NTRS)

    Mende, S. H.; Frey, H.; Vo, H.; Geller, S. P.; Doolittle, J. H.; Spann, J. F., Jr.

    1998-01-01

    Operation of the ultraviolet imager on the POLAR satellite permits the observation of Aurora Borealis in daylight during northern summer. With optical imagers in the Automatic Geophysical Observatories (AGO-s) large regions of the oval of Aurora Australis can be observed simultaneously during the southern winter polar night. This opportunity permits conducting a systematic study of the properties of auroras on opposite ends of the same field line. It is expected that simultaneously observed conjugate auroras occurring on closed field lines should be similar to each other in appearance because of the close connection between the two hemispheres through particle scattering and mirroring processes. On open or greatly distorted field lines there is no a priori expectation of similarity between conjugate auroras. To investigate the influence of different IMF conditions on auroral behavior we have examined conjugate data for periods of southward IMF. Sudden brightening and subsequent poleward expansions are observed to occur simultaneously in both hemispheres. The POLAR data show that sudden brightening are initiated at various local time regions. When the local time of this region is in the field of view of the AGO station network then corresponding brightening is also found to occur in the southern hemisphere. Large features such as substorm induced westward propagation and resulting auroral brightening seem to occur simultaneously on conjugate hemispheres. The widely different view scales make it difficult to make unique identification of individual auroral forms in the POLAR and in the ground based data but in a general sense the data is consistent with conjugate behavior.

  13. Omega band pulsating auroras observed onboard THEMIS spacecraft and on the ground

    NASA Astrophysics Data System (ADS)

    Sato, Natsuo; Kadokura, Akira; Tanaka, Yoshimasa; Nishiyama, Takanori; Hori, Tomoaki; Yukimatu, Akira Sessai

    2015-07-01

    We examined a fortuitous case of an omega band pulsating aurora observed simultaneously on the ground at Sanikiluaq in Canada and onboard the Time History of Events and Macroscale Interactions during Substorm (THEMIS) spacecraft on 1 March 2011. We observed almost the entire process of the generation of the omega band aurora from the initial growth to the declining through expansion period. The omega band aurora grew from a faint seed, not via distortion of a preexisting east-west band aurora. The size scale of the omega band aurora during the maximum period was ~500 km in the north-south direction and ~200 km in the east-west direction. The mesoscale omega band aurora consisted of more than 15 patches of complex-shaped small-scale auroras. Each patch contained an intense pulsating aurora with a recurrent period of ~9-12 s and a poleward moving form. The footprints of the THEMIS D and THEMIS E spacecraft crossed the poleward part of the omega band aurora. THEMIS D observed significant signatures in the electromagnetic fields and particles associated with the time at which the spacecraft crossed the omega band aurora. In particular, it was found that the Y and Z components of the DC electric field intensity, especially the Z component, modulated with almost the same period as that of the optical pulsating auroras. The electrostatic low-frequency waves of less than 30 Hz showed quasiperiodic intensity variations similar to those of the DC electric field. These observations suggest that DC electric field variation and low-frequency electrostatic waves may play important roles in the driving mechanism of omega band pulsating auroras.

  14. Signal-to-noise enhancement in ground-based intensity observations of solar p modes

    NASA Technical Reports Server (NTRS)

    Germain, Marvin E.

    1995-01-01

    Intensity observations of solar p modes are needed to form a complete picture of wave propagation in the photosphere. Ground-based intensity observations are severely hampered by terrestrial atmospheric noise. Partial cancellation of the noise power can be achieved if two spectra having disparate signal-to- noise ratios, and based on time series acquired simultaneously at the same site, are combined. A method of combining the spectra is suggested in which one amplitude is scaled and subtracted from the other. The result is squared yielding a positive-definite power density. To test the method, the intensity of light scattered by the Earth's atmnosphere was recorded at fifteen- second intervals in two narrow bands centered on 0.5 microns and 1.6 microns. When the two resulting spectra were combined, the noise power was attenuated by a factor of 2.7. The scale factor was varied about its optimum value, revealing that noise peaks have a different siganture than signal peaks, and opening up the possibility of a new tool in discrimination against noise peaks. Maxima at symmetry-allowed frequencies and minima at symmetry- forbidden frequencies indicate that the possibility that these results are obtained by chance is only 6.1 x 10(exp -4). The positions of these maxima and minima also support the solar-cycle dependent frequency shifts found by Palle, Regulo, and Roca Cortes.

  15. HiRISE observations of new impact craters exposing Martian ground ice

    USGS Publications Warehouse

    Dundas, Colin M.; Byrne, Shane; McEwen, Alfred S.; Mellon, Michael T.; Kennedy, Megan R.; Daubar, Ingrid J.; Saper, Lee

    2014-01-01

    Twenty small new impact craters or clusters have been observed to excavate bright material inferred to be ice at mid and high latitudes on Mars. In the northern hemisphere, the craters are widely distributed geographically and occur at latitudes as low as 39°N. Stability modeling suggests that this ice distribution requires a long-term average atmospheric water vapor content around 25 precipitable microns, more than double the present value, which is consistent with the expected effect of recent orbital variations. Alternatively, near-surface humidity could be higher than expected for current column abundances if water vapor is not well-mixed with atmospheric CO2, or the vapor pressure at the ice table could be lower due to salts. Ice in and around the craters remains visibly bright for months to years, indicating that it is clean ice rather than ice-cemented regolith. Although some clean ice may be produced by the impact process, it is likely that the original ground ice was excess ice (exceeding dry soil pore space) in many cases. Observations of the craters suggest small-scale heterogeneities in this excess ice. The origin of such ice is uncertain. Ice lens formation by migration of thin films of liquid is most consistent with local heterogeneity in ice content and common surface boulders, but in some cases nearby thermokarst landforms suggest large amounts of excess ice that may be best explained by a degraded ice sheet.

  16. PSC and volcanic aerosol routine observations in Antarctica by UV-visible ground-based spectrometry

    NASA Technical Reports Server (NTRS)

    Sarkissian, A.; Pommereau, J. P.; Goutail, F.

    1994-01-01

    Polar statospheric clouds (PSC) and stratospheric aerosol can be observed by ground-based UV-visible spectrometry by looking at the variation of the color of the sky during twilight. A radiative transfer model shows that reddenings are caused by high altitude (22-28 km) thin layers of scatterers, while low altitude (12-20 km) thick ones result in blueings. The color index method applied on 4 years of observations at Dumont d'Urville (67 deg S), from 1988 to 1991, shows that probably because the station is located at the edge of the vortex, dense PSC are uncommon. More unexpected is the existence of a systematic seasonal variation of the color of the twilight sky - bluer at spring - which reveals the formation of a dense scattering layer at or just above the tropopause at the end of the winter. Large scattering layers are reported above the station in 1991, first in August around 12-14 km, later in September at 22-24 km. They are attributed to volcanic aerosol from Mt Hudson and Mt Pinatubo respectively, which erupted in 1991. Inspection of the data shows that the lowest entered rapidly into the polar vortex but not the highest which remained outside, demonstrating that the vortex was isolated at 22-26 km.

  17. The Palomar kernel-phase experiment: testing kernel phase interferometry for ground-based astronomical observations

    NASA Astrophysics Data System (ADS)

    Pope, Benjamin; Tuthill, Peter; Hinkley, Sasha; Ireland, Michael J.; Greenbaum, Alexandra; Latyshev, Alexey; Monnier, John D.; Martinache, Frantz

    2016-01-01

    At present, the principal limitation on the resolution and contrast of astronomical imaging instruments comes from aberrations in the optical path, which may be imposed by the Earth's turbulent atmosphere or by variations in the alignment and shape of the telescope optics. These errors can be corrected physically, with active and adaptive optics, and in post-processing of the resulting image. A recently developed adaptive optics post-processing technique, called kernel-phase interferometry, uses linear combinations of phases that are self-calibrating with respect to small errors, with the goal of constructing observables that are robust against the residual optical aberrations in otherwise well-corrected imaging systems. Here, we present a direct comparison between kernel phase and the more established competing techniques, aperture masking interferometry, point spread function (PSF) fitting and bispectral analysis. We resolve the α Ophiuchi binary system near periastron, using the Palomar 200-Inch Telescope. This is the first case in which kernel phase has been used with a full aperture to resolve a system close to the diffraction limit with ground-based extreme adaptive optics observations. Excellent agreement in astrometric quantities is found between kernel phase and masking, and kernel phase significantly outperforms PSF fitting and bispectral analysis, demonstrating its viability as an alternative to conventional non-redundant masking under appropriate conditions.

  18. Convective cloud fields in the Atlantic sector of the Arctic: Satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Esau, I. N.; Chernokulsky, A. V.

    2015-12-01

    Convective cloudiness in the Atlantic sector of the Arctic is considered as an atmospheric spatially self-organized convective field. Convective cloud development is usually studied as a local process reflecting the convective instability of the turbulent planetary boundary layer over a heated surface. The convective cloudiness has a different dynamical structure in high latitudes. Cloud development follows cold-air outbreaks into the areas with a relatively warm surface. As a result, the physical and morphological characteristics of clouds, such as the type of convective cloud, and their geographical localization are interrelated. It has been shown that marginal sea ice and coastal zones are the most frequently occupied by Cu hum, Cu med convective clouds, which are organized in convective rolls. Simultaneously, the open water marine areas are occupied by Cu cong, Cb, which are organized in convective cells. An intercomparison of cloud statistics using satellite data ISCCP and ground-based observations has revealed an inconsistency in the cloudiness trends in these data sources: convective cloudiness decreases in ISCCP data and increases in the groundbased observation data. In general, according to the stated hypothesis, the retreat of the sea-ice boundary may lead to an increase in the amount of convective clouds.

  19. Tragaldabas: a muon ground-based detector for the study of the solar activity; first observations

    NASA Astrophysics Data System (ADS)

    José Blanco, Juan

    2016-04-01

    A new RPC-based cosmic ray detector, TRAGALDABAS (acronym of "TRAsGo for the AnaLysis of the nuclear matter Decay, the Atmosphere, the earth's B-field And the Solar activity") has been installed at the Univ. of Santiago de Compostela, Spain (N:42°52'34",W:8°33'37"). The detector, in its present layout, consists of three 1.8 m2 planes of three 1mm-gap glass RPCs. Each plane is readout with 120 pads with grounded guard electrodes between them to minimize the crosstalk noise. The main performances of the detectors are: an arrival time resolution of about ~300 ps, a tracking angular resolution below 3°, a detection efficiency close to 1, and a solid angle acceptance of ~5 srad. TRAGALDABAS will be able to monitor the cosmic ray low energy component strongly modulated by solar activity by mean the observation of secondary muons from the interaction between cosmic rays and atmospheric molecules. Its cadence and its angular resolution will allow to study in detail, small variations in cosmic ray anisotropy. These variations can be a key parameter to understand the effect of solar disturbances on the propagation of cosmic ray in the inner heliosphere and, maybe, provide a new tool for space weather analysis. In this work first TRAGALDABAS observations of solar events are shown

  20. Observation of the bottomonium ground state in the decay Upsilon(3S)-->gammaetab.

    PubMed

    Aubert, B; Bona, M; Karyotakis, Y; Lees, J P; Poireau, V; Prencipe, E; Prudent, X; Tisserand, V; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Pappagallo, M; Eigen, G; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Cahn, R N; Jacobsen, R G; Kerth, L T; Kolomensky, Yu G; Lynch, G; Osipenkov, I L; Ronan, M T; Tackmann, K; Tanabe, T; Hawkes, C M; Soni, N; Watson, A T; Koch, H; Schroeder, T; Walker, D; Asgeirsson, D J; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Barrett, M; Khan, A; Blinov, V E; Bukin, A D; Buzykaev, A R; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Gary, J W; Liu, F; Long, O; Shen, B C; Vitug, G M; Yasin, Z; Zhang, L; Sharma, V; Campagnari, C; Hong, T M; Kovalskyi, D; Mazur, M A; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Martinez, A J; Schalk, T; Schumm, B A; Seiden, A; Wilson, M G; Winstrom, L O; Cheng, C H; Doll, D A; Echenard, B; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Andreassen, R; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Bloom, P C; Ford, W T; Gaz, A; Hirschauer, J F; Nagel, M; Nauenberg, U; Smith, J G; Ulmer, K A; Wagner, S R; Ayad, R; Soffer, A; Toki, W H; Wilson, R J; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Karbach, M; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Kobel, M J; Mader, W F; Nogowski, R; Schubert, K R; Schwierz, R; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Verderi, M; Clark, P J; Playfer, S; Watson, J E; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Santoro, V; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Adametz, A; Marks, J; Schenk, S; Uwer, U; Klose, V; Lacker, H M; Bard, D J; Dauncey, P D; Nash, J A; Tibbetts, M; Behera, P K; Chai, X; Charles, M J; Mallik, U; Cochran, J; Crawley, H B; Dong, L; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y Y; Gritsan, A V; Guo, Z J; Lae, C K; Arnaud, N; Béquilleux, J; D'Orazio, A; Davier, M; da Costa, J Firmino; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Burke, J P; Chavez, C A; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Touramanis, C; Bevan, A J; Clarke, C K; George, K A; Di Lodovico, F; Sacco, R; Sigamani, M; Cowan, G; Flaecher, H U; Hopkins, D A; Paramesvaran, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Denig, A G; Fritsch, M; Gradl, W; Schott, G; Alwyn, K E; Bailey, D; Barlow, R J; Chia, Y M; Edgar, C L; Jackson, G; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Dallapiccola, C; Li, X; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Sciolla, G; Spitznagel, M; Taylor, F; Yamamoto, R K; Zhao, M; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, G; Lista, L; Monorchio, D; Onorato, G; Sciacca, C; Raven, G; Snoek, H L; Jessop, C P; Knoepfel, K J; LoSecco, J M; Wang, W F; Benelli, G; Corwin, L A; Honscheid, K; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Sekula, S J; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Castelli, G; Gagliardi, N; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; del Amo Sanchez, P; Ben-Haim, E; Briand, H; Calderini, G; Chauveau, J; David, P; Del Buono, L; Hamon, O; Leruste, Ph; Ocariz, J; Perez, A; Prendki, J; Sitt, S; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Carpinelli, M; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Lopes Pegna, D; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Anulli, F; Baracchini, E; Cavoto, G; del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Gioi, L Li; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Franek, B; Olaiya, E O; Wilson, F F; Emery, S; Escalier, M; Esteve, L; Ganzhur, S F; de Monchenault, G Hamel; Kozanecki, W; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; White, R M; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Benitez, J F; Bertsche, K; Cai, Y; Cenci, R; Coleman, J P; Convery, M R; Decker, F J; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Ecklund, S; Erickson, R; Field, R C; Fisher, A; Fox, J; Gabareen, A M; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Innes, W R; Iverson, R; Kaminski, J; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Kulikov, A; Leith, D W G S; Li, S; Lindquist, B; Luitz, S; Luth, V; Lynch, H L; Macfarlane, D B; Marsiske, H; Messner, R; Muller, D R; Neal, H; Nelson, S; Novokhatski, A; O'Grady, C P; Ofte, I; Perazzo, A; Perl, M; Ratcliff, B N; Rivetta, C; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Seeman, J; Snyder, A; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; Van Winkle, D; Wagner, A P; Weaver, M; West, C A; Wienands, U; Wisniewski, W J; Wittgen, M; Wittmer, W; Wright, D H; Wulsin, H W; Yan, Y; Yarritu, A K; Yi, K; Yocky, G; Young, C C; Ziegler, V; Burchat, P R; Edwards, A J; Majewski, S A; Miyashita, T S; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Ernst, J A; Pan, B; Saeed, M A; Zain, S B; Spanier, S M; Wogsland, B J; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Drummond, B W; Izen, J M; Lou, X C; Bianchi, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Choi, H H F; Hamano, K; Kowalewski, R; Lewczuk, M J; Nugent, I M; Roney, J M; Sobie, R J; Gershon, T J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Band, H R; Chen, X; Dasu, S; Flood, K T; Pan, Y; Pierini, M; Prepost, R; Vuosalo, C O; Wu, S L

    2008-08-15

    We report the results of a search for the bottomonium ground state etab(1S) in the photon energy spectrum with a sample of (109+/-1) million of Upsilon(3S) recorded at the Upsilon(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. We observe a peak in the photon energy spectrum at Egamma=921.2(-2.8)+2.1(stat)+/-2.4(syst) MeV with a significance of 10 standard deviations. We interpret the observed peak as being due to monochromatic photons from the radiative transition Upsilon(3S)-->gammaetab(1S). This photon energy corresponds to an etab(1S) mass of 9388.9(-2.3)+3.1(stat)+/-2.7(syst) MeV/c2. The hyperfine Upsilon(1S)-etab(1S) mass splitting is 71.4(-3.1)+2.3(stat)+/-2.7(syst) MeV/c2. The branching fraction for this radiative Upsilon(3S) decay is estimated to be [4.8+/-0.5(stat)+/-1.2(syst)]x10(-4). PMID:18764521

  1. HiRISE observations of new impact craters exposing Martian ground ice

    NASA Astrophysics Data System (ADS)

    Dundas, Colin M.; Byrne, Shane; McEwen, Alfred S.; Mellon, Michael T.; Kennedy, Megan R.; Daubar, Ingrid J.; Saper, Lee

    2014-01-01

    Twenty small new impact craters or clusters have been observed to excavate bright material inferred to be ice at mid-latitudes and high latitudes on Mars. In the northern hemisphere, the craters are widely distributed geographically and occur at latitudes as low as 39°N. Stability modeling suggests that this ice distribution requires a long-term average atmospheric water vapor content around 25 precipitable micrometers, more than double the present value, which is consistent with the expected effect of recent orbital variations. Alternatively, near-surface humidity could be higher than expected for current column abundances if water vapor is not well mixed with atmospheric CO2, or the vapor pressure at the ice table could be lower due to salts. Ice in and around the craters remains visibly bright for months to years, indicating that it is clean ice rather than ice-cemented regolith. Although some clean ice may be produced by the impact process, it is likely that the original ground ice was excess ice (exceeding dry soil pore space) in many cases. Observations of the craters suggest small-scale heterogeneities in this excess ice. The origin of such ice is uncertain. Ice lens formation by migration of thin films of liquid is most consistent with local heterogeneity in ice content and common surface boulders, but in some cases, nearby thermokarst landforms suggest large amounts of excess ice that may be best explained by a degraded ice sheet.

  2. Astrometric Star Catalogues as Combination of Hipparcos/Tycho Catalogues with Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Vondrak, J.

    The successful ESA mission Hipparcos provided very precise parallaxes, positions and proper motions of many stars in optical wavelength. Therefore, it is a primary representation of International Celestial Reference System in this wavelength. However, the shortness of the mission (less than four years) causes some problems with proper motions of the stars that are double or multiple. Therefore, a combination of the positions measured by Hipparcos satellite with ground-based observations with much longer history provides a better reference frame that is more stable in time. Several examples of such combinations are presented (ACT, TYCHO-2, FK6, GC+HIP, TYC2+HIP, ARIHIP) and briefly described. The stress is put on the most recent Earth Orientation Catalogue (EOC) that uses about 4.4 million optical observations of latitude/universal time variations (made during the twentieth century at 33 observatories in Earth orientation programmes), in combination with some of the above mentioned combined catalogues. The second version of the new catalogue EOC-2 contains 4418 objects, and the precision of their proper motions is far better than that of Hipparcos Catalogue.

  3. Upscaling sparse ground-based soil moisture observations for the validation of coarse-resolution satellite soil moisture products

    NASA Astrophysics Data System (ADS)

    Crow, Wade T.; Berg, Aaron A.; Cosh, Michael H.; Loew, Alexander; Mohanty, Binayak P.; Panciera, Rocco; de Rosnay, Patricia; Ryu, Dongryeol; Walker, Jeffrey P.

    2012-06-01

    The contrast between the point-scale nature of current ground-based soil moisture instrumentation and the ground resolution (typically >102 km2) of satellites used to retrieve soil moisture poses a significant challenge for the validation of data products from current and upcoming soil moisture satellite missions. Given typical levels of observed spatial variability in soil moisture fields, this mismatch confounds mission validation goals by introducing significant sampling uncertainty in footprint-scale soil moisture estimates obtained from sparse ground-based observations. During validation activities based on comparisons between ground observations and satellite retrievals, this sampling error can be misattributed to retrieval uncertainty and spuriously degrade the perceived accuracy of satellite soil moisture products. This review paper describes the magnitude of the soil moisture upscaling problem and measurement density requirements for ground-based soil moisture networks. Since many large-scale networks do not meet these requirements, it also summarizes a number of existing soil moisture upscaling strategies which may reduce the detrimental impact of spatial sampling errors on the reliability of satellite soil moisture validation using spatially sparse ground-based observations.

  4. High-precision ground-based observations of transiting exoplanets to detect their magnetic fields and undiscovered companions

    NASA Astrophysics Data System (ADS)

    Ryleigh Fitzpatrick, Morgan; Watson, Zachary; Zellem, Robert; Pearson, Kyle; Griffith, Caitlin Ann; AzGOE

    2015-01-01

    Here we present U and B band photometric light curves of several bright transiting exoplanets observed with the University of Arizona's 61''/Mont4k in order to better determine their physical parameters and search for their magnetic fields and undiscovered planetary companions. Recent studies suggest that it is possible to determine the presence and constrain the strength of a magnetic field by observing an exoplanet's bow shock. The shock would be detected via asymmetries in the UV and optical light curves, specifically if the ingress in the near-UV occurs earlier than in the optical. The size of this offset indicates the planet's magnetic field strength. In addition, our photometry, which spans multiple nights, is used to more precisely measure the radius of these exoplanets and determine any transit timing variations that could potentially indicate a nearby companion. The data are reduced via an in-house, publicly available pipeline, ExoDRPL. Our research group, AzGOE, is made primarily of undergraduate students from the University of Arizona in cooperation with the University of Arizona Astronomy Club, and gives these students the ability to take, reduce, and publish their own ground based observations.

  5. Assessing the Leakage Potential of CO2 into Ground Water Resources at SACROC, West Texas

    NASA Astrophysics Data System (ADS)

    Stauffer, P. H.; Pawar, R. J.; Han, W. S.; McPherson, B. J.

    2008-12-01

    In this paper we apply CO2-PENS to characterize the long-term CO2 storage performance at SACROC, specifically with respect to potential impacts on ground water resources located above the CO2 injection depth. CO2-PENS is a hybrid process/system model composed of a library of process level modules linked together to allow simulations to span a range of spatial and temporal scales. SACROC is the oldest CO2-EOR operation in the Permian Basin and has been operational for over 35 years. We describe how CO2-PENS is used to couple CO2 migration at three different scales; from a reservoir module, through a borehole leakage module, and into an aquifer impact module. Both the reservoir module and wellbore leakage module are based on abstractions of the underlying physics of multiphase fluid flow, using reductions in complexity to allow fast Monte-Carlo simulation while capturing the behavior of these processes. Finally, we show how results from CO2-PENS can be used to delineate areas that are susceptible to ground water impacts from CO2 leakage and discuss how this information can be used in risk analysis.

  6. Determination of chlorophyll photosynthetic potential in vegetation using ground-based and satellite methods

    NASA Astrophysics Data System (ADS)

    Botvich, Irina; Alexander, Sidko; Pisman, Tamara; Shevyrnogov, Anatoly

    An integrated study of the vegetation in the south of Krasnoyarsk Territory was carried out on the basis of ground-based and satellite remote measurements. The research objects were agricultural crops (wheat, oats) during the vegetation period. The satellite calculations were based on the data having high (Landsat 7 ETM+) and medium spatial resolution (Terra-Modis). Both kinds of data were used to calculate the chlorophyll photosynthetic potential (CPSP) as the area of the triangle made up by the reflection values in the green, red and near infrared spectrum regions. The connection was determined between the ground-based and satellite measurements of CPSP. Having analyzed the remote field and satellite measurements of the brightness spectral ratios of agricultural crops during vegetation, we showed the possibility of estimation of structural changes in the near infrared spectrum region. A lack or excess of water in plants causes structural changes in their phytoelements, which affects their reflectance. We showed the possibility of assessing morpho-physiological changes and species composition of crops. We determined the correlation between the spectral reflectance in various crops with chlorophyll content in plants and biomass changes.

  7. Potential use of ground-based sensor technologies for weed detection.

    PubMed

    Peteinatos, Gerassimos G; Weis, Martin; Andújar, Dionisio; Rueda Ayala, Victor; Gerhards, Roland

    2014-02-01

    Site-specific weed management is the part of precision agriculture (PA) that tries to effectively control weed infestations with the least economical and environmental burdens. This can be achieved with the aid of ground-based or near-range sensors in combination with decision rules and precise application technologies. Near-range sensor technologies, developed for mounting on a vehicle, have been emerging for PA applications during the last three decades. These technologies focus on identifying plants and measuring their physiological status with the aid of their spectral and morphological characteristics. Cameras, spectrometers, fluorometers and distance sensors are the most prominent sensors for PA applications. The objective of this article is to describe-ground based sensors that have the potential to be used for weed detection and measurement of weed infestation level. An overview of current sensor systems is presented, describing their concepts, results that have been achieved, already utilized commercial systems and problems that persist. A perspective for the development of these sensors is given.

  8. Evaluating the Potential for Landfill Leachate to Affect Surface and Ground Water Quality

    NASA Astrophysics Data System (ADS)

    Pederson, D. T.; Towerton, M. M.

    2005-12-01

    As precipitation percolates through waste in a landfill, contaminants associated with waste dissolve, forming leachate. Landfill leachate has the potential to pollute ground and surface water if not properly managed. Predicting chemical parameters and quantity of leachate generated is vital not only to understand how ground and surface water may be affected by landfill leachate, but also useful in determining when leachate components are in compliance with US Environment Protection Agency's drinking water standards. The Bluff Road landfill in Lincoln, Nebraska provided sixteen years of data from active land filling operation. Data included quarterly chemical analyses of leachate and quantity of leachate generated. Linear regression between chemical parameters and time determine if the long-term concentration trend is increasing, decreasing, or stable. Predictions of quantity of leachate generated were made through application of a published model. Long-term trends for inorganic macro components appear to mirror each other indicating that physical processes dominate over chemical processes. Heavy metal concentrations show a decline with time for all parameters except for iron, cadmium, and copper which is in agreement with published studies. Modeling the quantity of leachate generated was successful in duplicating the general trend of measured values, but was not accurate in matching quantitative values.

  9. Sub-Seasonal Variability of Tropical Rainfall Observed by TRMM and Ground-based Polarimetric Radar

    NASA Astrophysics Data System (ADS)

    Dolan, Brenda; Rutledge, Steven; Lang, Timothy; Cifelli, Robert; Nesbitt, Stephen

    2010-05-01

    Studies of tropical precipitation characteristics from the TRMM-LBA and NAME field campaigns using ground-based polarimetric S-band data have revealed significant differences in microphysical processes occurring in the various meteorological regimes sampled in those projects. In TRMM-LMA (January-February 1999 in Brazil; a TRMM ground validation experiment), variability is driven by prevailing low-level winds. During periods of low-level easterlies, deeper and more intense convection is observed, while during periods of low-level westerlies, weaker convection embedded in widespread stratiform precipitation is common. In the NAME region (North American Monsoon Experiment, summer 2004 along the west coast of Mexico), strong terrain variability drives differences in precipitation, with larger drops and larger ice mass aloft associated with convection occurring over the coastal plain compared to convection over the higher terrain of the Sierra Madre Occidental, or adjacent coastal waters. Comparisons with the TRMM precipitation radar (PR) indicate that such sub-seasonal variability in these two regions are not well characterized by the TRMM PR reflectivity and rainfall statistics. TRMM PR reflectivity profiles in the LBA region are somewhat lower than S-Pol values, particularly in the more intense easterly regime convection. In NAME, mean reflectivities are even more divergent, with TRMM profiles below those of S-Pol. In both regions, the TRMM PR does not capture rain rates above 80 mm hr-1 despite much higher rain rates estimated from the S-Pol polarimetric data, and rain rates are generally lower for a given reflectivity from TRMM PR compared to S-Pol. These differences between TRMM PR and S-Pol may arise from the inability of Z-R relationships to capture the full variability of microphysical conditions or may highlight problems with TRMM retrievals over land. In addition to the TRMM-LBA and NAME regions, analysis of sub-seasonal precipitation variability and

  10. Testing the inversion of asteroids' Gaia photometry combined with ground-based observations

    NASA Astrophysics Data System (ADS)

    Santana-Ros, T.; Bartczak, P.; Michałowski, T.; Tanga, P.; Cellino, A.

    2015-06-01

    We investigated the reliability of the genetic algorithm which will be used to invert the photometric measurements of asteroids collected by the European Space Agency Gaia mission. To do that, we performed several sets of simulations for 10 000 asteroids having different spin axis orientations, rotational periods and shapes. The observational epochs used for each simulation were extracted from the Gaia mission simulator developed at the Observatoire de la Côte d'Azur, while the brightness was generated using a Z-buffer standard graphic method. We also explored the influence on the inversion results of contaminating the data set with Gaussian noise with different σ values. The research enabled us to determine a correlation between the reliability of the inversion method and the asteroid's pole latitude. In particular, the results are biased for asteroids having quasi-spherical shapes and low pole latitudes. This effect is caused by the low light-curve amplitude observed under such circumstances, as the periodic signal can be lost in the photometric random noise when both values are comparable, causing the inversion to fail. Such bias might be taken into account when analysing the inversion results, not to mislead it with physical effects such as non-gravitational forces. Finally, we studied what impact on the inversion results has combining a full light curve and Gaia photometry collected simultaneously. Using this procedure we have shown that it is possible to reduce the number of wrong solutions for asteroids having less than 50 data points. The latter will be of special importance for planning ground-based observations of asteroids aiming to enhance the scientific impact of Gaia on Solar system science.

  11. Polarization analysis of Pc 1 geomagnetic pulsations at multi-point ground observations at middle latitudes

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Shiokawa, K.; Shevtsov, B. M.

    2008-12-01

    Pc 1 geomagnetic pulsations propagate from the high-latitude source region to middle latitudes in the ionosphere. The high-latitude source region links to the magnetosphere where ion cyclotron instability occurs around the plasmapause. Since Pc 1 pulsation observed by ground magnetometers at middle latitudes can be a mixture of waves from several high-latitude source regions, the polarization analysis of Pc 1 pulsations enables us to understand the spatial structure and time variations of the high-latitude source region. In order to investigate spectral and propagation characteristics of the Pc 1 at mid-latitudes, we have installed three induction magnetometers at Paratunka (PTK, 53.0N, 158.2E, magnetic latitude (MLAT): 45.8N), Moshiri (MSR, 44.4N, 142.3E, MLAT: 35.7N) and Sata (STA, 31.0N, 130.7E, MLAT: 22.0N). The observations with a 64-Hz sample recording have been started on July 5, 2007, at MSR, on August 21, 2007, at PTK, and on September 5, 2007, at STA and will be started at Magadan (MGD, 59.7N, 151.0E, MLAT: 50.6N) on November 2008. Polarization analysis with these multi-point data indicates that the Pc 1 polarization directions on November 11, 2007 depend on frequency with a difference of ~30 degree. For December 17, 2007 event, the polarization angle varies in time for ~30 deg/hour. These facts may indicate either the structure and motion of the high-latitude Pc 1 source region or the effects of the duct propagations in the inhomogeneous ionosphere. In this presentation, we also show the statistical results of these polarization analyses using 1-year data of middle latitude Pc 1 observations.

  12. Geomorphological Evidence for Pervasive Ground Ice on Ceres from Dawn Observations of Craters and Flows.

    NASA Astrophysics Data System (ADS)

    Schmidt, B. E.; Chilton, H.; Hughson, K.; Scully, J. E. C.; Russell, C. T.; Sizemore, H. G.; Nathues, A.; Platz, T.; Bland, M. T.; Schenk, P.; Hiesinger, H.; Jaumann, R.; Byrne, S.; Schorghofer, N.; Ammannito, E.; Marchi, S.; O'Brien, D. P.; Sykes, M. V.; Le Corre, L.; Capria, M. T.; Reddy, V.; Raymond, C. A.; Mest, S. C.; Feldman, W. C.

    2015-12-01

    Five decades of observations of Ceres' albedo, surface composition, shape and density suggest that Ceres is comprised of both silicates and tens of percent of ice. Historical suggestions of surficial hydrated silicates and evidence for water emission, coupled with its bulk density of ~2100 kg/m3 and Dawn observations of young craters containing high albedo spots support this conclusion. We report geomorphological evidence from survey data demonstrating that evaporative and fluid-flow processes within silicate-ice mixtures are prevalent on Ceres, and indicate that its surface materials contain significant water ice. Here we highlight three classes of features that possess strong evidence for ground ice. First, ubiquitous scalloped and "breached" craters are characterized by mass wasting and by the recession of crater walls in asymmetric patterns; these appear analogous to scalloped terrain on Mars and protalus lobes formed by mass wasting in terrestrial glaciated regions. The degradation of crater walls appears to be responsible for the nearly complete removal of some craters, particularly at low latitudes. Second, several high latitude, high elevation craters feature lobed flows that emanate from cirque-shaped head walls and bear strikingly similar morphology to terrestrial rock glaciers. These similarities include lobate toes and indications of furrows and ridges consistent with ice-cored or ice-cemented material. Other lobed flows persist at the base of crater walls and mass wasting features. Many flow features evidently terminate at ramparts. Third, there are frequent irregular domes, peaks and mounds within crater floors that depart from traditional crater central peaks or peak complexes. In some cases the irregular domes show evidence for high albedo or activity, and thus given other evidence for ice, these could be due to local melt and extrusion via hydrologic gradients, forming domes similar to pingos. The global distribution of these classes of features

  13. Ground and satellite observations of multiple sun-aligned auroral arcs on the duskside

    NASA Astrophysics Data System (ADS)

    Hosokawa, K.; Maggiolo, R.; Zhang, Y.; Fear, R. C.; Fontaine, D.; Cumnock, J. A.; Kullen, A.; Milan, S. E.; Kozlovsky, A.; Echim, M.; Shiokawa, K.

    2014-12-01

    Sun-aligned auroral arcs (SAAs) are one of the outstanding phenomena in the high-latitude region during periods of northward interplanetary magnetic field (IMF). Smaller scale SAAs tend to occur either in the duskside or dawnside of the polar cap and are known to drift in the dawn-dusk direction depending on the sign of the IMF By. Studies of SAAs are of particular importance because they represent dynamical characteristics of their source plasma in the magnetosphere, for example in the interaction region between the solar wind and magnetosphere or in the boundary between the plasma sheet and tail lobe. To date, however, very little has been known about the spatial structure and/or temporal evolution of the magnetospheric counterpart of SAAs. In order to gain more comprehensive understanding of the field-aligned plasma transport in the vicinity of SAAs, we have investigated an event of SAAs on November 10, 2005, during which multiple SAAs were detected by a ground-based all-sky camera at Resolute Bay, Canada. During this interval, several SAAs were detached from the duskside oval and moved poleward. The large-scale structure of these arcs was visualized by space-based imagers of TIMED/GUVI and DMSP/SSUSI. In addition to these optical observations, we employ the Cluster satellites to reveal the high-altitude particle signature corresponding to the small-scale SAAs. The ionospheric footprints of the 4 Cluster satellites encountered the SAAs sequentially and observed well correlated enhancements of electron fluxes at weak energies (< 1 keV). The Cluster satellites also detected signatures of upflowing beams of ions and electrons in the vicinity of the SAAs. This implies that these ions and electrons were accelerated upward by a quasi-stationary electric field existing in the vicinity of the SAAs and constitute a current system in the magnetosphere-ionosphere coupling system. Ionospheric convection measurement from one of the SuperDARN radars shows an indication that

  14. Monitoring geospace disturbances through coordinated space-borne and ground-based magnetometer observations

    NASA Astrophysics Data System (ADS)

    Balasis, Georgios

    2014-05-01

    Recently automated methods of deriving the characteristics of ultra low frequency (ULF) waves in the magnetosphere have been developed (Balasis et al., 2012, 2013), which can be effectively applied to the huge datasets from the new ESA Swarm mission, in order to retrieve, on an operational basis, new information about the near-Earth electromagnetic environment. Processing Swarm measurements with these methods will help to elucidate the processes influencing the generation and propagation of ULF waves, which in turn play a crucial role in magnetospheric dynamics. Moreover, a useful platform based on a combination of wavelet transforms and artificial neural networks has been developed to monitor the wave evolution from the outer boundaries of Earth's magnetosphere through the topside ionosphere down to the surface. Data from a Low Earth Orbit (LEO) satellite (CHAMP) and two magnetospheric missions (Cluster and Geotail) along with three ground-based magnetic networks (CARISMA, GIMA and IMAGE), during the Halloween 2003 magnetic superstorm when the Cluster and CHAMP spacecraft were in good local time (LT) conjunction, are used to demonstrate the potential of the analysis technique in studying wave evolution in detail.

  15. Effects on motor unit potentiation and ground reaction force from treadmill exercise

    NASA Technical Reports Server (NTRS)

    Elam, Reid P.

    1989-01-01

    This study was conducted to analyze the characteristics of motor unit potentiation (MUP) and ground reaction force (GRF) in treadmill exercise at the inclines of 0, 5.5 and 11 percent with conjuctive speeds of 7.5, 6, and 5 mph respectively. These speeds and corresponding inclines were set to provide equivalent physiological workloads at 12.5 METS. EMG recordings were taken from the rectus femoris and gastrocnemius of the right leg from 5 subjects. Simultaneous GRF recordings were obtained from a Delmar Avionic treadmill rigged with load cells. Measures for MUP and GRF were taken over a period containing 10 strides at steady pace. It was concluded that the gastrocnemius was more evident in EMG activity in all speed/incline settings over the rectus femoris, and that inclines from 5.5 to 11 percent produced greater GRF's over 0 percent. Recommendations for future studies was made.

  16. Degenerate ground states and nonunique potentials: Breakdown and restoration of density functionals

    SciTech Connect

    Capelle, K.; Ullrich, C. A.; Vignale, G.

    2007-07-15

    The Hohenberg-Kohn (HK) theorem is one of the most fundamental theorems of quantum mechanics, and constitutes the basis for the very successful density-functional approach to inhomogeneous interacting many-particle systems. Here we show that in formulations of density-functional theory (DFT) that employ more than one density variable, applied to systems with a degenerate ground state, there is a subtle loophole in the HK theorem, as all mappings between densities, wave functions, and potentials can break down. Two weaker theorems which we prove here, the joint-degeneracy theorem and the internal-energy theorem, restore the internal, total, and exchange-correlation energy functionals to the extent needed in applications of DFT to atoms, molecules, and solids. The joint-degeneracy theorem constrains the nature of possible degeneracies in general many-body systems.

  17. ITAIPU HVDC ground electrodes; Interference considerations and potential curve measurements during Bipole 2 commissioning

    SciTech Connect

    Caroli, C.E.; Santos, N. ); Kovarsky, D.; Pinto, L.J. )

    1990-07-01

    During the commissioning of Bipole II electrodes, important performance aspects were brought to light, in addition to those reported previously, after the measurements made during Bipole I commissioning. The following aspects are treated in the paper: the mutual influence between two neighboring electrodes was examined, leading to a simple methodology for the measurement of the grounding resistance of one of them, provided the other's resistance is known; Electrode I curves were remeasured after 2 1/2 years, and the changes in these curves quantified; measurements in more favorable conditions in an irrigation system were analyzed, leading to a change in the touch potential calculation method previously adopted; and the allowable voltage limits for immersed body situations were reviewed leading to appropriate mitigation criteria for a floating dredge installation.

  18. Ground-based RGB imaging to determine the leaf water potential of potato plants

    NASA Astrophysics Data System (ADS)

    Zakaluk, Robert F.

    The determination of plant water status from leaf water potential (Psi L) data obtained by conventional methods is impractical for meeting real time irrigation monitoring requirements. This research, undertaken first, in a greenhouse and then in the field, examined the use of artificial neural network (ANN) modeling of RGB (red green blue) images, captured by a ground-based, five mega pixel digital camera, to predict the leaf water potential of potato (Solanum tuberosum L). The greenhouse study examined cv. Russet Burbank, while the field study examined cv. Sangre. The protocol was similar in both studies: (1) images were acquired over different soil nitrate (N) and volumetric water content levels, (2) images were radiometrically calibrated, (3) green foliage was classified and extracted from the images, and (4) image transformations, and vegetation indices were calculated and transformed using principal components analysis (PCA). The findings from both studies were similar: (1) the R and G bands were more important than the B image band in the classification of green leaf pigment, (2) soil N showed an inverse linear relationship against leaf reflectance in the G image band, (3) the ANN model input neuron weights with more separation between soil N and PsiL were more important than other input neurons in predicting PsiL, and (4) the measured and predicted PsiL validation datasets were normally distributed with equal variances and means that were not significantly different. Based on these research findings, the ground-based digital camera proved to be an adequate sensor for image acquisition and a practical tool for acquiring data for predicting the PsiL of potato plants. Keywords: nitrogen, IHS transformation, chromaticity transformation, principal components, vegetation indices, remote sensing, artificial neural network, digital camera.

  19. Ground states of nonlinear Choquard equations with multi-well potentials

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Xiang, Jianlin; Zeng, Xiaoyu

    2016-08-01

    In this paper, we study minimizers of the Hartree-type energy functional E a ( u ) ≔ ∫ R N (" separators=" |" separators=" ∇ u ( x ) | 2 + V ( x ) |" separators=" u ( x ) | 2 " separators=" ) d x - /a p ∫ R N (" separators=" I α ∗ |" separators=" u ( x ) | p " separators=" ) |" separators=" u ( x ) | p d x , a ≥ 0 under the mass constraint ∫ R N |" separators=" u | 2 d x = 1 , where p = /N + α + 2 N with α ∈ (0, N) for N ≥ 2 is the mass critical exponent. Here Iα denotes the Riesz potential and the trapping potential 0 ≤ V ( x ) ∈ Lloc ∞ ( R N ) satisfies lim |" separators=" x | → ∞ V ( x ) = ∞ . We prove that minimizers exist if and only if a satisfies a < a ∗ = ↑"separators=" Q ↑ 2 2 ( p - 1 ) , where Q is a positive radially symmetric ground state of - Δ u + u = ( I α ∗ |" separators=" u | p ) |" separators=" u | p - 2 u in ℝN. The uniqueness of positive minimizers holds if a > 0 is small enough. The blow-up behavior of positive minimizers as a↗a∗ is also derived under some general potentials. Especially, we prove that minimizers must blow up at the central point of the biggest inscribed sphere of the set Ω ≔ {x ∈ ℝN, V(x) = 0} if |" separators=" Ω | > 0 .

  20. Using Apollo Sites and Soils to Compositionally Ground Truth Diviner Lunar Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Greenhagen, Benjamin T.; Lucey, P. G.; Song, E.; Thomas, I R.; Bowles, N. E.; DonaldsonHanna, K. L.; Allen, C.; Foote, E. J.; Paige, D .A.

    2012-01-01

    Apollo landing sites and returned soils afford us a unique opportunity to "ground truth" Diviner Lunar Radiometer compositional observations, which are the first global, high resolution , thermal infrared measurements of an airless body. The Moon is the most accessible member of the most abundant class of solar system objects, which includes Mercury, asteroids, and icy satellites. And the Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. Here we compare Diviner observations of Apollo landing sites and compositional and spectral laboratory measurements of returned Apollo soils. Diviner, onboard NASA's Lunar Reconnaissance Orbiter, has three spectral channels near 8 micron that were designed to characterize the mid-infrared emissivity maximum known as the Christiansen feature (CF), a well-studied indicator of silicate mineralogy. It has been observed that thermal infrared spectra measured in simulated lunar environment (SLE) are significantly altered from spectra measured under terrestrial or martian conditions, with enhanced CF contrast and shifted CF position relative to other spectral features. Therefore only thermal emission experiments conducted in SLE are directly comparable to Diviner data. With known compositions, Apollo landing sites and soils are important calibration points for the Diviner dataset, which includes all six Apollo sites at approximately 200 m spatial resolution. Differences in measured CFs caused by composition and space weathering are apparent in Diviner data. Analyses of Diviner observations and SLE measurements for a range of Apollo soils show good agreement, while comparisons to thermal reflectance measurements under ambient conditions do not agree well, which underscores the need for SLE measurements and validates our measurement technique. Diviner observations of Apollo landing sites are also correlated with geochemical measurements of Apollo soils from the Lunar Sample Compendium

  1. Direct detection of terrestrial exoplanets: comparing the potential for space and ground telescopes

    NASA Astrophysics Data System (ADS)

    Angel, Roger

    2003-10-01

    Telescopes of various different designs are potentially capable of detecting extrasolar terrestrial planets. We analyze here in a consistent way the limiting sensitivities set by photon noise from the background underlying the planet signal, which may be of thermal, zodiacal or stellar origin. The strength of the unsuppressed stellar halo is itself set by photon noise in wavefront measurement. While optical telescopes have potentially higher limiting sensitivity, thermal detection is more secure. At 11 μm wavelength, the planet/star contrast is 1000 times more favorable than in the optical. Together with the longer wavelength, this leads to a 500 times more relaxed tolerance for star suppression, one that can be met by a fast servo based on the bright star flux sensed at shorter wavelengths. Either Darwin or a 100 m ground telescope should be capable of thermal detection of the earth in a solar system twin at 10 pc at 5 to 10σ in 24hr. At optical wavelengths, the limiting sensitivity for space telescopes is set at the 10-30σ level by photon noise in the zodiacal background. Reaching this limit, as do the deep fields of the Hubble Space Telescope, will require extreme coronagraphic suppression of the bright star at 0.1 arcsec separation. The ~1 m-scale Fourier components of the wavefront would need to have stable amplitude ≤2 picometers, a severe challenge. On the ground, fast atmospheric correction at the photon noise limit will leave residual Fourier amplitudes of 20-60 pm, for a halo background 100-1000 times zodiacal. But given larger apertures and stronger fluxes, optical sensitivity can still be high, provided the photon noise limit of short halo exposures can be maintained in a long-term average. If this challenge can be met, detection in 24 hr would be at the 5σ level for a 20 m Antarctic telescope, ~50σ for the 100 m OWL. If a terrestrial planet were detected at 10 pc, a spectrum that could reveal water and oxygen would be of great interest. Thermal

  2. A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels

    NASA Astrophysics Data System (ADS)

    Delahaye, Thibault; Nikitin, Andrei; Rey, Michaël; Szalay, Péter G.; Tyuterev, Vladimir G.

    2014-09-01

    In this paper we report a new ground state potential energy surface for ethylene (ethene) C2H4 obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C2H4 molecule was obtained with a RMS(Obs.-Calc.) deviation of 2.7 cm-1 for fundamental bands centers and 5.9 cm-1 for vibrational bands up to 7800 cm-1. Large scale vibrational and rotational calculations for 12C2H4, 13C2H4, and 12C2D4 isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm-1 are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of 13C2H4 and 12C2D4 and rovibrational levels of 12C2H4.

  3. Ground-based Optical Observations of Geophysical Phenomena: Aurora Borealis and Meteors

    NASA Astrophysics Data System (ADS)

    Samara, Marilia

    2010-10-01

    Advances in low-light level imaging technology have enabled significant improvements in the ground based study of geophysical phenomena. In this talk we focus on two such phenomena that occur in the Earth's ionosphere: aurorae and meteors. Imaging the aurora which is created by the interplay of the Earth's magnetosphere, ionosphere and atmosphere, provides a tool for remote sensing physical processes that are otherwise very difficult to study. By quantifying the intensities, scale sizes and lifetimes of auroral structures, we can gain significant insight into the physics behind the generation of the aurora and the interaction of the magnetosphere with the solar wind. Additionally, the combination of imaging with radars provides complimentary data and therefore more information than either method on its own. Meteor observations are a perfect example of this because the radar can accurately determine only the line-of-sight component of velocity, while imaging provides the direction of motion, the perpendicular velocity and brightness (a proxy for mass), therefore enabling a much more accurate determination of the full velocity vector and mass.

  4. Correcting atmospheric effects in thermal ground observations for hyperspectral emissivity estimation

    NASA Astrophysics Data System (ADS)

    Timmermans, Joris; Buitrago, Maria

    2014-05-01

    Knowledge of Land surface temperature is of crucial importance in energy balance studies and environmental modeling. Accurate retrieval of land surface temperature (LST) demands detailed knowledge of the land surface emissivity. Measured radiation by remote sensing sensors to land surface temperature can only be performed using a-priori knowledge of the emissivity. Uncertainties in the retrieval of this emissivity can cause huge errors in LST estimations. The retrieval of emissivity (and LST) is per definition an underdetermined inversion, as only one observation is made while two variables are to be estimated. Several researches have therefore been performed on measuring emissivity, such as the normalized emissivity method, the temperature-emissivity separation (TES) using the minimum and maximum difference of emissivity and the use of vegetation indices. In each of these approaches atmospherically corrected radiance measurements by remote sensing sensors are correlated to ground measurements. Usually these ground measurements are performed with the ground equivalent of the remote sensing sensors; the CIMEL 312-2 has the same spectral bands as ASTER. This way parameterizations acquired this way are only usable for specific sensors and need to be redone for newer sensors. Recently hyperspectral thermal radiometers, such as the MIDAC, have been developed that can solve this problem. By using hyperspectral observations of emissivity, together with sensor simulators, ground measurements of different satellite sensor can be simulated. This facilitates the production of validation data for the different TES algorithms. However before such measurements can be performed extra steps of processing need to be performed. Atmospheric correction becomes more important in hyperspectral observations than for broadband observations, as energy levels measured per band is lower. As such the atmosphere has a relative larger contribution if bandwidths become smaller. The goal of this

  5. Estimating atmospheric visibility using synergy of MODIS data and ground-based observations

    NASA Astrophysics Data System (ADS)

    Komeilian, H.; Mohyeddin Bateni, S.; Xu, T.; Nielson, J.

    2015-05-01

    Dust events are intricate climatic processes, which can have adverse effects on human health, safety, and the environment. In this study, two data mining approaches, namely, back-propagation artificial neural network (BP ANN) and supporting vector regression (SVR), were used to estimate atmospheric visibility through the synergistic use of Moderate Resolution Imaging Spectroradiometer (MODIS) Level 1B (L1B) data and ground-based observations at fourteen stations in the province of Khuzestan (southwestern Iran), during 2009-2010. Reflectance and brightness temperature in different bands (from MODIS) along with in situ meteorological data were input to the models to estimate atmospheric visibility. The results show that both models can accurately estimate atmospheric visibility. The visibility estimates from the BP ANN network had a root-mean-square error (RMSE) and Pearson's correlation coefficient (R) of 0.67 and 0.69, respectively. The corresponding RMSE and R from the SVR model were 0.59 and 0.71, implying that the SVR approach outperforms the BP ANN.

  6. Ground Radar Polarimetric Observations of High-Frequency Earth-Space Communication Links

    NASA Technical Reports Server (NTRS)

    Bolen, Steve; Chandrasekar, V.; Benjamin, Andrew

    2002-01-01

    Strategic roadmaps for NASA's Human Exploration and Development of Space (REDS) enterprise support near-term high-frequency communication systems that provide moderate to high data rates with dependable service. Near-earth and human planetary exploration will baseline Ka-Band, but may ultimately require the use of even higher frequencies. Increased commercial demand on low-frequency earth-space bands has also led to increased interest in the use of higher frequencies in regions like K u - and K,- band. Data is taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), which operates at 13.8 GHz, and the true radar reflectivity profile is determined along the PR beam via low-frequency ground based polarimetric observations. The specific differential phase (Kdp) is measured along the beam and a theoretical model is used to determine the expected specific attenuation (k). This technique, called the k-Kdp method, uses a Fuzzy-Logic model to determine the hydrometeor type along the PR beam from which the appropriate k-Kdp relationship is used to determine k and, ultimately, the total path-integrated attenuation (PIA) on PR measurements. Measurements from PR and the NCAR S-POL radar were made during the TEFLUN-B experiment that took place near Melbourne, FL in 1998, and the TRMM-LBA campaign near Ji-Parana, Brazil in 1999.

  7. A semiempirical study of the optimized ground and excited state potential energy surfaces of retinal and its protonated Schiff base

    NASA Technical Reports Server (NTRS)

    Parusel, A. B.; Pohorille, A.

    2001-01-01

    The electronic ground and first excited states of retinal and its Schiff base are optimized for the first time using the semiempirical AM1 Hamiltonian. The barrier for rotation about the C(11)-C(12) double bond is characterized by variation of both the twist angle delta(C(10)-C(11)-C(12)-C(13)) and the bond length d(C(11)-C(12)). The potential energy surface is obtained by varying these two parameters. The calculated ground state rotational barrier is equal to 15.6 kcal/mol for retinal and 20.5 kcal/mol for its Schiff base. The all-trans conformation is more stable by 3.7 kcal/mol than the 11-cis geometry. For the first excited state, S(1,) the 90 degrees twisted geometry represents a saddle point for retinal with the rotational barrier of 14.6 kcal/mol. In contrast, this conformation is an energy minimum for the Schiff base. It can be easily reached at room temperature from the planar minima since it is separated from them by a barrier of only 0.6 kcal/mol. The 90 degrees minimum conformation is more stable than the all-trans by 8.6 kcal/mol. We are thus able to present a reaction path on the S(1) surface of the retinal Schiff base with an almost barrier-less geometrical relaxation into a twisted minimum geometry, as observed experimentally. The character of the ground and first excited singlet states underscores the need for the inclusion of double excitations in the calculations.

  8. Sensitivity of aerosol retrieval to geometrical configuration of ground-based sun/sky radiometer observations

    NASA Astrophysics Data System (ADS)

    Torres, B.; Dubovik, O.; Toledano, C.; Berjon, A.; Cachorro, V. E.; Lapyonok, T.; Litvinov, P.; Goloub, P.

    2014-01-01

    A sensitivity study of aerosol retrievals to the geometrical configuration of the ground-based sky radiometer observations is carried out through inversion tests. Specifically, this study is focused on principal plane and almucantar observations, since these geometries are employed in AERONET (AErosol RObotic NETwork). The following effects have been analyzed with simulated data for both geometries: sensitivity of the retrieval to variability of the observed scattering angle range, uncertainties in the assumptions of the aerosol vertical distribution, surface reflectance, possible instrument pointing errors, and the effects of the finite field of view. The synthetic observations of radiometer in the tests were calculated using a previous climatology data set of retrieved aerosol properties over three AERONET sites: Mongu (Zambia) for biomass burning aerosol, Goddard Space Flight Center (GSFC; Maryland, USA) for urban aerosol and Solar Village (Saudi Arabia) for desert dust aerosol. The results show that almucantar retrievals, in general, are more reliable than principal plane retrievals in presence of the analyzed error sources. This fact partially can be explained by practical advantages of the almucantar geometry: the symmetry between its left and right branches that helps to eliminate some observational uncertainties and the constant value of optical mass during the measurements, that make almucantar observations nearly independent of the vertical variability of aerosol. Nevertheless, almucantar retrievals present instabilities at high sun elevations due to the reduction of the scattering angle range coverage, resulting in decrease of information content. It is in such conditions that principal plane retrievals show a better stability, as shown by the simulation analysis of the three different aerosol models. The last part of the study is devoted to the identification of possible differences between the aerosol retrieval results obtained from real AERONET data

  9. Dust forecast over North Africa: verification with satellite and ground based observations

    NASA Astrophysics Data System (ADS)

    Singh, Aditi; Kumar, Sumit; George, John P.

    2016-05-01

    Arid regions of North Africa are considered as one of the major dust source. Present study focuses on the forecast of aerosol optical depth (AOD) of dust over different regions of North Africa. NCMRWF Unified Model (NCUM) produces dust AOD forecasts at different wavelengths with lead time upto 240 hr, based on 00UTC initial conditions. Model forecast of dust AOD at 550 nm up to 72 hr forecast, based on different initial conditions are verified against satellite and ground based observations of total AOD during May-June 2014 with the assumption that except dust, presence of all other aerosols type are negligible. Location specific and geographical distribution of dust AOD forecast is verified against Aerosol Robotic Network (AERONET) station observations of total and coarse mode AOD. Moderate Resolution Imaging Spectroradiometer (MODIS) dark target and deep blue merged level 3 total aerosol optical depth (AOD) at 550 nm and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) retrieved dust AOD at 532 nm are also used for verification. CALIOP dust AOD was obtained by vertical integration of aerosol extinction coefficient at 532 nm from the aerosol profile level 2 products. It is found that at all the selected AERONET stations, the trend in dust AODs is well predicted by NCUM up to three days advance. Good correlation, with consistently low bias (~ +/-0.06) and RMSE (~ 0.2) values, is found between model forecasts and point measurements of AERONET, except over one location Cinzana (Mali). Model forecast consistently overestimated the dust AOD compared to CALIOP dust AOD, with a bias of 0.25 and RMSE of 0.40.

  10. Jovian thundercloud observation with Jovian orbiter and ground-based telescope

    NASA Astrophysics Data System (ADS)

    Takahashi, Yukihiro; Nakajima, Kensuke; Takeuchi, Satoru; Sato, Mitsuteru; Fukuhara, Tetsuya; Watanabe, Makoto; Yair, Yoav; Fischer, Georg; Aplin, Karen

    The latest observational and theoretical studies suggest that thunderstorms in Jupiter's at-mosphere are very important subject not only for understanding of meteorology, which may determine the large scale structures such as belt/zone and big ovals, but also for probing the water abundance of the deep atmosphere, which is crucial to constrain the behavior of volatiles in early solar system. Here we suggest a very simple high-speed imager on board Jovian orbiter, Optical Lightning Detector, OLD, optimized for detecting optical emissions from lightning dis-charge in Jupiter. OLD consists of radiation-tolerant CMOS sensors and two H Balmer Alpha line (656.3nm) filters. In normal sampling mode the frame intervals is 29ms with a full frame format of 512x512 pixels and in high-speed sampling mode the interval could be reduced down to 0.1ms by concentrating a limited area of 30x30 pixels. Weight, size and power consump-tion are about 1kg, 16x7x5.5 cm (sensor) and 16x12x4 cm (circuit), and 4W, respectively, though they can be reduced according to the spacecraft resources and required environmental tolerance. Also we plan to investigate the optical flashes using a ground-based middle-sized telescope, which will be built by Hokkaido University, with narrow-band high speed imaging unit using an EM-CCD camera. Observational strategy with these optical lightning detectors and spectral imagers, which enables us to estimate the horizontal motion and altitude of clouds, will be introduced.

  11. Conjugate observations of a remarkable quasiperiodic event by the low-altitude DEMETER spacecraft and ground-based instruments

    NASA Astrophysics Data System (ADS)

    Bezdekova, Barbora; Nemec, Frantisek; Manninen, Jyrki; Parrot, Michel; Santolik, Ondrej; Hayosh, Mykhaylo

    2016-04-01

    Quasiperiodic (QP) events are electromagnetic waves observed in the inner magnetosphere at frequencies between about 0.5 and 4 kHz that exhibit a nearly periodic modulation of the wave intensity. The modulation periods may range from tens of seconds up to minutes. We present a detailed multipoint analysis of a remarkable QP event observed consecutively for several hours on 26 February 2008. The event was detected by ground-based instruments of Sodankyla Geophysical Observatory (Finland) and by the low-altitude DEMETER spacecraft, both in the same and conjugate hemispheres. The time intervals when the event was observed on board the satellite/on the ground provide us with an estimate of the event dimensions. When the event is detected simultaneously by the satellite and on the ground, its observed frequency-time structure is generally the same. However, the ratio of detected intensities varies significantly as a function of the spacecraft latitude. Moreover, there is a delay as large as about 10 s between the times when individual QP elements are detected by the spacecraft/on the ground. This appears to be related to the azimuthal separation of the instruments, and it is highly relevant to the identification of a possible source mechanism. Finally, we find that the intensity of the QP event is correlated with the amplitude of Alfvenic ULF pulsations measured on the ground.

  12. Secular gravity variation at Svalbard (Norway) from ground observations and GRACE satellite data

    NASA Astrophysics Data System (ADS)

    Mémin, A.; Rogister, Y.; Hinderer, J.; Omang, O. C.; Luck, B.

    2011-03-01

    The Svalbard archipelago, Norway, is affected by both the present-day ice melting (PDIM) and Glacial Isostatic Adjustment (GIA) subsequent to the Last Pleistocene deglaciation. The induced deformation of the Earth is observed by using different techniques. At the Geodetic Observatory in Ny-Ålesund, precise positioning measurements have been collected since 1991, a superconducting gravimeter (SG) has been installed in 1999, and six campaigns of absolute gravity (AG) measurements were performed between 1998 and 2007. Moreover, the Gravity Recovery and Climate Experiment (GRACE) satellite mission provides the time variation of the Earth gravity field since 2002. The goal of this paper is to estimate the present rate of ice melting by combining geodetic observations of the gravity variation and uplift rate with geophysical modelling of both the GIA and Earth's response to the PDIM. We estimate the secular gravity variation by superimposing the SG series with the six AG measurements. We collect published estimates of the vertical velocity based on GPS and VLBI data. We analyse the GRACE solutions provided by three groups (CSR, GFZ, GRGS). The crux of the problem lies in the separation of the contributions from the GIA and PDIM to the Earth's deformation. To account for the GIA, we compute the response of viscoelastic Earth models having different radial structures of mantle viscosity to the deglaciation histories included in the models ICE-3G or ICE-5G. To account for the effect of PDIM, we compute the deformation of an elastic Earth model for six models of ice-melting extension and rates. Errors in the gravity variation and vertical velocity are estimated by taking into account the measurement uncertainties and the variability of the GRACE solutions and GIA and PDIM models. The ground observations agree with models that involve a current ice loss of 25 km3 water equivalent yr-1 over Svalbard, whereas the space observations give a value in the interval [5, 18] km3

  13. Tropospheric nitrogen dioxide column retrieval based on ground-based zenith-sky DOAS observations

    NASA Astrophysics Data System (ADS)

    Tack, Frederik; Hendrick, Francois; Goutail, Florence; Fayt, Caroline; Merlaud, Alexis; Pinardi, Gaia; Pommereau, Jean-Pierre; Van Roozendael, Michel

    2014-05-01

    Nitrogen dioxide (NO2) is one of the most important chemically active trace gases in the troposphere. Listed as primary pollutant, it is also a key precursor in the formation of tropospheric ozone, aerosols, and acid rain, and can contribute locally to radiative forcing. The long-term monitoring of this species is therefore of great relevance. Here we present a new method to retrieve tropospheric NO2 vertical column amounts from ground-based zenith-sky measurements of scattered sunlight. It is based on a four-step approach consisting of (1) the DOAS analysis of zenith radiance spectra using a fixed reference spectrum corresponding to low tropospheric NO2 content, (2) the determination of the residual amount in the reference spectrum using a Langley-plot-type method, (3) the removal of the stratospheric content from the daytime total slant column using stratospheric vertical columns measured at twilight and simulated stratospheric NO2 diurnal variation, (4) estimation of the tropospheric vertical columns by dividing the resulting tropospheric slant columns by appropriate air mass factors. The retrieval algorithm is tested on a 2 month dataset acquired from June to July 2009 by the BIRA MAX-DOAS instrument in the framework of the Cabauw (51.97° N, 4.93° E) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). The tropospheric vertical column amounts derived from zenith-sky observations are compared to the vertical columns retrieved from the off-axis and direct-sun measurements of the same MAX-DOAS instrument as well as to data of a co-located SAOZ (Système d'Analyse par Observations Zénithales) spectrometer operated by LATMOS. First results show a good agreement between the different data sets with correlation coefficients and slopes close to or larger than 0.85. We observe that the main error sources arise from the uncertainties in the determination of the residual NO2 amount in the reference spectrum, the stratospheric NO2 abundance and

  14. Ground deformation in the Rio-Antirio area, Corinth Gulf, Greece, based on PS images interferometry and potential related geo-hazards

    NASA Astrophysics Data System (ADS)

    Diakogianni, G.; Foumelis, M.; Papadopoulos, G. A.; Parcharidis, I.

    2009-04-01

    Ground deformation is the surface expression of various physical processes such as landslides, ground subsidence and earthquakes. Construction and operation of engineering structures in urban or in rural areas can be affected seriously by ground conditions leading to casualties and economic losses. We focus at the example of the new bridge Rio-Antirrio, an important infrastructure which is the longest cable stayed bridge all over the world. Being of a length of 2,250 m it is located in the strait at the northwest edge of Peloponnese, connecting the Gulf of Corinth and the Gulf of Patras, in central Greece. This important bridge facilitates the transportation between Greece and the Western Europe through the Patra's harbor. The area of the strait is characterized by a variety of natural hazards like the absence of stiff seabed, strong seismic activity, tectonic movements, which make the area highly susceptible to ground deformation and the bridge an element at risk. The aim of this paper is to study the observed ground deformation in the area of Rio-Antirrio and interpret the potential causes of the deformation. We combine results of the PS interferometry (IPTA method) covering the period from 1992 to the present using ERS1 & 2 scenes and ENVISAT with seismicity data, active tectonics, slope failure, coastal sediment compaction, hydrology and seabed stability. Hazard assessment, prevention and mitigation are discussed under the light of the results in a scheme which includes the exposure item (bridge), hazard (multi-source induced ground stability) and risk (possible impact).

  15. Ground-Water Quality and Potential Effects of Individual Sewage Disposal System Effluent on Ground-Water Quality in Park County, Colorado, 2001-2004

    USGS Publications Warehouse

    Miller, Lisa D.; Ortiz, Roderick F.

    2007-01-01

    In 2000, the U.S. Geological Survey, in cooperation with Park County, Colorado, began a study to evaluate ground-water quality in the various aquifers in Park County that supply water to domestic wells. The focus of this study was to identify and describe the principal natural and human factors that affect ground-water quality. In addition, the potential effects of individual sewage disposal system (ISDS) effluent on ground-water quality were evaluated. Ground-water samples were collected from domestic water-supply wells from July 2001 through October 2004 in the alluvial, crystalline-rock, sedimentary-rock, and volcanic-rock aquifers to assess general ground-water quality and effects of ISDS's on ground-water quality throughout Park County. Samples were analyzed for physical properties, major ions, nutrients, bacteria, and boron; and selected samples also were analyzed for dissolved organic carbon, human-related (wastewater) compounds, trace elements, radionuclides, and age-dating constituents (tritium and chlorofluorocarbons). Drinking-water quality is adequate for domestic use throughout Park County with a few exceptions. Only about 3 percent of wells had concentrations of fluoride, nitrate, and (or) uranium that exceeded U.S. Environmental Protection Agency national, primary drinking-water standards. These primary drinking-water standards were exceeded only in wells completed in the crystalline-rock aquifers in eastern Park County. Escherichia coli bacteria were detected in one well near Guffey, and total coliform bacteria were detected in about 11 percent of wells sampled throughout the county. The highest total coliform concentrations were measured southeast of the city of Jefferson and west of Tarryall Reservoir. Secondary drinking-water standards were exceeded more frequently. About 19 percent of wells had concentrations of one or more constituents (pH, chloride, fluoride, sulfate, and dissolved solids) that exceeded secondary drinking-water standards

  16. Phytoremediation potential of selected plants for nitrate and phosphorus from ground water.

    PubMed

    Sundaralingam, T; Gnanavelrajah, N

    2014-01-01

    The phytoremediation potential of three aquatic plants namely, water lettuce (Pistia stratioes), water hyacinth (Eichhornia crassipes), and water spinach (Ipomoea aquatica) for nitrate N and phosphorus from nutrient treated ground water was assessed. A total of twelve treatment combinations including four levels of nitrate (expressed as nitrate N 0, 20, 40, and 60 mg/l) and three levels of phosphorus (0, 20, and 40 mg/l) were treated for the total volume of 1 and 20 liters of water respectively, for Pistia stratiotes and Eichhornia crassipes. For Ipomoea aquatica ten treatment combinations with five levels of nitrate N (0, 10, 20, 40, and 50 mg/l) and two levels of phosphorus (0 and 5 mg/l) were treated to 3 liters of water. The design used was a two factor factorial with three replicates. Water was analyzed at weekly interval for nitrate N and phosphorus. Pistia stratiotes, Eichhornia crassipes and Ipomoea aquatica had the potential to remove nitrate N between 61.5-91.8%, 40-63.5%, and 29.3-75% during the period of six, three and three and weeks, respectively. In addition, 90-99%, 75-97.2%, and 75-83.3% of phosphorus was removed from water by Pistia stratiotes, Eichhornia crassipes and Ipomoea aquatica respectively, during the same period.

  17. Simultaneous Ground Based Monitoring of Brown Dwarfs Being Observed with Spitzer

    NASA Astrophysics Data System (ADS)

    Heinze, Aren; Metchev, Stanimir; Apai, Daniel; Flateau, Davin

    2012-08-01

    Brown dwarfs are the only objects beyond the solar system on which we can currently observe weather. Patchy clouds cause periodic, rotationally modulated photometric variability in some brown dwarfs; others show apparently non-periodic variations, potentially because rapid cloud evolution washes out the rotational photometric modulation. Measuring the relative amplitudes of a brown dwarf's photometric variability at different wavelengths reveals the altitude and other physical properties of its clouds. However, non-periodic variations require that the amplitudes be measured simultaneously in time. We propose to obtain simultaneous, multi-band photometry of brown dwarfs by observing them in the optical or near-IR at the same time as they are being monitored at longer wavelengths with Spitzer. These observations will have unique leverage to constrain the properties of brown dwarf clouds. Given the uncertain future of the Spitzer Warm Mission and the lack of any other mission with similar capability, the present semester represents a limited window of opportunity for carrying out such observations.

  18. Ground-Based Venusian Thermal Structure and Dynamics Observations in August 2010

    NASA Astrophysics Data System (ADS)

    Hewagama, Tilak; Kostiuk, Theodor; Livengood, Timothy; Stangier, Tobias; Fast, Kelly; Annen, John; Sornig, Manuela; Krause, Pia

    2015-11-01

    We measured equatorial winds above the cloud tops of Venus and in the lower thermosphere over 19-23 Aug 2010 (UT), a component of a Venus measurement program that extends over ~30+ years using ground-based Infrared Heterodyne Spectroscopy (IRHS). IRHS obtains sub-Doppler resolution on molecular transitions of atmospheric species. We used the Heterodyne Instrument for Planetary Winds and Composition (HIPWAC, NASA Goddard Space Flight Center) at the NASA Infrared Telescope Facility to acquire high-resolution spectra on pressure-broadened CO2 absorption features,probing the lower mesosphere (70 km altitude) with non-LTE core emission that probes the lower thermosphere (110 km). The two features probe the transition from zonal wind flow near the cloud tops to subsolar-to-antisolar flow in the thermosphere. Fully resolved carbon dioxide transitions were measured near the 952.8808 cm-1 (10.494 µm) rest frequency at resolving power λ/Δλ = 2.5×107 on the equator on positions distributed about the central meridian and across the terminator at ~15° intervals in longitude. The non-LTE emission is solar-pumped and appears only on the daylight side, probing subsolar-to-antisolar wind velocity flowing radially from the subsolar point through the terminator, which was near the central meridian in these observations, with maximum tangential velocity but zero line-of-sight projection at the terminator and zero tangential velocity but maximum projection at the limb. The maximum measurable Doppler shift thus appears within the disc, between central meridian and limb. The velocity of the zonal flow is approximately uniform, with constant tangential velocity and maximum line-of-sight projection at the limb, and can be measured by the frequency of the absorption line on both the daylight and dark side. Variations in Doppler shift between the observable features and the differing angular dependence of the contributing wind phenomena thus provide independent mechanisms to

  19. A ground-based trace gas observing system for detection of Arctic and Boreal change

    NASA Astrophysics Data System (ADS)

    Karion, A.; Miller, J. B.; Sweeney, C.; Bruhwiler, L.; Newberger, T.; Miller, C. E.; Dinardo, S. J.; Wolter, S.; Ledlow, L.

    2012-12-01

    The large reservoir of below-ground organic carbon in the Arctic and Boreal region (ABR) permafrost, combined with large observed and predicted temperature changes leads to the expectation of increasing surface emissions of CO2 and/or CH4 this century. However, the near-term response of northern ecosystems could be enhanced ecosystem productivity and carbon sequestration via, among other causes, longer growing seasons and encroachment of woody species into Arctic tundra. Regardless of the temporal evolution of carbon (both CO2 and CH4) sources and sinks in the ABR, monitoring these changes at regional (~10^5 - 10^6 km^2) scales using trace gas mixing and isotopic ratios will be a critical complement to detailed process-based studies at the plot scale and remote sensing of the land surface. Turbulent mixing in the lower few kilometers of the atmosphere naturally integrates emissions from all known and unknown processes and can provide a powerful bottom-line constraint on the net result of both sources and sinks. We will present the first year of results of a trace-gas measurement system capable of daily or more frequent observations of more than 50 trace gas species, including CO2, CH4 and their stable and radio isotope ratios. The measurements were initiated as part of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and come from a 30 m tower located on a ridge in central Alaska. Central Alaska is dominated by discontinuous permafrost, which is likely to undergo significant changes in the coming decades. Footprint analysis suggests that mixing ratios measured at the tower are influenced by large swaths of central Alaska, although in winter, anthropogenic emissions form the city of Fairbanks are evident. In summer, as expected, we observe a large drawdown of CO2. The seasonal cycle of CH4 is dominated by the large-scale destruction of methane by hydroxyl radical (OH). However, based on previous measurements from other ABR sites, we expect summer

  20. Connecting ground-based in-situ observations, ground-based remote sensing and satellite data within the Pan Eurasian Experiment (PEEX) program

    NASA Astrophysics Data System (ADS)

    Petäjä, Tuukka; de Leeuw, Gerrit; Lappalainen, Hanna K.; Moisseev, Dmitri; O'Connor, Ewan; Bondur, Valery; Kasimov, Nikolai; Kotlyakov, Vladimir; Guo, Huadong; Zhang, Jiahua; Matvienko, Gennadii; Kerminen, Veli-Matti; Baklanov, Alexander; Zilitinkevich, Sergej; Kulmala, Markku

    2014-10-01

    Human activities put an increasing stress on the Earth' environment and push the safe and sustainable boundaries of the vulnerable eco-system. It is of utmost importance to gauge with a comprehensive research program the current status of the environment, particularly in the most vulnerable locations. The Pan-Eurasian Experiment (PEEX) is a new multidisciplinary research program aiming at resolving the major uncertainties in the Earth system science and global sustainability questions in the Arctic and boreal Pan-Eurasian regions. The PEEX program aims to (i) understand the Earth system and the influence of environmental and societal changes in both pristine and industrialized Pan-Eurasian environments, (ii) establish and sustain long-term, continuous and comprehensive ground-based airborne and seaborne research infrastructures, and utilize satellite data and multi-scale model frameworks filling the gaps of the insitu observational network, (iii) contribute to regional climate scenarios in the northern Pan-Eurasia and determine the relevant factors and interactions influencing human and societal wellbeing (iv) promote the dissemination of PEEX scientific results and strategies in scientific and stake-holder communities and policy making, (v) educate the next generation of multidisciplinary global change experts and scientists, and (vi) increase the public awareness of climate change impacts in the Pan- Eurasian region. In this contribution, we underline general features of the satellite observations relevant to the PEEX research program and how satellite observations connect to the ground-based observations.

  1. The Irregular Shape of (21) Lutetia as Determined from Ground-based Observations

    NASA Astrophysics Data System (ADS)

    Conrad, A.; Carry, B.; Merline, W. J.; Drummond, J. D.; Chapman, C. R.; Tamblyn, P. M.; Christou, J. C.; Dumas, C.; Weaver, H. A.; Rosetta OSIRIS Instument Team

    2010-12-01

    We report the results of our campaign to improve our understanding of the physical characteristics of asteroid (21) Lutetia ahead of the Rosetta flyby in 2010 July. This included measurements of shape, size, pole, density, and a search for satellites. We utilized primarily adaptive optics (AO) on large ground-based telescopes (Keck, Gemini, and VLT). We coordinated these efforts with HST observations (Weaver et al. 2010, A&A 518, A4), made in support of Rosetta’s ALICE UV spectrometer. Preliminary results were supplied to Rosetta mission teams in fall of 2009 to assist in planning for the mission. Observations and analyses were complete and submitted for publication before the flyby (Drummond et al. 2010, A&A, in press; Carry et al. 2010, A&A, in press). Using more than 300 AO images of Lutetia, which subtended only slightly more than two resolution-elements (0.10”) for these large telescopes, we were able to derive accurate size and shape information, as well as a pole and spin period. We modeled the size and shape using both a triaxial-ellipsoid model and a 3D radius-vector model. The radius-vector model used our new technique of multi-dataset inversion, called KOALA (for Knitted Occultation, Adaptive optics, and Lightcurve Analysis), in which we utilized not only our AO imaging, but also 50 lightcurves spanning 48 years. We combined the best aspects of each model to produce our best-estimate 3D shape model, a hybrid having ellipsoid-equivalent dimensions of 124 x 101 x 93 km (± 5 x 4 x 13 km) and effective diameter 105 ± 7 km. We found the spin axis of Lutetia to lie within 5 deg of [long, lat (52,-6)] or [RA DEC (52,+12)] and determined an improved sidereal period of 8.168270 ± 0.000001 h. We predicted the geometry of Lutetia during the flyby and showed that the southern hemisphere would be in seasonal shadow at that time. The model suggested the presence of several concavities and irregularities that may be associated with large impacts. The model

  2. Coordinated observations of Pc5 pulsations in a field line; ground, SuperDARN, and a satellite

    NASA Astrophysics Data System (ADS)

    Sakaguchi, K.; Nagatsuma, T.; Obara, T.; Troshichev, O. A.

    2010-12-01

    Pc5 pulsations are electromagnetic wave at periods of 150-600 s in the ultra-low frequency (ULF) range, which are often observed and have been studied well by ground and satellite magnetometers. The most common mode of Pc5 pulsations is the field line resonance (FLR) of shear Alfvén waves standing along Earth’s magnetic field lines. The ionosphere in both hemisphere acts the reflection boundary of FLR and the ionospheric current generated by electromagnetic waves results in Pc5 pulsations of magnetic fields on the ground. In the magnetosphere, magnetometers and electric field instruments onboard satellites observe directly in situ amplitude of Pc5 pulsations. Previous studies identified Pc5 pulsations in the magnetosphere as one of the key mechanisms of transport and acceleration of energetic electrons in Earth’s outer radiation belt; wave power of Pc5 band is well correlated with radiation belt electron fluxes. In particular, waves in global mode (low-m) are likely more effective than localized mode (high-m). It is important for the space whether study to classify Pc5 effectiveness for radiation belt particles. However, it is difficult to know correct wave numbers from satellite nor ground observations, because satellites know only in situ signals and ground magnetometers integrate all neighbor signals. Thus, we investigated Pc5 pulsations using data from SuperDARN radars, which can observe two-dimensionally the Doppler velocity of ionospheric plasma due to electric-field pulsations of Pc5 along in the line of sight throughout the high latitude. First of all, we investigate the similarity and difference of Pc5 properties among on the ground at Pebek (PBK), Russia by the magnetometer, on the ionosphere in the Doppler velocity in the field-of-view of the SuperDARN rader at King Salmon (KSR), and in the magnetosphere at the geosynchronous ETS-8 satellite by the magnetometer; these align the almost same meridian. In this study, we focus on the toroidal mode

  3. Observations on syntactic landmine detection using impulse ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Nasif, Ahmed O.; Hintz, Kenneth J.

    2011-06-01

    We discuss some results and observations on applying syntactic pattern recognition (SPR) methodology for landmine detection using impulse ground-penetrating radar (GPR). In the SPR approach, the GPR A-scans are first converted into binary-valued strings by inverse filtering, followed by concavity detection to identify the peaks and valleys representing the locations of impedance discontinuities in the return signal. During the training phase, the characteristic binary strings for a particular landmine are found by looking at all the exemplars of that mine and selecting the collection of strings that yield the best detection results on these exemplars. These characteristic strings can be detected very efficiently using finite state machines (FSMs). Finally, the FSM detections are clustered to assign confidence to each detection, and discard sparse detections. Provided that the impulse GPR provides enough resolution in range, the SPR method can be a robust and high-speed solution for landmine detection and classification, because it aims to exploit the impedance discontinuity profile of the target, which is a description of the internal material structure of the target and little affected by external clutter. To evaluate the proposed methodology, the SPR scheme is applied to a set of impulse GPR data taken at a government test site. We suggest that coherent frequency-agile radar may be a better option for the SPR approach, since it addresses some of the drawbacks of a non-coherent impulse GPR caused by internally non-coherent within-channel signals which necessitate non-coherent integration and its attendant longer integration times, and non-coherent adjacent channels which severely limit the ability to do spatial, or at a minimum, cross-range processing if the GPR is in a linear array antenna.

  4. Ground Deformation Measurement with SAR Interferometry - Exupéry Project WP2 Space Based Observations

    NASA Astrophysics Data System (ADS)

    Cong, Xiaoying; Eineder, Michael; Minet, Christian

    2010-05-01

    As one of major natural hazards volcanic unrest and volcanic eruption are gaining more attention nowadays. The Exupéry project aimed at setting-up an Early Response System (VFRS) for volcanic activity was funded by the German Federal Ministry of Education and Research. Within Work Package 2 'Space Based Observations' SAR interferometry is used for monitoring the ground deformation. In comparison with conventional monitoring techniques like GPS the surface changes can be directly detected by using 2 SAR images from different acquisition times and an external DEM. Persistent scatterer SAR interferometry (PSI) method is applied by using a stack of interferograms with common master image. Instead of whole SAR scene only the coherent scatterers during whole acquisition duration are selected and its phase measurements are used to estimate modelled parameters such as deformation velocity, DEM error and atmospheric distortions. In mountainous area backscatterers are decorrelated during the time because of vegetation. To ensure the coherence corner reflector (CR) is used to get stable backscattering. To test the whole system a campaign was carried out during April to August 2009. Two CRs were installed for TerraSAR-X satellite on the test site Lagoa do Fogo volcano. During the campaign 11 strip-map scenes were gathered consequently. Post-processed interferograms as well as the coherence maps were delivered to database center in Hannover and would be published in project website. Time series analysis with coherent scatterers from the stacking was applied in order to detect complex deformation from mountainous area. The CRs were successfully detected in SAR image and will be used as reference points in PSI processing. At the end the interferograms computed from different wavelengths will be compared in this area.

  5. Intuitive terrain reconstruction using height observation-based ground segmentation and 3D object boundary estimation.

    PubMed

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-01-01

    Mobile robot operators must make rapid decisions based on information about the robot's surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot's array of sensors, but some upper parts of objects are beyond the sensors' measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances. PMID:23235454

  6. Intuitive Terrain Reconstruction Using Height Observation-Based Ground Segmentation and 3D Object Boundary Estimation

    PubMed Central

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-01-01

    Mobile robot operators must make rapid decisions based on information about the robot’s surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot’s array of sensors, but some upper parts of objects are beyond the sensors’ measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances. PMID:23235454

  7. Intuitive terrain reconstruction using height observation-based ground segmentation and 3D object boundary estimation.

    PubMed

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-12-12

    Mobile robot operators must make rapid decisions based on information about the robot's surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot's array of sensors, but some upper parts of objects are beyond the sensors' measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances.

  8. Observing Campaign for Potential Deep Impact Flyby Target 163249 (2002 GT)

    NASA Astrophysics Data System (ADS)

    Pittichova, Jana; Chesley, S. R.; Abell, P. A.; Benner, L. A. M.

    2012-10-01

    The Deep Impact spacecraft is currently on course for a proposed 2020-Jan-4 flyby of Potentially Hazardous Asteroid 163249 (2002 GT). The re-targeting will be complete with a final small maneuver scheduled for 2012-Oct-04. 2002 GT has a well-determined orbit and absolute magnitude 18.3 ( 800m diameter). Little more is known about the nature of this object, but in late June 2013 it will pass 0.012 AU from Earth, affording an exceptional opportunity for ground-based characterization. At this apparition 2002 GT will be in range of Arecibo, which should provide radar delay observations with precisions of a few microseconds, potentially revealing whether the system is binary or not. The asteroid will reach magnitude V=16.1 and will be brighter than V=18 for over two months, facilitating a host of observations at a variety of wavelengths. Light curve measurements across a wide range of viewing perspectives will reveal the rotation rate and ultimately lead to strong constraints on the shape and pole orientation. Visible and infrared spectra will constrain the mineralogy, taxonomy, albedo and size. Radar and optical astrometry will further constrain the orbit, both to facilitate terminal guidance operations and, when combined with spacecraft flyby data, to potentially reveal nongravitational forces acting on the asteroid. Coordinating all of these observations will be a significant task and we encourage interested observers to collaborate in this effort. The 2013 apparition will be the last time 2002 GT will be brighter than magnitude 18 until after the 2020 spacecraft flyby and thus represents a unique opportunity to characterize a potential flyby target, which will aid planning and development of the flyby imaging sequence and interpretation of flyby imagery. The knowledge gained from this proposed flyby will be highly relevant to NASA’s human exploration program, which desires more information on the characteristics of sub-kilometer near-Earth asteroids.

  9. Potential Of VIRAC* RT-32 And RT-16 Antennas To Serve As Satellite Ground Station

    NASA Astrophysics Data System (ADS)

    Bleiders, M.; Trokss, J.; Elerts, M.

    2015-02-01

    The basic application of RT-32 and RT-16 parabolic antennas is radio astronomy observations, both the radio-telescopes have been upgraded with state-of-the art cryogenic receivers, and now a large-scale modernization of the infrastructure is underway. Since the radio-astronomical observations are not full-time activities, a research work has been done to clear up whether these antennas, besides the mentioned activities, can be used as a satellite ground station. The main goal of this added functionality is to make possible the use of the extremely high reception systems' figure-of-merit thus raising the satellite downlink data rates without increasing the on-board power consumption, which would be particularly important for developers of small satellites. In this paper, the progress in the research project is reported, which includes successful S-band satellite signal reception experiments and possible options as to integration of the related equipment into the system so that both functionalities could successfully coexist. Performance of the existing and the upgraded antenna positioning systems is estimated to determine if the latter are usable even for servicing low-Earth orbiting satellites. In addition, possible options are considered as to upgrading the system with automatic beam tracking capability, which would increase the antenna pointing accuracy even further.

  10. Accurate intermolecular ground state potential of the Ne-N2 van der Waals complex.

    PubMed

    Munteanu, Cristian R; López Cacheiro, Javier; Fernández, Berta

    2004-05-15

    Ab initio ground state potential energy surfaces are obtained from interaction energies calculated with the coupled cluster singles and doubles model including connected triples corrections [CCSD(T)] and the aug-cc-pVXZ (X=5,Q,T,D) basis sets augmented with two different sets of midbond functions (denoted 33221 and 33211). The aug-cc-pV5Z-33221 surface is characterized by a T-shaped 49.5 cm(-1) minimum at Re=3.38 Angstroms and a linear saddle point at 3.95 Angstroms with De=36.6 cm(-1). These results agree well with the values provided by the accurate semiempirical potentials available. The rovibronic spectroscopic properties are determined and compared to the available experimental data and previous theoretical results. We study the basis set convergence of the intermolecular potentials and the rotational frequencies. The aug-cc-pVTZ basis sets provide reasonable binding parameters, but seem not to be converged enough for the evaluation of the microwave spectra. The aug-cc-pVQZ basis sets considerably improve the triple zeta results. The differences between the results obtained with the aug-cc-pVTZ-33221 basis set surface and those with the aug-cc-pVQZ-33221 are smaller than those of the corresponding bases with the set of 33211 midbond functions. The aug-cc-pVQZ surfaces are close to the aug-cc-pV5Z, that are expected to be close to convergence. With our best surfaces the errors in the frequencies with respect to the accurate experimental results go down to 0.6%.

  11. Observations of basin ground motions from a dense seismic array in San Jose, California

    USGS Publications Warehouse

    Frankel, A.; Carver, D.; Cranswick, E.; Bice, T.; Sell, R.; Hanson, S.

    2001-01-01

    We installed a dense array of 41 digital seismographs in San Jose, California, to evaluate in detail the effects of a deep sedimentary basin and shallow sedimentary deposits on earthquake ground motions. This urban array is located near the eastern edge of the Santa Clara Valley and spans the Evergreen sedimentary basin identified by gravity data. Average station spacing is 1 km, with three stations initially spaced 110 m apart. Despite the high-noise urban environment, the stations of the array successfully triggered on and recorded small local earthquakes (M 2.5-2.8 at 10-25 km distance) and larger regional events such as the M 5.0 Bolinas earthquake (90 km distance), M 4.6-5.6 earthquakes near Mammoth Lakes (270 km distance), M 4.9-5.6 events in western Nevada (420 km distance) and the M 7.1 Hector Mine earthquake (590 km distance). Maps of spectral ratios across the array show that the highest amplitudes in all frequency bands studied (0.125-8 Hz) are generally observed at stations farther from the eastern edge of the Santa Clara Valley. Larger spectral amplitudes are often observed above the western edge of the Evergreen Basin. Snapshots of the recorded wavefield crossing the array for regional events to the east reveal that large, low-frequency (0.125-0.5 Hz) arrivals after the S-wave travel from south to north across the array. A moving-window, cross-correlation analysis finds that these later arrivals are surface waves traveling from the south. The timing and propagation direction of these arrivals indicates that they were likely produced by scattering of incident S waves at the border of the Santa Clara Valley to the south of the array. It is remarkable that the largest low-frequency phases at many of the valley sites for regional events to the east are basin surface waves coming from a direction about 70 degrees different from that of the epicenters. Basin surface waves emanating from the eastern edge of the valley are also identified by the cross

  12. Analysis and study of magnetospheric ULF waves using multi-spacecraft and ground-based observations

    NASA Astrophysics Data System (ADS)

    Balasis, Georgios; Daglis, Ioannis A.; Papadimitriou, Constantinos; Georgiou, Marina; Giamini, Sigiava

    In the past decade, a critical mass of high-quality scientific data on the electric and magnetic fields in the Earth’s magnetosphere and topside ionosphere has been progressively collected. This data pool will be further enriched by the measurements of ESA's Swarm mission, a constellation of three satellites in three different polar orbits between 400 and 550 km altitude, which was launched on the 22nd of November 2013. New analysis tools that can cope with measurements of various spacecraft at various regions of the magnetosphere and in the topside ionosphere as well as ground stations will effectively enhance the scientific exploitation of the accumulated data. Here, we report on a new suite of algorithms aiming at automated detection and classification of ultra-low frequency (ULF) wave events. Our approach is based on a combination of wavelet spectral methods and artificial neural network techniques. Moreover, we demonstrate the applicability of these recently developed analysis tools both for individual case studies and statistical studies of ULF waves. First, we provide evidence for a rare simultaneous observation of a ULF wave event in the Earth's magnetosphere, topside ionosphere and surface: we have found a specific time interval during the Halloween 2003 magnetic storm, when the Cluster and CHAMP spacecraft were in good local time (LT) conjunction, and have examined the ULF wave activity in the Pc3 (22-100 mHz) and Pc4-5 (1-22 mHz) frequency bands using data from the Geotail, Cluster and CHAMP missions, as well as the CARISMA and GIMA magnetometer networks. Then, we perform a statistical study of Pc3 wave events observed by CHAMP: the creation of a database of such events enabled us to derive valuable statistics for many important physical properties relating to the spatio-temporal location of these waves, the wave power and frequency, as well as other parameters and their correlation with solar wind conditions, magnetospheric indices, electron density

  13. Observing Campaign for Potential Deep Impact Flyby Target 163249 (2002 GT)

    NASA Technical Reports Server (NTRS)

    Pittichova, Jana; Chesley, S. R.; Abell, P. A.; Benner, L. A. M.

    2012-01-01

    The Deep Impact spacecraft is currently on course for a Jan. 4, 2020 flyby of the sub-kilometer near-Earth asteroid 163249 (2002 GT). The re-targeting will be complete with a final small maneuver scheduled for Oct. 4, 2012. 2002 GT, which is also designated as a Potentially Hazardous Asteroid (PHA), has a well-determined orbit and is approx 800 m in diameter (H=18.3). Little more is known about the nature of this object, but in mid-2013 it will pass near the Earth, affording an exceptional opportunity for ground-based characterization. At this apparition 2002 GT will be in range of Arecibo. In addition to Doppler measurements, radar delay observations with precisions of a few microseconds are expected and have a good chance of revealing whether the system is binary or not. The asteroid will be brighter than 16th mag., which will facilitate a host of observations at a variety of wavelengths. Light curve measurements across a wide range of viewing perspectives will reveal the rotation rate and ultimately lead to strong constraints on the shape and pole orientation. Visible and infrared spectra will constrain the mineralogy, taxonomy, albedo and size. Along with the radar observations, optical astrometry will further constrain the orbit, both to facilitate terminal guidance operations and to potentially reveal nongravitational forces acting on the asteroid. Coordinating all of these observations will be a significant task and we encourage interested observers to collaborate in this effort. The 2013 apparition of 2002 GT represents a unique opportunity to characterize a potential flyby target, which will aid interpretation of the high-resolution flyby imagery and aid planning and development of the flyby imaging sequence. The knowledge gained from this flyby will be highly relevant to the human exploration program at NASA, which desires more information on the physical characteristics of sub-kilometer near-Earth asteroids.

  14. Observations from Integrated Ground Motion Using EarthScope's USArray Transportable Array

    NASA Astrophysics Data System (ADS)

    West, J. D.; Fouch, M. J.

    2012-12-01

    Integrated Ground Motion (IGM) is a new method for visualizing and investigating long-term changes in seismic background levels. These new time series present an opportunity to evaluate variations in background seismic levels on intermediate time scales longer than those usually considered in processing seismic event data, but shorter than the time scales typically utilized when measuring the power spectral density (PSD) function of a seismic channel or instrument. Example uses for this new method include determining relationships between weather and seismic noise, detection of uncataloged small seismic and slow slip events, detection and characterization of remotely triggered seismicity, detection and monitoring of induced seismicity and detection of non-seismic signals. Here we apply the IGM processing method to broadband seismic data from the EarthScope USArray Transportable Array (TA) [www.usarray.org], and present some preliminary observations of the observed patterns in seismicity. We generate IGM time series from raw broadband seismic data by filtering and evaluating the envelope of a sliding time window. We further process the resulting IGM time series to remove peaks from short-duration seismic events by clipping the series at the 95th percentile value and normalizing each resulting series on a 0-1 scale. For this initial evaluation, we process IGM from overlapping 15-minute windows sampled every 5 minutes from four weeks of TA data for the western US in early 2008, bandpass filtering over four different ranges: 7-19 Hz, 1-8 Hz, 1-20 sec, and 20-100 sec. We create a series of animations overlaying the IGM values on a map of the western US and compressing the time scale to 2 hours/second. We observe that IGM in the 7-19 Hz and 1-8 Hz bands is primarily influenced by diurnal variations in background seismic levels, which generally overwhelm the signals from small (M<1.5) local earthquakes. Small earthquakes are somewhat more visible in the 1-8 Hz band. In

  15. Perfluoroalkyl substances in a firefighting training ground (FTG), distribution and potential future release.

    PubMed

    Baduel, Christine; Paxman, Christopher J; Mueller, Jochen F

    2015-10-15

    The present study investigates the occurrence and fate of 15 perfluoroalkyl substances (PFASs) and one fluorotelomer sulfonate from a firefighting training ground (FTG) that was contaminated by intensive use of aqueous film forming foams (AFFF). The contamination levels and their spatial and vertical distribution are assessed in the structure. At the surface of the pad, perfluorooctane sulphonate (PFOS) is the dominant PFASs measured, with concentration varying from 10 to 200 μg g(-1). PFASs were also detected in a concrete core at up to 12 cm depth, suggesting the vertical movement and higher transport potential of shorter chain compounds. The estimated mass load of linear PFOS in this specific pad was >300 g with a total of 1.7 kg for the sum of all PFASs analyzed. The kinetics of desorption of PFOS, PFOA and 6:2FTS from the concrete into an overlaying static water volume has been measured under field conditions at two constant temperatures. Fitting the desorption data and estimated rainfall/runoff to a kinetic model suggests that this and similar firefighting training pads will likely remain a source of PFASs for many decades (t0.5=25 years for PFOS).

  16. Potential Application of NASA Aerospace Technology to Ground-Based Power System

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A.; Welch, Gerard E.; Bakhle, Milind A.; Brown, Gerald V.

    2000-01-01

    A review of some of the basic gas turbine technology being developed at the NASA John H. Glenn Research Center at Lewis Field, which may have the potential to be applied to ground-based systems, is presented in this paper. Only a sampling of the large number of research activities underway at the Glenn Research Center can be represented here. The items selected for presentation are those that may lead to increased power and efficiency, reduced cycle design time and cost, improved thermal design, reduced fatigue and fracture, reduced mechanical friction and increased operating margin. The topic of improved material will be presented in this conference and shall not be discussed here. The topics selected for presentation are key research activities at the Glenn Center of Excellence on Turbo-machinery. These activities should be of interest and utility to this ISABE (International Symposium on Air Breathing Engines) Special Forum on Aero-Derivative Land-Based Gas Turbines and to the power industry.

  17. Potential energy curves for the ground and low-lying excited states of CuAg

    SciTech Connect

    Alizadeh, Davood; Shayesteh, Alireza E-mail: ashayesteh@ut.ac.ir; Jamshidi, Zahra E-mail: ashayesteh@ut.ac.ir

    2014-10-21

    The ground and low-lying excited states of heteronuclear diatomic CuAg are examined by multi-reference configuration interaction (MRCI) method. Relativistic effects were treated and probed in two steps. Scalar terms were considered using the spin-free DKH Hamiltonian as a priori and spin-orbit coupling was calculated perturbatively via the spin-orbit terms of the Breit-Pauli Hamiltonian based on MRCI wavefunctions. Potential energy curves of the spin-free states and their corresponding Ω components correlating with the separated atom limits {sup 2}S(Cu) + {sup 2}S(Ag) and {sup 2}D(Cu) + {sup 2}S(Ag) are obtained. The results are in fine agreement with the experimental measurements and tentative conclusions for the ion-pair B0{sup +} state are confirmed by our theoretical calculations. Illustrative results are presented to reveal the relative importance and magnitude of the scalar and spin-orbit effects on the spectroscopic properties of this molecule. Time dependent density functional theory calculations, using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for CuAg and the accuracy of TD-DFT has been compared with ab initio results.

  18. Potential hydrologic impacts of ground-water withdrawal from the Cape Cod National Seashore, Truro, Massachusetts

    USGS Publications Warehouse

    LeBlanc, Denis R.

    1982-01-01

    The hydrologic impacts of continuous ground-water withdrawals at 0.75, 1.0, and 1.24 Mgal/d (million gallons per day) from a test-well site in the Cape Cod National Seashore, Truro, Massachusetts, were evaluated with a three-dimensional finite-difference steady-state-flow digital model. The digital model was prepared during an earlier study and is only briefly described. Continuous withdrawal of more than 1.0 Mgal/d from a well screened from 10 to 40 feet below sea level at the test site will result in upward movement of the freshwater-saltwater interface, and most likely saltwater will eventually contaminate the well. Pumping from a shallower well will decrease the potential for the movement of saltwater into the well, but the water table may be drawn down to the well screen. It is unlikely that movement of the freshwater-saltwater interface in response to pumping from the test site at the simulated rates will result in saltwater contamination of the shallow domestic supply wells in Truro. For the simulated pumping schemes, the water-table decline below average (1963-76) levels did not exceed 0.6 foot except near the pumping wells. Continuous withdrawal at the average year-round rate and the average summer rate will decrease freshwater discharge to the wetland and ocean along the northeastern boundary of the aquifer. (USGS)

  19. Potential health impacts from range fires at Aberdeen Proving Ground, Maryland.

    SciTech Connect

    Willians, G.P.; Hermes, A.M.; Policastro, A.J.; Hartmann, H.M.; Tomasko, D.

    1998-03-01

    This study uses atmospheric dispersion computer models to evaluate the potential for human health impacts from exposure to contaminants that could be dispersed by fires on the testing ranges at Aberdeen Proving Ground, Maryland. It was designed as a screening study and does not estimate actual human health risks. Considered are five contaminants possibly present in the soil and vegetation from past human activities at APG--lead, arsenic, trichloroethylene (TCE), depleted uranium (DU), and dichlorodiphenyltrichloroethane (DDT); and two chemical warfare agents that could be released from unexploded ordnance rounds heated in a range fire--mustard and phosgene. For comparison, dispersion of two naturally occurring compounds that could be released by burning of uncontaminated vegetation--vinyl acetate and 2-furaldehyde--is also examined. Data from previous studies on soil contamination at APG are used in conjunction with conservative estimates about plant uptake of contaminants, atmospheric conditions, and size and frequency of range fires at APG to estimate dispersion and possible human exposure. The results are compared with US Environmental Protection Agency action levels. The comparisons indicate that for all of the anthropogenic contaminants except arsenic and mustard, exposure levels would be at least an order of magnitude lower than the corresponding action levels. Because of the compoundingly conservative nature of the assumptions made, they conclude that the potential for significant human health risks from range fires is low. The authors recommend that future efforts be directed at fire management and control, rather than at conducting additional studies to more accurately estimate actual human health risk from range fires.

  20. Accurate intermolecular ground state potential of the Ar-N2 van der Waals complex.

    PubMed

    Munteanu, Cristian R; Cacheiro, Javier López; Fernández, Berta

    2004-12-01

    After carrying out a systematic basis set convergence study, we evaluate several ground state potential energy surfaces of the Ar-N(2) van der Waals complex at the coupled cluster singles and doubles model including connected triples corrections. We use the aug-cc-pVXZ (X=5,Q,D) and the daug-cc-pVQZ basis sets augmented with a set of 3s3p2d1f1g (denoted 33211) and 3s3p2d2f1g (denoted 33221) midbond functions, respectively. aug-cc-pVTZ-33211 results were available in the literature. The aug-cc-pV5Z-33211 (daug-cc-pVQZ-33221) surface is characterized by a T-shaped minimum at R(e)=3.709 (3.701) A and of 99.01 (102.50) cm(-1), and a linear saddle point at 4.260 (4.257) A and D(e)=75.28 (79.73) cm(-1). These results are compared with the values provided by the semiempirical potentials available, and those of previous theoretical studies. The basis set convergence of the intermolecular potentials is also analyzed. From the potentials the rovibronic spectroscopic properties are determined. We study the basis set convergence of the rotational frequencies. The binding parameters that characterized the aug-cc-pVTZ-33211 surface are reasonable, but the surface is not good enough to evaluate the microwave spectra. The aug-cc-pVQZ-33211 basis set results considerably improve the triple zeta and are close to the aug-cc-pV5Z-33211. Considering the small differences between the quadruple and the quintuple zeta surfaces, the latter results can be expected to be close to convergence. At this level the differences with respect to the accurate experimental frequencies are in the order of 0.7%. In the case of the daug-cc-pVXZ-33211,33221 (X=5,Q,T,D) series, the convergence of the interaction energies with respect to basis set improvement is not so smooth. The errors in the frequencies obtained with the daug-cc-pVQZ-33221 basis set with respect to experiment are in the order of 0.4%.

  1. Science results from a Mars drilling simulation (Río Tinto, Spain) and ground truth for remote science observations.

    PubMed

    Bonaccorsi, Rosalba; Stoker, Carol R

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" to interpret remote science observations made as part of the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling mission simulation. The experiment was successful in detecting evidence for life, habitability, and preservation potential of organics in a relevant astrobiological analogue of Mars. SCIENCE RESULTS: Borehole 7 was drilled near the Río Tinto headwaters at Peña de Hierro (Spain) in the upper oxidized remnant of an acid rock drainage system. Analysis of 29 cores (215 cm of core was recovered from 606 cm penetrated depth) revealed a matrix of goethite- (42-94%) and hematite-rich (47-87%) rocks with pockets of phyllosilicates (47-74%) and fine- to coarse-grained loose material. Post-mission X-ray diffraction (XRD) analysis confirmed the range of hematite:goethite mixtures that were visually recognizable (approximately 1:1, approximately 1:2, and approximately 1:3 mixtures displayed a yellowish-red color whereas 3:1 mixtures displayed a dark reddish-brown color). Organic carbon was poorly preserved in hematite/goethite-rich materials (C(org) <0.05 wt %) beneath the biologically active organic-rich soil horizon (C(org) approximately 3-11 wt %) in contrast to the phyllosilicate-rich zones (C(org) approximately 0.23 wt %). GROUND TRUTH VS. REMOTE SCIENCE ANALYSIS: Laboratory-based analytical results were compared to the analyses obtained by a Remote Science Team (RST) using a blind protocol. Ferric iron phases, lithostratigraphy, and inferred geologic history were correctly identified by the RST with the exception of phyllosilicate-rich materials that were misinterpreted as weathered igneous rock. Adenosine 5'-triphosphate (ATP) luminometry, a tool available to the RST, revealed ATP amounts above background noise, i.e., 278-876 Relative Luminosity Units (RLUs) in only 6 cores, whereas organic carbon was detected in all

  2. Science results from a Mars drilling simulation (Río Tinto, Spain) and ground truth for remote science observations.

    PubMed

    Bonaccorsi, Rosalba; Stoker, Carol R

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" to interpret remote science observations made as part of the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling mission simulation. The experiment was successful in detecting evidence for life, habitability, and preservation potential of organics in a relevant astrobiological analogue of Mars. SCIENCE RESULTS: Borehole 7 was drilled near the Río Tinto headwaters at Peña de Hierro (Spain) in the upper oxidized remnant of an acid rock drainage system. Analysis of 29 cores (215 cm of core was recovered from 606 cm penetrated depth) revealed a matrix of goethite- (42-94%) and hematite-rich (47-87%) rocks with pockets of phyllosilicates (47-74%) and fine- to coarse-grained loose material. Post-mission X-ray diffraction (XRD) analysis confirmed the range of hematite:goethite mixtures that were visually recognizable (approximately 1:1, approximately 1:2, and approximately 1:3 mixtures displayed a yellowish-red color whereas 3:1 mixtures displayed a dark reddish-brown color). Organic carbon was poorly preserved in hematite/goethite-rich materials (C(org) <0.05 wt %) beneath the biologically active organic-rich soil horizon (C(org) approximately 3-11 wt %) in contrast to the phyllosilicate-rich zones (C(org) approximately 0.23 wt %). GROUND TRUTH VS. REMOTE SCIENCE ANALYSIS: Laboratory-based analytical results were compared to the analyses obtained by a Remote Science Team (RST) using a blind protocol. Ferric iron phases, lithostratigraphy, and inferred geologic history were correctly identified by the RST with the exception of phyllosilicate-rich materials that were misinterpreted as weathered igneous rock. Adenosine 5'-triphosphate (ATP) luminometry, a tool available to the RST, revealed ATP amounts above background noise, i.e., 278-876 Relative Luminosity Units (RLUs) in only 6 cores, whereas organic carbon was detected in all

  3. Science Results from a Mars Drilling Simulation (Río Tinto, Spain) and Ground Truth for Remote Science Observations

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, Rosalba; Stoker, Carol R.

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" to interpret remote science observations made as part of the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling mission simulation. The experiment was successful in detecting evidence for life, habitability, and preservation potential of organics in a relevant astrobiological analogue of Mars. Science results. Borehole 7 was drilled near the Río Tinto headwaters at Peña de Hierro (Spain) in the upper oxidized remnant of an acid rock drainage system. Analysis of 29 cores (215 cm of core was recovered from 606 cm penetrated depth) revealed a matrix of goethite- (42-94%) and hematite-rich (47-87%) rocks with pockets of phyllosilicates (47-74%) and fine- to coarse-grained loose material. Post-mission X-ray diffraction (XRD) analysis confirmed the range of hematite:goethite mixtures that were visually recognizable (˜1:1, ˜1:2, and ˜1:3 mixtures displayed a yellowish-red color whereas 3:1 mixtures displayed a dark reddish-brown color). Organic carbon was poorly preserved in hematite/goethite-rich materials (Corg <0.05 wt %) beneath the biologically active organic-rich soil horizon (Corg ˜3-11 wt %) in contrast to the phyllosilicate-rich zones (Corg ˜0.23 wt %). Ground truth vs. remote science analysis. Laboratory-based analytical results were compared to the analyses obtained by a Remote Science Team (RST) using a blind protocol. Ferric iron phases, lithostratigraphy, and inferred geologic history were correctly identified by the RST with the exception of phyllosilicate-rich materials that were misinterpreted as weathered igneous rock. Adenosine 5‧-triphosphate (ATP) luminometry, a tool available to the RST, revealed ATP amounts above background noise, i.e., 278-876 Relative Luminosity Units (RLUs) in only 6 cores, whereas organic carbon was detected in all cores. Our manned vs. remote observations based on automated

  4. Upcoming and Future Missions in the Area of Infrared Astronomy: Spacecraft and Ground-based Observations

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.

    2004-01-01

    The IRIS instrument on the Voyager spacecrafts made major discoveries with regard to the giant planets, their moons and rings and paved the way for future infrared observations for planetary missions within our solar system. The CIRS instrument of Cassini with much greater spectral-spatial resolution and sensitivity than that provided by IRIS is now rapidly approaching the Saturnian system with orbit insertion on July 1, 2004, for which CIRS is expected to provide an order of magnitude advance beyond that provided by IRIS. The Mars program is also presently dominated by infrared observations in the near to mid-infrared spectral bands for missions such as Mars Global Surveyor and its TES instrument and Odyssey with its THEMIS instrument. In the case of Earth science we have such missions as TIMED, which makes infrared observations of the thermosphere using the SABER instrument. With the newly formed New Frontiers Program we have the opportunity for $650M missions such as Kuiper Belt-Pluto Explorer and Jupiter Polar Orbiter with Probes. Under the Flagship line, once per decade, we have the opportunity for $1B missions for which Europa is presently being considered; for this mission infrared measurements could look for hot spots within the maze of cracks and faults on Europa s surface. On Kuiper Belt- Pluto there is an imaging near-IR spectrometer called LEISA. Another mission on the horizon is Titan Orbiter Aerorover Mission (TOAM) for which there is planned a state-of-art version of CIRS called TIRS on the orbiter that will map out the atmospheric composition with unprecedented wavelength coverage and spectral-spatial resolution. This instrument will also provide temperature maps of the surface of Titan to look for hot spots where life may form. On the same mission there will be a descent imager on the Aerorover (i.e., balloon) similar to that provided by LEISA on the Pluto mission to provide compositional-topographical maps of Titan s surface. Other future mission

  5. On the role of ground-based observations in substorm research: Can one recognize the beast from its foot prints?

    NASA Astrophysics Data System (ADS)

    Kauristie, K.

    2003-04-01

    The first coordinated efforts of ground-based auroral observations were carried out already during the International Geophysical Year (IGY) 1957-1958, during which all-sky camera pictures and magnetometer data were collected from several stations in the northern polar regions. This huge amount of data were later organized by Syun-Ichi Akasofu to describe the original auroral substorm concept, main parts of which belong also to the wider magnetospheric substorm schema which started to build up when satellite observations became available. Also the IGY concept is still living strong as versatile networks of ground-based instruments support the ambitious international satellite missions (like Cluster or ILWS) investigating the different solar-terrestrial coupling processes. Many magnetospheric substorm processes have their own specific ionospheric signatures. Consequently, ground-based observations are often used to provide the background context that helps the interpretation of the localized magnetospheric satellite observations. The possibility to analyse phenomena of very different scale sizes is a further advantage. With the modern high-resolution imagers auroral structures of less than kilometer-scale can be analysed. On the other hand, with the combination of the data of the global SuperDARN network and several magnetometer networks the entire polar cap convection and current pattern can be monitored. The development of various data analysis tools and assimilation methods has pushed the interpretation of ground-based data towards more quantitative analysis and resulted in several important findings. In the presentation we will discuss the benefits and pitfalls of ground-based observations, review the most important contributions to substorm research, and envisage some of the future challenges.

  6. Ground-based observations of Saturn's H3+ aurora and ring rain from Keck in 2013

    NASA Astrophysics Data System (ADS)

    O'Donoghue, J.; Melin, H.; Stallard, T.; Provan, G.; Moore, L.; Badman, S. V.; Baines, K. H.; Miller, S.; Cowley, S. W. H.

    2014-12-01

    The ground-based 10-metre Keck telescope was used to probe Saturn's H3+ ionosphere in 2013. The slit on the high resolution near infrared spectrometer (NIRSPEC; (R~25,000) was aligned pole-to-pole along Saturn's rotational axis at local noon. This is also aligned (within uncertainties) to the effectively dipolar magnetic field. Four polar/auroral regions of Saturn's ionosphere were measured simultaneously as the planet rotated: 1) the northern noon main auroral oval; 2) the northern midnight main oval; 3) the northern polar cap and 4) the southern main oval at noon. The results here contain twenty-three H3+ temperatures, column densities and total emissions located at the above regions spread over timescales of both hours and days. The main findings of this study are that ionospheric temperatures in the northern main oval are cooler than their southern counterparts by tens of K; supportive of the hypothesis that the total thermospheric heating rate (Joule heating and ion drag) is inversely proportional to magnetic field strength. The main oval H3+ density and emission is lower at northern midnight than at noon, and this is in agreement with an electron influx peaking at 08:00 Saturn local time and having a minimum at midnight. When ordering the northern main oval parameters of H3+ as a function of the oscillation period seen in Saturn's magnetic field - the planetary period oscillation (PPO) phase - we see a large peak in H3+ density and emission at ˜110° phase, with a full-width at half-maximum (FWHM) of ˜40°. This seems to indicate that the influx of electrons associated with the PPO phase at 90° is responsible at least in part for the behavior of all H3+ parameters. In addition to the auroral/polar data we also present the latest results from observations of Saturn's mid-to-low latitude H3+ emission. This emission is thought to be modulated by charged water product influx which flows into the planet along magnetic field lines from Saturn's rings, i.e. ring

  7. School Ground as Environmental Learning Resources: Teachers' and Pupils' Perspectives on Its Potentials, Uses and Accessibility

    ERIC Educational Resources Information Center

    Atmodiwirjo, Paramita

    2013-01-01

    This paper addresses the role of school ground as outdoor learning resources for environmental education. The opportunities to use school ground are particularly prominent in tropical climate, where the weather permits plenty of outdoor learning activities. A study in primary schools in Jakarta explored the relationship between the spatial aspects…

  8. Atmospheric methane variability at the Peterhof station (Russia): ground-based observations and modeling

    NASA Astrophysics Data System (ADS)

    Makarova, Maria; Kirner, Oliver; Poberovskii, Anatoliy; Imhasin, Humud; Timofeyev, Yuriy; Virolainen, Yana; Makarov, Boris

    2014-05-01

    MF from the true ones were detected for the Peterhof station (0.4% for TC and -0.2% for MF). It should be also noted that the limited number of sunny days may distort the annual cycle estimated from FTIR data (comparing to true). This fact have to take into account when mean levels of CH4 TC and MF obtained from FTIR compare against climatological or averaged model data. Ground-based in situ (local) observations of CH4 mole fraction (LMF) are being performed by LGR GGA-24r-EP gas analyzer since 2013 (at the Peterhof station). The monthly averaged amplitude of LMF diurnal cycle shows variations which are similar to the temporal behavior of MF CH4 retrieved from FTIR for 2013. It is suggested that the value of the amplitude of CH4 LMF diurnal variation characterizes the intensity of methane sources for the North-western region of Russia and can be used to explain the observed features of the annual variation of FTIR MF CH4. However, to prove this statement further simultaneous FTIR and in situ measurements of CH4 should be continued. Both, FTIR observations and EMAC simulations, revealed the positive trend of CH4 over 2009-2012 of about 0.2% per year (statistically significant). FTIR data for 2013 that were taken into account led to a decrease in trend value from 0.2%/yr (2009-2012) to 0.13%/yr (2009-2013). It may indicate the end of the period of extremely high growth rates of methane in the atmosphere that have been registered by different observational systems since 2006. Acknowledgements: This study was funded by Saint-Petersburg State University (grant No.11.0.44.2010), Russian Foundation for Basic Research (grants No.12-05-00596, 14-05-897). Measurement facilities were provided by Geo Environmental Research Center "Geomodel" of Saint-Petersburg State University.

  9. Evaluation and proposed study of potential ground-water supplies, Gallup area, New Mexico

    USGS Publications Warehouse

    Hiss, William L.

    1975-01-01

    The ground-water potential of 5 areas in central-western New Mexico within 85 miles (135 km) of Gallup, N. Mex. was evaluated by reviewing the published literature, inspecting aerial and space photographs, and interviewing ranchers and personnel employed by well-drilling and mineral-exploration companies by telephone. The San Andres Limestone and underlying Glorieta Sandstone of Permian age are the oldest aquifers capable of yielding water of a quality suitable for municipal use. Extreme local variations in hydraulic conductivity and water quality reflect a karstic topography developed on the San Andres Limestone prior to burial by Upper Triassic sediments. The San Andres Limestone and Glorieta Sandstone form an important aquifer in the Grants-Bluewater area where yields of as much as 2,200 gallons per minute (140 l/s) have been obtained. Yields from wells completed in the San Andres-Glorieta aquifer on the Chaco slope and in the Gallup sag-Mogollon slope on the northeast and southeast flanks, respectively, of the Zuni uplift will be much less than those prevailing in the Grants-Bluewater area. Water quality in the San Andres Limestone and Glorieta Sandstone deteriorates with distance away from the axis of the Zuni uplift. Sandstones of Triassic, Jurassic, and Cretaceous age are potential aquifers wherever they are present. Yields to wells tapping these aquifers are generally less than 200 gallons per minute (13 l/s) due to the relatively low hydraulic conductivity. Wells tapping alluvium of Late Cenozoic age along the Rio San Jose and Puerco River and interbedded volcanics and alluvium elsewhere in the area generally yield less than 100 gallons per minute (6 l/s) of water. Tributaries ,of the Rio San Jose that have eroded canyons into Paleozoic and Mesozoic rocks east of the Continental Divide and south of the eastern part of the Zuni uplift have been repeatedly displaced and (or) covered by Quaternary volcanic rocks. The exact location, extent, and depth of

  10. Potentials of L-band ALOS interferometry for the measurement of ground deformations at Etna volcano

    NASA Astrophysics Data System (ADS)

    Briole, P.; Panagiotis, E.; Puglisi, G.; Guglielmino, F.; Bonforte, A.; Murakami, M.

    2009-04-01

    Using eleven ascending PALSAR scenes acquired by the Japanese satellite ALOS over Etna, between January 2007 and September 2008, we produced a series of interferograms covering the volcano and surroundings, by using ROI-PAC software. We compare our results with ENVISAT interferograms covering the same period. The coherence is significantly higher than C-band and it is particularly high in the inhabited areas and on lava flows emplaced during last centuries, where local subsidence is observed on the most recent ones; important improvements in the coherency are also achieved on forested areas. L-band interferometric pairs having large baselines, up to 3 km, are still usable but the coherency significantly fall off, as the baseline increases. Deformation patterns are well measured, and the use of L-band dataset is particular useful in those cases where the coherency in C-band is usually low. This is the case, for instance, of the north-eastern sector of the volcano, where the large forested area made difficult to measure the important ground deformations produced by the dynamic of the Pernicana Fault and the NE Rift zone. The known left lateral strike slip creep across the Pernicana fault is, indeed, well mapped. It can be quantified over the observation interval along the entire fault and compared with the GPS measurements. In the next years, we hope that the acquisition plan of ALOS will permit the capture of more PALSAR scene with the same sensor and orbit parameters. This will constitute a new and exceptional data base, crucial for the knowledge of the dynamics of Etna.

  11. Illinois ground-water observation network; a preliminary planning document for network design

    USGS Publications Warehouse

    Frost, L.R.; O'Hearn, Michael; Gibb, J.P.; Sherrill, M.G.

    1984-01-01

    Water-level and water-quality networks in Illinois were evaluated to determine the adequacy and completeness of available data bases. Ground-water data in present data bases are inadequate to provide information on ground-water quality and water levels in large areas of Illinois and in the major geohydrologic units underlying Illinois and surrounding areas. Data-management needs indicate that a new data base is desirable and could be developed by use of carefully selected available data and new data. Types of data needed to define ground-water quality and water levels in selected geohydrologic units were tentatively identified. They include data on concentrations of organic chemicals related to activities of man, and concentrations of inorganic chemicals which relate either to man 's activities or to the chemical composition of the source aquifer. Water-level data are needed which can be used to describe short- and long-term stresses on the ground-water resources of Illinois. Establishment of priorities for data collection has been deferred until existing hydrologic data files can be stored for usable data and until input from other local, State, and Federal agencies can be solicited and compiled. (USGS)

  12. Ground-water levels in observation wells in Oklahoma, 1982-83 climatic years

    USGS Publications Warehouse

    Goemaat, R.L.; Mize, L.D.; Spiser, D.E.

    1984-01-01

    In the 1982-83 climatic years, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources, collected ground-water level data in Oklahoma from 1,087 sites in 77 counties. This report presents those data points.

  13. Ground-water levels in observation wells in Oklahoma, 1983-84 climatic year

    USGS Publications Warehouse

    Goemaat, R.L.; Mize, L.D.; Spiser, D.E.

    1985-01-01

    During the 1983-84 climatic years, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, collected ground-water level data in Oklahoma from 1,083 sites in 77 counties. This report presents those data points.

  14. A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels

    SciTech Connect

    Delahaye, Thibault Rey, Michaël Tyuterev, Vladimir G.; Nikitin, Andrei; Szalay, Péter G.

    2014-09-14

    In this paper we report a new ground state potential energy surface for ethylene (ethene) C{sub 2}H{sub 4} obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C{sub 2}H{sub 4} molecule was obtained with a RMS(Obs.–Calc.) deviation of 2.7 cm{sup −1} for fundamental bands centers and 5.9 cm{sup −1} for vibrational bands up to 7800 cm{sup −1}. Large scale vibrational and rotational calculations for {sup 12}C{sub 2}H{sub 4}, {sup 13}C{sub 2}H{sub 4}, and {sup 12}C{sub 2}D{sub 4} isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm{sup −1} are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of {sup 13}C{sub 2}H{sub 4} and {sup 12}C{sub 2}D{sub 4} and rovibrational levels of {sup 12}C{sub 2}H{sub 4}.

  15. Comparison of MODIS and VIIRS cloud properties with ARM ground-based observations over Finland

    NASA Astrophysics Data System (ADS)

    Sporre, Moa K.; O'Connor, Ewan J.; Håkansson, Nina; Thoss, Anke; Swietlicki, Erik; Petäjä, Tuukka

    2016-07-01

    Cloud retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the satellites Terra and Aqua and the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi-NPP satellite are evaluated using a combination of ground-based instruments providing vertical profiles of clouds. The ground-based measurements are obtained from the Atmospheric Radiation Measurement (ARM) programme mobile facility, which was deployed in Hyytiälä, Finland, between February and September 2014 for the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) campaign. The satellite cloud parameters cloud top height (CTH) and liquid water path (LWP) are compared with ground-based CTH obtained from a cloud mask created using lidar and radar data and LWP acquired from a multi-channel microwave radiometer. Clouds from all altitudes in the atmosphere are investigated. The clouds are diagnosed as single or multiple layer using the ground-based cloud mask. For single-layer clouds, satellites overestimated CTH by 326 m (14 %) on average. When including multilayer clouds, satellites underestimated CTH by on average 169 m (5.8 %). MODIS collection 6 overestimated LWP by on average 13 g m-2 (11 %). Interestingly, LWP for MODIS collection 5.1 is slightly overestimated by Aqua (4.56 %) but is underestimated by Terra (14.3 %). This underestimation may be attributed to a known issue with a drift in the reflectance bands of the MODIS instrument on Terra. This evaluation indicates that the satellite cloud parameters selected show reasonable agreement with their ground-based counterparts over Finland, with minimal influence from the large solar zenith angle experienced by the satellites in this high-latitude location.

  16. Designing of a risk assessment architecture to analyze potential risks from space weather to space and ground based assets

    NASA Astrophysics Data System (ADS)

    Sattar, Erum

    2016-07-01

    Today's world is more vulnerable to space weather due to ever increased advance and costly space technology deployed in space and on ground. The space weather has a natural potential of posing harmful effects on space and ground based assets and on astronaut's life. This global challenge of space weather essentially demands global and regional preparedness to develop its situational awareness, analyzing risks and devise possible mitigation procedures. Considering risk mitigation architecture as inevitable for all scientific missions, this paper focuses to develop a risk assessment architecture for the space environment and to map its utility in identifying and analyzing potential risks to space and ground based assets from space weather in the South Asia region. Different risk assessment tools will be studied and would conclude in the most effective tool or strategy that may help to develop our capability in identifying, protecting and mitigating from the devastating effects of the space weather.

  17. A comparison of airborne and ground-based radar observations with rain gages during the CaPE experiment

    NASA Technical Reports Server (NTRS)

    Satake, Makoto; Short, David A.; Iguchi, Toshio

    1992-01-01

    The vicinity of KSC, where the primary ground truth site of the Tropical Rainfall Measuring Mission (TRMM) program is located, was the focal point of the Convection and Precipitation/Electrification (CaPE) experiment in Jul. and Aug. 1991. In addition to several specialized radars, local coverage was provided by the C-band (5 cm) radar at Patrick AFB. Point measurements of rain rate were provided by tipping bucket rain gage networks. Besides these ground-based activities, airborne radar measurements with X- and Ka-band nadir-looking radars on board an aircraft were also recorded. A unique combination data set of airborne radar observations with ground-based observations was obtained in the summer convective rain regime of central Florida. We present a comparison of these data intending a preliminary validation. A convective rain event was observed simultaneously by all three instrument types on the evening of 27 Jul. 1991. The high resolution aircraft radar was flown over convective cells with tops exceeding 10 km and observed reflectivities of 40 to 50 dBZ at 4 to 5 km altitude, while the low resolution surface radar observed 35 to 55 dBZ echoes and a rain gage indicated maximum surface rain rates exceeding 100 mm/hr. The height profile of reflectivity measured with the airborne radar show an attenuation of 6.5 dB/km (two way) for X-band, corresponding to a rainfall rate of 95 mm/hr.

  18. A comparison of airborne and ground-based radar observations with rain gages during the CaPE experiment

    NASA Technical Reports Server (NTRS)

    Satake, Makoto; Short, David A.; Iguchi, Toshio

    1992-01-01

    The vicinity of KSC, where the primary ground truth site of the Tropical Rainfall Measuring Mission (TRMM) program is located, was the focal point of the Convection and Precipitation/Electrification (CaPE) experiment in July and Aug. 1991. In addition to several specialized radars, local coverage was provided by the C-band (5 cm) radar at Patrick AFB. Point measurements of rain rate were provided by tipping bucket rain gage networks. Besides these ground-based activities, airborne radar measurements with X- and Ka-band nadir-looking radars on board an aircraft were also recorded. A unique combination data set of airborne radar observations with ground-based observations was obtained in the summer convective rain regime of central Florida. We present a comparison of these data intending a preliminary validation. A convective rain event was observed simultaneously by all three instrument types on the evening of 27 July 1991. The high resolution aircraft radar was flown over convective cells with tops exceeding 10 km and observed reflectivities of 40 to 50 dBZ at 4 to 5 km altitude, while the low resolution surface radar observed 35 to 55 dBZ echoes and a rain gage indicated maximum surface rain rates exceeding 100 mm/hr. The height profile of reflectivity measured with the airborne radar show an attenuation of 6.5 dB/km (two way) for X-band, corresponding to a rainfall rate of 95 mm/hr.

  19. Observations of Blazar S5 0716+714 With Ground Based Telescopes and the Spitzer Infrared Space Telescope

    NASA Astrophysics Data System (ADS)

    Adkins, Jeffery; Lacy, M.; Morton, A.; Travagli, T.; Mulaveesala, M.; Santiago, J.; Rapp, S.; Stefaniak, L.

    2006-12-01

    The Gamma-Ray Large Area Space Telescope (GLAST) to be launched in 2007 has a proposed observing list that includes AGNs and Polars bright enough to be observed optically by amateurs and students. This observing list is maintained by the Global Telescope Network (GTN). One of our targets, S5 0716+714, was observed with the Spitzer Space Telescope MIPS and IRAC instruments and also using ground based telescopes. Observations were made in seven infrared bands with Spitzer. Additional observations made from the ground by students, amateur astronomers, and college observatories in R,V, and I were nearly simultaneous with the Spitzer observations. This data were used to construct light curves over the course of the observation and the Spectral Energy Distribution (SED) of the target using all the sources. These data were compared to models of the dust emission from the torus, synchrotron emission from the radio core, and thermal emission from the accretion disk to determine the relative importance of the different emission mechanisms in this object as a function of wavelength. Results were compared to observations of 4C 29.45 made last year. This research was supported by the Spitzer Science Center, the National Optical Astronomy Observatory, and the California Department of Education's Specialized Secondary Program.

  20. Potentially toxic Pseudo-nitzschia species in plankton and fecal samples of Eubalaena australis from Península Valdés calving ground, Argentina

    NASA Astrophysics Data System (ADS)

    D'Agostino, Valeria C.; Hoffmeyer, Mónica S.; Almandoz, Gastón O.; Sastre, Viviana; Degrati, Mariana

    2015-12-01

    Península Valdés (PV) in Argentina is an important calving ground for the southern right whale Eubalaena australis. However, a high mortality of calves has been observed in the last years, which could be associated with phycotoxin exposure. During a sampling program conducted late in the calving seasons of 2004, 2005 and 2010, potentially toxic species of the genus Pseudo-nitzschia were observed to be an important component of the phytoplankton community and they were also found in fecal samples of two live whales and three stranded whales. In line with this, in the present study Pseudo-nitzschia australis, Pseudo-nitzschia fraudulenta, Pseudo-nitzschia pungens and the complex Pseudo-nitzschia pseudodelicatissima were identified in fecal samples and phytoplankton samples by light and electron microscopy. Although no toxin analysis was carried out in the present study, our findings suggest that E. australis could be exposed to domoic acid in their calving ground.

  1. Comparison of the CALIPSO satellite and ground-based observations of cirrus clouds at the ARM TWP sites

    SciTech Connect

    Thorsen, Tyler J.; Fu, Q.; Comstock, Jennifer M.

    2011-11-10

    Statistics of ice cloud macrophysical and optical properties from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite are compared with those from ground-based lidar observations over a 31 month period. Ground-based lidar observations are taken from the micropulse lidars (MPL) at the three Department of Energy Atmospheric Radiation Measurement (ARM) tropical western pacific (TWP) sites: Manus, Nauru and Darwin. CALIPSO observations show a larger cloud fraction at high altitudes while the ground-based MPLs show a larger cloud fraction at low altitudes. The difference in mean ice cloud top and base heights at the Manus and Nauru sites are all within 0.51 km, although differences are statistically significant. Mean ice cloud geometrical thickness agree to within 0.05 km at the Manus and Nauru sites. Larger differences exist at Darwin due to excessive degradation of the MPL output power during our sampling period. Both sets of observations show thicker clouds during the nighttime which may be real but could also be partially an artifact of the decreased signal-to-noise ratio during the daytime. The number of ice cloud layers per profile are also shown to be consistent after accounting for the difference in spatial resolution. For cloud optical depths, four different retrieval methods are compared, two for each set of observations. All products show that the majority of ice cloud optical depths ({approx}60%) fall below an optical depth of 0.2. For most comparisons all four retrievals agree to within the uncertainty intervals. We find that both CALIPSO retrievals agree best to ground-based optical depths when the lidar ratio in the latter is retrieved instead of set to a fixed value. Also thoroughly compared is the cloud properties for the subset of ice clouds which reside in the tropical tropopause layer (TTL).

  2. Ground level environmental protein concentrations in various ecuadorian environments: potential uses of aerosolized protein for ecological research

    USGS Publications Warehouse

    Staton, Sarah J.R.; Woodward, Andrea; Castillo, Josemar A.; Swing, Kelly; Hayes, Mark A.

    2014-01-01

    Large quantities of free protein in the environment and other bioaerosols are ubiquitous throughout terrestrial ground level environments and may be integrative indicators of ecosystem status. Samples of ground level bioaerosols were collected from various ecosystems throughout Ecuador, including pristine humid tropical forest (pristine), highly altered secondary humid tropical forest (highly altered), secondary transitional very humid forest (regrowth transitional), and suburban dry montane deforested (suburban deforested). The results explored the sensitivity of localized aerosol protein concentrations to spatial and temporal variations within ecosystems, and their value for assessing environmental change. Ecosystem specific variations in environmental protein concentrations were observed: pristine 0.32 ± 0.09 μg/m3, highly altered 0.07 ± 0.05 μg/m3, regrowth transitional 0.17 ± 0.06 μg/m3, and suburban deforested 0.09 ± 0.04 μg/m3. Additionally, comparisons of intra-environmental differences in seasonal/daily weather (dry season 0.08 ± 0.03 μg/m3 and wet season 0.10 ± 0.04 μg/m3), environmental fragmentation (buffered 0.19 ± 0.06 μg/m3 and edge 0.15 ± 0.06 μg/m3), and sampling height (ground level 0.32 ± 0.09 μg/m3 and 10 m 0.24 ± 0.04 μg/m3) demonstrated the sensitivity of protein concentrations to environmental conditions. Local protein concentrations in altered environments correlated well with satellite-based spectral indices describing vegetation productivity: normalized difference vegetation index (NDVI) (r2 = 0.801), net primary production (NPP) (r2 = 0.827), leaf area index (LAI) (r2 = 0.410). Moreover, protein concentrations distinguished the pristine site, which was not differentiated in spectral indices, potentially due to spectral saturation typical of highly vegetated environments. Bioaerosol concentrations represent an inexpensive method to increase understanding of environmental changes, especially in densely vegetated

  3. Observations of Random Walk of the Ground In Space and Time

    SciTech Connect

    Shiltsev, Vladimir; /Fermilab

    2010-01-01

    We present results of micron-resolution measurements of the ground motions in large particle accelerators over the range of spatial scales L from several meters to tens of km and time intervals T from minutes to several years and show that in addition to systematic changes due to tides or slow drifts, there is a stochastic component which has a 'random-walk' character both in time and in space. The measured mean square of the relative displacement of ground elements scales as dY{sup 2} {approx} ATL over broad range of the intervals, and the site dependent constant A is of the order of 10{sup -5{+-}1} {micro}m{sup 2}/(s{center_dot}m).

  4. Assessing the potential global extent of SWOT river discharge observations

    NASA Astrophysics Data System (ADS)

    Pavelsky, Tamlin M.; Durand, Michael T.; Andreadis, Konstantinos M.; Beighley, R. Edward; Paiva, Rodrigo C. D.; Allen, George H.; Miller, Zachary F.

    2014-11-01

    Despite its importance as a major element of the global hydrologic cycle, runoff remains poorly constrained except at the largest spatial scales due to limitations of the global stream gauge network and inadequate data sharing. Efforts using remote sensing to infer runoff from discharge estimates are limited by characteristics of present-day sensors. The proposed Surface Water and Ocean Topography (SWOT) mission, a joint project between the United States and France, aims to substantially improve space-based estimates of river discharge. However, the extent of rivers observable by SWOT, likely limited to those wider than 50-100 m, remains unknown. Here, we estimate the extent of SWOT river observability globally using a downstream hydraulic geometry (DHG) approach combining basin areas from the Hydro1k and Hydrosheds elevation products, discharge from the Global Runoff Data Centre (GRDC), and width estimates from a global width-discharge relationship. We do not explicitly consider SWOT-specific errors associated with layover and other phenomena in this analysis, although they have been considered in formulation of the 50-100 m width thresholds. We compare the extent of SWOT-observable rivers with GRDC and USGS gauge datasets, the most complete datasets freely available to the global scientific community. In the continental US, SWOT would match USGS river basin coverage only at large scales (>25,000 km2). Globally, SWOT would substantially improve on GRDC observation extent: SWOT observation of 100 m (50 m) rivers will allow discharge estimation in >60% of 50,000 km2 (10,000 km2) river basins. In contrast, the GRDC observes fewer than 30% (15%) of these basins. SWOT could improve characterization of global runoff processes, especially with a 50 m observability threshold, but in situ gauge data remains essential and must be shared more freely with the international scientific community.

  5. An approach to decision aid of boreal forest fire control using both of ground observation and remote sensing

    NASA Astrophysics Data System (ADS)

    Nakau, K.; Fukuda, M.; Hayasaka, H.; Kimura, K.; Kushida, K.; Matsuura, N.

    2004-12-01

    Burned area of boreal forest fires is increasing in these decades. Two thirds of forest fires are judged as man-made in Siberia. On the other hand, for boreal forest fire emits global warming gas due to combustion and to change of land coverage, forest fire may accelerate global warming. In 2003 summer, 17million hectares are burned in Siberia and CO2 emission is estimated as 3 hundred million tons. Thus, it is important to control forest fire. Toward this aim, we collected data of boreal forest fire in Alaska and east Siberia in summer fire seasons for two years. Data were acquired from each of ground observation, observation from aircraft and remotely sensed fire detection in June and July. Remotely detected fire using some algorisms were compared with observed data to evaluate the accuracy and earliness of automatic detection. Study areas are Alaska and East Siberia in this year and squares of 1000km centered on Yakutsk, Irkutsk and Krasnoyarsk for each in 2003. Daily NOAA and MODIS satellite images are corrected and used for fire detection. 750 ground observation reports are corrected from Russian agency including location, weather and fire front size and severity. 178 reports are corrected from JAL aircraft flying across Siberia including location and time. Comparison between ground truth data and satellite images was done for validation of automatic forest fire detection. Almost all location of ground and aircraft observation data of forest fires as large as 1 hectare were automatically detected at almost same time using satellite images where whether permitting. We are developing connection of fire detection algorithm and fire expansion simulation model to forecast the possible burned area. On the basis of fire expansion forecast, risk analysis of possible fire expansion for decision aid of fire-fighting activities will be analyzed.@@On the basis of these analyses, we will discuss some possible utilizations of remotely sensed forest fire to control them.

  6. Possible magma intrusion revealed by temporal gravity, ground deformation and ground temperature observations at Mount Komagatake (Hokkaido) during the 1996-1998 crisis

    NASA Astrophysics Data System (ADS)

    Jousset, Philippe; Mori, Hitoshi; Okada, Hiromu

    2000-12-01

    Mount Komagatake (1131m above sea level) is a subduction-related active volcano in Hokkaido (Japan), where two phreatic eruptions occurred in 1996 March and 1998 October, after 54years of dormancy. We analyse four sessions of geodetic, microgravity and ground temperature observations made over a two-year period. From November 1996 to May 1997, neither significant gravity nor significant elevation changes (GPS or levelling) were observed. From May 1997 to November 1997, we observed a slight subsidence (1-2cm) and contraction (within 1cm) of the edifice, a gravity increase (15-30 μgal) at the benchmarks inside the 2km wide summit crater, and a local temperature increase, of 15-20°C, at the summit crater. From November 1997 to May 1998, we observed an edifice-wide gravity increase of about 15µgal, with no significant elevation change for benchmarks outside the summit crater. Besides this edifice-scale variation, we recorded a subsidence of about 5-6cm and apparently no change of gravity inside the summit crater. We inverted our data using models of increasing complexity. Elastic models are able to explain our deformation observations, but they cannot explain either the gravity data or the temperature observations satisfactorily. We introduced both an isothermal and a non-isothermal porous medium filled with fluids to model deformation and gravity variations, and we used a fissure model to invert the temperature anomaly. Our observations are consistent with a model of underground shallow-water evaporation occurring as a result of heat rising from a hot and dense body (density contrast of 200kgm-3) of about 1011 kg at 4-5km depth. This interpretation suggests a possible intrusion of a magmatic body within the edifice.

  7. Ground-water levels, water quality, and potential effects of toxic-substance spills or cessation of quarry dewatering near a municipal ground-water supply, southeastern Franklin County, Ohio

    USGS Publications Warehouse

    Sedam, A.C.; Eberts, S.M.; Bair, E.S.

    1989-01-01

    A newly completed municipal ground-water supply that produces from a sand and gravel aquifer in southern Franklin County, Ohio, may be susceptible to potential sources of pollution. Among these are spills of toxic substances that could enter recharge areas of the aquifer or be carried by surface drainage and subsequently enter the aquifer by induced infiltration. Ground water of degraded quality also is present in the vicinity of several landfills located upstream from the municipal supply. Local dewatering by quarrying operations has created a ground-water divide which, at present, prevents direct movement of the degraded ground water to the municipal supply. In addition, the dewatering has held water levels at the largest landfills below the base of the landfill. Should the dewatering cease, concern would be raised regarding the rise of water levels at this landfills and transport of contaminants through the aquifer to the Scioto River and subsequently by the river to the well field. From June 1984 through July 1986, the U.S. Geological Survey, in cooperation with the City of Columbus, Ohio, investigated the relations among the ground-water supply and potential sources of contamination by means of an observation-well network and a program of measuring water levels and sampling for water quality. Sample collections included those made to determine the baseline levels of organic chemicals and metals, as well as periodic sampling and analysis for common constituents to evaluate any changes taking place in the system. Finally, a steady-state, three-dimensional numerical model was used to determine ground-water flow directions and average ground-water velocities to asses potential effects of toxic-substance spills. The model also was used to simulate changes in the ground-water flow system that could result if part or all of the quarry dewatering ceased. Few of the organic-chemical and metal constituents analyzed for were present at detectable levels. With respect to

  8. Expanding the Discovery Potential of VERITAS via Moonlight Observations

    SciTech Connect

    Benbow, Wystan R.

    2014-10-27

    This grant partially supported the base research efforts of the Smithsonian Astrophysical Observatory (SAO), Very-High-Energy (VHE; E > 100 GeV) gamma-ray research group from 8/1/09 to 7/31/14. During the project period, the SAO gamma-ray group carried out a wide-range of research efforts, but focused on VHE observations of extragalactic sources with VERITAS. The SAO group led or co-lead nearly all VERITAS extragalactic working groups and the observations addressed themes in Particle Physics and Fundamental Laws, Cosmology, and Black Holes. The primary topics of this research were processes in exotic galaxies, especially active galactic nuclei and starburst galaxies, which have implications for cosmology and Lorentz invariance violation, as well as indirect dark matter detection via VERITAS observations of dwarf spheroidal galaxies. In addition, the SAO group let the development of unique capabilities for VERITAS to observe during all periods of moonlight. Overall, this has increased the VERITAS data yield by 60% and these data are both scientifically useful and regularly published. This grant funded research that led to contributions towards the publication of 51 refereed journal articles during the project period, including several led by, or with significant contributions from, the SAO group.

  9. Precipitation and microphysical processes observed by three polarimetric X-band radars and ground-based instrumentation during HOPE

    NASA Astrophysics Data System (ADS)

    Xie, Xinxin; Evaristo, Raquel; Simmer, Clemens; Handwerker, Jan; Trömel, Silke

    2016-06-01

    This study presents a first analysis of precipitation and related microphysical processes observed by three polarimetric X-band Doppler radars (BoXPol, JuXPol and KiXPol) in conjunction with a ground-based network of disdrometers, rain gauges and vertically pointing micro rain radars (MRRs) during the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) during April and May 2013 in Germany. While JuXPol and KiXPol were continuously observing the central HOPE area near Forschungszentrum Jülich at a close distance, BoXPol observed the area from a distance of about 48.5 km. MRRs were deployed in the central HOPE area and one MRR close to BoXPol in Bonn, Germany. Seven disdrometers and three rain gauges providing point precipitation observations were deployed at five locations within a 5 km × 5 km region, while three other disdrometers were collocated with the MRR in Bonn. The daily rainfall accumulation at each rain gauge/disdrometer location estimated from the three X-band polarimetric radar observations showed very good agreement. Accompanying microphysical processes during the evolution of precipitation systems were well captured by the polarimetric X-band radars and corroborated by independent observations from the other ground-based instruments.

  10. Ground deformation across the Corinth rift from 22 years of GPS observations

    NASA Astrophysics Data System (ADS)

    Briole, Pierre

    2013-04-01

    shows a co-seismic displacement in January 2010. The extension rate at all stations except Efpalio is steady over the ten years period. The velocities determined at approximately a hundred network points (1st order and 2nd order observed twice or more) show no temporal variation during the sampled period except the co-seismic of the large 1995 Aigion earthquake. The southern side of the rift behaves as a rigid body with less than 1mm/yr internal deformation except around the Psathopirgos fault. Most of the extension, more than 12 mm/yr at the longitude of Trizonia, occurs offshore in the centre of the rift. The northern side of the rift is less rigid, with 3 mm/yr accommodated between Trizonia and Lidoriki. The points located along the northern shore between Nafpaktos and Itea show a westward (or clockwise) component with respect to the overall velocity field. No significant deformation is observed in the area located between Nafpaktos and the eastern termination of the Trichonis lake and the block located between Etoliko, Thermo, Lidoriki and Nafpaktos has less than 1mm/yr internal deformation. At the western termination of the Psathopirgos fault both GPS and SAR interferometry show the existence of localized deformation in the first few kilometres inland that becomes progressively dominated by right lateral strike slip corresponding probably to the northern termination of the crustal discontinuity activated more to the southwest during the M=6.4 June 8, 2008 Andravida earthquake. No vertical motion is detected at campaign points except at the Drepano lighthouse northwest of the Psathopirgos fault. Further steps forward in the knowledge of the deformation of this exceptional area during the next few decades require among others the deployment of a few ten of permanent GPS stations across the main actives structures on both sides of the rift and at its western termination around Patras, a complete analysis of the available and future InSAR data and fusion with the GPS

  11. Inverse modeling of Texas NOx emissions using space-based and ground-based NO2 observations

    NASA Astrophysics Data System (ADS)

    Tang, W.; Cohan, D. S.; Lamsal, L. N.; Xiao, X.; Zhou, W.

    2013-11-01

    Inverse modeling of nitrogen oxide (NOx) emissions using satellite-based NO2 observations has become more prevalent in recent years, but has rarely been applied to regulatory modeling at regional scales. In this study, OMI satellite observations of NO2 column densities are used to conduct inverse modeling of NOx emission inventories for two Texas State Implementation Plan (SIP) modeling episodes. Addition of lightning, aircraft, and soil NOx emissions to the regulatory inventory narrowed but did not close the gap between modeled and satellite-observed NO2 over rural regions. Satellite-based top-down emission inventories are created with the regional Comprehensive Air Quality Model with extensions (CAMx) using two techniques: the direct scaling method and discrete Kalman filter (DKF) with decoupled direct method (DDM) sensitivity analysis. The simulations with satellite-inverted inventories are compared to the modeling results using the a priori inventory as well as an inventory created by a ground-level NO2-based DKF inversion. The DKF inversions yield conflicting results: the satellite-based inversion scales up the a priori NOx emissions in most regions by factors of 1.02 to 1.84, leading to 3-55% increase in modeled NO2 column densities and 1-7 ppb increase in ground 8 h ozone concentrations, while the ground-based inversion indicates the a priori NOx emissions should be scaled by factors of 0.34 to 0.57 in each region. However, none of the inversions improve the model performance in simulating aircraft-observed NO2 or ground-level ozone (O3) concentrations.

  12. Inverse modeling of Texas NOx emissions using space-based and ground-based NO2 observations

    NASA Astrophysics Data System (ADS)

    Tang, W.; Cohan, D.; Lamsal, L. N.; Xiao, X.; Zhou, W.

    2013-07-01

    Inverse modeling of nitrogen oxide (NOx) emissions using satellite-based NO2 observations has become more prevalent in recent years, but has rarely been applied to regulatory modeling at regional scales. In this study, OMI satellite observations of NO2 column densities are used to conduct inverse modeling of NOx emission inventories for two Texas State Implementation Plan (SIP) modeling episodes. Addition of lightning, aircraft, and soil NOx emissions to the regulatory inventory narrowed but did not close the gap between modeled and satellite observed NO2 over rural regions. Satellite-based top-down emission inventories are created with the regional Comprehensive Air Quality Model with extensions (CAMx) using two techniques: the direct scaling method and discrete Kalman filter (DKF) with Decoupled Direct Method (DDM) sensitivity analysis. The simulations with satellite-inverted inventories are compared to the modeling results using the a priori inventory as well as an inventory created by a ground-level NO2 based DKF inversion. The DKF inversions yield conflicting results: the satellite-based inversion scales up the a priori NOx emissions in most regions by factors of 1.02 to 1.84, leading to 3-55% increase in modeled NO2 column densities and 1-7 ppb increase in ground 8 h ozone concentrations, while the ground-based inversion indicates the a priori NOx emissions should be scaled by factors of 0.34 to 0.57 in each region. However, none of the inversions improve the model performance in simulating aircraft-observed NO2 or ground-level ozone (O3) concentrations.

  13. Inverse Modeling of Texas NOx Emissions Using Space-Based and Ground-Based NO2 Observations

    NASA Technical Reports Server (NTRS)

    Tang, Wei; Cohan, D.; Lamsal, L. N.; Xiao, X.; Zhou, W.

    2013-01-01

    Inverse modeling of nitrogen oxide (NOx) emissions using satellite-based NO2 observations has become more prevalent in recent years, but has rarely been applied to regulatory modeling at regional scales. In this study, OMI satellite observations of NO2 column densities are used to conduct inverse modeling of NOx emission inventories for two Texas State Implementation Plan (SIP) modeling episodes. Addition of lightning, aircraft, and soil NOx emissions to the regulatory inventory narrowed but did not close the gap between modeled and satellite observed NO2 over rural regions. Satellitebased top-down emission inventories are created with the regional Comprehensive Air Quality Model with extensions (CAMx) using two techniques: the direct scaling method and discrete Kalman filter (DKF) with Decoupled Direct Method (DDM) sensitivity analysis. The simulations with satellite-inverted inventories are compared to the modeling results using the a priori inventory as well as an inventory created by a ground-level NO2 based DKF inversion. The DKF inversions yield conflicting results: the satellite based inversion scales up the a priori NOx emissions in most regions by factors of 1.02 to 1.84, leading to 3-55% increase in modeled NO2 column densities and 1-7 ppb increase in ground 8 h ozone concentrations, while the ground-based inversion indicates the a priori NOx emissions should be scaled by factors of 0.34 to 0.57 in each region. However, none of the inversions improve the model performance in simulating aircraft-observed NO2 or ground-level ozone (O3) concentrations.

  14. Simultaneous ground-satellite observation of Pi 2 pulsations associated with upward/downward FACs of the substorm current wedge

    NASA Astrophysics Data System (ADS)

    Uozumi, T.; Yumoto, K.; Imajo, S.; Koga, K.; Obara, T.; Baishev, D. G.; Shevtsov, B. M.; Milling, D. K.; Mann, I. R.; Ikeda, A.; Abe, S.; Yoshikawa, A.; Kawano, H.

    2011-12-01

    The formation of a substorm current wedge (SCW) is one of the fundamental processes in the expansion phase of the magnetospheric substorm [e.g. McPherron et al., 1973]. Uozumi et al. [2011] found that the ground Pi 2 timeseries had high coherencies with simultaneously observed AKR timeseries, regardless of whether the Pi 2 timeseries were associated with upward FAC or downward FAC; this fact suggests that the upward SCW and the downward SCW oscillated in a synchronized manner. This aspect was deduced from ground observations, and should be verified by a simultaneous observation on the ground and in the magnetosphere. In order to clarify the timing relation of Pi 2s that are associated with SCW oscillations, we made a comparative study by combining the ground and satellite data. We analyzed simultaneous ground-satellite observation of Pi 2 pulsation at the ETS-VIII geosynchronous orbit [Koga and Obara, 2008] and at MAGDAS/CPMN [Yumoto and the MAGDAS Group, 2006] high-, middle- and low-latitude stations. We picked up a Pi 2 event that exhibited a high coherency in the waveform among the ground and satellite Pi 2. A typical Pi 2 occurred around 1121UT on July 28, 2008. MLT of each ground station and ETS-VIII at the occurrence of the Pi 2 was as follows: TIK: 19.5h, KUJ: 20.0h, ETS-VIII: 20.8h, ZYK: 20.9h, MGD: 21.0h, PTK: 21.5h and WAD: 3.7h. Characteristics of the Pi 2 event are summarized as follows: (1) the initial deflection of the ground Pi 2s and magnetic bay variations in the D (eastward) component indicate the signature of the upward (at TIK, ZYK, MGD and PTK) and downward (at WAD) FAC of the SCW. (2) Pi 2 oscillated in- or 180deg out-of-phase among the D on the ground and N (eastward) components at the geosynchronous altitude (correlation coefficient: |Υ|> 0.75, phase delay: |ΔT|<10s). (3) Pi 2 oscillations in the H (northward) and P (parallel to the earth rotation axis) component exhibited phase (time) difference among them (|ΔT| < ~50s). By taking into

  15. Automated ground-water monitoring with robowell-Case studies and potential applications

    USGS Publications Warehouse

    Granato, G.E.; Smith, K.P.; ,

    2001-01-01

    Robowell is an automated system and method for monitoring ground-water quality. Robowell meets accepted manual-sampling protocols without high labor and laboratory costs. Robowell periodically monitors and records water-quality properties and constituents in ground water by pumping a well or multilevel sampler until one or more purge criteria have been met. A record of frequent water-quality measurements from a monitoring site can indicate changes in ground-water quality and can provide a context for the interpretation of laboratory data from discrete samples. Robowell also can communicate data and system performance through a remote communication link. Remote access to ground-water data enables the user to monitor conditions and optimize manual sampling efforts. Six Robowell prototypes have successfully monitored ground-water quality during all four seasons of the year under different hydrogeologic conditions, well designs, and geochemical environments. The U.S. Geological Survey is seeking partners for research with robust and economical water-quality monitoring instruments designed to measure contaminants of concern in conjunction with the application and commercialization of the Robowell technology. Project publications and information about technology transfer opportunities are available on the Internet at URL http://ma.water.usgs.gov/automon/.

  16. Ground water chlorinated ethenes in tree trunks: Case studies, influence of recharge, and potential degradation mechanism

    USGS Publications Warehouse

    Vroblesky, D.A.; Clinton, B.D.; Vose, J.M.; Casey, C.C.; Harvey, G.J.; Bradley, P.M.

    2004-01-01

    Trichloroethene (TCE) was detected in cores of trees growing above TCE-contaminated ground at three sites: the Carswell Golf Course in Texas, Air Force Plant PJKS in Colorado, and Naval Weapons Station Charleston in South Carolina. This was true even when the depth to water was 7.9 m or when the contaminated aquifer was confined beneath ???3 m of clay. Additional ground water contaminants detected in the tree cores were cis-1,2-dichloroethene at two sites and tetrachloroethene at one site. Thus, tree coring can be a rapid and effective means of locating shallow subsurface chlorinated ethenes and possibly identifying zones of active TCE dechlorination. Tree cores collected over time were useful in identifying the onset of ground water contamination. Several factors affecting chlorinated ethene concentrations in tree cores were identified in this investigation. The factors include ground water chlorinated ethene concentrations and depth to ground water contamination. In addition, differing TCE concentrations around the trunk of some trees appear to be related to the roots deriving water from differing areas. Opportunistic uptake of infiltrating rainfall can dilute prerain TCE concentrations in the trunk. TCE concentrations in core headspace may differ among some tree species. In some trees, infestation of bacteria in decaying heartwood may provide a TCE dechlorination mechanism within the trunk.

  17. Milagro Observations of Potential TeV Emitters

    NASA Astrophysics Data System (ADS)

    Abeysekara, Anushka; Linnemann, James

    2012-03-01

    We searched for point sources in Milagro sky maps at the locations in four catalogs of potential TeV emitting sources. Our candidates are selected from the Fermi 2FGL pulsars, Fermi 2FGL extragalactic sources, TeVCat extragalactic sources, and from the BL Lac TeV Candidate list published by Costamante and Ghisellini in 2002. The False Discovery Rate (FDR) statistical procedure is used to select the sources. The FDR procedure controls the fraction of false detections. Our results are presented in this talk.

  18. Interplanetary Charged Dust Magnetic Clouds Striking the Magnetosphere: Coordinated Space-based and Ground-based Observations

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Chi, Peter; Lai, Hairong

    In general, asteroids, meteoroids and dust do not interact with the plasma structures in the solar system, but after a collision between fast moving bodies the debris cloud contains nanoscale dust particles that are charged and behave like heavy ions. Dusty magnetic clouds are then accelerated to the solar wind speed. While they pose no threat to spacecraft because of the particle size, the coherency imposed by the magnetization of the cloud allows the cloud to interact with the Earth’s magnetosphere as well as the plasma in the immediate vicinity of the cloud. We call these clouds Interplanetary Field Enhancements (IFEs). These IFEs are a unique class of interplanetary field structures that feature cusp-shaped increases and decreases in the interplanetary magnetic field and a thin current sheet. The occurrence of IFEs is attributed to the interaction between the solar wind and dust particles produced in inter-bolide collisions. Previous spacecraft observations have confirmed that IFEs move with the solar wind. When IFEs strike the magnetosphere, they may distort the magnetosphere in several possible ways, such as producing a small indentation, a large scale compression, or a glancing blow. In any event if the IFE is slowed by the magnetosphere, the compression of the Earth’s field should be seen in the ground-based magnetic records that are continuously recorded. Thus it is important to understand the magnetospheric response to IFE arrival. In this study, we investigate the IFE structure observed by spacecraft upstream of the magnetosphere and the induced magnetic field perturbations observed by networks of ground magnetometers, including the THEMIS, CARISMA, McMAC arrays in North America and the IMAGE array in Europe. We find that, in a well-observed IFE event on December 24, 2006, all ground magnetometer stations observed an impulse at approximately 1217 UT when the IFE was expected to arrive at the Earth’s magnetopause. These ground stations spread across

  19. Ring Laser Observations Near Christchurch, New Zealand, of Rotational Ground Motions Induced by Teleseismic and Regional Earthquakes

    NASA Astrophysics Data System (ADS)

    Holdaway, J.; Igel, H.; Savage, M. K.; Townend, J.; Wells, J.; Hurst, R.; Syracuse, E. M.; Thurber, C. H.; Graham, R.

    2012-12-01

    With the development of high sensitivity ring lasers it has become possible to measure directly the rotational ground motions produced by earthquakes for a wide range of magnitudes and epicentral distances. The UG3 ring laser located near Christchurch, New Zealand is the largest currently existing in the world, measuring 76.9 m in perimeter and horizontally orientated in an underground cavern. It operates with a He-Ne gas mix at 632.8 nm, measuring rotations relative to inertial space by observing frequency differences between oppositely directed beams, which directly relate to rotational velocity (RV) from the Sagnac effect. Our measurements of RV from multiple teleseismic events at UG3 show a similar consistency and overall behaviour to past observations made with the G ring laser in Wettzell, Germany. Instrument response-corrected transverse accelerations (TA) from a co-located seismometer show an excellent fit with RV at periods of 20-120 s, and phase velocities derived from RV and TA match well with modelled values. Multiple passages of surface waves around the earth are clearly distinguished in the rotational data, an indication of the ring laser's sensitivity. Cross-correlations of TA and RV using sliding windows are consistent with expectations from elastic wave propagation, with a high degree of similarity evident especially during dominant SH motion - indicating that an assumption of plane-wave propagation is approximately correct. Significant correlations between RV and TA extending for 2500 s after the fundamental Love wave modes seem to indicate the presence of scattered SH waves or Love-Rayleigh wave coupling due to anisotropy. Regions of increased correlation between TA and RV are identified in the P coda, indicating rotational motions are present prior to the onset of direct SH motion and suggesting the possibility of P-SH scattering. Rotational ground motions have also been analysed for over 300 earthquakes of M2.0-4.5 following the M7.1 Darfield

  20. Characterization and disinfection by-product formation potential of natural organic matter in surface and ground waters from Northern Florida

    USGS Publications Warehouse

    Rostad, C.E.; Leenheer, J.A.; Katz, B.; Martin, B.S.; Noyes, T.I.

    2000-01-01

    Streamwaters in northern Florida have large concentrations of natural organic matter (NOM), and commonly flow directly into the ground water system through karst features, such as sinkholes. In this study NOM from northern Florida stream and ground waters was fractionated, the fractions characterized by infrared (IR) and nuclear magnetic resonance (NMR), and then chlorinated to investigate their disinfection by-product (DBP) formation potential (FP). As the NOM character changed (as quantified by changes in NOM distribution in various fractions, such as hydrophilic acids or hydrophobic neutrals) due to migration through the aquifer, the total organic halide (TOX)-FP and trihalomethane (THM)-FP yield of each of these fractions varied also. In surface waters, the greatest DBP yields were produced by the colloid fraction. In ground waters, DBP yield of the hydrophobic acid fraction (the greatest in terms of mass) decreased during infiltration.

  1. Ab initio potential energy surfaces of HCS+: A study of the ground and the low-lying excited electronic states

    NASA Astrophysics Data System (ADS)

    Kaur, Rajwant; Dhilip Kumar, T. J.

    2016-11-01

    Three dimensional ab initio potential energy surfaces (PESs) have been computed for the ground state and low-lying excited states of HCS+ molecular ion using the internally contracted multi-reference (single and double) configuration interaction and augmented correlation consistent polarized valence quadruple zeta (aug-cc-pVQZ) basis sets. Ground state global PES is analyzed as dissociation of molecular ion into H + CS+. The ground state PES (H + CS+) has been fitted by the inverse power series expansion function. The anisotropy of the surface has been analyzed in terms of the multipolar expansion coefficients for the rigid-rotor surface. The surface will be useful for detailed understanding of collision dynamics in terms of ro-vibrational cross sections and rate coefficients.

  2. Potential hydrologic effects of ground-water withdrawals from the Dakota Aquifer, southwestern Kansas

    USGS Publications Warehouse

    Watts, K.R.

    1985-01-01

    A study was conducted to evaluate the effects of potential development of the Dakota aquifer on the layered aquifer system above Permian rocks in a 5,000 sq mi area of southwestern Kansas. Transmissivity of the Dakota aquifer, determined from analyses of pumping tests, ranges from 100 to 7,100 sq ft/day. Water in the Dakota aquifer is a calcium bicarbonate type water, similar to water in the High Plains aquifer, in the subcrop area. However, in areas distant from the subcrop, water in the Dakota aquifer is a sodium bicarbonate type water with dissolved solids concentrations in excess of 500 mg/L. Gradual declines in the potentiometric surface of the Dakota aquifer have occurred since the onset of pumpage in the 1960's; however, water levels in some wells have risen during the late 1970's. A digital computer model of 3-D groundwater flow was developed to simulate hydrologic conditions of a five-layer hydrologic system for 1975-82 conditions. The major components of the simulated 1975-82 water budget were well discharge from the High Plains aquifer and loss of ground water from storage in the High Plains aquifer. Although downward leakage from the High Plains aquifer in the study area represented only 18,000 acre-ft of the 1,365 ,000 acre-ft discharged from the High Plains aquifer during 1982 , it was a major source of inflow to the Dakota aquifer. Changes in storage in the Dakota aquifer in the study area during 1982 were about 5,000 acre-ft. A base-line projection was made using 1982 simulated hydraulic heads from the calibrated model and 1982 rates of pumpage from both the High Plains and the Dakota aquifers for comparison with eight additional projection simulations in which maximum pumpage from the Dakota aquifer at the end of the projections ranged from about 78,000 to 294,000 acre-ft/yr. The results from the projections indicate that: (1) pumpage from the Dakota aquifer will have a limited effect on hydraulic heads in the High Plains aquifer, (2) drawdown in

  3. Exploring the relationship between a ground-based network and airborne CCN spectra observed at the cloud level

    NASA Astrophysics Data System (ADS)

    Corrigan, C.; Roberts, G. C.; Ritchie, J.; Creamean, J.; White, A. B.

    2011-12-01

    Cloud condensation nuclei (CCN) are aerosol particles that participate in the formation of clouds, and consequently, play a significant role in the influence of anthropogenic aerosols on atmospheric processes and climate change. Ultimately, the CCN of the most interest occupy the part of the atmosphere where cloud processes are occurring. A question arises as to whether in-cloud CCN are properly represented by the measurements of CCN at the ground level. While different locations may result in different answers depending upon local meteorology, the data set collected during CalWater 2011 may allow us to answer to what degree the ground-based observations of CCN are sufficient for evaluating cloud micro-physics over California's Central Valley and the lower slopes of the Sierra Nevada Mountains. During CalWater 2011, ground observations were performed at three different altitudes to assess the evolution of cloud-active aerosols as they were transported from sources in California's Central Valley to the lower slopes of the Sierra Nevada Mountains. CCN spectra were collected over a supersaturation range of 0.08 to 0.80%. Results from these data sets show a diurnal cycle with aerosol concentrations increasing during the afternoon and retreating during the night. In addition, a CCN instrument was placed aboard aircraft for several flights and was able to collect vertical profiles that encompassed the altitudes of the ground sites. The flight data shows a large drop in CCN concentration above the boundary layer and suggests the highest altitude ground site at China Wall ( 1540 masl)was sometimes above the Central Valley boundary layer. By using estimates of boundary layer heights over the mid-altitude site at Sugar Pine Dam (1060 masl), the events when the China Wall site is near or above the boundary layer are identified. During these events, the CCN measurements at China Wall best represent in-cloud CCN behavior. The results of this analysis may be applied towards a

  4. ELF/VLF wave propagation at subauroral latitudes: Conjugate observation between the ground and Van Allen Probes A

    NASA Astrophysics Data System (ADS)

    Martinez-Calderon, Claudia; Shiokawa, Kazuo; Miyoshi, Yoshizumi; Keika, Kunihiro; Ozaki, Mitsunori; Schofield, Ian; Connors, Martin; Kletzing, Craig; Hanzelka, Miroslav; Santolik, Ondrej; Kurth, William S.

    2016-06-01

    We report simultaneous observation of ELF/VLF emissions, showing similar spectral and frequency features, between a VLF receiver at Athabasca (ATH), Canada, (L = 4.3) and Van Allen Probes A (Radiation Belt Storm Probes (RBSP) A). Using a statistical database from 1 November 2012 to 31 October 2013, we compared a total of 347 emissions observed on the ground with observations made by RBSP in the magnetosphere. On 25 February 2013, from 12:46 to 13:39 UT in the dawn sector (04-06 magnetic local time (MLT)), we observed a quasiperiodic (QP) emission centered at 4 kHz, and an accompanying short pulse lasting less than a second at 4.8 kHz in the dawn sector (04-06 MLT). RBSP A wave data showed both emissions as right-hand polarized with their Poynting vector earthward to the Northern Hemisphere. Using cross-correlation analysis, we did, for the first time, time delay analysis of a conjugate ELF/VLF event between ground and space, finding +2 to +4 s (ATH first) for the QP and -3 s (RBSP A first) for the pulse. Using backward tracing from ATH to the geomagnetic equator and forward tracing from the equator to RBSP A, based on plasmaspheric density observed by the spacecraft, we validate a possible propagation path for the QP emission which is consistent with the observed time delay.

  5. Understanding the Potential of Aeroelastic Couplings to Stabilize Ground and Air Resonance in a Soft-Inplane Tiltrotor

    NASA Technical Reports Server (NTRS)

    Howard, Anna K. T.

    1999-01-01

    The tiltrotor offers the best mix of hovering and cruise flight of any of the current V/STOL configurations. One possible improvement on the tiltrotors of today designs would be using a soft-inplane hingeless hub. The advantages to a soft-inplane hingeless hub range from reduced weight and maintenance to reduced vibration and loads. However, soft-inplane rotor systems are inherently in danger of the aeromechanical instabilities of ground and air resonance. Furthermore tiltrotors can be subject to whirl flutter. At least in part because of the potential for air and ground resonance in a soft-inplane rotor, the Bell XV-15, the Bell-Boeing V-22 Osprey, and the new Bell Augusta 609 have stiff-inplane, gimballed rotors which do not experience these instabilities. In order to design soft-inplane V/STOL aircraft that do not experience ground or air resonance, it is important to be able to predict these instabilities accurately. Much of the research studying the stability of tiltrotors has been focused on the understanding and prediction of whirl flutter. As this instability is increasingly well understood, air and ground resonance for a tiltrotor need to be investigated. Once we understand the problems of air and ground resonance in a tiltrotor, we must look for solutions to these instabilities. Other researchers have found composite or kinematic couplings in the blades of a helicopter helpful for ground and air resonance stability. Tiltrotor research has shown composite couplings in the wing to be helpful for whirl flutter. Therefore, this project will undertake to model ground and air resonance of a soft-inplane hingeless tiltrotor to understand the mechanisms involved and to evaluate whether aeroelastic couplings in the wing or kinematic couplings in the blades would aid in stabilizing these instabilities in a tiltrotor.

  6. Analysis of stratospheric NO2 trends above Kiruna using ground-based zenith sky DOAS observations

    NASA Astrophysics Data System (ADS)

    Gu, Myojeong; Enell, Carl-Fredrik; Hendrick, François; Platt, Ulrich; Pukite, Janis; Raffalski, Uwe; Van Roozendael, Michel; Wagner, Thomas

    2016-04-01

    Stratospheric NO2 not only destroys ozone but acts as a buffer against halogen catalyzed ozone loss by converting halogen species into stable nitrates. To a better understanding of the impacts of stratospheric NO2 and O3 chemistry, we need long-term measurement data. In this study, ground-based zenith sky DOAS has successfully monitored trace gases related to stratospheric ozone chemistry since 1997. In this study, we shows the trend in stratospheric NO2 vertical column densities (VCDs) at Kiruna, Sweden (68.84°N, 20.41°E) as derived from ground-based zenith sky DOAS over the period 1997 to 2015. The results will be compared with satellite data measured from GOME on ERS-2, SCIAMACHY on EnviSAT, and GOME-2 on METOP-A. To calculate the trends, we apply a multiple linear regression model including variables to describe effects caused by the quasi-biennial oscillation (QBO), solar activity, and stratospheric aerosol amount.

  7. Degradation of ground ice in a changing climate: the potential impact of groundwater flow

    NASA Astrophysics Data System (ADS)

    de Grandpré, I.; Fortier, D.; Stephani, E.

    2011-12-01

    Climate changes affecting the North West portion of Canada alter the thermal state of the permafrost and promote ground ice degradation. Melting of ground ice leads to greater water flow into the ground and to significant hydraulic changes (i.e. drainage of peatland and lakes, triggering of thermokarst and new groundwater flow patterns). Road infrastructures built on permafrost are particularly sensitive to permafrost degradation. Road construction and maintenance induce heat flux into the ground by the increase of solar radiation absorption (comparing to natural ground), the increase of snow cover on side slopes, the infiltration of water in embankment material and the migration of surface water in the active layer. The permafrost under the roads is therefore submitted to a warmer environment than in natural ground and his behavior reflects how the permafrost will act in the future with the global warming trend. The permafrost degradation dynamic under a road was studied at the Beaver Creek (Yukon) experimental site located on the Alaska Highway. Permafrost was characterized as near-zero Celcius and highly susceptible to differential thaw-settlement due to the ground ice spatial distribution. Ice-rich cryostructures typical of syngenetic permafrost (e.g. microlenticular) were abundant in the upper and lower cryostratigraphic units of fine-grained soils (Units 1, 2A, and 2C). The middle ice-poor silt layer (Unit 2B) characterized by porous cryostructure comprised the top of a buried ice-wedge network extending several meters in the underlying layers and susceptible to degradation by thermo-erosion. These particular features of the permafrost at the study site facilitated the formation of taliks (unfrozen zones) under the road which leaded to a greater water flow. We believe that water flow is promoting an acceleration of permafrost degradation by advective heat transfer. This process remains poorly studied and quantified in permafrost environment. Field data on

  8. Potential for ground-water contamination from movement of wastewater through the unsaturated zone, upper Mojave River Basin, California

    USGS Publications Warehouse

    Umari, A.M.; Martin, P.M.; Schroeder, R.A.; Duell, L.F.; Fay, R.G.

    1993-01-01

    Septic-tank wastewater disposed in 30-foot-deep seepage pits (dry wells) at 46,000 residences is estimated to equal 18 percent of the natural recharge to the sole-source aquifer in the rapidly developing upper Mojave River Basin (Victor Valley) in the high desert northeast of Los Angeles. Vertical rates of movement of the wastewater wetting front through the unsaturated zone at three newly occupied residences ranged from 0.07 to 1.0 foot per day. These rates translate to traveltimes of several months to several years for the wastewater wetting front to reach the water table and imply that wastewater from many disposal systems already has reached the water table, which averages about 150 feet below land surface in the Victor Valley. As wastewater percolates from seepage pits into the adjacent unsaturated zone, the nitrogen present in reduced form is rapidly converted to nitrate. Analyses on soil-core extracts and soil moisturefrom suction lysimeters installed beneath the seepage pits at eight residences showed that nitrate concentrations and nitrate/ chloride ratios generally become lower with increasing depth. The intervals of greatest decline seemed to coincide with finer soil texture or were near the water table. Nitrate-reducing bacteria were tested for and found to be present in soil cores from two residences. Sparse nitrogen-15 data from suction lysimeters at one of these residences, where thenitrate concentration decreased by about one-half at a depth of 200 feet, indicate that the nitrate decline was accompanied by nitrogen-15 enrichment in the residual nitrate with an isotope-separation factor of about -10 permil. Despite the potential input of abundant nitrogen with the domestic wastewater recharge, nitrate concentrations in the area's ground water are generally low. The absence of high nitrate concentrations in the ground water is consistent with the existence of denitrification, a microbial nitrogen-removal mechanism, as wastewater moves through the

  9. Comparison of Ground-Based 3-Dimensional Lightning Mapping Observations with Satellite-Based LIS Observations in Oklahoma: Comparison of LMS and LIS Lightning Mapping

    NASA Technical Reports Server (NTRS)

    Thomas, Ronald J.; Krehbiel, Paul R.; Rison, William; Hamlin, Timothy; Boccippio, Dennis J.; Goodman, Steven J.; Christian, Hugh J.

    1999-01-01

    3-dimensional lightning mapping observations obtained during the MEaPRS program in central Oklahoma during June, 1998 have been compared with observations of the discharges from space, obtained by NASA's Lightning Imaging Sensor (LIS) on the TRMM satellite. Excellent spatial and temporal correlations were observed between the two sets of observations. Most of the detected optical events were associated with intracloud discharges that developed into the upper part of the storm. Cloud-to-ground discharges that were confined to mid- and lower-altitudes tended not to be detected by LIS. Extensive illumination tended to occur in impulsive bursts toward the end or part way through intracloud flashes and appeared to be produced by energetic K-changes that typically occur at these times.

  10. Comparison of the remotely sensed start of the season and ground phenology observations of the cereal crops

    NASA Astrophysics Data System (ADS)

    Bohovic, Roman; Hlavinka, Petr; Semerádová, Daniela; Bálek, Jan; Trnka, Mirek

    2015-04-01

    Phenology monitoring such as start of the season of agricultural crops are important characteristics observed on the ground basis by the farmers and authorities already for the long time. Due to costs, coverage, site disparities and time demands of ground observations is remote sensing phenology an interesting option. Satellite observations enable monitoring of the ground vegetation already at sufficient resolution and in country and regional scale at the same time. However, ground and remote sensing phenology differ in nature of its object. First is focused on single species and limited individuals at the observation spot. Remote sensing is from its construction definition able to monitor area-wide vegetation communities. To understand these differences and to set the procedures to overcome it is the aim of this study. Case study area covers Czech Republic in Central Europe with typical four season temperate climate that strongly influence the vegetation. Daily MODIS (Moderate Resolution Imaging Spectroradiometer) remote sensing data in 250 by 250 meters resolution were used to compute NDVI (normalized difference vegetation index). Iterative developed method for the filtering of NDVI time series since 2000 up till now is crucial for overcoming missing periods mainly due to atmospheric conditions. From improved curve of NDVI start of the season is derived as absolute threshold value of 50% NDVI. Comparison of remotely sensed start of the season with observations of emergence of spring barley and beginning of leaf sheath elongation for winter wheat was done. Data were correlated at 90 ground stations across Czech Republic between the years 2000 and 2012. Correlations at original 250x250 meters resolution and aggregations of 5x5 km were investigated. Different land cover classes were considered for aggregated areas. Correlation of start of the season shows lower results for spring barley caused by strong influence of winter signal and crop sowing date by farmers

  11. Comparing Observed Hurricane Conditions Against Potential Future Climate Change Influences

    NASA Astrophysics Data System (ADS)

    Graham, W. D.

    2012-12-01

    Climate Adaptation Science Investigators: (CASI) is to advance and apply NASA's scientific expertise and products to develop climate adaptation strategies that support NASA's overall mission by minimizing risks to each center's operations, physical assets, and personnel. Using Hurricane Katrina observations as a baseline, we use ADCIRC to model surge extent with simple modifications of the storm track. We examine two time now (T0) scenarios of present-day climatological factors: 1) translating the 2005 path 7 km west; and 2) rotating the approach angle from due-north to WNW. Second, we examine two future time scenarios (TX) by infusing climate change conditions, such as sea level rise and increased storm intensity, into a T0 baseline to assess future impacts. The primary goal of this work entails planning and protecting NASA assets and infrastructure. The adjacent communities, state and local emergency managers, gain benefit from this NASA work as data and analysis includes the surrounding geography.

  12. Theoretical study of the structure and analytic potential energy function for the ground state of the PO2 molecule

    NASA Astrophysics Data System (ADS)

    Zeng, Hui; Zhao, Jun

    2012-07-01

    In this paper, the energy, equilibrium geometry, and harmonic frequency of the ground electronic state of PO2 are computed using the B3LYP, B3P86, CCSD(T), and QCISD(T) methods in conjunction with the 6-311++G(3df, 3pd) and cc-pVTZ basis sets. A comparison between the computational results and the experimental values indicates that the B3P86/6-311++G(3df, 3pd) method can give better energy calculation results for the PO2 molecule. It is shown that the ground state of the PO2 molecule has C2ν symmetry and its ground electronic state is X2A1. The equilibrium parameters of the structure are RP-O = 0.1465 nm, ∠OPO = 134.96°, and the dissociation energy is Ed = 19.218 eV. The bent vibrational frequency ν1 = 386 cm-1, symmetric stretching frequency ν2 = 1095 cm-1, and asymmetric stretching frequency ν3 = 1333 cm-1 are obtained. On the basis of atomic and molecular reaction statics, a reasonable dissociation limit for the ground state of the PO2 molecule is determined. Then the analytic potential energy function of the PO2 molecule is derived using many-body expansion theory. The potential curves correctly reproduce the configurations and the dissociation energy for the PO2 molecule.

  13. Interannaul variations of the vertical and their possible influence on the star catalogs derived from ground-based astrometric observations

    NASA Astrophysics Data System (ADS)

    Li, Z. X.

    The efforts at Shanghai Observatory since 1991, in response to the Resolution of IAU Comm.19: "Applications of optical astrometry time and latitude programs", is described in the paper, especially the studies concerned with the interannual variations of the vertical and their influence on the astronomical studies. It is clear now that there is a component of the order 0.01 - 0.02" on an interannual time scale in latitude residuals which is correlated with geophysical phenomena on the Earth. A recent study has confirmed that the component discovered is actually the variation of the vertical, related to ground-based observation in astronomy. So, it should be emphasized now that the variation of the vertical is significant enough to be considered in astronomy from now on. Its influence on the past studies, including the star catalogs already published and the ERP before 1980 when optical astrometry observations were still used, should be studied in the future. In comparing the HIPPARCOS catalog with those derived by the past observations, we should keep in mind the existence of this error in an astrometric observation and its influence on the star catalogs and other results derived from ground-based astrometric observations.

  14. Observation and prediction of dynamic ground strains, tilts, and torsions caused by the Mw 6.0 2004 Parkfield, California, earthquake and aftershocks, derived from UPSAR array observations

    USGS Publications Warehouse

    Spudich, P.; Fletcher, Joe B.

    2008-01-01

    The 28 September 2004 Parkfield, California, earthquake (Mw 6.0) and four aftershocks (Mw 4.7-5.1) were recorded on 12 accelerograph stations of the U.S. Geological Survey Parkfield seismic array (UPSAR), an array of three-component accelerographs occupying an area of about 1 km2 located 8.8 km from the San Andreas fault. Peak horizontal acceleration and velocity at UPSAR during the mainshock were 0.45g and 27 cm/sec, respectively. We determined both time-varying and peak values of ground dilatations, shear strains, torsions, tilts, torsion rates, and tilt rates by applying a time-dependent geodetic analysis to the observed array displacement time series. Array-derived dilatations agree fairly well with point measurements made on high sample rate recordings of the Parkfield-area dilatometers (Johnston et al., 2006). Torsion Fourier amplitude spectra agree well with ground velocity spectra, as expected for propagating plane waves. A simple predictive relation, using the predicted peak velocity from the Boore-Atkinson ground-motion prediction relation (Boore and Atkinson, 2007) scaled by a phase velocity of 1 km/sec, predicts observed peak Parkfield and Chi-Chi rotations (Huang, 2003) well. However, rotation rates measured during Mw 5 Ito, Japan, events observed on a gyro sensor (Takeo, 1998) are factors of 5-60 greater than those predicted by our predictive relation. This discrepancy might be caused by a scale dependence in rotation, with rotations measured over a short baseline exceeding those measured over long baselines. An alternative hypothesis is that events having significant non-double-couple mechanisms, like the Ito events, radiate much stronger rotations than double-couple events. If this is true, then rotational observations might provide an important source of new information for monitoring seismicity in volcanic areas.

  15. An observation on flash evoked cortical potentials and Qigong meditation.

    PubMed

    Zhang, W; Zheng, R; Zhang, B; Yu, W; Shen, X

    1993-01-01

    The purpose of this study was to investigate the functional state of the cerebral cortex during Qigong meditation with flash visual evoked potentials (F-VEPs) recorded from the occipital scalp in four groups of adults. The first group included 14 subjects who had exercised in Neiyang Gong for 0.5-5.5 years. The second group was composed of 12 subjects who had practiced Neiyang Gong for only 0.5-3 months. Eleven subjects who had never practiced Qigong before made up the third group and served as control. Eleven Qigong practitioners constituted the fourth group. It was found that F-VEP amplitudes were increased in the first group and decreased in the fourth group with the exception of one subject during Qigong meditation. No significant changes were found in the second group and controls. The results were discussed and it is shown that Qigong mediation may have either facilitative or inhibitory effects on the visual cortex depending on the Qigong methods practiced by different individuals.

  16. Estimation of High-Frequency Earth-Space Radio Wave Signals via Ground-Based Polarimetric Radar Observations

    NASA Technical Reports Server (NTRS)

    Bolen, Steve; Chandrasekar, V.

    2002-01-01

    Expanding human presence in space, and enabling the commercialization of this frontier, is part of the strategic goals for NASA's Human Exploration and Development of Space (HEDS) enterprise. Future near-Earth and planetary missions will support the use of high-frequency Earth-space communication systems. Additionally, increased commercial demand on low-frequency Earth-space links in the S- and C-band spectra have led to increased interest in the use of higher frequencies in regions like Ku and Ka-band. Attenuation of high-frequency signals, due to a precipitating medium, can be quite severe and can cause considerable disruptions in a communications link that traverses such a medium. Previously, ground radar measurements were made along the Earth-space path and compared to satellite beacon data that was transmitted to a ground station. In this paper, quantitative estimation of the attenuation along the propagation path is made via inter-comparisons of radar data taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and ground-based polarimetric radar observations. Theoretical relationships between the expected specific attenuation (k) of spaceborne measurements with ground-based measurements of reflectivity (Zh) and differential propagation phase shift (Kdp) are developed for various hydrometeors that could be present along the propagation path, which are used to estimate the two-way path-integrated attenuation (PIA) on the PR return echo. Resolution volume matching and alignment of the radar systems is performed, and a direct comparison of PR return echo with ground radar attenuation estimates is made directly on a beam-by-beam basis. The technique is validated using data collected from the TExas and Florida UNderflights (TEFLUN-B) experiment and the TRMM large Biosphere-Atmosphere experiment in Amazonia (LBA) campaign. Attenuation estimation derived from this method can be used for strategiC planning of communication systems for

  17. Simulation of autonomous observing with a ground-based telescope: the LSST experience

    NASA Astrophysics Data System (ADS)

    Ridgway, Stephen; Cook, Kem; Miller, Michelle; Petry, Catherine; Chandrasekharan, Srinivasan; Saha, Abhijit; Allsman, Robyn; Axelrod, Timothy; Claver, Charles; Delgado, Francisco; Ivezic, Zeljko; Jones, R. Lynne; Krughoff, Simon; Pierfederici, Francesco; Pinto, Phillip

    2010-07-01

    A survey program with multiple science goals will be driven by multiple technical requirements. On a ground-based telescope, the variability of conditions introduces yet greater complexity. For a program that must be largely autonomous with minimal dwell time for efficiency it may be quite difficult to foresee the achievable performance. Furthermore, scheduling will likely involve self-referential constraints and appropriate optimization tools may not be available. The LSST project faces these issues, and has designed and implemented an approach to performance analysis in its Operations Simulator and associated post-processing packages. The Simulator has allowed the project to present detailed performance predictions with a strong basis from the engineering design and measured site conditions. At present, the Simulator is in regular use for engineering studies and science evaluation, and planning is underway for evolution to an operations scheduling tool. We will describe the LSST experience, emphasizing the objectives, the accomplishments and the lessons learned.

  18. SAFE Project: An integrated system of earthquake physics study from ground and space observations

    NASA Astrophysics Data System (ADS)

    De Santis, Angelo; De Franceschi, Giorgiana; Di Giovambattista, Rita; Perrone, Loredana; Alfonsi, Lucilla; Cianchini, Gianfranco; Pavón-Carrasco, Javier F.; Cesaroni, Claudio; Spogli, Luca; Piscini, Alessandro; De Santis, Anna; D'Angelo, Giulia; Musicò, Elvira; Malagnini, Andrea; Amoruso, Leonardo; Carbone, Marianna; Abbattista, Cristoforo; Drimaco, Daniela

    2016-04-01

    The Swarm satellite mission by ESA has the primary goal to measure the magnetic signals from the Earth to get new insights of the geomagnetic field and its sources. The SAFE ("Swarm for Earthquake study") project (funded by ESA in the framework "STSE Swarm+lnnovation", 2014) aims at applying the new approach of geosystemics to the analysis of Swarm satellite electromagnetic data for investigating the preparatory phase of earthquakes. The main objective of this project is to explore the possible link between magnetic ionospheric anomalies and large earthquakes analysing Swarm as well as ground based data (seismic, magnetic, GNSS, etc.). This work will show the state of the art in the study of lithosphere-atmosphere-ionosphere coupling (LAIC) together with some recent case studies.

  19. The 2006 SPIE Symposium on Astronomical Telescopes and Instrumentation ? Observing the Universe from Ground and Space

    NASA Astrophysics Data System (ADS)

    Moorwood, A.

    2006-06-01

    The most recent of these biennial SPIE (The International Society for Optical Engineering) Symposia was held from 24-31 May in the Orlando World Center Marriott Resort & Convention Center in Florida, USA. Over the last decade, these meetings have grown to become the main forum for presenting and discussing all aspects of ground-based, airborne and space telescopes and their instrumentation, including associated advances in technology, software, operations and even astronomical results. As a consequence the meetings are large and well attended by people at all levels in the process of initiating, approving, implementing and operating astronomical projects and facilities. This year there were ~ 1700 registered participants who presented ~ 1600 papers and posters in the following 12 parallel conferences which formed the heart of the meeting.

  20. Temperature Effect in Secondary Cosmic Rays (MUONS) Observed at the Ground: Analysis of the Global MUON Detector Network Data

    NASA Astrophysics Data System (ADS)

    de Mendonça, R. R. S.; Braga, C. R.; Echer, E.; Dal Lago, A.; Munakata, K.; Kuwabara, T.; Kozai, M.; Kato, C.; Rockenbach, M.; Schuch, N. J.; Jassar, H. K. Al; Sharma, M. M.; Tokumaru, M.; Duldig, M. L.; Humble, J. E.; Evenson, P.; Sabbah, I.

    2016-10-01

    The analysis of cosmic ray intensity variation seen by muon detectors at Earth's surface can help us to understand astrophysical, solar, interplanetary and geomagnetic phenomena. However, before comparing cosmic ray intensity variations with extraterrestrial phenomena, it is necessary to take into account atmospheric effects such as the temperature effect. In this work, we analyzed this effect on the Global Muon Detector Network (GMDN), which is composed of four ground-based detectors, two in the northern hemisphere and two in the southern hemisphere. In general, we found a higher temperature influence on detectors located in the northern hemisphere. Besides that, we noticed that the seasonal temperature variation observed at the ground and at the altitude of maximum muon production are in antiphase for all GMDN locations (low-latitude regions). In this way, contrary to what is expected in high-latitude regions, the ground muon intensity decrease occurring during summertime would be related to both parts of the temperature effect (the negative and the positive). We analyzed several methods to describe the temperature effect on cosmic ray intensity. We found that the mass weighted method is the one that best reproduces the seasonal cosmic ray variation observed by the GMDN detectors and allows the highest correlation with long-term variation of the cosmic ray intensity seen by neutron monitors.

  1. Prominence activity related to CME observed by SOHO, Yohkoh and ground-based observatories

    NASA Technical Reports Server (NTRS)

    Schmieder, B.; vanDriel-Gesztelyi, L.; Wiik, J. E.; Kucera, T.; Thompson, B.; DeForest, C.; SaintCyr, C.; Simnett, G. M.

    1997-01-01

    Examples of destabilization of prominences and their associated coronal mass ejections (CMEs) are presented. During the 1996 campaigns of multi-wavelength observations with the Solar and Heliospheric Observatory (SOHO), the Yohkoh satellite's soft X-ray telescope (SXT) and the Meudon (France) H alpha spectroheliograph eruptive solar filaments and prominences associated with the CMEs were observed. Two of the observed events showed that CMEs and 'brusques disparitions' (BDs) seem to be consequences of global magnetic field instability.

  2. Potential sea-level rise from Antarctic ice-sheet instability constrained by observations.

    PubMed

    Ritz, Catherine; Edwards, Tamsin L; Durand, Gaël; Payne, Antony J; Peyaud, Vincent; Hindmarsh, Richard C A

    2015-12-01

    Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

  3. Potential sea-level rise from Antarctic ice-sheet instability constrained by observations.

    PubMed

    Ritz, Catherine; Edwards, Tamsin L; Durand, Gaël; Payne, Antony J; Peyaud, Vincent; Hindmarsh, Richard C A

    2015-12-01

    Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers. PMID:26580020

  4. China radiometric calibration sites ground-based automatic observing systems for CAL/VAL

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Li, Xin; Rong, Zhiguo; Zhang, Lijun; Hu, Xiuqing; Ba, Xiutian

    2015-10-01

    A brand-new field observing station has been built up in the China radiometric calibration sites (CRCS) of Dunhuang Gobi for CAL/VAL, include house, observing field, power supply, tower crane, et al. Many automatic observation instruments designed and manufactured by Anhui Institute of Optics and Fine Mechanical Chinese Academy of Sciences were deployed in CRCS Dunhuang Site and introduced deeply in this paper. Followed with the finishing of the basic constructions of the field observing station, it will be an open field test and exchange platform for sharing of test data, research and infrastructure, promote exchanges and cooperation between the relevant disciplines and units.

  5. Research of Earthquake Potential from Active Fault Observation in Taiwan

    NASA Astrophysics Data System (ADS)

    Chien-Liang, C.; Hu, J. C.; Liu, C. C.; En, C. K.; Cheng, T. C. T.

    2015-12-01

    We utilize GAMIT/GLOBK software to estimate the precise coordinates for continuous GPS (CGPS) data of Central Geological Survey (CGS, MOEA) in Taiwan. To promote the software estimation efficiency, 250 stations are divided by 8 subnets which have been considered by station numbers, network geometry and fault distributions. Each of subnets include around 50 CGPS and 10 international GNSS service (IGS) stations. After long period of data collection and estimation, a time series variation can be build up to study the effect of earthquakes and estimate the velocity of stations. After comparing the coordinates from campaign-mode GPS sites and precise leveling benchmarks with the time series from continuous GPS stations, the velocity field is consistent with previous measurement which show the reliability of observation. We evaluate the slip rate and slip deficit rate of active faults in Taiwan by 3D block model DEFNODE. First, to get the surface fault traces and the subsurface fault geometry parameters, and then establish the block boundary model of study area. By employing the DEFNODE technique, we invert the GPS velocities for the best-fit block rotate rates, long term slip rates and slip deficit rates. Finally, the probability analysis of active faults is to establish the flow chart of 33 active faults in Taiwan. In the past two years, 16 active faults in central and northern Taiwan have been assessed to get the recurrence interval and the probabilities for the characteristic earthquake occurred in 30, 50 and 100 years.

  6. Milagro Observations of Potential TeV Emitters

    NASA Technical Reports Server (NTRS)

    Abdo, A. A.; Abeysekara, A. U.; Allen, B. T.; Aune, T.; Barber, A. S.; Berley, D.; Braun, J.; Chen, C.; Christopher, G. E.; DeYoung, T.; Dingus, B. L.; Ellsworth, R. W.; Gonzalez, M. M.; Goodman, J. A.; Hays, E.; Hoffman, C. M.; Huentemeyer, P. H.; Imran, A.; Kolterman, B. E.; Linnemann, J. T.; McEnery, J. E.; Morgan, T.; Mincer, A. I.; Nemethy, P.; Pretz, J.

    2014-01-01

    This paper reports the results from three targeted searches of Milagro TeV sky maps: two extragalactic point source lists and one pulsar source list. The first extragalactic candidate list consists of 709 candidates selected from the Fermi-LAT 2FGL catalog. The second extragalactic candidate list contains 31 candidates selected from the TeVCat source catalog that have been detected by imaging atmospheric Cherenkov telescopes (IACTs). In both extragalactic candidate lists Mkn 421 was the only source detected by Milagro. This paper presents the Milagro TeV flux for Mkn 421 and flux limits for the brighter Fermi- LAT extragalactic sources and for all TeVCat candidates. The pulsar list extends a previously published Milagro targeted search for Galactic sources. With the 32 new gamma-ray pulsars identified in 2FGL, the number of pulsars that are studied by both Fermi-LAT and Milagro is increased to 52. In this sample, we find that the probability of Milagro detecting a TeV emission coincident with a pulsar increases with the GeV flux observed by the Fermi-LAT in the energy range from 0.1 GeV to 100 GeV.

  7. Spirit at Gusev Crater: Preliminary Observations, Potential Processes and Hypotheses

    NASA Technical Reports Server (NTRS)

    Cabrol, N. A.; desMarais, D.; Farmer, J.; Crumpler, L.; Grin, E. A.; Milam, K.; Grant, J.; Greeley, R.; Anderson, R. C.; Grotzinger, J.

    2004-01-01

    Spirit landed in a flat plain in Gusev crater with local undulations at meters scales generated by ridges covered with blocks, some of them looking rounded. Several, flat-topped, mesas are visible in the far field in direction of Ma adim Vallis. A set of north/south oriented hills reaches approximately 150 m elevation to the east of the landing site (LS). A dipping brighter unit with possibly some scarps is associated with it. This setting could be consistent with layering observed on the MOC images of the hills, local exposure of material with variable dust cover, or deflated or allochtonous material. Numerous small depressions are visible from LS referred to as "Columbia Memorial Station"* (CMS). Floors are partially filled with finer-grained, high albedo material. At least one of them, nicknamed "Sleepy Hollow"* (approximately 30 m diameter) may be an eroded secondary impact crater. It is unclear if they can all be related to small impact structures. Some of them are elongated and aligned with the ridges. The morphology of rocks and soil at this Gusev Crater is presented. Evidence of dynamic aeolian action along this Crater is also discussed.

  8. Electrical Potentials Observed During Frictional Stick-Slip - A Semiconductor Mechanism

    NASA Astrophysics Data System (ADS)

    Leeman, J.; Scuderi, M.; Marone, C.; Saffer, D. M.

    2013-12-01

    Electromagnetic phenomena are commonly reported during and after large earthquakes. Various lines of evidence including charring of plant roots, magnetic remnant signatures in pseudotachylite, and visible earthquake lights indicate a strong electrical potential separation during co-seismic rupture. Suggested explanations have included triboelectricity, piezoelectricity, and streaming potentials. The 'semiconductor effect', or migration of electron holes, has been proposed as an alternative explanation and studied extensively in solids. We present evidence of a similar migration effect in a granular material that exhibits repeated frictional stick-slip events under a variety of conditions. Soda-lime glass beads were sheared in a double-direct shear configuration in a biaxial loading frame. Glass beads exhibit consistent, repetitive stick-slip and rate/state friction effects that are similar to rock. Layers of 5 mm thickness were sheared under a constant normal load of 4MPa, at load point velocities of 1, 30, and 100 μm/s. This was done for mono-disperse particle size distributions of 100-150 μm and 420-500 μm. Tests were conducted at room humidity, at 100% humidity, and under submerged conditions. During shearing, the electrical potential of the surface was monitored relative to the system ground with a non-contact electrostatic volt meter (ESVM) manufactured by Trek Incorporated. During stick-slip events, we observe electrical potential anomalies that appear to be related to failure of force chains supporting the shear load. Two distinct types of behavior are delineated by the attainment of steady state frictional sliding. In the pre-steady state phase, as shear stress is increasing, layers are observed to charge during stick-slip and the potential of the entire system rises. When shear stress rises to the level of steady state frictional sliding, the system begins to discharge, with superimposed anomalies characterized by potential drops of several volts that

  9. Seismo-traveling ionospheric disturbances of earthquake and tsunami waves observed by space- and ground-based GPS receivers

    NASA Astrophysics Data System (ADS)

    Liu, J. Y. G.; Chen, C. Y.; Lin, C. H.

    2015-12-01

    FORMOSAT-3/COSMIC (F3/C) is a constellation of six microsatellites launched on April 15, 2006 and has been orbiting with 72° inclination at 700 to 800 km above the earth since December 2007. The main payload of the F3/C is the GPS Occultation eXperiment (GOX) which carries out probing the radio occultation (RO) total electron content between GPS satellite and F3/C. Therefore, F3/C provides us an excellent opportunity to vertically scan ionospheric electron density from 100 up to 800 km altitude. On the other hand, worldwide ground-based GPS receivers can be employed to observe traveling ionospheric disturbances of the TEC. Here, we present the ionosphere response to seismic and tsunami waves by means of F3/C RO TEC and worldwide ground-based GPS TEC as well as existing data of infrasondes, magnetometers, and Doppler sounding systems during the 11 March 2011 M9.0 Tohoku earthquake.

  10. Observation of dipropenyldisulfide and other organic sulfur compounds in the atmosphere of a beech forest with Allium ursinum ground cover

    NASA Astrophysics Data System (ADS)

    Puxbaum, H.; König, G.

    Dipropenyldisulfide, methylpropenyldisulfide, cis-propenylpropyldisulfide, diallylsulfide, dimethyldisulfide and 3-methylthiopropene were detected in the atmosphere of a beech forest with Allium ursinum (broad-leaved garlic) ground cover plants. Furthermore, it was shown that the Allium plants were the source of the organic sulfur compounds. The atmospheric concentrations of the organic sulfur observed on one day in May 1994 in a suburban forest in Vienna ranged from 0.3 to 7.8 ppb S with an average level of 2.9 ppb S. The atmospheric emission rate of organic sulfur species from A. ursinum determined with an enclosure box was the highest ever reported for terrestrial continental plants. The total organic sulfur flux on the average was at least 1 jug g-1h-1 (plant dry weight) or 60 gmgm-2 h-1 (per unit of ground area).

  11. Biogeographic patterns in below-ground diversity in New York City's Central Park are similar to those observed globally.

    PubMed

    Ramirez, Kelly S; Leff, Jonathan W; Barberán, Albert; Bates, Scott Thomas; Betley, Jason; Crowther, Thomas W; Kelly, Eugene F; Oldfield, Emily E; Shaw, E Ashley; Steenbock, Christopher; Bradford, Mark A; Wall, Diana H; Fierer, Noah

    2014-11-22

    Soil biota play key roles in the functioning of terrestrial ecosystems, however, compared to our knowledge of above-ground plant and animal diversity, the biodiversity found in soils remains largely uncharacterized. Here, we present an assessment of soil biodiversity and biogeographic patterns across Central Park in New York City that spanned all three domains of life, demonstrating that even an urban, managed system harbours large amounts of undescribed soil biodiversity. Despite high variability across the Park, below-ground diversity patterns were predictable based on soil characteristics, with prokaryotic and eukaryotic communities exhibiting overlapping biogeographic patterns. Further, Central Park soils harboured nearly as many distinct soil microbial phylotypes and types of soil communities as we found in biomes across the globe (including arctic, tropical and desert soils). This integrated cross-domain investigation highlights that the amount and patterning of novel and uncharacterized diversity at a single urban location matches that observed across natural ecosystems spanning multiple biomes and continents.

  12. Observer variability in pinniped counts: Ground-based enumeration of walruses at haul-out sites

    USGS Publications Warehouse

    Udevitz, M.S.; Jay, C.V.; Cody, M.B.

    2005-01-01

    Pinnipeds are often monitored by counting individuals at haul-out sites, but the often large numbers of densely packed individuals at these sites are difficult to enumerate accurately. Errors in enumeration can induce bias and reduce precision in estimates of population size and trend. We used data from paired observers monitoring walrus haul-outs in Bristol Bay, Alaska, to quantify observer variability and assess its relative importance. The probability of a pair of observers making identical counts was 50 individuals. Mean count differences ranged up to 25% for the largest counts, depending on beach and observers. In at least some cases, there was a clear tendency for counts of one observer to be consistently greater than counts of the other observer in a pair, indicating that counts of at least one of the observers were biased. These results suggest that efforts to improve accuracy of counts will be worthwhile. However, we also found that variation among observers was relatively small compared to variation among visits to a beach so that efforts to account for other sources of variation will be more important.

  13. Quantitative estimation of Tropical Rainfall Mapping Mission precipitation radar signals from ground-based polarimetric radar observations

    NASA Astrophysics Data System (ADS)

    Bolen, Steven M.; Chandrasekar, V.

    2003-06-01

    The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35°, and period of 91.5 min. The PR is a single-frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant and as high as 10-15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR signal returns. Quantitative estimation of PR attenuation is made along the PR beam via ground-based polarimetric observations to validate attenuation correction procedures used by the PR. The reflectivity (Zh) at horizontal polarization and specific differential phase (Kdp) are found along the beam from S-band ground radar measurements, and theoretical modeling is used to determine the expected specific attenuation (k) along the space-Earth path at Ku-band frequency from these measurements. A theoretical k-Kdp relationship is determined for rain when Kdp ≥ 0.5°/km, and a power law relationship, k = a Zhb, is determined for light rain and other types of hydrometers encountered along the path. After alignment and resolution volume matching is made between ground and PR measurements, the two-way path-integrated attenuation (PIA) is calculated along the PR propagation path by integrating the specific attenuation along the path. The PR reflectivity derived after removing the PIA is also compared against ground radar observations.

  14. Evaluation of ground failure susceptibility, opportunity, and potential in the urban area of Anchorage, Alaska : final technical report

    USGS Publications Warehouse

    Moriwaki, Yoshiharu; Idriss, I.M.

    1987-01-01

    This study was conducted as a part of the U.s. Geological Survey's Earthquake Hazards Reduction Program. The goal of this program is a reduction of earthquake hazards through the incorporation of research findings on these hazards into land-use planning decisions. An important objective of the Earthquake Hazards Reduction Program is assessment of the potential for earthquake-induced ground failure in areas of high seismicity.

  15. Plasmasphere pulsations observed simultaneously by midlatitude SuperDARN radars, ground magnetometers and THEMIS spacecraft during an auroral substorm

    NASA Astrophysics Data System (ADS)

    Ruohoniemi, J. M.; Shi, X.; Baker, J. B. H.; Frissell, N. A.; Hartinger, M.; Liu, J.

    2015-12-01

    We present simultaneous ground and space-based observations of ultra-low frequency (ULF) pulsations which occurred during an auroral substorm on September 25th, 2014. Expansion phase onset began at 06:04 UT at which time three midlatitude SuperDARN radars observed strong pulsations in the Pi2 frequency range with peak to peak amplitude reaching as high as 1km/s. Similar pulsations occurred during a later auroral intensification which started at 06:20 UT. Both sets of pulsations were detected in a region of radar backscatter located inside the subauroral polarization stream (SAPS) equatorward of the auroral oval specified by THEMIS all sky imagers and inside the midlatitude density trough as mapped by GPS/TEC measurements. The amplitude of the pulsations was large enough to reverse the direction of the SAPS flow from westward to eastward. Similar pulsations were detected by electric field instrument aboard the THEMIS probe D located inside the plasmasphere. Simultaneous observations from several low-latitude ground magnetometers (some located on the dayside) further illustrate the global nature of the pulsations and suggest they may have been associated with a plasmaspheric cavity resonance (PCR). Pulsed tailward plasma flow observed by THEMIS probe E at the geosynchronous orbit suggests that the compressional energy to generate the PCR was from the Bursty Bulk Flows (BBFs) braking against the magnetospheric dipolar region.

  16. Coordinated Polar Spacecraft, Geosynchronous Spacecraft, and Ground-based Observations of Magnetopause Oscillations and Pc5 Waves in the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Le, G.; Chen, S.; Zheng, Y.; Russell, C. T.; Slavin, J. A.; Huang, C.-S.; Petrinec, S. S.; Moore, T. E.; Samson, J.; Singer, H. J.

    2005-01-01

    In this paper, we present in situ observations of surface waves at the magnetopause and oscillatory magnetospheric field lines, and coordinated observations Pc5 waves at geosynchronous orbit by the GOES spacecraft, and on the ground by CANOPUS and 210 Degree Magnetic Meridian (210MMJ magnetometer arrays. On February 7,2002 during a highspeed solar wind stream, the Polar spacecraft was skimming the magnetopause in a post-noon meridian plane for approximately 3 hours. During this interval, it made two short excursions and a few partial crossings into the magnetosheath and observed quasi-periodic cold ion bursts in the region adjacent to the magnetopause current layer. The multiple magnetopause crossings as well as the velocity of the cold ion bursts indicate that the magnetopause was oscillating with about 6 minute period. Simultaneous observations of Pc5 waves at geosynchronous orbit by the GOES spacecraft and on the ground by the CANOPUS magnetometer array reveal that these magnetospheric pulsations were forced oscillations of magnetic field lines directly driven by the magnetopause oscillations. The magnetospheric pulsations occurred only in a limited longitudinal region in the post-noon dayside sector, and were not a global phenomenon as one would expect for global field line resonance. Thus, the magnetopause oscillations at the source were also limited to a localized region spanning about 4 hours in local time.

  17. Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network

    NASA Astrophysics Data System (ADS)

    Sprovieri, Francesca; Pirrone, Nicola; Bencardino, Mariantonia; D'Amore, Francesco; Carbone, Francesco; Cinnirella, Sergio; Mannarino, Valentino; Landis, Matthew; Ebinghaus, Ralf; Weigelt, Andreas; Brunke, Ernst-Günther; Labuschagne, Casper; Martin, Lynwill; Munthe, John; Wängberg, Ingvar; Artaxo, Paulo; Morais, Fernando; Barbosa, Henrique de Melo Jorge; Brito, Joel; Cairns, Warren; Barbante, Carlo; Diéguez, María del Carmen; Garcia, Patricia Elizabeth; Dommergue, Aurélien; Angot, Helene; Magand, Olivier; Skov, Henrik; Horvat, Milena; Kotnik, Jože; Read, Katie Alana; Mendes Neves, Luis; Gawlik, Bernd Manfred; Sena, Fabrizio; Mashyanov, Nikolay; Obolkin, Vladimir; Wip, Dennis; Feng, Xin Bin; Zhang, Hui; Fu, Xuewu; Ramachandran, Ramesh; Cossa, Daniel; Knoery, Joël; Marusczak, Nicolas; Nerentorp, Michelle; Norstrom, Claus

    2016-09-01

    Long-term monitoring of data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS) project was funded by the European Commission (http://www.gmos.eu) and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010-2015), analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.

  18. Three-dimensional ionospheric tomography using observation data of GPS ground receivers and ionosonde by neural network

    NASA Astrophysics Data System (ADS)

    Ma, X. F.; Maruyama, T.; Ma, G.; Takeda, T.

    2005-05-01

    In this paper we present a new method based on a Residual Minimization Training Neural Network (RMTNN) to reconstruct the three-dimensional electron density distribution of the local ionosphere with high spatial resolution (about 50 km × 50 km in east/west and 30 km in altitude) using GPS and ionosonde observation data. In this method we reconstruct an approximate three-dimensional electron density distribution as a computer tomographic image by making use of the excellent capability of a multilayer neural network to approximate an arbitrary function. For this application the network training is carried out by minimizing the squared residuals of an integral equation. We combine several additional techniques with the new method, i.e., input space discretization, use of ionosonde observation data to improve the vertical resolution, automatic estimation of the biases of the satellite and the ground receivers by using the parameter estimation method, and estimation of plasmasphere contributions to the total electron content on the basis of an assumption of diffusive equilibrium with constant scale height. Numerical experiments for the actual positions of the GPS satellites and the ground receivers are used to validate the reliability of the method. We also applied the method to the analysis of real observation data and compared the results with ionosonde observations which were not used for the network training.

  19. Linking ground motion measurements and macroseismic observations in France: a case study based on accelerometric and macroseismic databases

    NASA Astrophysics Data System (ADS)

    Lesueur, Chloé; Cara, Michel; Scotti, Oona; Schlupp, Antoine; Sira, Christophe

    2013-04-01

    Comparison between accelerometric and macroseismic observations is made for three M w = 4.5 earthquakes, which occurred in north-eastern France and south-western Germany in 2003 and 2004. Scalar and spectral instrumental parameters are processed from the accelerometric data recorded by nine accelerometric stations located between 29 and 180 km from the epicentres. Macroseismic data are based on French Internet reports. In addition to the single questionnaire intensity, analysis of the internal correlation between the encoded answers highlights four predominant fields of questions bearing different physical meanings: (1) "vibratory motions of small objects", (2) "displacement and fall of objects", (3) "acoustic noise" and (4) "personal feelings". Best correlations between macroseismic and instrumental observations are obtained when the macroseismic parameters are averaged over 10-km-radius circles around each station. Macroseismic intensities predicted by published peak ground velocity (PGV)-intensity relationships agree with our observed intensities, contrary to those based on peak ground acceleration (PGA). Correlation between the macroseismic and instrumental data for intensities between II and V (EMS-98) is better for PGV than for PGA. Correlation with the response spectra exhibits clear frequency dependence for all macroseismic parameters. Horizontal and vertical components are significantly correlated with the macroseismic parameters between 1 and 10 Hz, a range corresponding to both natural frequencies of most buildings and high energy content in the seismic ground motion. Between 10 and 25 Hz, a clear lack of correlation between macroseismic and instrumental observations exists. It could be due to a combination of the decrease in the energy signal above 10 Hz, a high level of anthropogenic noise and an increase in variability in soil conditions. Above 25 Hz, the correlation coefficients between the acceleration response spectra and the macroseismic

  20. Surface solar radiation variability over Eastern Mediterranean: A high spatial resolution view from satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Alexandri, Georgia; Georgoulias, Aristeidis K.; Meleti, Charikleia; Balis, Dimitris

    2013-04-01

    Surface Solar Radiation (SSR) has been measured for decades from ground-based observations for several spots around the planet. On the other hand, during the last decades, satellite observations made possible the assessment of the spatial variability of the SSR at a global as well as regional scale. In this study, a detailed view of the SSR spatiotemporal variability is presented at a high spatial resolution, focusing on the region of Eastern Mediterranean. This is a region of particular interest since it is affected by aerosols of various origins (continental, sea, dust and biomass burning particles) and encloses countries with significant socioeconomical changes during the last decades. The SSR satellite data used in this study have been obtained from the Satellite Application Facility on Climate Monitoring (CM SAF) (www.cmsaf.eu). The CM SAF SSR dataset is based on reflections in the visible channel of Meteosat First Generation, has a spatial resolution of 0.03ox0.03o and spans from 1983 to 2005. The satellite observations are validated against ground-based measurements for the city of Thessaloniki, a coastal city of ~1 million inhabitants in northern Greece, situated in the heart of Eastern Mediterranean. Measurements from two pyranometers, an Eppley Precision pyranometer (1983-1992) and a Kipp & Zonen CM-11 pyranometer (1993-2005), both located at the center of the city, were homogenized and a uniform time series for the 23 year period was constructed. SSR was also calculated with the use of MODIS level-2 aerosol and cloud satellite data for the region of Thessaloniki and the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model. These new satellite-based results are compared to both CM SAF and ground-based observations in order to examine whether SBDART and MODIS could be further used for the investigation of the spatial patterns of SSR in the area.

  1. Hydrogeology, water quality, and potential for transport of organochlorine pesticides in ground water at the North Hollywood Dump, Memphis, Tennessee

    USGS Publications Warehouse

    Broshears, R.E.; Bradley, M.W.

    1992-01-01

    Geologic, hydrologic, and water-quality data indicate that ground-water contamination is confined to shallow horizons within the unconfined aquifer underlying the North Hollywood Dump in Memphis, Tennessee. The dump is a closed municipal-industrial landfill that has been ranked as Tennessee's potentially most dangerous hazardous-waste site. Toxic constituents of concern at the dump include residues from the manufacture of organochlorine pesticides. The dump overlies an unconfined aquifer of unconsolidated sands, silts, and clays. During average hydrologic conditions, ground waterflows beneath the dump at a mean velocity of approximately 3 feet per day and discharges to the Wolf River. Leachate from the dump mixes with underlying ground water, resulting in increased concentrations of dissolved solids and organic carbon downgradient from the dump. The mobility of chlordane, a representative organochlorine pesticide, is limited by its low solubility and its strong affinity for sand, silt, and clays of the aquifer. Degradation of chlordane may occur slowly, if at all, in the aquifer. Based on estimates of mean ground-water velocity and retardation of the pesticide due to sorption, mean travel times for chlordane migrating from the dump to the ground-water discharge zone are of the order of 50 to 500 years. Simulations of chlordane concentration resulting from the discharge of contaminated ground water and complete mixing in the Wolf River are sensitive to assumptions about chlordane persistence in the unconfined aquifer. If the half life of chlordane in the aquifer is assumed to be 30 years or less, the simulated concentration of chlordane in the Wolf River under average flow conditions is less than the most stringent water-quality criterion.

  2. Ground-based microwave radar and optical lidar signatures of volcanic ash plumes: models, observations and retrievals

    NASA Astrophysics Data System (ADS)

    Mereu, Luigi; Marzano, Frank; Mori, Saverio; Montopoli, Mario; Cimini, Domenico; Martucci, Giovanni

    2013-04-01

    The detection and quantitative retrieval of volcanic ash clouds is of significant interest due to its environmental, climatic and socio-economic effects. Real-time monitoring of such phenomena is crucial, also for the initialization of dispersion models. Satellite visible-infrared radiometric observations from geostationary platforms are usually exploited for long-range trajectory tracking and for measuring low level eruptions. Their imagery is available every 15-30 minutes and suffers from a relatively poor spatial resolution. Moreover, the field-of-view of geostationary radiometric measurements may be blocked by water and ice clouds at higher levels and their overall utility is reduced at night. Ground-based microwave radars may represent an important tool to detect and, to a certain extent, mitigate the hazard from the ash clouds. Ground-based weather radar systems can provide data for determining the ash volume, total mass and height of eruption clouds. Methodological studies have recently investigated the possibility of using ground-based single-polarization and dual-polarization radar system for the remote sensing of volcanic ash cloud. A microphysical characterization of volcanic ash was carried out in terms of dielectric properties, size distribution and terminal fall speed, assuming spherically-shaped particles. A prototype of volcanic ash radar retrieval (VARR) algorithm for single-polarization systems was proposed and applied to S-band and C-band weather radar data. The sensitivity of the ground-based radar measurements decreases as the ash cloud is farther so that for distances greater than about 50 kilometers fine ash might be not detected anymore by microwave radars. In this respect, radar observations can be complementary to satellite, lidar and aircraft observations. Active remote sensing retrieval from ground, in terms of detection, estimation and sensitivity, of volcanic ash plumes is not only dependent on the sensor specifications, but also on

  3. K-12 Students as Ground Observers of Contrails in Support of Scientific Research

    NASA Technical Reports Server (NTRS)

    Chambers, Lin H.; Moore, Susan W.; Fischer, Joyce D.; Sepulveda, Roberto; Clark, C.

    2004-01-01

    Scientists are very interested in the formation of contrails, both the type and the coverage. To be detected by a satellite-born instrument, the contrail must be of a certain size, which means that some contrails go undetected. The K-12 education community is assisting with the study of contrails by participating in a network of student observers. To provide a venue for student contrail observations, the GLOBE Contrails protocol was developed as part of the GLOBE Atmospheric Science protocols. The first year of observations has provided a rich resource for researcher.

  4. Observation of TGFs onboard "Vernov" satellite and TGEs in ground-based experiments

    NASA Astrophysics Data System (ADS)

    Bogomolov, Vitaly; Panasyuk, Mikhail; Svertilov, Sergey; Garipov, Gali; Iyudin, Anatoly; Klimov, Pavel; Morozenko, Violetta; Maximov, Ivan; Mishieva, Tatiana; Klimov, Stanislav; Pozanenko, Alexey; Rothkaehl, Hanna

    2016-04-01

    "Vernov" satellite with RELEC experiment on-board was launched on 2014 July, 8 into a polar solar-synchronous orbit. The payload includes DRGE gamma-ray spectrometer providing measurements in 10-3000 keV energy range with four detectors directed to atmosphere. Total area of DRGE detectors is ~500 cm2. The data were recorded both in monitoring and gamma by gamma modes with timing accuracy ~15 us. Several TGF candidates with 10-40 gammas in a burst with duration <1ms were detected. Analysis of data from other instruments on-board "Vernov" satellite shows the absence of significant electromagnetic pulses around correspondent time moments. Comparison with WWLLN lightning network data base also indicates that there were no thunderstorms connected with most of detected TGF candidates. Possible connection of these flashes with electron precipitations is discussed. Ground-based experiments, with similar gamma-spectrometers were conducted, to study the spectral, temporal and spatial characteristics of TGEs in 20-3000 keV energy range, as well, as to search the fast hard X-ray and gamma-ray flashes possibly appearing at the moment of lightning. The time of each gamma-quantum interaction was recorded with an ~15 us s accuracy together with detailed spectral data. Measurements were done on the ground at Moscow region, and at mountain altitude in Armenia at Aragatz station. During the time interval covering spring, summer and autumn of 2015 a number of TGEs were detected. Measured low-energy gamma-ray spectra usually contain a set of lines that can be interpreted as radiation of Rn-222 daughter isotopes. The increase of Rn-222 radiation was detected during rainfalls with thunderstorm, as well, as during rainy weather without thunderstorms. Variations of Rn-222 radiation dominate at low energies (<2.6MeV) and must be taken into account in the experiments performed to measure low energy gamma-radiation from the electrons accelerated in thunderclouds. There were no significant

  5. Fault locking near Istanbul: indication of earthquake potential from InSAR and GPS observations

    NASA Astrophysics Data System (ADS)

    Diao, Faqi; Walter, Thomas R.; Solaro, Giuseppe; Wang, Rongjiang; Bonano, Manuela; Manzo, Mariarosaria; Ergintav, Semih; Zheng, Yong; Xiong, Xiong; Lanari, Riccardo

    2016-04-01

    A sequence of large earthquakes occurred along the North Anatolian fault in the 20th century. These earthquakes, including the 1999 İzmit/Düzce earthquakes, generally propagated westward towards the Marmara Sea, defining the Main Marmara fault as a potential seismic gap. It is important to conduct a detailed assessment of the seismic hazards along the main Marmara fault because the megacity Istanbul lies only approximately 10 km north of the eastern segment of the Main Marmara fault, which is referred to as the Princes' Islands Fault segment (PIF). Here, we study the locking status of this fault segment to evaluate the seismic hazard potential. For the first time, combined ascending and descending Interferometric Synthetic Aperture Radar and Global Positioning System observations were used to investigate the crustal deformation associated with the PIF. After careful corrections of the estimated ground velocity, a deformation pattern relating to fault locking near the Princes' Islands was identified. The modeling results revealed that the slip rate and locking depth of the fault segment show a clear trade-off, which were estimated as 18.9 ± 7.2 mm yr-1 and 12.1 ± 7.0 km, respectively. With a moment accumulation rate of 1.7 ± 0.4 × 1017 Nm yr-1 (proportional to the product of slip rate and locking depth), our results imply a build-up of a geodetic moment on the PIF and therefore a potential for earthquake hazards in the vicinity of the Istanbul megacity.

  6. Data on observation wells, ground-water levels, and ground-water quality for the stratified-drift aquifer in the northwestern basin of Country Pond, Kingston, New Hampshire

    USGS Publications Warehouse

    Stekl, P.J.

    1994-01-01

    Observation-well, ground-water-level, and ground- water-quality data were collected for a study of ground-water contamination in stratified drift at Country Pond in Kingston, New Hampshire. The report includes drilling records for 30 wells installed at various depths in stratified drift beneath Country Pond. Ground-water levels are recorded for nine wells drilled under the direction of the U.S. Geological Survey in May 1991. Water-quality analyses are presented for 56 ground-water samples collected from 30 wells drilled during the investigation. Samples were analyzed in the laboratory for 40 volatile organic compounds. Ground-water contamination from volatile organic compounds was found in 23 of the 56 samples collected.

  7. The Jovian sodium nebula: Two years of ground-based observations

    NASA Technical Reports Server (NTRS)

    Flynn, Brian; Mendillo, Michael; Baumgardner, Jeffrey

    1994-01-01

    The 1000-R(sub J)-wide neutral sodium nebula of Jupiter has now been observed on four separate occasions from late 1989 to early 1992. The observations have consisted of both low-dispersion spectroscopy and direct imaging. These observations have allowed us to establish some of the general features of the nebula, such as the largely equatorial confinement of emission, the r(exp -1) intensity behavior in the equatorial plane, and flaring of the emission with respect to the equator. Some additional evidence exists for more subtle morphology, such as a possible variable east-west intensity asymmetry. In this paper, we present a summary of observational evidence of variability in overall intensity, as well as in some of the morphological features of the nebula, over timescales of days, months, and years.

  8. The Jovian sodium nebula: Two years of ground-based observations

    NASA Astrophysics Data System (ADS)

    Flynn, B.; Mendillo, M.; Baumgardner, J.

    1994-04-01

    The 1000-RJ-wide neutral sodium nebula of Jupiter has now been observed on four separate occasions from late 1989 to early 1992. The observations have consisted of both low-dispersion spectroscopy and direct imaging. These observations have allowed us to establish some of the general features of the nebula, such as the largely equatorial confinement of emission, the r-1 intensity behavior in the equatorial plane, and flaring of the emission with respect to the equator. Some additional evidence exists for more subtle morphology, such as a possible variable east-west intensity asymmetry. In this paper, we present a summary of observational evidence of variability in overall intensity, as well as in some of the morphological features of the nebula, over timescales of days, months, and years.

  9. Environmental influences on potential recruitment of pink shrimp, Fatlantopenaeus duorarum, from Florida Bay nursery grounds

    USGS Publications Warehouse

    Browder, Joan A.; Restrepo, V.R.; Rice, J.K.; Robblee, M.B.; Zein-Eldin, Z.

    1999-01-01

    Two modeling approaches were used to explore the basis for variation in recruitment of pink shrimp, Farfantepenaeus duorarum, to the Tortugas fishing grounds. Emphasis was on development and juvenile densities on the nursery grounds. An exploratory simulation modeling exercise demonstrated large year-to-year variations in recruitment contributions to the Tortugas rink shrimp fishery may occur on some nursery grounds, and production may differ considerably among nursery grounds within the same year, simply on the basis of differences in temperature and salinity. We used a growth and survival model to simulate cumulative harvests from a July-centered cohort of early-settlement-stage postlarvae from two parts of Florida Bay (western Florida Bay and northcentral Florida Bay), using historic temperature and salinity data from these areas. Very large year-to-year differences in simulated cumulative harvests were found for recruits from Whipray Basin. Year-to-year differences in simulated harvests of recruits from Johnson Key Basin were much smaller. In a complementary activity, generalized linear and additive models and intermittent, historic density records were used to develop an uninterrupted multi-year time series of monthly density estimates for juvenile rink shrimp in the Johnson Key Basin. The developed data series was based on relationships of density with environmental variables. The strongest relationship was with sea-surface temperature. Three other environmental variables (rainfall, water level at Everglades National Park Well P35, and mean wind speed) also contributed significantly to explaining variation in juvenile densities. Results of the simulation model and two of the three statistical models yielded similar interannual patterns for Johnson Key Basin. While it is not possible to say that one result validates the other, the concordance of the annual patterns from the two models is supportive of both approaches.

  10. Ground-Based Thermal-IR Spectroscopic Observations of Jupiter During the Galileo Encounter

    NASA Astrophysics Data System (ADS)

    Sada, P. V.; Jennings, D.; McCabe, G.; Deming, D.; Bjoraker, G.

    1995-12-01

    High resolution spectroscopic observations of Jupiter at selected thermal-infrared wavelengths are scheduled to be performed using CELESTE, a Goddard-developed cryogenic echelle spectrometer. These observations will be carried out in conjunction with the McMath-Pierce 60-inch Solar Telescope (KPNO/NSO) during the inital encounter phase of the Galileo spacecraft with the planet. This arrangement was successfully used in 1994-95 to perform daytime observations of Jupiter close to the Sun. The planet will be located 9(deg) away from the Sun in the sky on 7 December 1995, the day Galileo's probe is scheduled to enter the atmosphere of the planet. Galileo's entry probe is programmed to shed its heat shield and start directly sampling the atmosphere of Jupiter at a pressure level of about 100 mbar. We plan to carry out observations of a complementary nature to those of the entry probe by using molecular species which better sample the stratosphere of Jupiter. These observations, in conjunction with those obtained by Galileo, will help characterize the state of the atmosphere of Jupiter at the time of the encounter. In particular we plan to observe the 587 cm(-1) S(1) quadrupole line of H2, which yields abundance-independent temperature information on the upper troposphere and lower stratosphere of Jupiter. We also plan to measure strong stratospheric emission features from molecules such as CH4, C2H6, and C2H2. These spectral observations will be used to retrieve temperature and species abundance information with some degree of spatial discrimination. Preliminary results from these observations will be presented. (1) National Research Council Resident Research Associate. (2) Hughes/STX.

  11. Full dimension Rb2He ground triplet potential energy surface and quantum scattering calculations.

    PubMed

    Guillon, Grégoire; Viel, Alexandra; Launay, Jean-Michel

    2012-05-01

    We have developed a three-dimensional potential energy surface for the lowest triplet state of the Rb(2)He complex. A global analytic fit is provided as in the supplementary material [see supplementary material at http://dx.doi.org/10.1063/1.4709433 for the corresponding Fortran code]. This surface is used to perform quantum scattering calculations of (4)He and (3)He colliding with (87)Rb(2) in the partial wave J = 0 at low and ultralow energies. For the heavier helium isotope, the computed vibrational relaxation probabilities show a broad and strong shape resonance for a collisional energy of 0.15 K and a narrow Feshbach resonance at about 17 K for all initial Rb(2) vibrational states studied. The broad resonance corresponds to an efficient relaxation mechanism that does not occur when (3)He is the colliding partner. The Feshbach resonance observed at higher collisional energy is robust with respect to the isotopic substitution. However, its effect on the vibrational relaxation mechanism is faint for both isotopes. PMID:22583230

  12. Vibrational Levels and Resonances on a New Potential Energy Surface for the Ground Electronic State of Ozone

    NASA Astrophysics Data System (ADS)

    Ndengue, Steve Alexandre; Dawes, Richard; Wang, Xiao-Gang; Carrington, Tucker

    2014-06-01

    The isotopic ratios for ozone observed in laboratory and atmospheric measurements, known as the ozone isotopic anomaly,[1,2] have been an open question in physical and atmospheric chemistry for the past 30 years. The biggest limitation in achieving agreement between theory and experiment has been the availability of a satisfactory[3-5] ground state potential energy surface (PES). The presence of a spurious reef feature in the asymptotic region of most PESs has been associated with large discrepancies between calculated and observed rates of formation especially at low temperature. We recently proposed a new global potential energy surface for ozone[6,7] possessing 4 features that make it suitable for kinetics and dynamics studies: excellent equilibrium parameters, good agreement with experimental vibrational levels, accurate dissociation energy and a transition region with accurate topography (without the reef artifact). This PES has been used recently to simulate the temperature dependent exchange reaction (16O+16O2) with a quantum statistical model[6,7], and, for the first time, a negative temperature dependence which agrees with experiments was obtained, indicating the good quality of this global surface. A quantum description of the ozone exchange and recombination reaction requires knowledge of the resonances but also the rovibrational levels just below the dissociation. We present results of global 3-well vibrational-state calculations up to the dissociation threshold and (J = 0) resonances up to 1000 wn beyond. The calculations were done using a large DVR basis ( 24 million functions) with a symmetry-adapted Lanczos algorithm as well as MCTDH. Results indicate the presence of localized bound states at energies close to the dissociation threshold beyond which some long-lived resonances follow, contrasted with a few delocalized bound states with density at large values of the stretching coordinates. References: 1- K. Mauersberger et al., Adv. At. Mol. Opt

  13. Interpretation of ground-based radiometric observations in terms of a gravity wave model

    NASA Technical Reports Server (NTRS)

    Canavero, F. G.; Einaudi, F.; Westwater, E. R.; Falls, M. J.; Schroeder, J. A.

    1990-01-01

    An analysis is presented of 2-hour and 4-hour segments of data taken at Denver, Colorado, on February 3, 1984, by a ground-based radiometer designed and operated by the Wave Propagation Laboratory of the National Oceanic and Atmospheric Administration (NOAA). The zenith-viewing instrument has two moisture-sensing and four temperature-sensing channels. It is demonstrated that a peak at a period of 10 min, present in the spectra of the measured brightness temperature and of the derived geopotential heights, thicknesses, and vertically integrated water vapor content, is due to an internal gravity wave generated by wind shear in the jet aloft. This analysis shows that the radiometer has the sensitivity to detect such disturbances and that the mathematical inversion technique used to retrieve the geopotential field and other integrated quantities retains the derived information as well. Finally, a linear expression is derived which relates the brightness temperature to the atmospheric temperature, density, humidity, and cloud liquid perturbation fields.

  14. Probing the limitations of isotropic pair potentials to produce ground-state structural extremes via inverse statistical mechanics.

    PubMed

    Zhang, G; Stillinger, F H; Torquato, S

    2013-10-01

    Inverse statistical-mechanical methods have recently been employed to design optimized short-range radial (isotropic) pair potentials that robustly produce novel targeted classical ground-state many-particle configurations. The target structures considered in those studies were low-coordinated crystals with a high degree of symmetry. In this paper, we further test the fundamental limitations of radial pair potentials by targeting crystal structures with appreciably less symmetry, including those in which the particles have different local structural environments. These challenging target configurations demanded that we modify previous inverse optimization techniques. In particular, we first find local minima of a candidate enthalpy surface and determine the enthalpy difference ΔH between such inherent structures and the target structure. Then we determine the lowest positive eigenvalue λ(0) of the Hessian matrix of the enthalpy surface at the target configuration. Finally, we maximize λ(0)ΔH so that the target structure is both locally stable and globally stable with respect to the inherent structures. Using this modified optimization technique, we have designed short-range radial pair potentials that stabilize the two-dimensional kagome crystal, the rectangular kagome crystal, and rectangular lattices, as well as the three-dimensional structure of the CaF(2) crystal inhabited by a single-particle species. We verify our results by cooling liquid configurations to absolute zero temperature via simulated annealing and ensuring that such states have stable phonon spectra. Except for the rectangular kagome structure, all of the target structures can be stabilized with monotonic repulsive potentials. Our work demonstrates that single-component systems with short-range radial pair potentials can counterintuitively self-assemble into crystal ground states with low symmetry and different local structural environments. Finally, we present general principles that offer

  15. Ground observation and AMIE-TIEGCM modeling of a storm-time traveling ionospheric disturbance

    NASA Astrophysics Data System (ADS)

    Shiokawa, K.; Lu, G.; Otsuka, Y.; Ogawa, T.; Yamamoto, M.; Nishitani, N.; Sato, N.

    2007-05-01

    This paper reports the first comparison between comprehensive observations of equatorward moving traveling ionospheric disturbance at midlatitudes and thermospheric general circulation model with high-latitude energy input based on data assimilation. A prominent traveling ionospheric disturbance (TID) was observed during the major magnetic storm of 31 March 2001. The TID propagated from north to south over Japan with phase speeds of 370-640 m/s. The assimilative mapping of ionospheric electrodynamics (AMIE) technique was used as input to the thermosphere-ionosphere-electrodynamics general circulation model (TIEGCM) to investigate generation and propagation of the observed TID. In the model, two Joule heating enhancements in the high-latitude dayside sector produced two distinct traveling atmospheric waves (TADs), which propagated to Japan in the midnight sector as enhancements in thermospheric temperature and southward wind speed. The phase speed of the TADs was much faster (˜1100 m/s) in the model, probably due to the overestimation of Joule heating in the model. The second TAD corresponds to the observed prominent TID, while signatures of the first TAD were also seen in the observed ionosonde data. The observed TID was characterized by a decrease in southward wind speed, causing a significant F-layer height decrease and a temporal enhancement of F-layer peak density. These characteristics were reproduced by the model as a rarefaction of the second TAD. The temporal enhancement of F-layer peak density was because of the vertical shear of meridional wind. The absolute value of F-layer electron density in the model was several factors smaller than that observed, probably because of the underestimation of the supply of O+ ions from the plasmasphere.

  16. Ab initio ground and the first excited adiabatic and quasidiabatic potential energy surfaces of H + + CO system

    NASA Astrophysics Data System (ADS)

    George, D. X. F.; Kumar, Sanjay

    2010-08-01

    Ab initio global adiabatic as well as quasidiabatic potential energy surfaces for the ground and the first excited electronic states of the H + + CO system have been computed as a function of the Jacobi coordinates ( R, r, γ) using Dunning's cc-pVTZ basis set at the internally contracted multi-reference (single and double) configuration interaction level of accuracy. In addition, nonadiabatic coupling matrix elements arising from radial motion, mixing angle and coupling potential have been computed using the ab initio procedure [Simah et al. (1999) [66

  17. Integrating ground observations of phenology with remotely sensed measurements: A 2007 growing season experiment at Sevilleta LTER

    NASA Astrophysics Data System (ADS)

    Bradley, B.; Wetherill, K.; Vanderbilt, K.; Nickeson, J.

    2007-12-01

    The use of satellites to monitor land surface phenology is important for understanding local and regional ecosystem variability, identifying change over time, and potentially predicting ecosystem response to short and long-term changes in climate. However, the relationship between how phenology is expressed on the ground and how it is interpreted from satellites is poorly understood because phenological stages do not always correspond well to changes in spectral reflectance. Rather than focusing on phenological stages (e.g., first leaf, first flower), the ground measurements in this study focus on changes in ecosystem greenness during the 2007 growing season. We collected bi-monthly measurements of community greenness in two perennial grasslands at the Sevilleta National Wildlife Refuge in central New Mexico, a Long Term Ecological Research (LTER) site. One site is dominated by blue grama grass (Bouteloua gracilis); the other is dominated by black grama grass (Bouteloua eriopoda). Grama grasses grow during the summer/fall time period, with onset of greenness typically occurring mid-July and peak greenness occurring in September. Bi-monthly ground measurements were collected from July 2, 2007 - October 4, 2007 within systematically arrayed 30x30 cm quadrats. Within each quadrat, we recorded percent green cover (grass or forb), percent non- photosynthetic cover, and percent soil. A nadir oriented digital photograph was also taken of each quadrat, from which a greenness index was calculated. Field sampling was timed within two days of an ASTER satellite image acquisition. Here, we compare three greenness measurements from ground sampling, digital photography, and ASTER satellite imagery for the 2007 growing season. We show the degree of correlation between the three measurements through time and draw inferences about how satellite imagery can be used to assess ecosystem phenology. This study is an important first step in furthering the linkage between remotely sensed

  18. The Gaia spectrophotometric standard stars survey: II. Instrumental effects of six ground-based observing campaigns

    NASA Astrophysics Data System (ADS)

    Altavilla, G.; Marinoni, S.; Pancino, E.; Galleti, S.; Ragaini, S.; Bellazzini, M.; Cocozza, G.; Bragaglia, A.; Carrasco, J. M.; Castro, A.; Di Fabrizio, L.; Federici, L.; Figueras, F.; Gebran, M.; Jordi, C.; Masana, E.; Schuster, W.; Valentini, G.; Voss, H.

    2015-08-01

    The Gaia SpectroPhotometric Standard Stars (SPSS) survey started in 2006, was awarded almost 450 observing nights and accumulated almost 100 000 raw data frames with both photometric and spectroscopic observations. Such large observational effort requires careful, homogeneous, and automatic data reduction and quality control procedures. In this paper, we quantitatively evaluate instrumental effects that might have a significant (i.e., ≥ 1 %) impact on the Gaia SPSS flux calibration. The measurements involve six different instruments, monitored over the eight years of observations dedicated to the Gaia flux standards campaigns: DOLORES@TNG in La Palma, EFOSC2@NTT and ROSS@REM in La Silla, CAFOS@2.2 m in Calar Alto, BFOSC@Cassini in Loiano, and LaRuca@1.5 m in San Pedro Mártir. We examine and quantitatively evaluate the following effects: CCD linearity and shutter times, calibration frames stability, lamp flexures, second order contamination, light polarization, and fringing. We present methods to correct for the relevant effects which can be applied to a wide range of observational projects at similar instruments. Based on data obtained with BFOSC@Cassini in Loiano, Italy; EFOSC2@NTT in La Silla, Chile; DOLORES@TNG in La Palma, Spain; CAFOS@2.2 m in Calar Alto, Spain; LaRuca@1.5 m in San Pedro Mártir, Mexico (see acknowledgements for more details).

  19. Gaia-FUN-SSO: a network for ground-based follow-up observations of Solar System Objects

    NASA Astrophysics Data System (ADS)

    Thuillot, W.; Carry, B.; Berthier, J.; David, P.; Hestroffer, D.; Rocher, P.

    2014-12-01

    Gaia-FUN-SSO (shortly described at https://www.imcce.fr/gaia-fun-sso/) is a ground-based network of observatories set up in the framework of the Gaia consortium (DPAC-CU4) for the follow-up of critical Solar System objects to be discovered from space by the Gaia satellite. Its goal is to retrieve from the ground a newly detected object and to complement the astrometry measurements carried out by Gaia to determine its heliocentric orbit. Data from both Gaia and the ground-based network will be sent to the Minor Planet Center, used to determine the orbit and thus to update the database of minor planet orbits, which is subsequently used by Gaia for the identification of moving objects. We are expecting the detection of many asteroids, mainly from the main belt, and also new near-Earth objects (NEO) at low solar elongation. Owing to the specific conditions of Gaia observations, we even expect the detection of objects whose orbit is fully contained within Earth's orbit (called inner-Earth or Atira asteroids). Several training campaigns have already been organized with the network and it is now able to enter in an operating mode when alerts will be triggered. We describe here the expected number of discoveries, the network, its activity, and the data processing of the central node of the network set in place for the operating mode.

  20. Using grounded theory methodology to conceptualize the mother-infant communication dynamic: potential application to compliance with infant feeding recommendations.

    PubMed

    Waller, Jennifer; Bower, Katherine M; Spence, Marsha; Kavanagh, Katherine F

    2015-10-01

    Excessive, rapid weight gain in early infancy has been linked to risk of later overweight and obesity. Inappropriate infant feeding practices associated with this rapid weight gain are currently of great interest. Understanding the origin of these practices may increase the effectiveness of interventions. Low-income populations in the Southeastern United States are at increased risk for development of inappropriate infant feeding practices, secondary to the relatively low rates of breastfeeding reported from this region. The objective was to use grounded theory methodology (GTM) to explore interactions between mothers and infants that may influence development of feeding practices, and to do so among low-income, primiparous, Southeastern United States mothers. Analysis of 15 in-depth phone interviews resulted in development of a theoretical model in which Mother-Infant Communication Dynamic emerged as the central concept. The central concept suggests a communication pattern developed over the first year of life, based on a positive feedback loop, which is harmonious and results in the maternal perception of mother and infant now speaking the same language. Importantly, though harmonious, this dynamic may result from inaccurate maternal interpretation of infant cues and behaviours, subsequently leading to inappropriate infant feeding practices. Future research should test this theoretical model using direct observation of mother-infant communication, to increase the understanding of maternal interpretation of infant cues. Subsequently, interventions targeting accurate maternal interpretation of and response to infant cues, and impact on rate of infant weight gain could be tested. If effective, health care providers could potentially use these concepts to attenuate excess rapid infant weight gain.

  1. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

    DOE PAGES

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations.more » The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.« less

  2. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

    SciTech Connect

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations. The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.

  3. HST and ground-based observations of bright storms on Uranus during 2014-2015.

    NASA Astrophysics Data System (ADS)

    Sayanagi, K. M.; Sromovsky, L. A.; Fry, P. M.; De Pater, I.; Hammel, H. B.; Rages, K. A.; Baranec, C.; Delcroix, M.; Wesley, A.; Hueso, R.; Sanchez-Lavega, A.; Simon, A. A.; Wong, M. H.; Orton, G. S.; Irwin, P. G.

    2015-12-01

    We report the temporal evolution of bright, long-lived cloud features on Uranus. We observed and tracked the features between August 2014 and January 2015 with the Hubble Space Telescope, the Keck 2 10-m telescope, VLT, Gran Telescopio Canarias, Gemini, William Herschel Telescope, Robo-AO, Pic du Midi 1-m telescope, and multiple smaller telescopes operated by amateur astronomers. Surprisingly bright features were first revealed in the Keck adaptive-optics images in August; this initial set of observations motivated follow-up observations around the world. One of the storms (identified as "Feature F" in Sromovsky et al. 2015, and Feature 2 in de Pater et al. 2015), which was the deepest in that dataset, was bright enough that it was detected by multiple amateur observers, permitting us to trigger a Hubble Target of Opportunity (ToO) observation on October 14th, 2014. A complex of features at this latitude was also observed by Hubble as part of the Outer Planet Atmospheres Legacy (OPAL) program on November 8-9, 2014. We will present the temporal evolution of the cloud activities from August 2014 through January 2015, and analyze the vertical structure of the cloud features in the Hubble datasets. The Hubble images used in our study were collected with support of HST grants GO13712 to KMS and GO13937 to AAS. Sromovsky et al. 2015, "High S/N Keck and Gemini AO imaging of Uranus during 2012-2014: New cloud patterns, increasing activity, and improved wind measurements." Icarus 258, 192-223. de Pater et al. 2014, "Record-breaking storm activity on Uranus in 2014." Icarus 252, 121-128

  4. Observations of Pc2 waves by Cluster and ground stations in Antarctica

    NASA Astrophysics Data System (ADS)

    Liu, Y.

    2013-12-01

    We analyzed a Pc2 wave event above the He+ cyclotron frequency detected by the four Cluster satellites and multiple ground stations in Antarctica. During the wave event, Cluster satellites were located sunward from L~13 in the outer magnetosphere to the magnetopause, over 13o - 20o magnetic latitude, north of the equator near local magnetic noon. The Poynting flux results show that the wave packet energy propagated dominantly along the geomagnetic field direction and in alternating directions rather than uni-directionally from the equator, implying the wave source was located in a high latitude region away from the equator, where a minimum in the B field is located. The footprint of Cluster was closest to the Zhong Shan and Davis (ZHS/DAV) stations (L~14) in Antarctica. Consequently, the frequency range and the burst-pattern of the dynamic spectra from ZHS and DAV are highly consistent with those seen by Cluster. Although wave packets on Cluster occurred from 0800 UT to 1430 UT, lasting for 6.5 hours, the wave bursts on ZHS and DAV stations were concentrated earlier at 0800-1040 UT. This suggests the azimuthal extent of the wave source may be estimated at 2.6 hours and the wave packets were guided by the field lines from Cluster to ZHS/DAV. The waves at Mawson (L~9) and Casey (L~38.8) are rather weak and the wave burst-patterns appear obviously different from those at ZHS/DAV and Cluster, suggesting the wave energy propagated toward both high and low latitudes via the inonospheric waveguide.

  5. Direct-potential-fit analyses yield improved empirical potentials for the ground X ^1Σ _g^+ state of Be2

    NASA Astrophysics Data System (ADS)

    Meshkov, Vladimir V.; Stolyarov, Andrey V.; Heaven, Michael C.; Haugen, Carl; LeRoy, Robert J.

    2014-02-01

    We have performed new direct-potential-fit (DPF) analyses of the rotationally resolved A ^1Π _u(v^' }=2,3;J^' }=1,2)rArr X ^1Σ _g^+(v^' ' }in [0, 11];J^' ' }in [0,3]) stimulated emission pumping spectra of Be2 [J. M. Merritt, V. E. Bondybey, and M. C. Heaven, Science 324, 1548 (2009)] using two quite different analytical potential energy functions that incorporate the correct theoretically known long-range behaviour in different ways. These functions are: the damped Morse/long-range potential [R. J. Le Roy, C. C. Haugen, J. Tao, and H. Li, Mol. Phys. 109, 435 (2011)], and the Chebyshev polynomial expansion potential [L. Busevica, I. Klincare, O. Nikolayeva, M. Tamanis, R. Ferber, V. V. Meshkov, E. A. Pazyuk, and A. V. Stolyarov, J. Chem. Phys. 134, 104307 (2011)]. In contrast with the expanded Morse oscillator potential determined in the original DPF analysis of Merritt et al. [Science 324, 1548 (2009)], both of these functions unambiguously support the existence of the v″ = 11 last vibrational levels which is bound by only ˜0.5 cm-1, and they give equivalent, essentially exact predictions for this level when using the original data set which ended at v″ = 10. These empirical potentials predict an equilibrium distance of re = 2.445(5) Å and a well depth of {{D}}_e=934.9(0.4) cm-1, values which agree (within the uncertainties) with the best ab initio estimates of 2.444(10) Å and 935(10) cm-1, respectively [J. Koput, Phys. Chem. Chem. Phys. 13, 20311 (2011)].

  6. Ground-based observations of the corona in the visible and NIR spectral ranges

    NASA Technical Reports Server (NTRS)

    Epple, Alexander; Schwenn, Rainer

    1995-01-01

    Since late 1993 we have been using a mirror coronagraph on Pic du Midi (PICO) to observe the solar emission corona in several spectral lines of (FE-X), (FE-XIII), and (FE-XIV). For good meteorological conditions the diffuse corona and coronal holes in between can be seen out to 1.2 solar mass for sun center. Active regions can be mapped to bond 1.5 solar mass in the green and infrared lines. Recent observations of PICO are presented.

  7. Assessment of ground-based atmospheric observations for verification of greenhouse gas emissions from an urban region.

    PubMed

    McKain, Kathryn; Wofsy, Steven C; Nehrkorn, Thomas; Eluszkiewicz, Janusz; Ehleringer, James R; Stephens, Britton B

    2012-05-29

    International agreements to limit greenhouse gas emissions require verification to ensure that they are effective and fair. Verification based on direct observation of atmospheric greenhouse gas concentrations will be necessary to demonstrate that estimated emission reductions have been actualized in the atmosphere. Here we assess the capability of ground-based observations and a high-resolution (1.3 km) mesoscale atmospheric transport model to determine a change in greenhouse gas emissions over time from a metropolitan region. We test the method with observations from a network of CO(2) surface monitors in Salt Lake City. Many features of the CO(2) data were simulated with excellent fidelity, although data-model mismatches occurred on hourly timescales due to inadequate simulation of shallow circulations and the precise timing of boundary-layer stratification and destratification. Using two optimization procedures, monthly regional fluxes were constrained to sufficient precision to detect an increase or decrease in emissions of approximately 15% at the 95% confidence level. We argue that integrated column measurements of the urban dome of CO(2) from the ground and/or space are less sensitive than surface point measurements to the redistribution of emitted CO(2) by small-scale processes and thus may allow for more precise trend detection of emissions from urban regions.

  8. Assessment of Ground-based Atmospheric Observations for Tracking Changes in Greenhouse Gas Emissions from Urban Areas

    NASA Astrophysics Data System (ADS)

    McKain, K.; Wofsy, S. C.; Nehrkorn, T.; Eluszkiewicz, J.

    2011-12-01

    The fairness and effectiveness of agreements to limit greenhouse gas emissions depends on our ability to verify reported changes in emissions using direct atmospheric observations. The goal of this work was to test whether ground-based measurements of greenhouse gases from urban regions can be used to quantify changes in emissions. We performed an atmospheric inversion for Salt Lake City, Utah using an existing dataset of CO2 measurements, prior estimates of emissions, and a high-resolution Lagrangian atmospheric transport model. By comparing simulated and observed CO2 for Salt Lake City, we were able to constrain emissions to within 15%. Substantial improvements in our ability to estimate emissions using urban surface observations are not expected because of limitations imposed by the character of the data, namely the dominance of the stochastic component of the signal and the inverse relationship between the daily cycle of emissions and CO2 concentration enhancements. Based on these results, we believe ground- and space-based measurements of column enhancements in the urban dome offer a superior route for verification purposes.

  9. Assessment of ground-based atmospheric observations for verification of greenhouse gas emissions from an urban region

    NASA Astrophysics Data System (ADS)

    McKain, Kathryn; Wofsy, Steven C.; Nehrkorn, Thomas; Eluszkiewicz, Janusz; Ehleringer, James R.; Stephens, Britton B.

    2012-05-01

    International agreements to limit greenhouse gas emissions require verification to ensure that they are effective and fair. Verification based on direct observation of atmospheric greenhouse gas concentrations will be necessary to demonstrate that estimated emission reductions have been actualized in the atmosphere. Here we assess the capability of ground-based observations and a high-resolution (1.3 km) mesoscale atmospheric transport model to determine a change in greenhouse gas emissions over time from a metropolitan region. We test the method with observations from a network of CO2 surface monitors in Salt Lake City. Many features of the CO2 data were simulated with excellent fidelity, although data-model mismatches occurred on hourly timescales due to inadequate simulation of shallow circulations and the precise timing of boundary-layer stratification and destratification. Using two optimization procedures, monthly regional fluxes were constrained to sufficient precision to detect an increase or decrease in emissions of approximately 15% at the 95% confidence level. We argue that integrated column measurements of the urban dome of CO2 from the ground and/or space are less sensitive than surface point measurements to the redistribution of emitted CO2 by small-scale processes and thus may allow for more precise trend detection of emissions from urban regions.

  10. Ground-based infrared observations of variable IRAS sources as candidates for late asymptotic giant branch stars

    NASA Technical Reports Server (NTRS)

    Kwok, Sun; Boreiko, R. T.; Hrivnak, Bruce J.

    1987-01-01

    Analysis of the color distribution of OH/IR stars and IRAS low-resolution spectra class 30 objects suggests the presence of a well-defined evolutionary sequence which is populated by late asymptotic giant branch (LAGB) stars. The paper reports ground-based identification and infrared photometry of 10 candidates of news LAGB stars. None of the selected sources are found to have optical counterparts, and eight of the 10 show a strong 10-micron silicate absorption feature. It is suggested that these stars represent an invisible extension of extreme Mira variables and are some of the most evolved stars observed to date.

  11. RTTOV-gb - Adapting the fast radiative transfer model RTTOV for the assimilation of ground-based microwave radiometer observations

    NASA Astrophysics Data System (ADS)

    De Angelis, Francesco; Cimini, Domenico; Hocking, James; Martinet, Pauline; Kneifel, Stefan

    2016-04-01

    The Planetary Boundary Layer (PBL) is the single most important under-sampled part of the atmosphere. According to the WMO Statement Of Guidance For Global Numerical Weather Prediction (NWP), temperature and humidity profiles (in cloudy areas) are among the four critical atmospheric variables not adequately measured in the PBL. Ground-based microwave radiometers (MWR) provide temperature and humidity profiles in both clear- and cloudy-sky conditions with high temporal resolution and low-to-moderate vertical resolution, with information mostly residing in the PBL. Ground-based MWR offer to bridge this observational gap by providing continuous temperature and humidity information in the PBL. The MWR data assimilation into NWP models may be particularly important in nowcasting and severe weather initiation. The assimilation of thermodynamic profiles retrieved from MWR data has been recently experimented, but a way to possibly increase the impact is to directly assimilate measured radiances instead of retrieved profiles. The assimilation of observed radiances in a variational scheme requires the following tools: (i) a fast radiative transfer (RT) model to compute the simulated radiances at MWR channels from the NWP model fields (ii) the partial derivatives (Jacobians) of the fast radiative transfer model with respect to control variables to optimize the distances of the atmospheric state from both the first guess and the observations. Such a RT model is available from the EUMETSAT NWPSAF (Numerical Weather Prediction Satellite Application Facility) and well accepted in the NWP community: RTTOV. This model was developed for nadir-viewing passive visible, infrared, and microwave satellite radiometers, spectrometers and interferometers. It has been modified to handle ground-based microwave radiometer observations. This version of RTTOV, called RTTOV-gb, provides the tools needed to exploit ground-based upward looking MWR brightness temperatures into NWP variational data

  12. Reconciling the discrepancy in ground- and satellite-observed trends in the spring phenology of winter wheat in China from 1993 to 2008

    NASA Astrophysics Data System (ADS)

    Guo, Li; An, Ning; Wang, Kaicun

    2016-02-01

    Monitoring crop phenology has become a growing concern for food security. Crop phenology can be traditionally observed at plot scale in the field or recently at a much larger scale by satellites. In this study, we compared the spring phenology of winter wheat (Triticum sp.), quantified as the timing of start-of-spring-season (SOS), using 8 km resolution satellite data and ground observations at 112 agrometeorological stations across China from 1993 to 2008. We found that ground and satellite observations displayed opposing trends in winter wheat SOS. Ground observation exhibited a delayed onset of SOS at 86% of ground stations, whereas satellite data suggested an earlier arrival of SOS at 78% of stations. The meteorological SOS calculated from daily air temperature supported the earlier occurrence of SOS indicated by satellite data. Moreover, satellite data showed more agreement with meteorological data with respect to interannual SOS variations than did field phenology records. Given the dominant control of air temperature on winter wheat's spring phenology, satellite observation provides a reliable measure of the long-term trends and dynamics of SOS. Ground-observed SOS trends were impaired by data heterogeneity and limited spatial coverage. However, compared with ground observations, satellite-derived phenological timings are often lack of biological meanings. Therefore, integrating ground and satellite observations could enhance the monitoring of winter wheat SOS, which would increase the knowledge of vegetation's response to the changing climate and help to optimize timely crop management.

  13. Vertical Ground Deformation Detected by the Leveling and the Tidal Observation in Tokai Region, Central Japan in 1980 - 2002

    NASA Astrophysics Data System (ADS)

    Takano, K.; Kimata, F.; Fujii, N.

    2003-12-01

    Great earthquakes more than M8 have occurred along the Suruga-Nankai subduction zone of the Philippine Sea Plate (PHS), southeast Japan, every 100 to 150 years. The last events are 1944 M7.9 Tonankai and 1946 M8.0 Nankai earthquakes. Interseismic subsidence is detected along the subduction zone from the precise leveling and tide gauge. Discussion of the occurrence of great earthquake in near feature brought the expanding the measurements and observation of earthquake and ground deformation in Tokai region. Whereas nation-wide dense GPS network (GEONET) makes clear of the ground deformation of contraction in west-northwestward contraction and east-southeastward tilting in Tokai region, no northwestward horizontal displacements are observed since 2001 in the western Tokai region. Slow slip event (SSE) toward trough is discussed (Ozawa et al., 2002). Precise leveling and line length measurements also suggest the episodic changes with time interval of 4-5 years in the late 20 years (Kimata and Yamauchi, 1999; Kimata et al., 2001). Moreover pre-seismic ground tilt is suggested in the same area of the 2001 Tokai SSE from the leveling of the day in 1944 Tonankai Earthquake. Meanwhile pre-seismic slip is estimated in the SSE area from the numerical experiment of rock crusher (Kato, 2003). We discuss the episodic change of the ground deformation and the recurrence of the SSE in Tokai region with more detail from the vertical ground deformation detected by precise leveling and tide gauge in the period from 1980 to 2002. Geographical Survey Institute of Japan (GSI) has repeated the precise leveling in Tokai region every year since 1980. Tide gauge measurements have also been continued at more than 10 sites in Tokai region by GSI, Japan Meteorological Agency (JMA) and Aichi prefecture (AP). Time series of vertical movements at the benchmarks are analyzed by spline function and Annual relative sea levels at tide stations are corrected (Savage and Thatcher, 1992). The 2001 Tokai

  14. Finite Element Modeling of Ground Deformation and Gravity Data Observed at Mt Etna During the 1993-1997 Inflation Phase

    NASA Astrophysics Data System (ADS)

    Ganci, G.; Currenti, G.; Del Negro, C.

    2006-12-01

    Elastic finite element models are applied to investigate the effects of topography and medium heterogeneities on the surface deformation and the gravity field produced by volcanic pressure sources. Changes in the gravity field cannot be interpreted only in terms of gain of mass disregarding the deformations of the rocks surrounding the source. Contributions to gravity variations depend also on surface and subsurface mass redistribution driven by dilation of the volcanic source. Both ground deformation and gravity changes were firstly evaluated by solving a coupled axial symmetric problem to estimate the effects of topography and medium heterogeneities. Numerical results show significant discrepancies in the ground deformation and gravity field compared to those predicted by analytical solutions, which disregard topography, elastic heterogeneities and density subsurface structures. With this in mind, we reviewed the expected gravity changes accompanying the 1993- 1997 inflation phase on Mt Etna by setting up a fully 3D finite element model in which we used the real topography of Etna volcano to include the geometry and seismic tomography data to infer crustal heterogeneities. The inflation phase was clearly detected by different geodetic techniques (EDM, GPS, SAR and leveling data) that showed a uniform expansion of the overall volcano edifice. When the gravity data are integrated with ground deformation data and a coupled modeling is solved, a mass intrusion is expected at depth to justify both ground deformation and gravity observation. Our findings highlighted two main points. Firstly, geodetic and gravity data, which independently reflect the state of volcano, need to be jointly modeled in order to obtain a reliable estimate of the depth and density of the intrusion. Secondly, the application of finite element methods allows for a more accurate modeling procedure, which might provide sensible insight into volcanic source definition.

  15. Ozone tropospheric and stratospheric trends (1995-2008) over Western Europe from ground-based FTIR network observations

    NASA Astrophysics Data System (ADS)

    Vigouroux, Corinne; Demoulin, Philippe; Blumenstock, Thomas; Schneider, Matthias; Klyft, Jon; Palm, Mathias; Gardiner, Tom

    2010-05-01

    Five ground-based stations in Western Europe, from 79°N to 28°N, all part of the Network for the Detection of Atmospheric Composition Change (NDACC), have joined their efforts to homogenize and optimize the retrievals of ozone profiles from FTIR (Fourier transform infrared) solar absorption spectra. Using the optimal estimation method, distinct vertical information can be obtained in four layers: ground--10 km, 10--18 km, 18--27 km, and 27--42 km, in addition to total column amounts. A bootstrap resampling method has been implemented to determine annual partial and total column trends1. Vigouroux et al. (2008)2 applied this method to the ozone data and discussed the trends of the total columns and of the partial columns in the above four layers, over the period 1995-2004. Here, we present and discuss an update of this analysis for the 1995-2008 period. We obtain, among others, that at all the stations, the ozone total columns trends are non significant while the trends in the upper stratospheric layer (27-42 km) are significantly positive. 1 Gardiner, T., Forbes, A., Woods, P., De Mazière, M., Vigouroux, C., Mahieu, E., Demoulin, P., Velazco, V., Notholt, J., Blumenstock, T., Hase, F., Kramer, I., Sussmann, R., Stremme, W., Mellqvist, J., Strandberg, A., Ellingsen, K., and Gauss, M.: Method for evaluating trends in greenhouse gases from ground-based remote FTIR measurements over Europe, ACP, 8, 6719-6727, 2008. 2 Vigouroux, C., De Mazière, M., Demoulin, P., Servais, C., Hase, F., Blumenstock, T., Kramer, I., Schneider, M., Mellqvist, J., Strandberg, A., Velazco, V., Notholt, J., Sussmann, R., Stremme, W., Rockmann, A., Gardiner, T., Coleman, M., and Woods, P. : Evaluation of tropospheric and stratospheric ozone trends over Western Europe from ground-based FTIR network observations, ACP, 8, 6865-6886, 2008.

  16. Joint Variability of Airborne Passive Microwave and Ground-based Radar Observations Obtained in the TRMM Kwajalein Experiment

    NASA Astrophysics Data System (ADS)

    Yuter, S. E.; Kingsmill, D. E.

    2007-12-01

    The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) held July-September 1999 in the west Pacific was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. The majority of the precipitation was from mixed-phase clouds. Coordinated data sets were obtained from aircraft and ground-based sensors including passive microwave measurements by the Advanced Microwave Precipitation Radiometer (AMPR) instrument on the NASA DC-8 aircraft and S-band volumetric radar data by the KPOL radar. The AMPR and KPOL data sets were processed to yield a set of 25,049 matching observations at ~ 2 km x 2 km horizontal spatial resolution and within 6 min. The TRMM satellite Microwave Imager (TMI) has a similar set of channels to AMPR but coarser spatial resolution (19 GHz: 35 km, 85 GHz: 7.7 km). During KWAJEX, the 0 deg C level height was nearly constant at ~ 4800 m. Hence, two potential sources of uncertainty in relating passive microwave brightness temperatures (Tbs) to surface precipitation, inhomogeneous beam filling and variations in depth of the rain layer are much smaller sources of error in the KWAJEX data set than for TMI. TRMM was originally designed to yield monthly rainfall estimates over 5 deg x 5 deg grid boxes. The use of these data to yield instantaneous rainrate products at smaller spatial scales is more sensitive to the detailed characteristics of the joint distributions of passive microwave Tbs versus rain rate. KWAJEX data sets reveal poor correlations, very wide scatter, and weak modes in these distributions. The spread of emission Tb values for a given rain-layer reflectivity (e.g., 75 K at 30 dBZ for 19 GHz) is similar or larger within convective compared to stratiform precipitation regions. This result implies that the enhancement in emission Tbs associated with partially melted ice particles can occur whether the particles are concentrated within a thin layer in stratiform

  17. Geomagnetic Pulsations as Observed from Ground-Based Searchcoil Magnetometers (P52)

    NASA Astrophysics Data System (ADS)

    Sinha, A. K.; Pathan, B. M.; Vohat, P.

    2006-11-01

    ak50266@yahoo.com Magnetometer data from Searchcoil magnetometers in the Indian sectors have been analyzed to study geomagnetic pulsations in the low latitude region. On April 01 2005, we observe Pc 4 events at ~ 19 UT in the frequency range 10-15 mHz. The oscillations are seen in all the components (H, D, Z) indicating thereby that oscillations are compressional in nature. These pulsations are very much on the line of expectations at these latitudes. Apart from these normal pulsations, we observe the presence of pearl-type oscillations (~ 4 Hz) which is very unlikely at these latitude. These waves are common features of high latitude regions. The interesting aspect of these observed pearl-type features is that they follow a spike of broad-band source as revealed by the dynamic spectra. We are examining the role of thunderstorm lightening in generating these pearl-type pulses. Schumann resonances serve as indicators of lightning phenomena and we use their occurrences as parameter for lightening for correlating observed pulses to spiky broadband features preceding these pulses.

  18. Ground-based observations of 951 Gaspra: CCD lightcurves and spectrophotometry with the Galileo filters

    NASA Technical Reports Server (NTRS)

    Mottola, Stefano; Dimartino, M.; Gonano-Beurer, M.; Hoffmann, H.; Neukum, G.

    1992-01-01

    This paper reports the observations of 951 Gaspra carried out at the European Southern Observatory (La Silla, Chile) during the 1991 apparition, using the DLR CCD Camera equipped with a spare set of the Galileo SSI filters. Time-resolved spectrophotometric measurements are presented. The occurrence of spectral variations with rotation suggests the presence of surface variegation.

  19. Hubble Space Telescope and Ground-based Observations of the Type Iax Supernovae SN 2005hk and SN 2008A

    NASA Astrophysics Data System (ADS)

    McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Chornock, Ryan; Holtzman, Jon A.; Balam, David D.; Branch, David; Filippenko, Alexei V.; Frieman, Joshua; Fynbo, Johan; Galbany, Lluis; Ganeshalingam, Mohan; Garnavich, Peter M.; Graham, Melissa L.; Hsiao, Eric Y.; Leloudas, Giorgos; Leonard, Douglas C.; Li, Weidong; Riess, Adam G.; Sako, Masao; Schneider, Donald P.; Silverman, Jeffrey M.; Sollerman, Jesper; Steele, Thea N.; Thomas, Rollin C.; Wheeler, J. Craig; Zheng, Chen

    2014-05-01

    We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are observed in other SNe at late phases, spectra of SNe 2005hk and 2008A show lines of Fe II, Ca II, and Fe I more than a year past maximum light, along with narrow [Fe II] and [Ca II] emission. We use spectral features to constrain the temperature and density of the ejecta, and find high densities at late times, with ne >~ 109 cm-3. Such high densities should yield enhanced cooling of the ejecta, making these objects good candidates to observe the expected "infrared catastrophe," a generic feature of SN Ia models. However, our HST photometry of SN 2008A does not match the predictions of an infrared catastrophe. Moreover, our HST observations rule out a "complete deflagration" that fully disrupts the white dwarf for these peculiar SNe, showing no evidence for unburned material at late times. Deflagration explosion models that leave behind a bound remnant can match some of the observed properties of SNe Iax, but no published model is consistent with all of our observations of SNe 2005hk and 2008A.

  20. Hubble space telescope and ground-based observations of the type Iax supernovae SN 2005hk and SN 2008A

    SciTech Connect

    McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Chornock, Ryan; Holtzman, Jon A.; Balam, David D.; Branch, David; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li, Weidong; Frieman, Joshua; Fynbo, Johan; Leloudas, Giorgos; Galbany, Lluis; Garnavich, Peter M.; Graham, Melissa L.; Hsiao, Eric Y.; Leonard, Douglas C.; and others

    2014-05-10

    We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are observed in other SNe at late phases, spectra of SNe 2005hk and 2008A show lines of Fe II, Ca II, and Fe I more than a year past maximum light, along with narrow [Fe II] and [Ca II] emission. We use spectral features to constrain the temperature and density of the ejecta, and find high densities at late times, with n{sub e} ≳ 10{sup 9} cm{sup –3}. Such high densities should yield enhanced cooling of the ejecta, making these objects good candidates to observe the expected 'infrared catastrophe', a generic feature of SN Ia models. However, our HST photometry of SN 2008A does not match the predictions of an infrared catastrophe. Moreover, our HST observations rule out a 'complete deflagration' that fully disrupts the white dwarf for these peculiar SNe, showing no evidence for unburned material at late times. Deflagration explosion models that leave behind a bound remnant can match some of the observed properties of SNe Iax, but no published model is consistent with all of our observations of SNe 2005hk and 2008A.

  1. Evaluating Microphysics in Cloud-Resolving Models using TRMM and Ground-based Precipitation Radar Observations

    NASA Astrophysics Data System (ADS)

    Krueger, S. K.; Zulauf, M. A.; Li, Y.; Zipser, E. J.

    2005-05-01

    Global satellite datasets such as those produced by ISCCP, ERBE, and CERES provide strong observational constraints on cloud radiative properties. Such observations have been widely used for model evaluation, tuning, and improvement. Cloud radiative properties depend primarily on small, non-precipitating cloud droplets and ice crystals, yet the dynamical, microphysical and radiative processes which produce these small particles often involve large, precipitating hydrometeors. There now exists a global dataset of tropical cloud system precipitation feature (PF) properties, collected by TRMM and produced by Steve Nesbitt, that provides additional observational constraints on cloud system properties. We are using the TRMM PF dataset to evaluate the precipitation microphysics of two simulations of deep, precipitating, convective cloud systems: one is a 29-day summertime, continental case (ARM Summer 1997 SCM IOP, at the Southern Great Plains site); the second is a tropical maritime case: the Kwajalein MCS of 11-12 August 1999 (part of a 52-day simulation). Both simulations employed the same bulk, three-ice category microphysical parameterization (Krueger et al. 1995). The ARM simulation was executed using the UCLA/Utah 2D CRM, while the KWAJEX simulation was produced using the 3D CSU CRM (SAM). The KWAJEX simulation described above is compared with both the actual radar data and the TRMM statistics. For the Kwajalein MCS of 11 to 12 August 1999, there are research radar data available for the lifetime of the system. This particular MCS was large in size and rained heavily, but it was weak to average in measures of convective intensity, against the 5-year TRMM sample of 108. For the Kwajalein MCS simulation, the 20 dBZ contour is at 15.7 km and the 40 dBZ contour at 14.5 km! Of all 108 MCSs observed by TRMM, the highest value for the 40 dBZ contour is 8 km. Clearly, the high reflectivity cores are off scale compared with observed cloud systems in this area. A similar

  2. Effects of exchange-correlation potentials in density functional descriptions of ground-state and photoionization of fullerenes

    NASA Astrophysics Data System (ADS)

    Choi, Jinwoo; Chang, Eonho; Anstine, Dylan M.; Chakraborty, Himadri

    2016-05-01

    We study the ground state properties of C60 and C240 molecules in a spherical frame of local density approximation (LDA). Within this mean-field theory, two different approximations to the exchange-correlation (xc) functional are used: (i) The Gunnerson-Lundqvist parametrization augmented by a treatment to correct for the electron self-interaction and (ii) the van Leeuwen and Baerends (LB94) model potential that inclusively restores electron's asymptotic properties. Results show differences in the ground-state potential, level energies and electron densities between the two xc choices. We then use the ground structure to find the excited and ionized states of the systems and calculate dipole single-photoionization cross sections in a time-dependent LDA method that incorporates linear-response dynamical correlations. Comparative effects of the choices of xc on collective plasmon and single-excitation Auger resonances as well as on geometry driven cavity oscillations are found significant. The work is supported by the NSF, USA.

  3. Reconciling simulated melting and ground-state properties of metals with a modified embedded-atom method potential.

    PubMed

    Sushko, G B; Verkhovtsev, A V; Kexel, Ch; Korol, A V; Schramm, S; Solov'yov, A V

    2016-04-13

    We propose a modification of the embedded-atom method-type potential aiming at reconciling simulated melting and ground-state properties of metals by means of classical molecular dynamics. Considering titanium, magnesium, gold, and platinum as case studies, we demonstrate that simulations performed with the modified force field yield quantitatively correctly both th