Science.gov

Sample records for ground observations potential

  1. Seafloor ground rotation observations: potential for improving signal-to-noise ratio on horizontal OBS components

    NASA Astrophysics Data System (ADS)

    Lindner, Fabian; Wassermann, Joachim; Schmidt-Aursch, Mechita; Schreiber, Ulrich; Igel, Heiner

    2015-04-01

    It is well known that the horizontal components of ocean bottom seismometer (OBS) records have a very poor signal-to-noise (S/N) ratio compared to the vertical components, the difference substantially exceeding that of terrestrial records. This is unfortunate as 1) OBS experiments are expensive and the main possibility to gather data in offshore areas, and 2) today we are more and more interested in modelling complete waveforms including all three components aiming at optimally constraining geophysical parameters for inverse problems for Earth's structure and seismic sources. Despite the fact that it is expected that tilting is the major cause of this high S/N - to our knowledge - this effect has never been directly observed. The reason is that (standard) instruments for the measurement of uncontaminated rotational ground motions with the required sensitivity still do not exist. Here, we report observations from an experiment we carried out in the North Sea, close to the island of Helgoland in the summer of 2014. A commercial fibre-optic gyro (usually used for navigation purposes) recording ground rotation rate with a sensitivity of approx. 10-7 rad/s was mounted on an OBS system together with a broadband seismometer. The system was lowered to the seafloor for about a week. To investigate a potential connection between rotational ground motions around the two horizontal axes (i.e., tilting) we calculate the coherence between the corresponding motion components (e.g., rotations around x-axis and translational motions along y-axis, and vice versa). We find very high correlations, on average exceeding 0.73 in the period interval 7-13 seconds. Correlations seem to increase with noise amplitude. Rotation rate amplitudes are in the range of 10-6 -10-5 rad/s. This clearly indicates that the horizontal translational components are severely contaminated by rotations around the horizontal axes. The ground rotation observations allow correcting for this effect thereby

  2. 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.

  3. 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.

  4. Ground potential rise monitor

    DOEpatents

    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 ground observations and remotely sensed data: potential use for environmental public health surveillance.

    PubMed

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

    2009-07-01

    This study describes and demonstrates different techniques for surface fitting daily environmental hazards data of particulate matter with aerodynamic diameter less than or equal to 2.5 microm (PM2.5) for the purpose of integrating respiratory health and environmental data for the Centers for Disease Control and Prevention (CDC) pilot study of Health and Environment Linked for Information Exchange (HELIX)-Atlanta. It presents a methodology for estimating daily spatial surfaces of ground-level PM2.5 concentrations using the B-Spline and inverse distance weighting (IDW) surface-fitting techniques, leveraging National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectrometer (MODIS) data to complement U.S. 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 PM2.5 exposure estimates. This paper shows that merging MODIS remote sensing data with surface observations of PM,2. not only provides a more complete daily representation of PM,2. than either dataset alone would allow, but it also reduces the errors in the PM2.5-estimated surfaces. The results of this study also show that although the IDW technique can introduce some numerical artifacts that could be due to its interpolating nature, which assumes that the maxima and minima can occur only at the observation points, the daily IDW PM2.5 surfaces had smaller errors in general, with respect to observations, than those of the B-Spline surfaces. Finally, the methods discussed in this paper 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 high accuracy is critical. PMID:19645271

  7. 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.

  8. 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.

  9. Lightning: Ground observations of gamma radiation

    NASA Astrophysics Data System (ADS)

    Jayanthi, U. B.; Gusev, A. A.; Neri, J. A. C.; Pugacheva, G. I.; Talavera, K. C.

    Recent satellite and ground observations of emissions in x and gamma-rays ascribing association with lightning phenomena have triggered interest in this natural phenomena The incentive for this Ground Gamma Radiation GGR experiment in the Brazilian Geomagnetic Anomaly BGA region is due to the absence of satellite data As a first step we want to test and calibrate the system with rocket triggered lightning flashes in the International Lightning facility in our Campus The lightning associated gamma rays can be inferred as due to bremsstrahlung associated with electrons released moments after the return stroke and the likely radiation associated with radioactive decay products in the interactions of protons generated in the lightning with the atmospheric constituents Initially in 2005 to observe the later phenomena a very large area NaI Tl detector of 40 cm diameter with a PHA system monitoring every 10 s was set up near the two rocket launchers for the induced lightning In few months of operation in 2005 increases in gamma-rays above the ground radiation flux are observed due to many rain precipitation events and in one lightning event coincident with the rocket launch To identify the association of emission due to the lightning we investigated both the decay period and the spectral information of these gamma rays The radon progeny in rain has an associated decay period of sim 30 min but however the decay time associated with the lightning is different Although the spectral information indicates a power law index for both

  10. Potential Flow Analysis of Dynamic Ground Effect

    NASA Technical Reports Server (NTRS)

    Feifel, W. M.

    1999-01-01

    Interpretation of some flight test data suggests the presence of a 'dynamic ground effect'. The lift of an aircraft approaching the ground depends on the rate of descent and is lower than the aircraft steady state lift at a same height above the ground. Such a lift deficiency under dynamic conditions could have a serious impact on the overall aircraft layout. For example, the increased pitch angle needed to compensate for the temporary loss in lift would reduce the tail strike margin or require an increase in landing gear length. Under HSR2 an effort is under way to clarify the dynamic ground effect issue using a multi-pronged approach. A dynamic ground effect test has been run in the NASA Langley 14x22 ft wind tunnel. Northup-Grumman is conducting time accurate CFD (Computational Fluid Dynamics) Euler analyses on the National Aerodynamic Simulator facility. Boeing has been using linear potential flow methodology which are thought to provide much needed insight in, physics of this very complex problem. The present report summarizes the results of these potential flow studies.

  11. 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

  12. Reducing discrepancies in ground and satellite-observed eruption heights

    NASA Astrophysics Data System (ADS)

    Tupper, Andrew; Wunderman, Rick

    2009-09-01

    The plume height represents a crucial piece of evidence about an eruption, feeding later assessment of its size, character, and potential impact, and feeding real-time warnings for aviation and ground-based populations. There have been many observed discrepancies between different observations of maximum plume height for the same eruption. A comparison of maximum daily height estimates of volcanic clouds over Indonesia and Papua New Guinea during 1982-2005 shows marked differences between ground and satellite estimates, and a general tendency towards lower height estimates from the ground. Without improvements in the quality of these estimates, reconciled among all available methods, warning systems will be less effective than they should be and the world's record of global volcanism will remain hard to quantify. Examination of particular cases suggests many possible reasons for the discrepancies. Consideration of the satellite and radar cloud observations for the 1991 Pinatubo eruptions shows that marked differences can exist even with apparently good observations. The problem can be understood largely as a sampling issue, as the most widely reported parameter, the maximum cloud height, is highly sensitive to the frequency of observation. Satellite and radar cloud heights also show a pronounced clumping near the height of the tropopause and relative lack of eruptions reaching only the mid-troposphere, reinforcing the importance of the tropopause in determining the eruption height in convectively unstable environments. To reduce the discrepancies between ground and satellite estimates, a number of formal collaboration measures between vulcanological, meteorological and aviation agencies are suggested.

  13. 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.

  14. 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...

  15. Asteroseismology: Ground based efforts and the need for space observations

    NASA Technical Reports Server (NTRS)

    Gilliland, Ronald L.

    1994-01-01

    Detection of the oscillations expected to be present on solar-like stars is very difficult. Photometric observations from the ground suffer from two problems: (1) an atmospheric scintillation noise that drops only slowly with telescope aperture size, and (2) mode frequency spacings that require nearly continuous observations over at least several days for resolution. I will review the very limited possibilities for asteroseismology of solar-like stars from ground-based photometric observations. FRESIP could provide an excellent opportunity for pursuing asteroseismology observations of a far richer nature than can be contemplated from the ground.

  16. 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.

  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. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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).

  7. 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.

  8. Ground-water levels in observation wells in Oklahoma, 1975

    USGS Publications Warehouse

    Goemaat, Robert L.

    1977-01-01

    The objectives of the observation-well program are (1) to provide long-term records of water-level fluctuations in representative wells, (2) to facilitate the prediction of water-level trends and indicate the future availability of ground-water supplies, and (3) to provide information for use in basic research. These selected records serve as a framework to which other types of hydrologic data may be related. The stratigraphic nomenclature and age determinations used in this report are those accepted by the Oklahoma Geological Survey and do not necessarily agree with those of the U.S. Geological Survey.

  9. 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.

  10. Some unreliable types of ground-water observation wells

    USGS Publications Warehouse

    Remson, Irwin; Fox, G.S.

    1954-01-01

    Several primary requirements must be fulfilled by any observation well that is to be used as an indicator of ground-water levels over considerable distances. First of all, the water level inside the well must be the same as that outside of the well. the water level inside the well must be able to adjust to water -level fluctuations in the aquifer within a certain period of time, that time dependent upon the type of study for which the observations are to be used. Finally, to be of value in most areal studies, the water level outside the well must be representative of the level throughout the aquifer, and not reflect merely some speical local condition. Should any of these requirements remain unsatisfied, the derived data may be misleading. 

  11. 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

  12. Giant pulsations on the afternoonside: Geostationary satellite and ground observations

    NASA Astrophysics Data System (ADS)

    Motoba, Tetsuo; Takahashi, Kazue; Rodriguez, Juan V.; Russell, Christopher T.

    2015-10-01

    Giant pulsations (Pgs) are a special class of oscillations recognized in ground magnetometer records as exhibiting highly regular sinusoidal waveforms in the east-west component with periods around 100s. Previous statistical studies showed that Pgs occur almost exclusively on the morningside with peak occurrence in the postmidnight sector. In this paper, we present observations of Pgs extending to the afternoonside, using data from the GOES13 and 15 geostationary satellites and multiple ground magnetometers located in North America. For a long-lasting event on 29 February 2012, which spanned ˜08-18h magnetic local time, we show that basic Pg properties did not change with the local time, although the period of the pulsations was longer at later local time due to increasing mass loading. There is evidence that the Pgs resulted from fundamental poloidal mode standing Alfvén waves, both on the morning and afternoonsides. Oscillations of energetic particles associated with the field oscillations exhibited an energy-dependent phase, which has previously been reported and explained by drift resonance. A statistical analysis of the ground magnetic field data (L = 3.8-7.4) covering 2008-2013 confirms that afternoon Pgs are not unusual. We identified a total of 105 Pg events (about 70% (30%) of the events occurred during non-storm (late storm recovery) periods), 31 of which occurred on the afternoonside. The afternoon Pgs occur under solar wind and geomagnetic conditions that are similar to the morning Pgs, but the afternoon Pgs tend to have short durations and occur frequently in winter instead of around spring and fall equinoxes that are favored by the morning Pgs.

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

    SciTech Connect

    Potemra, T.A.; Zanetti, L.J.; Takahashi, K.; Erlandson, R.E. ); Luehr, H. ); Marklund, G.T.; Block, L.P.; Blomberg, L.G. ); Lepping, R.P. )

    1989-03-01

    A unique alignment of the Active Magnetospheric Particle Tracer Explorers (AMPTE) CCE and Viking satellites with respect to the EISCAT Magnetometer Cross has provided an opportunity to study transient ULF pulsations associated with variations in solar wind plasma density observed by the IMP 8 satellite. These observations were acquired during a relatively quiet period on April 24, 1986, during the Polar Region and Outer Magnetosphere International Study (PROMIS) period. An isolated 4-mHz (4-min period) pulsation was detected on the ground which was associated with transverse magnetic field oscillations observed by Viking at a {approximately} 2-R{sub E} altitude above the auroral zone and by CCE at {approximately} 8-R{sub E} in the equatorial plane on nearly the same flux tube. CCE detected a compressional oscillation in the magnetic field with twice the period ({approximately} 10 min) of the transverse waves, and with a waveform nearly identical to an isolated oscillation in the solar wind plasma density measured by IMP 8. The authors conclude that the isolated 10-min oscillation in solar wind plasma density produced magnetic field compression oscillations inside the magnetosphere at the same frequency which also enhanced resonant oscillations at approximately twice the frequency that were already present. The ground magnetic field variations are due to ionospheric Hall currents driven by the electric field of the standing Alfven waves. The time delay between surface and satellite data acquired at different local times supports the conclusion that the periodic solar wind density variation excites a tailward traveling large-scale magnetosphere wave train which excites local field line resonant oscillations. They conclude that these transient magnetic field variations are not associated with magnetic field reconnection or flux transfer events.

  14. A genetic algorithm for ground-based telescope observation scheduling

    NASA Astrophysics Data System (ADS)

    Mahoney, William; Veillet, Christian; Thanjavur, Karun

    2012-09-01

    A prototype genetic algorithm (GA) is being developed to provide assisted and ultimately automated observation scheduling functionality. Harnessing the logic developed for manual queue preparation, the GA can build suitable sets of queues for the potential combinations of environmental and atmospheric conditions. Evolving one step further, the GA can select the most suitable observation for any moment in time, based on allocated priorities, agency balances, and realtime availability of the skies' condition.

  15. 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.

  16. Stepped leaders observed in ground operations of ADELE

    NASA Astrophysics Data System (ADS)

    Smith, D. M.; Kelley, N.; Lowell, A.; Martinez-McKinney, F.; Dwyer, J. R.; Splitt, M. E.; Lazarus, S. M.; Cramer, E. S.; Levine, S.; Cummer, S. A.; Lu, G.; Shao, X.; Ho, C.; Eastvedt, E. M.; Trueblood, J.; Edens, H. E.; Hunyady, S. J.; Winn, W. P.; Rassoul, H. K.

    2010-12-01

    While the Airborne Detector for Energetic Lightning Emissions (ADELE) was designed primarily to study high-energy radiation associated with thunderstorms at aircraft altitude, it can also be used as a mobile ground-based instrument when mounted in a van. ADELE contains scintillation detectors optimized for faint and bright events and a flat-plate antenna measuring dE/dt. In July and August 2010, ADELE was brought to Langmuir Laboratory in New Mexico as a stationary detector and to the Florida peninsula (based at the Florida Institute of Technology in Melbourne) for rapid-response (storm-chasing) operations. In ten days of chasing, stepped-leader x-ray emission was observed from at least four close CG flashes, a much higher rate of success than can be achieved from a stationary detector or array. We will present these four events as well as the results of a study of candidate events of lesser statistical significance. We will also discuss the optimization of lightning-chasing strategies, science goals for future ground campaigns, and what additional instrumentation would be most scientifically beneficial. In the latter category, a proximity sensor (comparing flash and thunder arrival times) and a field mill are particularly important.

  17. Characteristics of negative lightning leaders to ground observed by TVLS

    NASA Astrophysics Data System (ADS)

    Qiu, Shi; Jiang, Zhidong; Shi, Lihua; Niu, Zhencong; Zhang, Peng

    2015-12-01

    The Thunder and VHF lightning Locating System (termed TVLS) is established and utilized to observe leader behaviors of negative cloud to ground (CG) flashes. This system takes advantages of VHF broadband interferometer and thunder imaging technique, which could provide the temporal and quasi-3D spatial evolution of lightning discharges. In conjunction with synchronized electric field changes (E-changes) and electric field derivatives (dE/dt) records, 10 leaders from two CG flashes are presented and analyzed. Based on the characteristic evolution of leader velocities, E-changes, dE/dt waveforms and VHF intervals, three stepped leaders, five dart leaders and two dart-stepped leaders are identified. The stepped leaders behave impulsive while approaching ground, with average speed (1.3∼3.9)×105 m/s. All normal dart leaders presented here exhibit irregular (or termed "chaotic") fluctuations in E-change and dE/dt waveforms, with the similar speeds ((1.0∼2.9)×107 m/s) and durations ((300∼700) μs) of the "chaotic" leaders observed by other investigators. The irregular fluctuations would be weak if the channels keep conductive until the leader enters the less conductive branches, coinciding with VHF radiations in time sequence. The dart-stepped leader could be divided into the dart stage and the stepped stage by a transition region, which usually lies around the branch junctions of previous active channel. The dart stage resembles the normal dart leader, and the stepped stage usually associates with regular pulse trains in E-change and dE/dt waveforms.

  18. 5 CFR 2425.6 - Grounds for review; potential dismissal or denial for failure to raise or support grounds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 3 2012-01-01 2012-01-01 false Grounds for review; potential dismissal... RELATIONS AUTHORITY REVIEW OF ARBITRATION AWARDS § 2425.6 Grounds for review; potential dismissal or denial... over an award relating to: (1) An action based on unacceptable performance covered under 5 U.S.C....

  19. 5 CFR 2425.6 - Grounds for review; potential dismissal or denial for failure to raise or support grounds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 3 2013-01-01 2013-01-01 false Grounds for review; potential dismissal... RELATIONS AUTHORITY REVIEW OF ARBITRATION AWARDS § 2425.6 Grounds for review; potential dismissal or denial... over an award relating to: (1) An action based on unacceptable performance covered under 5 U.S.C....

  20. 5 CFR 2425.6 - Grounds for review; potential dismissal or denial for failure to raise or support grounds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 3 2014-01-01 2014-01-01 false Grounds for review; potential dismissal... RELATIONS AUTHORITY REVIEW OF ARBITRATION AWARDS § 2425.6 Grounds for review; potential dismissal or denial... over an award relating to: (1) An action based on unacceptable performance covered under 5 U.S.C....

  1. Spatial mapping of ground-based observations of total ozone

    NASA Astrophysics Data System (ADS)

    Chang, K.-L.; Guillas, S.; Fioletov, V. E.

    2015-10-01

    Total column ozone variations estimated using ground-based stations provide important independent source of information in addition to satellite-based estimates. This estimation has been vigorously challenged by data inhomogeneity in time and by the irregularity of the spatial distribution of stations, as well as by interruptions in observation records. Furthermore, some stations have calibration issues and thus observations may drift. In this paper we compare the spatial interpolation of ozone levels using the novel stochastic partial differential equation (SPDE) approach with the covariance-based kriging. We show how these new spatial predictions are more accurate, less uncertain and more robust. We construct long-term zonal means to investigate the robustness against the absence of measurements at some stations as well as instruments drifts. We conclude that time series analyzes can benefit from the SPDE approach compared to the covariance-based kriging when stations are missing, but the positive impact of the technique is less pronounced in the case of drifts.

  2. Simulation experiments of gravitational potential determination using clocks onboard satellite and on ground

    NASA Astrophysics Data System (ADS)

    Shen, Ziyu; Shen, WenBin; Zhang, Shuangxi

    2016-04-01

    Here we present simulation results for determining the gravitational potential using high-frequency-stability microwave links between satellite and ground station. Two precise clocks (oscillators) are equipped onboard a satellite and at a ground station. Based on Doppler cancelling technique, the gravitational potential difference between the satellite and the ground station can be determined. In the simulations, we use multi satellites and multi observations in different periods, and results show that most offset values are in the order of 0.1 m (in equivalent height), and standard deviation is around 0.1 m. With quick development of atomic clocks, our proposed approach is prospective in the near future. This study is supported by National 973 Project China (grant No. 2013CB733301 and 2013CB733305) and NSFC (grant Nos. 41174011, 41210006, 41429401).

  3. 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.

  4. 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.

  5. 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.

  6. 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. PMID:26821751

  7. 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

  8. 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.

  9. 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.

  10. Self-potential observations during hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Moore, Jeffrey R.; Glaser, Steven D.

    2007-02-01

    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 microcracks 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 ˜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.

  11. Agreements between ground-based and satellite-based observations. [of earth magnetospheric currents

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.; Weimer, D.; Iijima, T.; Ahn, B.-H.; Kamide, Y.

    1990-01-01

    The polar ionospheric parameters obtained by the meridian chain of magnetometers are compared with those obtained by satellites, and a number of ionospheric quantities including the distribution of the electric potential, field-aligned currents, ionospheric currents and their equatorial counterparts, and the relationship between the AE index and the cross-polar cap potential is determined. It is noted that the agreement observed between the ground-based and satellite-based results allows to reduce the search for the driving mechanism of the ionospheric Pedersen current to identifying the driving mechanism of the Pedersen counterpart current in the equatorial plane.

  12. OTD Observations of Continental US Ground and Cloud Flashes

    NASA Technical Reports Server (NTRS)

    Koshak, William

    2007-01-01

    Lightning optical flash parameters (e.g., radiance, area, duration, number of optical groups, and number of optical events) derived from almost five years of Optical Transient Detector (OTD) data are analyzed. Hundreds of thousands of OTD flashes occurring over the continental US are categorized according to flash type (ground or cloud flash) using US National Lightning Detection Network TM (NLDN) data. The statistics of the optical characteristics of the ground and cloud flashes are inter-compared on an overall basis, and as a function of ground flash polarity. A standard two-distribution hypothesis test is used to inter-compare the population means of a given lightning parameter for the two flash types. Given the differences in the statistics of the optical characteristics, it is suggested that statistical analyses (e.g., Bayesian Inference) of the space-based optical measurements might make it possible to successfully discriminate ground and cloud flashes a reasonable percentage of the time.

  13. 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.

  14. 5 CFR 2425.6 - Grounds for review; potential dismissal or denial for failure to raise or support grounds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 3 2011-01-01 2011-01-01 false Grounds for review; potential dismissal or denial for failure to raise or support grounds. 2425.6 Section 2425.6 Administrative Personnel FEDERAL LABOR RELATIONS AUTHORITY, GENERAL COUNSEL OF THE FEDERAL LABOR RELATIONS AUTHORITY AND FEDERAL SERVICE IMPASSES PANEL FEDERAL LABOR...

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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

  2. 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

  3. Differences in the Optical Characteristics of Continental US Ground and Cloud Flashes as Observed from Space

    NASA Technical Reports Server (NTRS)

    Koshak, William

    2007-01-01

    Continental US lightning flashes observed by the Optical Transient Detector (OTD) are categorized according to flash type (ground or cloud flash) using US National Lightning Detection Network (TM) (NLDN) data. The statistics of the ground and cloud flash optical parameters (e.g., radiance, area, duration, number of optical groups, and number of optical events) are inter-compared. On average, the ground flash cloud-top emissions are more radiant, illuminate a larger area, are longer lasting, and have more optical groups and optical events than those cloud-top emissions associated with cloud flashes. Given these differences, it is suggested that the methods of Bayesian Inference could be used to help discriminate between ground and cloud flashes. The ability to discriminate flash type on-orbit is highly desired since such information would help researchers and operational decision makers better assess the intensification, evolutionary state, and severe weather potential of thunderstorms. This work supports risk reduction activities presently underway for the future launch of the GOES-R Geostationary Lightning Mapper (GLM).

  4. Ground magnetometer detection of a large-M Pc 5 pulsation observed with the STARE radar

    SciTech Connect

    Allan, W.; Poulter, E.M.; Glassmeier, K.; Nielsen, E.

    1983-01-01

    Ground-based magnetometer observations are used to confirm the properties of a large azimuthal wave number Pc 5 pulsation observed previously with the STARE radar. The magnetometer and STARE results allow an estimate to be made of the ionospheric height-integrated Hall conductivity, as well as supporting theories that predict 90/sup 0/ rotation of polarization between ionosphere and ground. The properties of the observed vertical magnetic component at the ground are also found to be consistent with recent theory.

  5. Observations of ground clutter using a millimeter wave radar

    NASA Astrophysics Data System (ADS)

    Sekine, Matsuo; Musha, Toshimitsu; Chikara, Sakae; Saji, Keiichi; Hagiwara, Seiji

    1990-02-01

    Ground clutter was measured using a millimeter-wave radar with frequency 34.86 GHz, which is located on the campus of the University of Electro-Communications. The pulsewidth of the radar was 30 nsec. Thus the spatial resolution was as small as 4.5 m. It is found that the clutter amplitude distribution obeys a Weibull distribution with shape parameter c = 0.497 to 0.675 at depression angles of 0.8 to 1.9 deg when reflectors are ordinary terrain and such structures as landing strips at airport and buildings. To improve target detectability in such Weibull distributed ground clutter, a Weibull CFAR system will be required.

  6. 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.

  7. 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.

  8. Ground-based lidar observations of ozone aerosol and temperature

    SciTech Connect

    Heaps, W.S.

    1987-09-01

    Several theories have been proposed to explain the recently discovered, springtime ozone depletion over Antarctica, but additional data is necessary to establish what processes are producing this phenomenon. The preliminary results of the 1986-1987 National Ozone Expedition indicate that nitrogen oxides were present smaller amounts than anticipated and that chlorine compounds were more prevalent. These findings support chemical theories based on chlorine or chlorine-bromine chemical mechanisms are affecting the level of ozone in the stratosphere; however, not all climate dynamic theories are discounted by these data. The objective is to use a ground-based laser radar system (lidar) in an upward-looking mode to record ozone profiles, aerosol content, and temperature profiles. Although the system was not principally designed for these measurements, the author has modified it slightly to collect these data.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. A discussion of the ground-based radio observations

    NASA Technical Reports Server (NTRS)

    Kerr, F. J.

    1971-01-01

    It is reasserted that the Gum nebula is not a single nebula but appears to be composed of several different entities. All the surveys of the southern sky in the continuum, recombination line, H I, and OH were considered. The large amount of high frequency radio emission from the small nebula is noted. The outer part of the Gum nebula has not been seen in any radio observations so far. Only the inner part has been observed to date. It is not justifiable to work out any parameters for the whole nebula by taking an average over the whole solid angle subtended by the big nebula. There appears to be a large difference in density between the small nebula and the big one.

  17. Spontaneous channelization in permeable ground: theory, experiment, and observation

    NASA Astrophysics Data System (ADS)

    Schorghofer, Norbert; Jensen, Bill; Kudrolli, Arshad; Rothman, Daniel H.

    2004-03-01

    Landscapes that are rhythmically dissected by natural drainage channels exist in various geologic and climatic settings. Such landscapes are characterized by a length-scale for the lateral spacing between channels. We observe a small-scale version of this process in the form of beach rills and reproduce channelization in a table-top seepage experiment. On the beach as well as in the experiments, channels are spontaneously incised by surface flow, but once initiated, they grow due to water emerging from underground. Field observation and experiment suggest the process can be described in terms of flow through a homogeneous porous medium with a freely shaped water table. According to this theory, small deformations of the underground water table amplify the flux into the channel and lead to further growth, a phenomenon we call ‘Wentworth instability’. Piracy of groundwater can occur over distances much larger than the channel width. Channel spacing coarsens with time, until channels reach their maximum length.

  18. 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.

  19. 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.

  20. 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.

  1. Analysis of simultaneous Skylab and ground based flare observations

    NASA Technical Reports Server (NTRS)

    Kulander, J. L.

    1976-01-01

    HeI and HeII resonance line data from Skylab were reduced, analyzed and compared with HeI D3 line intensities taken simultaneously from the Lockheed Rye Canyon Solar Observatory. Computer codes were developed for the calculation of total He line intensities and line profiles from model flare regions. These codes incorporate simultaneous solution of the line and continuum transport equations as needed together with the statistical equilibrium equations for a 30 level HeI, HeII, HeIII system. The energy level model consists of all terms through principal quantum number four. Interpretation of the observed data in terms of these parametric solutions and with simultaneous solution of the transport equations are discussed.

  2. Potential of radiotelescopes for atmospheric line observations: I. Observation principles and transmission curves for selected sites

    NASA Astrophysics Data System (ADS)

    Schneider, Nicola; Urban, Joachim; Baron, Philippe

    2009-10-01

    Existing and planned radiotelescopes working in the millimetre (mm) and sub-millimetre wavelengths range provide the possibility to be used for atmospheric line observations. To scrutinize this potential, we outline the differences and similarities in technical equipment and observing techniques between ground-based aeronomy mm-wave radiometers and radiotelescopes. Comprehensive tables summarizing the technical characteristics of existing and future (sub)-mm radiotelescopes are given. The advantages and disadvantages using radiotelescopes for atmospheric line observations are discussed. In view of the importance of exploring the sub-mm and far-infrared wavelengths range for astronomical observations and atmospheric sciences, we present model calculations of the atmospheric transmission for selected telescope sites (DOME-C/Antarctica, ALMA/Chajnantor, JCMT and CSO on Mauna Kea/Hawaii, KOSMA/Swiss Alpes) for frequencies between 0 and 2000 GHz ( 150μm) and typical atmospheric conditions using the forward model MOLIERE (version 5). For the DOME-C site, the transmission over a larger range of up to 10 THz ( 30μm) is calculated in order to demonstrate the quality of an Earth-bound site for mid-IR observations. All results are available on a dedicated webpage.

  3. 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.

  4. 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.

  5. Observation and Calculation of the Quasibound Rovibrational Levels of the Electronic Ground State of H2+

    NASA Astrophysics Data System (ADS)

    Beyer, Maximilian; Merkt, Frédéric

    2016-03-01

    Although the existence of quasibound rotational levels of the X+ 2Σg+ ground state of H2+ was predicted a long time ago, these states have never been observed. Calculated positions and widths of quasibound rotational levels located close to the top of the centrifugal barriers have not been reported either. Given the role that such states play in the recombination of H (1 s ) and H+ to form H2+, this lack of data may be regarded as one of the largest unknown aspects of this otherwise accurately known fundamental molecular cation. We present measurements of the positions and widths of the lowest-lying quasibound rotational levels of H2+ and compare the experimental results with the positions and widths we calculate using a potential model for the X+ state of H2+ which includes adiabatic, nonadiabatic, relativistic, and radiative corrections to the Born-Oppenheimer approximation.

  6. 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.

  7. 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.

  8. 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.

  9. vsini observations of potential exoplanet parent stars

    NASA Astrophysics Data System (ADS)

    Stankov, A.; Schulz, R.; Erd, C.; Ho, T.; Stüwe, J.; Smit, H.

    2013-09-01

    We present spectroscopic measurements for a sample of 19 stars with spectral types F, G, and K, suitable to host exoplanets. The relative strengths of the Ca II H and K emission lines were measured and from these the projected rotational velocities, v sin i, will be determined. Theory states that the v sin i value is smaller if the observed star hosts exoplanets [1]. This is valid for stars later than spectreal type F 5 [2]. The v sin i information can be used to prioritize a target star catalog for a project that is aiming at discovering new exoplanets. Here we describe this project in more detail and show first results for selected target stars.

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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

  16. 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

  17. 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.

  18. METHODOLOGY TO EVALUATE THE POTENTIAL FOR GROUND WATER CONTAMINATION FROM GEOTHERMAL FLUID RELEASES

    EPA Science Inventory

    This report provides analytical methods and graphical techniques to predict potential ground water contamination from geothermal energy development. Overflows and leaks from ponds, pipe leaks, well blowouts, leaks from well casing, and migration from injection zones can be handle...

  19. 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.

  20. 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.

  1. Simultaneous Observations of ULF Waves in the Magnetosphere, Ionosphere and on the Ground

    NASA Astrophysics Data System (ADS)

    Fraser, B. J.; Singer, H. J.; Ponomarenko, P. V.

    2004-12-01

    External solar wind sources transfer energy, either directly or indirectly, into the Earth's dayside magnetosphere to drive ultra-low frequency (ULF) waves in the Pc3-5 (1-100mHz) band. The wavelength of these waves is of the same order as the scale size of the magnetospheric cavity and consequently ULF wave energy is generally observed as standing wave resonances, either Alfven mode field line resonances or fast mode cavity/waveguide resonances. The ULF wave spectra seen by ground magnetometers contains information relating to the properties of the wave source and the magnetosphere and ionosphere regions and associated boundaries through which wave energy must travel to reach the ground. This study tracks individual daytime Pc3-5 wave trains, seen in the outer magnetosphere at geostationary orbit in September 2003 by magnetometers onboard the GOES 8 and 9 satellites (195 and 205 degrees west longitude), down through the ionosphere where they are observed by the Tasmanian TIGER SuperDARN HF radar, and to the ground where they are observed by the ground magnetometer at Macquarie Island. Of particular interest is a comparison of wave amplitudes seen in the magnetosphere, ionosphere and on the ground. Ionospheric ULF wave azimuthal wave numbers are known to differ from those measured on the ground due to spatial integration. Wave numbers in the magnetosphere, ionosphere and on the ground will be compared, and other wave properties observed simultaneous between the three regions, including travel time, phase and polarization characteristics will be discussed. This provides new knowledge on the transfer of ULF wave energy from the magnetosphere to the ground.

  2. An ionospheric travelling convection vortex event observed by ground-based magnetometers and by VIKING

    SciTech Connect

    Vogelsang, H.; Voelker, H. ); Luehr, H. ); Woch, J. ); Boesinger, T. ); Potemra, T.A. ); Lindqvist, P.A. )

    1993-11-05

    This paper reports the ground based observation of an ionospheric travelling convection vortex event, which was observed in coincidence with observation of the VIKING spacecraft passing through closed field lines which map to this region. The spacecraft saw electric and magnetic signatures which were consistent with it having passed through field aligned current tubes, oppositely directed. This is the first such simultaneous observation and supports the theoretical models which relate such ionospheric travelling convection vortex events to field aligned currents.

  3. An Efficient Optical Observation Ground Network is the Fundamental basis for any Space Based Debris Observation Segment

    NASA Astrophysics Data System (ADS)

    Cibin, L.; Chiarini, M.; Annoni, G.; Milani, A.; Bernardi, F.; Dimare, L.; Valsecchi, G.; Rossi, A.; Ragazzoni, R.; Salinari, P.

    2013-08-01

    A matter which is strongly debated in the SSA Community, concerns the observation of Space Debris from Space [1]. This topic has been preliminary studied by our Team for LEO, MEO and GEO orbital belts, allowing to remark a fundamental concept, residing in the fact that to be suitable to provide a functionality unavailable from ground in a cost to performance perspective, any Space Based System must operate in tight collaboration with an efficient Optical Ground Observation Network. In this work an analysis of the different functionalities which can be implemented with this approach for every orbital belt is illustrated, remarking the different achievable targets in terms of population size as a function of the observed orbits. Further, a preliminary definition of the most interesting missions scenarios, together with considerations and assessments on the observation strategy and P/L characteristics are presented.

  4. Battery Performance of ADEOS (Advanced Earth Observing Satellite) and Ground Simulation Test Results

    NASA Technical Reports Server (NTRS)

    Koga, K.; Suzuki, Y.; Kuwajima, S.; Kusawake, H.

    1997-01-01

    The Advanced Earth Observing Satellite (ADEOS) is developed with the aim of establishment of platform technology for future spacecraft and inter-orbit communication technology for the transmission of earth observation data. ADEOS uses 5 batteries, consists of two packs. This paper describes, using graphs and tables, the ground simulation tests and results that are carried to determine the performance of the ADEOS batteries.

  5. Spatiotemporal inhomogeneity in NO2 over Fukuoka observed by ground-based MAX-DOAS

    NASA Astrophysics Data System (ADS)

    Takashima, Hisahiro; Kanaya, Yugo; Irie, Hitoshi

    2015-01-01

    Continuous NO2 profile observations have been made using ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) at Fukuoka (33.55°N, 130.36°E), an urban area in Japan. Throughout the year, NO2 variations measured by MAX-DOAS (0-100 m) are in good agreement with in situ surface NO2 measurements on several-day, week-to-week, and seasonal timescales. We investigated the spatiotemporal inhomogeneity in NO2 over Fukuoka by observing at two azimuth angles: the Tenjin (towards the city center) and Itoshima (away from the city center) directions. In terms of diurnal variations, NO2 in both directions show clear morning maxima, on account of local emissions in the morning and the development of a boundary layer. The concentrations in the early morning are nearly the same in both directions, but they are higher in the Tenjin direction during most of the daytime on average. Variability in both directions, as well as spatial inhomogeneity, is large during most of the daytime except for in the morning. The diurnal maximum for 0-1 km between 10 and 13 LT is sometimes observed in the Tenjin direction; in some cases, 1 h after this maximum, a maximum is also observed in the Itoshima direction. The NO2 maxima for the upper level (1-2 km) in both directions are also delayed from the maximum in the Tenjin direction for 0-1 km. Analysis of the surface wind field indicates that the NO2 inhomogeneity is strongly related to vertical/horizontal transport of high concentrations of NO2 from the city center, and to horizontal transport of low concentrations from the ocean via a land-sea breeze. Three-dimensional continuous observations by MAX-DOAS are potentially a powerful tool for increasing our understanding of pollutant transport and mixing in urban areas.

  6. Entry Dispersion Analysis for the HAYABUSA Spacecraft using Ground-Based Optical Observation

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tomohiro; Yoshikawa, Makoto; Yagi, Masafumi; Tholen, David J.

    2011-10-01

    The HAYABUSA asteroid explorer successfully released its sample capsule to Australia on 2010 June 13. Since the Earth reentry phase of sample return was critical, many backup plans for predicting the landing location were prepared. This paper considers the reentry dispersion using ground-based optical observation as a backup observation for radiometric observation. Several scenarios were calculated and compared for the reentry phase of HAYABUSA to evaluate the navigation accuracy of the ground-based observation. The optical observation doesn't require any active reaction from a spacecraft, and thus these results show that optical observations could be a steady backup strategy even if a spacecraft had some trouble. We also evaluated the landing dispersion of HAYABUSA only with optical observation.

  7. 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.

  8. The potential of THEMIS satellite and ground-based measurements for data mining

    NASA Astrophysics Data System (ADS)

    Frey, S.; Angelopoulos, V.; Sibeck, D. G.; Phan, T.; Eastwood, J. P.; Runov, A.; Frey, H. U.

    2009-12-01

    Launched on February 17, 2007 on a DELTA II rocket, NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission is a Medium-class Explorer project and the first space mission to study the sequence of magnetospheric events that trigger gigantic auroral displays in the polar regions using a macro-scale constellation of spacecraft. THEMIS is composed of a space segment of 5 identical probes equipped with particle and field instruments and a ground segment of about 20 Ground-Based Observatories with all-sky cameras and magnetometers. During its nominal mission THEMIS has observed over 20 substorm events, measured radial profiles of high energy particles through the radiation belts year-round, and provided numerous multi-point measurements across the magnetopause and bow shock with upstream monitoring. THEMIS data as well as the methods developed to simultaneously detect magnetospheric processes or structures are ideal for the development of software tools to efficiently extract data. We will present the potential of the THEMIS data to catalog magnetospheric events, define search patterns for event detection as well standardized interfaces with models.

  9. Ground-water levels in observation wells in Oklahoma, 1969-70

    USGS Publications Warehouse

    Moore, R.L.

    1972-01-01

    The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. In addition to the water-supply papers, the U.S. Geological Survey, cooperation with the Oklahoma Water Resources Board, has published the following informal reports on water levels in Oklahoma. Ground-water levels in observations wells in Oklahoma, 1956-60 Ground-water levels in observations wells in Oklahoma, 1961-62 Ground-water levels in observations wells in Oklahoma, 1963-64 Ground-water levels in observations wells in Oklahoma, 1965-66 Ground-water levels in observations wells in Oklahoma, 1967-68 Records of water-level measurements in wells in the Oklahoma Panhandle, 1966-70 Records of water-level measurements in wells in the Oklahoma Panhandle, 1971-72 The basic observation-well network in Oklahoma during the period 1969-70 included the following counties: Alfalfa, Beaver, Beckham, Caddo, Cimarron

  10. 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.

  11. Observations of ion cyclotron waves near synchronous orbit and on the ground

    NASA Technical Reports Server (NTRS)

    Fraser, B. J.

    1985-01-01

    Ion cyclotron waves (ICWs) generated in the magnetosphere by the ion cyclotron instability of 10-100 keV protons are now known to be the origin of short-period (0.1-5 Hz) electromagnetic field oscillations observed by synchronous spacecraft and on the earth's surface. Observations of the various wave characteristics, including spectral and polarization properties, that lead to the identification of generation and propagation mechaniisms, and regions in the magnetosphere are described with reference to ATS-6, GEOS, and ground-based wave data and interpreted using cold plasma propagation theory. The presence of heavy ions (O/+/, He/+/) dramatically modifies ICW magnetospheric propagation characteristics giving rise to spectral slots and polarization reversals. These properties may be used in plasma diagnostics. Finally satellite-ground correlations and techniques for determining the magnetospheric source position of ICWs not seen at synchronous orbit but observed on the ground as structured Pc1 pulsations are considered.

  12. 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.

  13. Ground measurements and satellite observations of soil moisture over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Van der Velde, R.; Su, Z.; Wen, J.; Yang, K.; Ma, Y.

    2012-04-01

    The importance of the Tibetan Plateau for the atmospheric circulation and the development of large-scale weather systems over the Asian continent has been widely acknowledged. Due to its wide extent and high elevation, the Plateau plays a critical role in directing moist air from the eastern Indian Ocean and Bay of Bengal towards central China. Heat and moisture sources from the Plateau affect the flow of moist air from the ocean and seas creating a so-called "air pump" that influences the onset and maintenance of the Asian monsoon. In a changing climate, global warming will also change the partitioning of radiation into sensible and latent heat over the Plateau and, thus, the Tibetan air pump. A key land surface state controlling interactions between the land surface and atmosphere is soil moisture. Being highly variable in both space and time, it is not feasible to base large-scale soil moisture monitoring programmes on in-situ measurements alone. Hence, estimates derived from satellite observations can complement ground measuring networks by providing insight into spatial soil moisture distributions across large scales. In this study, we report on the development of large-scale ground measuring soil moisture/temperature networks across the Tibetan Plateau and their application in validating soil moisture retrieved from both active and passive microwave observations. An Advanced Synthetic Aperture Radar (ASAR) data set consisting of 150 scenes collected in the period from April 2005 to September 2007 is used as a demonstration of high resolution (100 m) soil moisture mapping over the central part of the Tibetan Plateau. Special Sensor Microwave/Imager (SSM/I) passive microwave observations from 1987 to 2008 are utilized to derive long-term soil moisture trends across the entire Tibetan Plateau. The soil moisture estimates from both ASAR and SSM/I are in agreement with our in-situ measurements. This study highlights the complementary information that can be

  14. 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.

  15. 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.

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. A simple volcano potential with an analytic, zero-energy, ground state

    NASA Astrophysics Data System (ADS)

    Nieto, M. M.

    2000-08-01

    We describe a simple volcano potential, which is supersymmetric and has an analytic, zero-energy, ground state. (The KK modes are also analytic.) It is an interior harmonic oscillator potential properly matched to an exterior angular momentum-like tail. Special cases are given to elucidate the physics, which may be intuitively useful in studies of higher-dimensional gravity.

  2. 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

  3. 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).

  4. Modeling Basin-scale Runoffs with Precipitation Data from Ground-based Observations and Mesoscale Simulations

    NASA Astrophysics Data System (ADS)

    Li, M.; Yang, M.; Soong, R.; Hwang, S.

    2002-12-01

    The purpose of this study is to investigate the applicability of distributed basin-scale runoff modeling, driven by rainfall data from either ground-based observations or mesoscale simulations, in response to typhoons invading Taiwan. Typhoons Herb (1996) and Zeb (1998) were selected for calibrating the runoff parameters reflecting the landuse conditions in the basin and evaluating the applicability of observed and simulated rainfall data toward runoff estimations, respectively. Upstream basins of Reservoir Shihmen with a drainage area of 764 km2 and Reservoir Feitsui with a drainage area of 303 km2 were the domains of interest in this preliminary study. Ground-based observations of both stream flows and station rainfalls were collected in an hourly resolution. The mesoscale model,MM5, simulation for Herb was conducted in 4-nested grids with the finest resolution of 2.2 km and 2-nested grids with the finest resolution of 15 km for Zeb, and the time resolution for both cases was 5 minutes. Accumulated total rain was accommodated with terrain elevation in MM5 simulations and station data to provide areal rainfall distributions. While the ground-based observations were sparse and incapable of correctly representing areal rainfall characteristics, the MM5 simulated data may introduce great uncertainties in basin-scale hydrological applications. The experience learned from this study is expected to provide an applicable approach with both ground-based observations and mesoscale simulations in basin-scale runoff computations.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    USGS Publications Warehouse

    Spudich, Paul; Fletcher, Jon 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.

  10. 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.

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

    USGS Publications Warehouse

    Croley, T.E., II; 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.

  12. The structure of a microburst - As observed by ground-based and airborne Doppler radar

    NASA Technical Reports Server (NTRS)

    Mueller, C. K.; Hildebrand, P. H.

    1983-01-01

    Attention is given to the microburst observed near Denver, CO, on June 29, 1982, in the course of the Joint Airport Weather Study (JAWS). The JAWS ground radar network was specifically established to furnish high spatial and temporal resolution multiple Doppler data for microburst observations. The data, which were collected from directly above the microburst, permitted direct measurements of vertical velocities to be made. P-3 surveillance aircraft Doppler data was also available for this microburst, whose considerable complexity is noted.

  13. PSC and volcanic aerosol observations during EASOE by UV-visible ground-based spectrometry

    SciTech Connect

    Sarkissian, A.; Pommereau, J.P.; Goutail, F. ); Kyro, E. )

    1994-06-22

    This paper presents results from ground-based spectrometry of twilight sky color in the UV and visible region, taken at four stations on the arctic circle. These stations observed the appearance of aerosol layers from the volcanic eruption of Mt. Pinatubo in mid 1991. The aerosol density increased steadily at lower stratospheric levels, and spread inside the polar vortex. These stations only observed one high altitude PSC during this winter campaign.

  14. Local - Air Project: Tropospheric Aerosol Monitoring by CALIPSO Lidar Satellite and Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Sarli, V.; Trippetta, S.; Bitonto, P.; Papagiannopoulos, N.; Caggiano, R.; Donvito, A.; Mona, L.

    2016-06-01

    A new method for the detection of the Planetary Boundary Layer (PBL) height from CALIPSO space-borne lidar data was developed and the possibility to infer the sub-micrometric aerosol particle (i.e., PM1) concentrations at ground level from CALIPSO observations was also explored. The comparison with ground-based lidar measurements from an EARLINET (European Aerosol Research LIdar Network) station showed the reliability of the developed method for the PBL. Moreover, empirical relationships between integrated backscatter values from CALIPSO and PM1 concentrations were found thanks to the combined use of the retrieved PBL heights, CALIPSO aerosol profiles and typing and PM1 insitu measurements.

  15. Longitudinal Characteristics of the Tropical Tropopause observed with ground based and space-borne observations

    NASA Astrophysics Data System (ADS)

    Mehta, Sanjay Kumar; Ratnam Madineni, Venkat; Krishna Murthy, B. V.

    In the present paper an attempt has been made to study the longitudinal characteristics of the tropical tropopause resolution observations obtained from Radiosonde COSMIC GPS radio occultation (RO) data collected for two year from August 2006-August 2008. The radiosonde stations (Gadanki, Truk, Rochambeau, Singapore, Seychelles, and Darwin) distributed across the globe within 13o from equator where data are available with good vertical resolution. In this study the behavior of the tropopause in west Pacific (convective region), non-Pacific and Indian monsoon region is emphasized. All stations including Gadanki shows strong annual cycle observed in temperature near tropical tropopause over Gadanki (13.45oE, 79.18oN) similar as observed in the equatorial belt (10oS-10oN). The tropopause over Gadanki is higher than the mean tropopause in the equatorial belt. The annual cycle in the upper tropospheric tempera-ture is in same phase as the lower stratospheric temperature, in contrast to Truk. Correlation between temperatures at 18 km with upper tropospheric temperature reveals that the strato-spheric feature is extending down to 125 hPa. The temperature lapse in upper troposphere is less pronounced at Gadanki than Truk. The tropopause height show dip at equator especially in the longitude of 0-120oE during summer season. The details of the study will be presented in the conference.

  16. 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.

  17. 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.

  18. Global ab initio ground-state potential energy surface of N4

    NASA Astrophysics Data System (ADS)

    Paukku, Yuliya; Yang, Ke R.; Varga, Zoltan; Truhlar, Donald G.

    2013-07-01

    We present a global ground-state potential energy surface for N4 suitable for treating high-energy vibrational-rotational energy transfer and collision-induced dissociation in N2-N2 collisions. To obtain the surface, complete active space second-order perturbation theory calculations were performed for the ground singlet state with an active space of 12 electrons in 12 orbitals and the maug-cc-pVTZ triple zeta basis set. About 17 000 ab initio data points have been calculated for the N4 system, distributed along nine series of N2 + N2 geometries and three series of N3 + N geometries. The six-dimensional ground-state potential energy surface is fitted using least-squares fits to the many-body component of the electronic energies based on permutationally invariant polynomials in bond order variables.

  19. Linear Ground-Motions in the Wabash Valley, Central United States: Two Decades of Unconventional Observations

    NASA Astrophysics Data System (ADS)

    Woolery, E. W.

    2012-12-01

    Since the mid-1980's small and moderate-sized earthquakes in the Ohio and Wabash River valleys of the central United States have been digitally recorded by seismographs, called blast monitors, deployed to monitor vibrations from chemical explosions associated with regional mining and quarrying. Because there were relatively few conventional networked strong-motion and broad-band instruments for this area between 1980 and the early 2000's, the more than 200 observations have provided a relatively widespread source of digital earthquake ground motions. Additional deployment of networked instrumentation during the last decade and their numerous recordings of the April 2008, Mt. Carmel, Illinois earthquake sequence have provided the first effective means for comparing free-field blast monitor and conventional network ground-motion observations. The peak ground-motion characteristics for both data sets relative to a common predictive relationship are similar, suggesting that blast monitor observations in the central U.S. compliment conventional network data for moderate-sized (< M5.5) events. Much of the ground motion prediction effort in the central United States has been focused on deep (>> 30 m) alluvial sites, such as those found in the Mississippi embayment. The free-field digital velocity records at blast-monitor sites in the Wabash Valley are more typical of the areas outside the embayment. The ground-motion database is composed of small to moderate size regional earthquakes with a magnitude range between M3 and M5.2; however, the bulk of the observations are associated with the 1987 M4.96 and 2008 M5.2 southeastern Illinois earthquakes, and the 2002 M4.5 southwestern Indiana earthquake. The velocity recordings and ancillary site investigations for the 2008 southeastern Illinois earthquake sequence put the findings into context with the previous observations, and quantify the reduction in ground-motion variability that can be achieved with conventional site

  20. 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.

  1. 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.

  2. 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.

  3. The Challenges of New Observing/Operating Modes at Ground Based Optical Observatories

    NASA Astrophysics Data System (ADS)

    Veillet, C.

    2012-09-01

    Over the past years, many ground-based optical observatories have moved away from the traditional “observing visitor mode” where the astronomer comes to the telescopes to carry the observations for which a given number of nights have been allocated. Remote observing, queued observations, service observing, remote or automated operations, these new observational modes are mainly implemented to minimize the operating costs, increase the efficiency of the observations, or better serve the users, leading ultimately to better data and hopefully better science. We will review these modes and the challenges of their implementation for the facilities as well as the users, stressing the need for the required appropriate software tools to keep the users satisfied while optimizing the use of the telescopes and their instrumentation.

  4. 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...

  5. Ground motion observations of the South Napa earthquake (M6.0 August 24, 2014)

    NASA Astrophysics Data System (ADS)

    Baltay, A.

    2014-12-01

    The South Napa earthquake generated peak ground motions in excess of 50%g and 50 cm/s in Napa Valley and also along strike to the south, and was recorded at 17 stations within 20 km rupture distance (Rrup) of the finite fault plane, 115 stations within 50 km, and 246 within 100 km. We compare the densely recorded ground motions to existing ground motion prediction equations (GMPEs) to understand both the spatial distribution of ground-motion amplitudes and also the relative excitation and attenuation terms from the earthquake. Using the ground-motion data as reported by ShakeMap, we examine the peak ground acceleration (PGA) and velocity, as well as the pseudo-spectral acceleration (PSA) at 0.3, 1.0 and 3.0 seconds, adjusted empirically to a single site condition of 760 m/s. Overall, the ground motions on the north-south components are larger than those on the east-west, consistent with both the generally north-south strike of the fault and the rupture directivity. At the higher frequencies (PGA and PSA of 0.3 s), the close data are very consistent with the GMPEs, implying a median stress drop near 5 MPa. For the longer period data, the GMPEs underpredict the data at close stations. At all frequencies, the distance attenuation seems to be stronger than the GMPEs would predict, which could either be a station coverage bias, given that most of the stations are to the south of the epicenter, or may indicate that the attenuation structure in the Napa and delta region is stronger than the average attenuation in California, on which the GMPEs were built. The spatial plot of the ground motion residuals is positive to the north, in both Napa and Sonoma Valley, consistent with both the directivity and basin effect. More interestingly, perhaps, is that there is strong ground motion to the south, as well, in the along-strike direction, particularly for PSA at 1.0s. These strongly positive residuals align along an older, Quaternary fault structure associated with the Franklin

  6. Submarine melting at the grounding line of Greenland's tidewater glaciers: Observations and Implications. (Invited)

    NASA Astrophysics Data System (ADS)

    Rignot, E. J.; Xu, Y.; Koppes, M. N.; Menemenlis, D.; Schodlok, M.; Spreen, G.

    2010-12-01

    . We observe a strong seasonality and large inter-annual variations in glacial fjords of interest. This enables a quantification of thermal forcing of the ocean on the calving faces of Greenland, its potential impact on submarine melting, which in turn effects glacier un-grounding, glacier velocity, glacier mass balance, and ultimately ice sheet mass balance as a whole.

  7. Estimation of Source and Attenuation Parameters from Ground Motion Observations for Induced Seismicity in Alberta

    NASA Astrophysics Data System (ADS)

    Novakovic, M.; Atkinson, G. M.

    2015-12-01

    We use a generalized inversion to solve for site response, regional source and attenuation parameters, in order to define a region-specific ground-motion prediction equation (GMPE) from ground motion observations in Alberta, following the method of Atkinson et al. (2015 BSSA). The database is compiled from over 200 small to moderate seismic events (M 1 to 4.2) recorded at ~50 regional stations (distances from 30 to 500 km), over the last few years; almost all of the events have been identified as being induced by oil and gas activity. We remove magnitude scaling and geometric spreading functions from observed ground motions and invert for stress parameter, regional attenuation and site amplification. Resolving these parameters allows for the derivation of a regionally-calibrated GMPE that can be used to accurately predict amplitudes across the region in real time, which is useful for ground-motion-based alerting systems and traffic light protocols. The derived GMPE has further applications for the evaluation of hazards from induced seismicity.

  8. Uncertainties in Instantaneous Rainfall Rate Estimates: Satellite vs. Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Amitai, E.; Huffman, G. J.; Goodrich, D. C.

    2012-12-01

    High-resolution precipitation intensities are significant in many fields. For example, hydrological applications such as flood forecasting, runoff accommodation, erosion prediction, and urban hydrological studies depend on an accurate representation of the rainfall that does not infiltrate the soil, which is controlled by the rain intensities. Changes in the rain rate pdf over long periods are important for climate studies. Are our estimates accurate enough to detect such changes? While most evaluation studies are focusing on the accuracy of rainfall accumulation estimates, evaluation of instantaneous rainfall intensity estimates is relatively rare. Can a speceborne radar help in assessing ground-based radar estimates of precipitation intensities or is it the other way around? In this presentation we will provide some insight on the relative accuracy of instantaneous precipitation intensity fields from satellite and ground-based observations. We will examine satellite products such as those from the TRMM Precipitation Radar and those from several passive microwave imagers and sounders by comparing them with advanced high-resolution ground-based products taken at overpass time (snapshot comparisons). The ground based instantaneous rain rate fields are based on in situ measurements (i.e., the USDA/ARS Walnut Gulch dense rain gauge network), remote sensing observations (i.e., the NOAA/NSSL NMQ/Q2 radar-only national mosaic), and multi-sensor products (i.e., high-resolution gauge adjusted radar national mosaics, which we have developed by applying a gauge correction on the Q2 products).

  9. 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)

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Nature of Pi1B pulsations as inferred from ground and satellite observations

    NASA Astrophysics Data System (ADS)

    Lessard, M. R.; Lund, E. J.; Jones, S. L.; Arnoldy, R. L.; Posch, J. L.; Engebretson, M. J.; Hayashi, K.

    2006-07-01

    The occurrence of Pi1B pulsations is well-documented, including the fact that these pulsations can be observed both on the ground and at geosynchronous orbit at substorm onset, although information about their propagation characteristics has been lacking. In this paper, data are presented from FAST, GOES 9 and various ground stations that show the simultaneous observations of Pi1B pulsations in association with an onset. While the data at GOES 9 show that the pulsations are compressional in nature, data from FAST show the presence of shear mode waves, implying that Pi1B mode conversion of some type must take place in the region between geosynchronous orbit and FAST altitudes. An additional point is that Pi1B pulsations apparently propagate through auroral phenomena routinely, begging the question of what role they may play.

  16. 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

  17. Comparison of tropospheric NO2 observations by GOME and ground stations over Tokyo, Japan

    NASA Astrophysics Data System (ADS)

    Noguchi, K.; Itoh, H.; Shibasaki, T.; Hayashida, S.; Uno, I.; Ohara, T.; Richter, A.; Burrows, J. P.

    2009-04-01

    Nitrogen oxides (NOx = NO + NO2) are anthropogenically emitted as a form of NO in the high-temperature burning processes of fossil fuels mainly in energy generations and vehicles. Because NOx is a precursor of ozone, which is composed of a so-called photochemical smog, and is a health-hazard matter, the monitoring of NO2 is important to control air quality. The satellite observation is one of the most suitable methods for the monitoring of air pollution because satellite observations can obtain a global distribution of the pollutants. However, the observation of tropospheric gases by satellites still includes technically challenging problems, and the field is developing. To test whether satellite observations could successfully detect the behavior of tropospheric NO2, we compared satellite and ground-based observations of tropospheric NO2 over the Tokyo region. The satellite data were tropospheric NO2 vertical column density (VCD) derived from Global Ozone Monitoring Experiment (GOME) spectrometer measurements (hereafter GOME-NO2) [Richter et al., 2005], and the ground-based data were surface NO2 volume mixing ratio (VMR) observed by the network of air-quality monitoring stations in Tokyo. The analysis was performed for the data from January 1996 to June 2003. We found a strong correlation between GOME-NO2 and the surface VMR. They showed a similar seasonal variation with a maximum in winter and a minimum in summer. The result suggested that GOME was observing the behavior of NO2 near the surface in the Tokyo region. A more rigorous comparison was conducted by scaling the surface NO2 VMR to the tropospheric VCD with vertical NO2 VMR profiles. The NO2 profiles were calculated by using the chemical transport model CMAQ/REAS [Uno et al., 2007; Ohara et al., 2007]. This second comparison indicated that the GOME observations represent the behavior of NO2 more closely at the relatively unpolluted ground stations than at the highly polluted ground stations of the air

  18. 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.

  19. 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

  20. Observing Large Ionospheric Spatial Decorrelation for Ground-Based Augmentation System in the Brazilian Region

    NASA Astrophysics Data System (ADS)

    Kim, D.; Yoon, M.; Choi, P.; Lee, J.

    2014-12-01

    Ground-Based Augmentation Systems (GBAS) support aircraft precision approach and landing by broadcasting differential Global Positioning System (GPS) corrections and integrity information to aviation users. Under anomalous ionospheric condition, unacceptably large residual errors can occur due to anomalously large ionospheric spatial decorrelation, and this can pose integrity threats to GBAS users. Thus, the development of an ionospheric anomaly threat model is required to simulate worst-case ionospheric errors and develop mitigation strategies. Ionosphere in low latitudes is known to be much more intense than that in mid latitudes due to active geomagnetic effect, and investigation of low latitude ionospheric anomalies must take precedence before operation of GBAS. In this paper, ionospheric spatial decorrelation is investigated for GBAS operation in the Brazilian region. Dual-frequency observation data are collected from Brazilian GPS reference stations. This analysis is performed using data sets collected on scintillating days, less-scintillating days, and storm days from 2012 to 2014. Precise ionospheric spatial gradient on the L1 signal is automatically estimated from dual-frequency observation data using simple truth method and station pair method. In the Brazilian region, however, intense ionospheric scintillations cause a large numbers of cycle slips in carrier-phase data. The simple truth process removes a considerably large number of those data through short-arc and outlier removals, and thus potential ionospheric gradients may not be detected. This motivates a data recovery process which skips short-arc and outlier removals if there appears a large ionospheric spatial gradient in the removed data. We also use a series of methods to validate anomalous ionospheric spatial gradients using manual validation with L1 single frequency measurement, station-wide check, satellite-wide check, and time-step check. In particular, the time-step check validates

  1. Cross Calibration of TOMS, SBUV/2 and Sciamachy Radiances from Ground Observations

    NASA Technical Reports Server (NTRS)

    Hillsenrath, Ernest; Ahmad, Ziauddin; Bhartia, Pawan K. (Technical Monitor)

    2001-01-01

    Verification of a stratospheric ozone recovery remains a high priority for environmental research and policy definition. 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 recovery. We have shown that validation of radiances is the most effective means for correcting absolute accuracy and long term drifts of backscatter type satellite measurements. This method by-passes the algorithms used for both satellite and ground based measurements which are normally used to validate and correct the satellite data. Validation of radiances will also improve all higher level data products derived from the satellite observations. Backscatter algorithms suffer from several errors such as unrepresentative a-priori data and air mass factor corrections. Radiance comparisons employ forward models but are inherently more accurate and than inverse (retrieval) algorithms. A new method for satellite validation is planned which will compliment measurements from the existing ground-based networks. This method will employ very accurate comparisons between ground based zenith sky radiances and satellite nadir radiances. These comparisons will rely heavily on the experience derived from the Shuttle SBUV (SSBUV) program which provided a reference standard of radiance measurements for SBUV/2, TOMS, and GOME. This new measurement program, called "Skyrad", employs two well established capabilities at the Goddard Space Flight Center, 1) the SSBUV calibration facilities and 2) the radiative transfer codes used for the TOMS and SBUV/2 algorithms and their subsequent refinements. Radiative transfer calculations show that ground based zenith sky and satellite nadir backscatter ultraviolet comparisons can be made very accurately under certain viewing conditions. The Skyrad instruments (SSBUV, Brewer spectrophotometers, and

  2. Hyperspectral Observations of Land Surfaces Using Ground-based, Airborne, and Satellite Sensors

    NASA Astrophysics Data System (ADS)

    Knuteson, R. O.; Best, F. A.; Revercomb, H. E.; Tobin, D. C.

    2006-12-01

    The University of Wisconsin-Madison Space Science and Engineering Center (UW-SSEC) has helped pioneer the use of high spectral resolution infrared spectrometers for application to atmospheric and surface remote sensing. This paper is focused on observations of land surface infrared emission from high spectral resolution measurements collected over the past 15 years using airborne, ground-based, and satellite platforms. The earliest data was collected by the High-resolution Interferometer Sounder (HIS), an instrument designed in the 1980s for operation on the NASA ER-2 high altitude aircraft. The HIS was replaced in the late 1990s by the Scanning-HIS instrument which has flown on the NASA ER-2, WB-57, DC-8, and Scaled Composites Proteus aircraft and continues to support field campaigns, such as those for EOS Terra, Aqua, and Aura validation. Since 1995 the UW-SSEC has fielded a ground-based Atmospheric Emitted Radiance Interferometer (AERI) in a research vehicle (the AERIBAGO) which has allowed for direct field measurements of land surface emission from a height of about 16 ft above the ground. Several ground-based and aircraft campaigns were conducted to survey the region surrounding the ARM Southern Great Plains site in north central Oklahoma. The ground- based AERIBAGO has also participated in surface emissivity campaigns in the Western U.S.. Since 2002, the NASA Atmospheric InfraRed Sounder (AIRS) has provided similar measurements from the Aqua platform in an afternoon sun-synchronous polar orbit. Ground-based and airborne observations are being used to validate the land surface products derived from the AIRS observations. These cal/val activities are in preparation for similar measurements anticipated from the operational Cross-track InfraRed Sounder (CrIS) on the NPOESS Preparatory Platform (NPP), expected to be launched in 2008. Moreover, high spectral infrared observations will soon be made by the Infrared Atmospheric Sounder Interferometer (IASI) on the

  3. 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

  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. 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.

  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. Precipitation observations from high frequency spaceborne polarimetric synthetic aperture radar and ground-based radar: Theory and model validation

    NASA Astrophysics Data System (ADS)

    Fritz, Jason P.

    Global weather monitoring is a very useful tool to better understand the Earth's hydrological cycle and provide critical information for emergency and warning systems in severe cases. Developed countries have installed numerous ground-based radars for this purpose, but they obviously are not global in extent. To address this issue, the Tropical Rainfall Measurement Mission (TRMM) was launched in 1997 and has been quite successful. The follow-on Global Precipitation Measurement (GPM) mission will replace TRMM once it is launched. However, a single precipitation radar satellite is still limited, so it would be beneficial if additional existing satellite platforms can be used for meteorological purposes. Within the past few years, several X-band Synthetic Aperture Radar (SAR) satellites have been launched and more are planned. While the primary SAR application is surface monitoring, and they are heralded as "all weather'' systems, strong precipitation induces propagation and backscatter effects in the data. Thus, there exists a potential for weather monitoring using this technology. The process of extracting meteorological parameters from radar measurements is essentially an inversion problem that has been extensively studied for radars designed to estimate these parameters. Before attempting to solve the inverse problem for SAR data, however, the forward problem must be addressed to gain knowledge on exactly how precipitation impacts SAR imagery. This is accomplished by simulating storms in SAR data starting from real measurements of a storm by ground-based polarimetric radar. In addition, real storm observations by current SAR platforms are also quantitatively analyzed by comparison to theoretical results using simultaneous acquisitions by ground radars even in single polarization. For storm simulation, a novel approach is presented here using neural networks to accommodate the oscillations present when the particle scattering requires the Mie solution, i

  8. 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.

  9. 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.

  10. Ground and satellite EMIC wave observations in conjunction with BARREL electron precipitation

    NASA Astrophysics Data System (ADS)

    Weaver, C.; Lessard, M.; Engebretson, M. J.; Millan, R. M.; Halford, A.; Horne, R. B.; Singer, H. J.; Green, J. C.

    2013-12-01

    Ground-based and satellite observations of electromagnetic ion-cyclotron (EMIC) waves are presented in conjunction with electron precipitation detected by high altitude balloons from the Balloon Array for RBSP Relativistic Electron Losses (BARREL) campaign. On 17 Jan 2013, a high density solar wind compressed the magnetosphere and four satellites (GOES 13 & 15, Van Allen Probes A & B) as well as several ground stations (Dawson City, Canada and Halley, Antarctica) detected simultaneous EMIC waves across the night sector for about 2.5 hours during the compression (0130 - 0400 UT). The satellites and ground stations cover approximately 10 hours of magnetic local time and four L-shells, suggesting the generation region(s) covers the same extended area. At the strongest point of the compression (around 0300 UT with proton density 50 n/cc, flow pressure 20 nPa, SYM/H 50 nT) BARREL balloon 1G, which magnetically mapped close to GOES 13, detected relativistic electron precipitation concurrently with enhanced EMIC wave activity on GOES 13, which may show a direct observation of EMIC waves scattering relativistic electrons.

  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. 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

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

    PubMed Central

    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.

    2012-01-01

    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. PMID:22492817

  15. 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.

  16. 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.

  17. 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.

  18. Multidisciplinary Approach for Earthquake Atmospheric Precursors Validation by Joint Satellite and Ground Based Observations

    NASA Astrophysics Data System (ADS)

    Ouzounov, D. P.; Pulinets, S. A.; Hattori, K.; Liu, J. G.; Parrot, M.; Kafatos, M.; Yang, T. F.; Jhuang, H.; Taylor, P.; Ohyama, K.; Kon, S.

    2010-12-01

    Previous studies have shown that there were electromagnetic (EM) effects in the atmosphere/ionosphere caused by some strong earthquakes. Several major earthquakes are accompanied by an intensification of the vertical transport of charged aerosols in the lower atmosphere. These processes lead to the generation of external electric currents in specific regions of the atmosphere and the modifications, by DC electric fields, in the ionosphere-atmosphere electric circuit. Our methodology of integrated satellite terrestrial framework (ISTF) is based on the use of multi-sensor data and a cross-correlation between ground and satellite observations to record any atmospheric thermal anomalies and ionospheric perturbations associated with these activities. We record thermal infrared data from the Aqua, GOES, POES satellites and DEMETER provides space plasma variations related to the growth of the DC electric field. Simultaneously we continuously monitor ground-based multi-parameter GPS/TEC, ion concentration, radon, and magnetic field array data. We integrate these joint observations into the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model. The significance of this combined satellite and ground-based analysis is that it permits us to generate hindcasts of historical seismicity in Japan, Taiwan (2003-2009) and recent catastrophic events in Italy (M6.3, 2009), Haiti (M7.0, 2010) and Chile (M8.8, 2010). This joint analysis of ground and satellite data during the time of major earthquakes has shown the presence of persistent anomalies in the atmosphere over regions of maximum stress (along plate boundaries), and are not of meteorological origin, since they are stationary over the same region. Our approach provides the framework for a multidisciplinary validation of earthquake precursors and we are looking forward to validating this approach over high seismicity regions.

  19. Near-Earth asteroids orbits using Gaia and ground-based observations

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Since the last decade, the number of Near-Earth Asteroids (hereafter NEA) discovery has exponentially increased. They are due to program surveys like LINEAR, Catalina and more recently to Pan-STARRS. The next generation surveys like LSST will contribute to these discoveries and to a lesser extent Gaia. Presently, almost 9500 NEAs are known and only 10% of them have a diameter greater than one kilometer. Among the others, some of them are under surveillance because they might come close or even possibly impact the Earth. Those asteroids, qualified as Potentially Hazardous Asteroids (hereafter PHA), are objets with absolute magnitude H <22.0 and with their Minimum Orbit Intersection Distance (MOID) with the Earth less that 0.05 AU. They are carefully monitored by two automatic systems at NASA/JPL and University of Pisa/NEODyS (monitoring program duplicated in University of Valladolid). With the constant observations (optical and radar) from professional or amateur observers, the particular orbit of PHAs are regularly refined to better assess and quantify the impact threat. Most of the PHAs do not have significant impact probability with the Earth. Some of them can temporarily reach level 1 of Torino Scale. Only one asteroid briefly reached an unprecedented level of risk on this scale: (99942) Apophis (previously designated 2004 MN4). Apophis was discovered in December 2004 and since the first observations, a collision event was predicted in 2029 with an unusual impact probability. Further observations increased this probability up to 2.3 % - the event was then classified level 4 on Torino Scale - but fortunately, thanks to precovery discovery by Spacewatch, the 2029-threat is no longer and is just a deep close encounter (~ 38000 km) with the Earth. Even if some impacts are possible in 2036 and later - but with lower chance - because of the chaotic 2029 post-encounter orbit, this asteroid will remain a study case because of its particular dynamical motion. We propose

  20. The potential for supershear earthquakes in damaged fault zones - theory and observations

    NASA Astrophysics Data System (ADS)

    Huang, Yihe; Ampuero, Jean-Paul; Helmberger, Don V.

    2016-01-01

    The potential for strong ground shaking in large earthquakes partly depends on how fast the earthquake rupture propagates. It is observed that strike-slip earthquakes usually propagate at speeds slower than the Rayleigh wave speed (vR) but occasionally jump to speeds faster than the S wave speed (vs), or supershear speeds. Supershear earthquakes can be more catastrophic and cause unusually large ground motions at long distances. Here we use both fully dynamic rupture simulations and high-resolution seismic observations to show that supershear earthquakes can be induced by damaged fault zones, the low-velocity layers of damaged rocks that typically exist around major faults and serve as waveguides for high-frequency energy. In contrast to supershear ruptures in homogeneous media, supershear ruptures in damaged fault zones can occur under relatively low fault stress and propagate stably at speeds within the range usually considered as unstable.

  1. Space-borne and ground-based observations of transient processes occurring around substorm onset

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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 (Nishimura et al., [2010]) and 630 nm (Kepko et al., [2010]) 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.

  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 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

  4. Ground and Satellite Observations of ULF Waves Artificially Produced by HAARP

    NASA Astrophysics Data System (ADS)

    Chang, C.; Labenski, J.; Shroff, H.; Doxas, I.; Papadopoulos, D.; Milikh, G.; Parrot, M.

    2008-12-01

    Modulated ionospheric heating at ULF frequencies using the HAARP heater was performed from April 28 to May 3, 2008 (http://www.haarp.alaska.edu). Simultaneous ground-based ULF measurements were made locally at Gakona, AK and at Lake Ozette, WA that is 2000 km away. The ground-based results showed that ULF amplitudes measured at Gakona are mostly proportional to the electrojet strength above HAARP, indicating electrojet modulation to be the source of the local ULF waves. However, the timing of ULF events recorded at Lake Ozette did not correlated with the electrojet strength at Gakona, indicating that modulation of F region pressure is the more likely source for distant ULF waves. These observations are consistent with the theoretical understanding that ULF waves generated by current modulation are shear Alfven waves propagating along the magnetic field line, thus at high latitude their observations are limited to the vicinity of the heated spot. On the other hand, propagation of ULF waves at significant lateral distances requires generation of magnetosonic waves since they are the only mode that propagates isotropically and can thus couple efficiently in the Alfvenic duct. In addition to ground-based observations, the DEMETER satellite also provided space measurements of the heating effects during its passes over HAARP. The DEMETER results showed direct detection of HAARP ULF waves at 0.1 Hz. Moreover, density dips were observed every time HAARP was operated at CW mode, which provides clear evidence of duct formation by direct HF heating at F peak. Details of these results will be presented at the meeting. We would like to acknowledge the support provided by the HAARP facility during our ULF experiments.

  5. 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.

  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. Determination of the ground-state potential energy curve of 6LiH up to dissociation

    NASA Astrophysics Data System (ADS)

    Verma, K. K.; Stwalley, W. C.

    1982-09-01

    An ultraviolet argon ion laser (3336 Å) has been used to excite the A 1Σ+-X1Σ+ system of the 6LiH molecule. A long progression of R-P doublets is observed in the range 0⩽v''⩽21. This is the first time ground-state levels above v''=12 have been observed for the lithium hydride molecule. Based upon these results, we have constructed a Rydberg-Klein-Rees (RKR) potential energy curve which corresponds to over 99% of the ground state potential well. This experimental curve is compared with theoretical ab initio calculations for the X 1Σ+ state of LiH. We find that Docken and Hinze's X state potential energy curve [J. Chem. Phys. 57, 4928 (1972)] is probably the most accurate among the published ab initio calculations in the region of curve crossing of the zero order curves representing the ionic and covalent configurations of LiH, although some more recent calculations are of comparable accuracy.

  8. 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

  9. Synergy of satellite and ground based observations in estimation of particulate matter in eastern China.

    PubMed

    Wu, Yerong; Guo, Jianping; Zhang, Xiaoye; Tian, Xin; Zhang, Jiahua; Wang, Yaqiang; Duan, Jing; Li, Xiaowen

    2012-09-01

    Estimating particulate matter (PM) from space is not straightforward and is mainly achieved using the aerosol optical depth (AOD) retrieved from satellite sensors. However, AOD is a columnar measure, whereas PM is a ground observation. Linking AOD and PM remains a challenge for air pollution monitoring. In this study, a back-propagation artificial neural network (BP ANN) algorithm trained with bayesian regularization that benefited from the synergy of satellite- and ground-based observations was developed to estimate PM in eastern China. Correlations between observed and estimated PM (denoted by R) during the period 2007-2008 over seven individual sites were investigated comprehensively in terms of site scale, seasonal scale, particle size, and spatio-temporal scale. With respect to site differences, the Nanning site had the best results with 80.3% of cases having a moderate or strong correlation value. Lushan and Zhengzhou followed with results of 75% and 73.8%, respectively. Furthermore, R exhibited a significant seasonal variation characterized by a maximum (80.2%) during the autumn period, whereas no obvious differences in R for various spatial scales (spatial averaging schemes of MODIS AOD) were observed. Likewise, the ratio value for daily averaging (64.7%) was found to be better than those for the two hourly temporal averaging schemes (i.e., 61.1% for HA1 and 58.3% for HA2). In addition, PM(1) estimated from the ANN algorithm developed in this study had slightly higher R values than did PM(10) and PM(2.5). The planetary boundary layer (PBL) effect on PM estimation was decreasing R with increasing height of the PBL, which is consistent with previous studies. Comparisons of observed versus estimated PM(10) mass time series implied that the ANN algorithm basically reproduced the observed PM concentration. However, PM mass at certain sites may be underestimated under the condition of high observed PM concentrations. PMID:22766424

  10. 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

  11. 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

  12. A Ground-Based Array to Observe Geospace Electrodynamics During Adverse Space Weather Conditions

    NASA Astrophysics Data System (ADS)

    Sojka, J. J.; Eccles, J. V.; Rice, D.

    2004-05-01

    Geomagnetic Storms occur with surprising frequency and create adverse space weather conditions. During these periods, our knowledge and ability to specify or forecast in adequate detail for user needs is negligible. Neither experimental observations nor theoretical developments have made a significant new impact on the problem for over two decades. Although we can now map Total Electron Content (TEC) in the ionosphere over a continent with sufficient resolution to see coherent long-lived structures, these do not provide constraints on the geospace electrodynamics that is at the heart of our lack of understanding. We present arguments for the need of a continental deployment of ground-based sensors to stepwise advance our understanding of the geospace electrodynamics when it is most adverse from a space weather perspective and also most frustrating from an understanding of Magnetosphere-Ionosphere coupling. That a continental-scale deployment is more productive at addressing the problem than a realizable global distribution is shown. Each measurement is discussed from the point-of-view of either providing new knowledge or becoming a key for future real-time specification and forecasting for user applications. An example of a storm database from one mid-latitude station for the 31 March 2002 is used as a conceptual point in a ground-based array. The presentation focuses on scientific questions that have eluded a quantitative solution for over three decades and view a ground-based array as an "IGY" type of catalyst for answering these questions.

  13. 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.

  14. The European Observation Network: Ground-Based Support for Gamma-Ray Satellites

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Spurný, P.; Florián, J.; Boček, J.; Tichy, M.; Tichá, J.; Vyskocil, L.; Wenzel, W.; Barthelmy, S.; Cline, T.; Gehrels, N.; Fishman, G.; Meegan, C.; Kouveliotou, C.; Mutafov, A.; Hovorka, F.

    While there is extended monitoring of the sky at gamma rays from satellites, mainly provided by the COMPTON Gamma Ray Observatory, there is still a lack of high-quality optical simultaneous and quasi-simultaneous data. On the other hand, the still puzzling nature of Gamma Ray Bursts requires a complex and multispectral approach. The situation changed significantly after the introduction of the BACODINE system which is able to notify ground-based observers immediately after the detection of bursts on the GRO satellite. We present and discuss preliminary results obtained with the European Observation Network providing such follow - up optical observations. This network consists of nine observatories in the Czech Republic, Germany and Bulgaria and has been involved into the BACODINE activities since April 1, 1994.

  15. 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.

  16. Total ozone variations 1970-74 using Backscattered Ultraviolet /BUV/ and ground-based observations

    NASA Technical Reports Server (NTRS)

    Miller, A. J.; Nagatani, R. M.; Rogers, T. G.; Fleig, A. J.; Heath, D. F.

    1982-01-01

    The most long-lived satellite set of ozone observations, to date, is that derived from the Backscatter Ultraviolet (BUV) ozone sensor on Nimbus 4 and extends from April 1970 through 1976. Unfortunately, this experiment suffered spacecraft power limitations which limited the spatial and temporal coverage and also appears to have suffered from long-term drifts which may be associated with changes in the instrument characteristics or the incident solar flux. Techniques have been developed to account for these problems, and this paper presents results of the BUV total ozone variations and compares them with those from ground-based observations, specifically the computations of Angell and Korshover (1978). After adjustments for the spatial gaps and comparison with concurrent Dobson ground-based observations, no significant trend was found in the BUV data over the years 1970-74. This finding is in contrast to a general decrease of about 2% during the same period appearing in the data of Angell and Korshover. The difference in these results is discussed in terms of the geographic sampling and the methods of hemispheric integration.

  17. Observations from Ground Zero at the World Trade Center in New York City, Part I.

    PubMed

    Levenson, R L; Acosta, J K

    2001-01-01

    The authors are mental health clinicians with the Police Organization Providing Peer Assistance (POPPA), an affiliate organization of the Patrolman's Benevolent Association of the New York Police Department (NYPD). Beginning on September 11, 2001 we were at Ground Zero of the World Trade Center (WTC) to assist in the all phases of crisis intervention and Critical Incident Stress Management (CISM), as indicated. Our observations and anecdoctal reports, as we worked on teams with NYPD Peer Support Officers (PSOs), are the subject of this paper. PMID:12025483

  18. Ground-water levels in observation wells in Oklahoma, 1971-74

    USGS Publications Warehouse

    Goemaat, Robert L.

    1976-01-01

    The objectives of the observation-well program are (1) to provide long-term records of water-level fluctuations in representative wells, (2) to facilitate the prediction of water-level trends and indicate the future availability of ground-water supplies, and (3) to provide information for use in basic research. These selected records serve as a framework to which other types of hydrologic data may be related. The stratigraphic nomenclature and age determinations used in this report are those accepted by the Oklahoma Geological Survey and do not necessarily agree with those of the U.S. Geological Survey.

  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. 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.

  2. Common ground on surgical abortion?--engaging Peter Singer on the moral status of potential persons.

    PubMed

    Camosy, Charles C

    2008-12-01

    The debate over surgical abortion is certainly one of the most divisive in ethical discourse and for many it seems interminable. However, this paper argues that a primary reason for this is confusion with regard to what issues are actually under dispute. When looking at an entrenched and articulate figure on one side of the debate, Peter Singer, and comparing his views with those of his opponents, one finds that the disputed issue is actually quite a narrow one: the moral status of potential persons. Finding this common ground clears the conceptual space for a fruitful argument: the thesis of which is that most, including Singer, who argue that potential persons do not have full personal moral status fail to make the necessary distinction between natural potential (which confers moral status) and practical potential (which admittedly does not). PMID:19098134

  3. 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

  4. High-lattitude ground observations of PC 1/2 micropulsations

    SciTech Connect

    Popecki, M.; Arnoldy, R.; Engebretson, M.J.

    1993-12-01

    A ground-based survey of Pc 1/2 (0.1-0.4 Hz) and Pc 1 micropulsations throughout 1986 has provided evidence for the location of the Pc 1/2 source region. Data were taken from three high-latitude stations, located at South Pole ({minus}75{degrees} geomagnetic latitude; 1530 UT local noon), Sondre Stromfjord (+74{degrees}, 1330 UT LN) and Siple ({minus}61{degrees}, 1700 UT LN). The study revealed a diurnal occurrence patterns of the waves above and below 0.4 Hz, it is concluded that the waves observed on the ground above 0.4 Hz come primarily from plasmapause latitudes, while the source of the Pc 1/2 lies between the plasmapause and the magnetopause. The estimate of source locations for waves above and below this frequency, combined with the typically sharp upper frequency limit of waves in the 0.1-0.4 Hz band (Pc 1/2) are interpreted as evidence that He{sup +} ions in the outer magnetosphere influence propagation and possibly wave growth. These results are compared with those of Anderson, who showed with a spacecraft study that Pc 1 are more commonly observed beyond L=7 than in regions closer to the Earth. It is concluded that many of the waves above the He{sup +} gyrofrequency from the outer magnetosphere do not always reach the ground. An extensive search for correlations between Pc 1/2 occurrence and solar wind pressure and magnetic field orientation showed no direct connection between solar wind parameters and Pc 1/2 generation. They may instead be amplified by plasma sheet ions that drift sunward on the dusk side of the magnetosphere and undergo ion-cyclotron resonance in the afternoon sector. This mechanism is consistent with the diurnal pattern and apparent source location of the Pc 1/2. 39 refs., 12 figs., 1 tab.

  5. 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

  6. 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.

  7. 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.

  8. Measured surface temperatures of the Hayabusa capsule during re-entry determined from ground observation

    NASA Astrophysics Data System (ADS)

    Löhle, Stefan; Mezger, Andreas; Fulge, Hannes

    2013-03-01

    The Hayabusa sample return capsule, which contained asteroid samples, re-entered the Earth's atmosphere on June 13, 2010. An ablative carbon-phenolic thermal protection system (TPS) was used to enable a safe return for the small capsule and the containing samples. Besides a research aircraft operated by NASA with a wide range of imaging and spectrographic cameras for remote sensing of the radiation of the Hayabusa capsule during its entry flight, observation from ground based stations has been realized. We participated in the ground based observation campaign with two instruments for spectroscopic and photometric measurements aiming to detect the surface temperature and the plasma radiation in front of the re-entering capsule. The system consists in an infrared camera and a wide range miniature fibre spectrometer. The paper presents the setup, the laboratory calibration procedure, and correction for transmission. The surface temperature of the capsule reached a peak of 3250 K when the capsule was at an altitude of 55.95 km. The thermographic camera measures independently slightly higher temperature at peak heating (3308 K).

  9. 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.

  10. 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.

  11. 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.

  12. Sounding rocket/ground-based observation campaign to study Medium-Scale Traveling Ionospheric Disturbances (MSTID)

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mamoru; Otsuka, Yuichi; Abe, Takumi; Yokoyama, Tatsuhiro; Bernhardt, Paul; Watanabe, Shigeto; Yamamoto, Masa-yuki; Larsen, Miguel; Saito, Akinori; Pfaff, Robert; Ishisaka, Keigo

    2012-07-01

    An observation campaign is under preparation. It is to launch sounding rockets S-520-27 and S-310-42 from Uchinoura Space Center of JAXA, while ground-based instruments measure waves in the ionosphere. The main purpose of the study is to reveal seeding mechanism of Medium-Scale Traveling Ionospheric Disturbances (MSTID). The MSTID is enhanced in the summer nighttime of the mid-latitude ionosphere. The MSTID is not only a simple reflection of atmospheric waves to the ionosphere, but includes complicated processes including the electromagnetic coupling of the F- and E-regions, and inter-hemisphere coupling of the ionosphere. We will measure ionospheric parameters such as electron density and electric fields together with neutral winds in the E- and F-regions. TMA and Lithium release experiment will be conducted with S-310-42 and S-520-27 rockets, respectively. The observation campaign is planned in summer 2012 or 2013. In the presentation we will overview characteristics of MSTID, and show plan and current status of the project. We also touch results from the sounding rocket S-520-26 that was launched on January 12, 2012. We will show results of the rocket-ground dual-band beacon experiment.

  13. 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.

    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.

  14. 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. PMID:21935896

  15. Simultaneous ground-satellite observations of Pi 2 magnetic pulsations and their high frequency enhancement

    NASA Technical Reports Server (NTRS)

    Arthur, C. W.; Mcpherron, R. L.

    1980-01-01

    Pi 2 magnetic pulsations are a frequent occurrence at the earth's surface and have been shown to be clearly correlated with substorm expansion onset. These pulsations are also observed in space at synchronous orbit at the same time as they are seen on the ground at the satellite conjugate point. This brief report describes three days in 1969 on which Pi 2 magnetic pulsations were simultaneously observed at the synchronous satellite ATS 1 and at Tungsten, N.W.T., Canada, near the foot of the ATS 1 magnetic field line. These Pi 2 bursts all exhibit the characteristic waveform and frequency, as well as an 0.3 Hz enhancement, at both locations. This high frequency enhancement appears to be an integral part of Pi 2 bursts both on the surface and at synchronous orbit and should be considered in the development of models of generation mechanisms.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  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. PMID:22016249

  1. 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.

  2. Diurnal variation of stratospheric and mesospheric ozone observed by ground-based microwave radiometry

    NASA Astrophysics Data System (ADS)

    Hocke, Klemens; Studer, Simone; Kämpfer, Niklaus; Schanz, Ansgar

    2013-04-01

    Knowledge on diurnal ozone variations in the middle atmosphere is of general interest for the estimation of atmospheric tides propagating throughout the whole atmosphere. Another aspect is the important area of ozone trend analysis. Does the ozone layer recover in the next decades? Expected trends are of the order of 1 percent per decade. If the diurnal ozone variation is not considered, avoided, or removed in the observational data sets then an ozone trend detection will be not possible since the amplitude of the diurnal variation of stratospheric ozone is of the same order as the decadal ozone trend. Ground-based microwave radiometry measures the diurnal ozone variation at a certain geographic location at altitudes from 25 to 65 km. Here we discuss the challenges for the measurement technique and the retrieval method. Finally we present characteristics of the diurnal ozone variation above Switzerland, continuously observed since 1994.

  3. Ground-water levels in observation wells in Oklahoma, 1963-64

    USGS Publications Warehouse

    Wood, P.R.

    1965-01-01

    The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. This report has been prepared primarily to present water-level records of wells not included in the Federal network. However, for the sake of completeness it includes water-level records of Federal wells that either have been or will be published in water-supply papers since 1955. This report, which contains water-level records for the 2-year period (1963-64), is the third of a series presenting water-level records for all permanent observations wells in Oklahoma. The first report, published in 1963, contains water-level records for the 5-year period of (1956-60). The second report, published in 1964, contains water-level records for the 2-year period (1961-62.) (available as photostat copy only)

  4. Ground-water levels in observation wells in Oklahoma, 1961-62

    USGS Publications Warehouse

    Wood, P.R.; Moeller, M.D.

    1964-01-01

    The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; and (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. This report has been prepared primarily to present water-level records of wells not included in the Federal network. However, for the sake of completeness it includes water-level records of Federal wells that either have been or will be published in water-supply papers since 1955. This report, which contains water-level records for the 2-year period (1960-62), is the second of a series presenting water-level records for all permanent observations wells in Oklahoma. The first report, published in 1963, contains water-level records for the 5-year period of (1956-60). (available as photostat copy only)

  5. 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.

  6. Simulation of ground-water flow and potential land subsidence, upper Santa Cruz Basin, Arizona

    USGS Publications Warehouse

    Hanson, R.T.; Benedict, J.F.

    1994-01-01

    A numerical ground-water flow model of the upper Santa Cruz basin in Pinal, Pima, and Santa Cruz Counties was developed to evaluate predevelopment conditions in 1940, ground-water withdrawals for 1940-86, and potential water-level declines and land subsidence for 1987-2024. Simulations of steady-state ground-water conditions indicate 12,900 acre-feet of ground-water inflow, 15,260 acre-feet of outflow, 53,000 acre-feet of pre- development pumpage, 29,840 acre-feet of mountain- front recharge, and 34,020 acre-feet of streamflow infiltration in 1940. Simulations of transient ground-water conditions indicate a total of 6.6 million acre-feet of net pumpage and 3.4 million acre-feet of water removed from aquifer storage for 1941-86. A difference of 1.2 million acre-feet between estimated and net pumpage is attributed to increased recharge from irrigation return flow, mine return flow, and infiltration of sewage effluent. Estimated natural recharge represents 40 percent of pumpage for 1966-86 and averaged 63,860 acre-feet per year for 1940-57 and 76,250 acre-feet per year for 1958-86. The increase in recharge after 1958 was coincident with above- average winter streamflow in the Santa Cruz River for 1959-86. Increased recharge after 1958 and decreased pumpage after 1975 contributed to decreased water-level declines or to recoveries after 1977 in wells near the Santa Cruz River and its tributaries. The results of projection simu- lations indicate that a maximum potential subsi- dence for 1987-2024 ranges from 1.2 feet for an inelastic specific storage of .0001 ft to 12 feet for an inelastic specific storage of .0015 ft. The simulations were made on the basis of pumpage and recharge rates from 1986 and by using a preconso- lidation-stress threshold of 100 feet. A permanent reduction in acquitard storage can range from 1 to 12 percent of the potential loss of 3.9 million acre-feet in aquifer-system storage for 1987-2024.

  7. 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

  8. 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

  9. 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.

  10. Evaluating Potential Causes of the Two Observational Classes of Exoplanets

    NASA Astrophysics Data System (ADS)

    Harrington, Joseph; Fortney, J. J.; Bowman, M. O.; UCF Exoplanets Team

    2012-10-01

    We compare Spitzer and ground-based broadband flux measurements for over 30 exoplanets by plotting brightness vs. equilibrium temperatures (Tb vs. Teq). Teq is a proxy for bolometric stellar flux; Tb is measured flux expressed as a temperature. This model-free comparison shows two classes of planet (Harrington et al. 2007, Nature; 2011 DPS). Below 1900 K, planets appear about as bright as their Teq, calculated with 0 Bond albedo and uniform redistribution of received radiation over the entire planetary surface. However, above 1900 K planets appear several hundred K brighter than the Tb = Teq line. There appears to be overlap between the two classes in the 1800 - 2000 K range, but the distinction is strong above 2000 K. Potential causes include clouds at cooler temperatures, permitting a deeper and therefore hotter view into the hotter planets; a reduced advection time scale for the hotter planets, causing more heat to be re-emitted on the dayside; ohmic heating for closer-in planets; the lack of a TiO cold trap for hotter planets, allowing this absorber to exist in gaseous form; and a mechanical (Kzz) greenhouse that is more effective for hotter planets. We evaluate these mechanisms against the data. This work was supported by the NASA Science Mission Directorate's Planetary Atmospheres Program under grant NNX12AI69G. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, which also provided support for this work.

  11. 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.

  12. Comparison of OMI UV observations with ground-based measurements at high northern latitudes

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Arola, A.; Dahlback, A.; Fioletov, V.; Heikkilä, A.; Johnsen, B.; Koskela, T.; Lakkala, K.; Svendby, T.; Tamminen, J.

    2015-03-01

    The Dutch-Finnish Ozone Monitoring Instrument (OMI) on board NASA's Aura spacecraft provides estimates of erythemal (sunburning) ultraviolet (UV) dose rates and erythemal daily doses. These data were compared with ground-based measurements at 13 stations located throughout the Arctic and Scandinavia from 60 to 83° N. The study corroborates results from earlier work, but is based on a longer time series (eight vs. two years) and considers additional data products, such as the erythemal dose rate at the time of the satellite overpass. Furthermore, systematic errors in satellite UV data resulting from inaccuracies in the surface albedo climatology used in the OMI UV algorithm are systematically assessed. At times when the surface albedo is correctly known, OMI data typically exceed ground-based measurements by 0-11%. When the OMI albedo climatology exceeds the actual albedo, OMI data may be biased high by as much as 55%. In turn, when the OMI albedo climatology is too low, OMI data can be biased low by up to 59%. Such large negative biases may occur when reflections from snow and ice, which increase downwelling UV irradiance, are misinterpreted as reflections from clouds, which decrease the UV flux at the surface. Results suggest that a better OMI albedo climatology would greatly improve the accuracy of OMI UV data products even if year-to-year differences of the actual albedo cannot be accounted for. A pathway for improving the OMI albedo climatology is discussed. Results also demonstrate that ground-based measurements from the center of Greenland, where high, homogenous surface albedo is observed year round, are ideally suited to detect systematic problems or temporal drifts in estimates of surface UV irradiance from space.

  13. Comparison of OMI UV observations with ground-based measurements at high northern latitudes

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Arola, A.; Dahlback, A.; Fioletov, V.; Heikkilä, A.; Johnsen, B.; Koskela, T.; Lakkala, K.; Svendby, T.; Tamminen, J.

    2015-07-01

    The Dutch-Finnish Ozone Monitoring Instrument (OMI) on board NASA's Aura spacecraft provides estimates of erythemal (sunburning) ultraviolet (UV) dose rates and erythemal daily doses. These data were compared with ground-based measurements at 13 stations located throughout the Arctic and Scandinavia from 60 to 83° N. The study corroborates results from earlier work, but is based on a longer time series (8 versus 2 years) and considers additional data products, such as the erythemal dose rate at the time of the satellite overpass. Furthermore, systematic errors in satellite UV data resulting from inaccuracies in the surface albedo climatology used in the OMI UV algorithm are systematically assessed. At times when the surface albedo is correctly known, OMI data typically exceed ground-based measurements by 0-11 %. When the OMI albedo climatology exceeds the actual albedo, OMI data may be biased high by as much as 55 %. In turn, when the OMI albedo climatology is too low, OMI data can be biased low by up to 59 %. Such large negative biases may occur when reflections from snow and ice, which increase downwelling UV irradiance, are misinterpreted as reflections from clouds, which decrease the UV flux at the surface. Results suggest that a better OMI albedo climatology would greatly improve the accuracy of OMI UV data products even if year-to-year differences of the actual albedo cannot be accounted for. A pathway for improving the OMI albedo climatology is discussed. Results also demonstrate that ground-based measurements from the center of Greenland, where high, homogenous surface albedo is observed year round, are ideally suited to detect systematic problems or temporal drifts in estimates of surface UV irradiance from space.

  14. 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

  15. Pluto’s Atmosphere from the 23 June 2011 Stellar Occultation: Airborne and Ground Observations

    NASA Astrophysics Data System (ADS)

    Person, Michael J.; Bosh, A. S.; Levine, S. E.; Gulbis, A. A. S.; Zangari, A. M.; Zuluaga, C. A.; Dunham, E. W.; Pasachoff, J. M.; Babcock, B. A.; Pandey, S.; Armhein, D.; Sallum, S.; Tholen, D. J.; Collins, P.; Bida, T.; Taylor, B.; Wolf, J.; Meyer, A.; Pfueller, E.; Wiedermann, M.; Roesser, H.; Lucas, R.; Kakkala, M.; Ciotti, J.; Plunkett, S.; Hiraoka, N.; Best, W.; Pilger, E. L.; Miceli, M.; Springmann, A.; Hicks, M.; Thackeray, B.; Emery, J.; Rapoport, S.; Ritchie, I.

    2012-10-01

    The double stellar occultation by Pluto and Charon of 2011 June 23 was observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 resulted in the best occultation chords recorded for the event, in three optical wavelength bands. The data obtained from SOFIA were combined with chords obtained from the ground at the IRTF (including a full spectral light curve), the USNO--Flagstaff Station, and Leeward Community College to give a detailed profile of Pluto’s atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee, or kink in the light curves separating them as was observed in 1988 (Millis et al. 1993), rather than the smoothly transitioning bowl-shaped light curves of recent years (Elliot et al. 2007). We analyze the upper atmosphere by fitting a model to all of the light curves obtained, resulting in a half-light radius of 1288 ± 1 km. We analyze the lower atmosphere with two different methods to provide results under the separate assumptions of particulate haze and a strong thermal gradient. Results indicate that the lower atmosphere evolves on short seasonal timescales, changing between 1988 and 2006, and then returning to approximately the 1988 state in 2011, though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again excepting the overall pressure changes. No evidence of the onset of atmospheric collapse predicted by frost migration models is yet seen, and the atmosphere appears to be remaining at a stable pressure level. This work was supported in part by NASA Planetary Astronomy grants to MIT (NNX10AB27G) and Williams College (NNX08AO50G, NNH11ZDA001N), as well as grants from USRA (#8500-98-003) and Ames Research (#NAS2-97-01) to Lowell Observatory.

  16. The 2011 June 23 Stellar Occultation by Pluto: Airborne and Ground Observations

    NASA Astrophysics Data System (ADS)

    Person, M. J.; Dunham, E. W.; Bosh, A. S.; Levine, S. E.; Gulbis, A. A. S.; Zangari, A. M.; Zuluaga, C. A.; Pasachoff, J. M.; Babcock, B. A.; Pandey, S.; Amrhein, D.; Sallum, S.; Tholen, D. J.; Collins, P.; Bida, T.; Taylor, B.; Bright, L.; Wolf, J.; Meyer, A.; Pfueller, E.; Wiedemann, M.; Roeser, H.-P.; Lucas, R.; Kakkala, M.; Ciotti, J.; Plunkett, S.; Hiraoka, N.; Best, W.; Pilger, E. J.; Micheli, M.; Springmann, A.; Hicks, M.; Thackeray, B.; Emery, J. P.; Tilleman, T.; Harris, H.; Sheppard, S.; Rapoport, S.; Ritchie, I.; Pearson, M.; Mattingly, A.; Brimacombe, J.; Gault, D.; Jones, R.; Nolthenius, R.; Broughton, J.; Barry, T.

    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 persist

  17. 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.

  18. 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

  19. Diurnal and seasonal behavior of the Hokkaido East SuperDARN ground backscatter: simulation and observation

    NASA Astrophysics Data System (ADS)

    Oinats, Alexey V.; Nishitani, Nozomu; Ponomarenko, Pavlo; Ratovsky, Konstantin G.

    2016-02-01

    We studied regular diurnal and seasonal behaviors of ground backscatter propagation characteristics corresponding to the Hokkaido East Super Dual Auroral Radar Network (SuperDARN) (43.53° N, 143.61° E). Firstly, we simulated key propagation characteristics using a high frequency (HF) calculation technique based on the waveguide approach and International Reference Ionosphere (IRI)-2012 model as background ionosphere. The minimum slant range, skip distance, corresponding elevation angle, and true reflection height were considered in this study. The behaviors of these characteristics were well explained by diurnal and seasonal variations in the critical frequency and maximum height of corresponding ionosphere layer in HF reflection point. We estimated the accuracy of the standard SuperDARN mapping technique and proposed a means for its improvement. Secondly, we constructed an algorithm for mass data processing and extracted diurnal dependencies of the minimum slant range, corresponding elevation angle, and effective reflection height from the Hokkaido East SuperDARN dataset for a period from 2007 to 2014. The algorithm uses the simulated characteristics for distinguishing regular ground backscatter echoes propagating in the E and F2 HF channels. Observed monthly mean and simulated values of the characteristics were compared, and the result showed that the accuracy of IRI-2012 significantly depends on solar activity level and orientation of HF propagation path. In general, the difference between observed and simulated values decreased with increases in solar activity and azimuth. We also analyzed the occurrence of echoes originating behind the radar and found that they most frequently appear in winter and equinoxes before sunrise in beam #0 and after sunset in beam #15. The probability of their observation for a specific local time could reach up to 35 %.

  20. Potentials and Limits of Sar Permanent Scatterers In Ground Deformation Monitoring

    NASA Astrophysics Data System (ADS)

    Rocca, F.; Colesanti, C.; Ferretti, A.; Prati, C.

    The Permanent Scatterers (PS) technique allows the identification of individual radar targets particularly suitable for SAR interferometric measurements. In fact, despite its remarkable potential, spaceborne SAR Differential Interferometry (DInSAR) has not been fully exploited as a reference tool for ground deformation mapping, due to the presence of atmospheric artefacts as well as geometrical and temporal phase decorrelation. Both drawbacks are overcome in a multi-image framework of interfer- ometric data (>25-30 images) jointly used in order to properly identify and exploit the subset of image pixels corresponding to privileged reflectors, the so-called Per- manent Scatterers. Provided that at least 3-4 PS/sqkm are available, accurate phase measurements carried out on the sparse PS grid allow one to compensate data for the atmospheric phase contributions. Average ground deformation rate as well as full dis- placement time series (both along the satellite Line of Sight, LOS) are estimated with millimetric accuracy on individual PS locations. The PS subset of image pixels can be thought of as a high density (100-400 PS/sqkm, in urban areas) "natural" geode- tic network. This study aims at discussing in detail potentials and limits of the PS approach in monitoring ground deformation phenomena characterised by a complex time non-uniform evolution (Non-Linear Motion, NLM). PS results highlighting sea- sonal displacement effects beneath San Jose (Santa Clara Valley, California) are going to be discussed. The deformation occurring there is related to the seasonal variation of the ground water level in the area delimited by the Silver Creek and the San Jose fault. The San Jose PS analysis is exploited as a significant case study to assess the main requirements for a successful detection of NLM phenomena (by means of PS), and to analyse their impact on the quality of results. Particular attention will be de- voted to the effect of irregularly sampled data and missing

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Education and Public Outreach for MSFC's Ground-Based Observations in Support of the HESSI Mission

    NASA Technical Reports Server (NTRS)

    Adams, Mitzi L.; Hagyard, Mona J.; Newton, Elizabeth K.

    1999-01-01

    A primary focus of NASA is the advancement of science and the communication of these advances to a number of audiences, both within the science research community and outside it. The upcoming High Energy Solar Spectroscopic Imager (HESSI) mission and the MSFC ground-based observing program, provide an excellent opportunity to communicate our knowledge of the Sun, its cycle of activity, the role of magnetic fields in that activity, and its effect on our planet. In addition to ground-based support of the HESSI mission, MSFC's Solar Observatory, located in North Alabama, will involve students and the local education community in its day-to-day operations, an experience which is more immediate, personal, and challenging than their everyday educational experience. Further, by taking advantage of the Internet, our program can reach beyond the immediate community. By joining with Fernbank Science Center in Atlanta, Georgia, we will leverage their almost 30 years'experience in science program delivery in diverse situations to a distance learning opportunity which can encompass the entire Southeast and beyond. This poster will outline our education and public outreach plans in support of the HESSI mission in which we will target middle and high school students and their teachers.

  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. Observations of northern latitude ground-surface and surface-air temperatures

    NASA Astrophysics Data System (ADS)

    Woodbury, Allan D.; Bhuiyan, A. K. M. H.; Hanesiak, John; Akinremi, O. O.

    2009-04-01

    Note that the magnitude of temperature increases reconstructed from borehole records seems to contrast with some proxy based reconstructions of surface air temperature (SAT) that indicate lower amounts of warming over the same period. We present data suggesting that ground and snow cover may bias climate reconstructions based on BT in portions of the Canadian northwest. Eight sites west of the Canadian cordillera, were examined for long-term SAT and GST changes. At seven of these sites precise borehole temperature profiles are used for the first time since the 1960s, thereby exploring the linkage between GST and SAT. New readings were made at four of these locations. All sites showed significant increasing SAT trends, in terms of annual mean minimum and maximum temperatures. Over a 54 year period, the minimum temperatures increased between 1.1°C and 1.5°C while the maximum increased between 0.8°C and 1.5°C, among those eight stations. Observations of GST at those sites, however, showed no obvious climate induced perturbations. Therefore, we believe that a trend in our area towards an increase in SAT temperatures only over the winter and spring is being masked by freeze thaw and latent energy effects. These results are important, particularly in northern locations where ground and snow cover may play an important role in creating a seasonal bias in GST reconstructions from borehole surveys.

  8. 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.

  9. Education and Public Outreach for MSFC's Ground-based Observations in Support of the HESSI Mission

    NASA Astrophysics Data System (ADS)

    Adams, M.; Hagyard, M. J.; Newton, E.

    1999-05-01

    A primary focus of NASA is the advancement of science and the communication of these advances to a number of audiences, both within the science research community and outside it. The upcoming High Energy Solar Spectroscopic Imager (HESSI) mission and the MSFC ground-based observing program, provide an excellent opportunity to communicate our knowledge of the Sun, its cycle of activity, the role of magnetic fields in that activity, and its effect on our planet. In addition to ground-based support of the HESSI mission, MSFC's Solar Observatory, located in North Alabama, will involve students and the local education community in its day-to-day operations, an experience which is more immediate, personal, and challenging than their everyday educational experience. Further, by taking advantage of the Internet, our program can reach beyond the immediate community. By joining with Fernbank Science Center in Atlanta, Georgia, we will leverage their almost 30 years' experience in science program delivery in diverse situations to a distance learning opportunity which can encompass the entire Southeast and beyond. This poster will outline our education and public outreach plans in support of the HESSI mission in which we will target middle and high school students and their teachers.

  10. Ground-based observation of emission lines from the corona of a red-dwarf star.

    PubMed

    Schmitt, J H; Wichmann, R

    2001-08-01

    All 'solar-like' stars are surrounded by coronae, which contain magnetically confined plasma at temperatures above 106 K. (Until now, only the Sun's corona could be observed in the optical-as a shimmering envelope during a total solar eclipse.) As the underlying stellar 'surfaces'-the photospheres-are much cooler, some non-radiative process must be responsible for heating the coronae. The heating mechanism is generally thought to be magnetic in origin, but is not yet understood even for the case of the Sun. Ultraviolet emission lines first led to the discovery of the enormous temperature of the Sun's corona, but thermal emission from the coronae of other stars has hitherto been detectable only from space, at X-ray wavelengths. Here we report the detection of emission from highly ionized iron (Fe XIII at 3,388.1 A) in the corona of the red-dwarf star CN Leonis, using a ground-based telescope. The X-ray flux inferred from our data is consistent with previously measured X-ray fluxes, and the non-thermal line width of 18.4 km s-1 indicates great similarities between solar and stellar coronal heating mechanisms. The accessibility and spectral resolution (45,000) of the ground-based instrument are much better than those of X-ray satellites, so a new window to the study of stellar coronae has been opened. PMID:11484044

  11. Revised global model of thermosphere winds using satellite and ground-based observations

    NASA Technical Reports Server (NTRS)

    Hedin, A. E.; Spencer, N. W.; Biondi, M. A.; Burnside, R. G.; Hernandez, G.; Johnson, R. M.

    1991-01-01

    Thermospheric wind data obtained from the Atmosphere Explorer E and Dynamics Explorer 2 satellites have been combined with wind data for the lower and upper thermosphere from ground-based incoherent scatter radar and Fabry-Perot optical interferometers to generate a revision (HWM90) of the HWM87 empirical model and extend its applicability to 100 km. Comparison of the various data sets with the aid of the model shows in general remarkable agreement, particularly at mid and low latitudes. The ground-based data allow modeling of seasonal/diurnal variations, which are most distinct at midlatitudes. While solar activity variations are now included, they are found to be small and not always very clearly delineated by the current data. They are most obvious at the higher latitudes. The model describes the transition from predominately diurnal variations in the upper thermosphere to semidiurnal variations in the lower thermosphere and a transition from summer to winter flow above 140 km to winter to summer flow below. Significant altitude gradients in the wind are found to extend to 300 km at some local times and pose complications for interpretation of Fabry-Perot observations.

  12. Seasonal ice cycle at the Mars Phoenix landing site: 2. Postlanding CRISM and ground observations

    NASA Astrophysics Data System (ADS)

    Cull, Selby; Arvidson, R. E.; Morris, R. V.; Wolff, M.; Mellon, M. T.; Lemmon, M. T.

    2010-05-01

    The combination of ground observations from the Mars Phoenix Lander and orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) provided a detailed view of the formation of late summer surface water ice at the landing site and surrounding regions. CRISM observations of the landing site during and immediately after Phoenix operations were analyzed to track the seasonal and diurnal ice cycles during the late spring to late summer, and a nonlinear mixing model was used to estimate grain sizes and relative abundances of water ice and dust. The surface around the Phoenix landing site was ice-free from late spring through midsummer, although transient patches of mobile ices were observed in an 85 m diameter crater to the northeast of the landing site. At the ˜10 km diameter Heimdal Crater, located ˜10 km east of the landing site, permanent patches of water ice were observed to brighten during the late spring and darken during the summer, possibly as fine-grained water ice that was cold trapped onto the ice during late spring sintered into larger grains or finally sublimated, exposing larger-grained ice. CRISM spectra first show evidence of widespread ice during the night at solar longitude (Ls) ˜ 109°, ˜9 sols before Phoenix’s Surface Stereo Imager detected it. CRISM spectra first show evidence of afternoon surface ice and water ice clouds after Ls ˜ 155°, after Phoenix operations ended.

  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. 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.

  16. Electrophysiological Potentials Reveal Cortical Mechanisms for Mental Imagery, Mental Simulation, and Grounded (Embodied) Cognition

    PubMed Central

    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. The January 26, 2001 Mw7.6 Bhuj, India, Earthquake: Observed and Predicted Ground Motions

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    It is unclear whether or not the 26 January, 2001, Bhuj earthquake occurred in an intraplate or interplate setting. However, to understand the damage caused by this earthquake, and the hazard posed by future similar earthquakes, one must consider not only the source setting but propagation issues as well. Although local and regional instrumental recordings of the devastating January 26, 2001, Bhuj earthquake are sparse, the distribution of macroseismic effects can provide constraints on the ground motions. We compiled news accounts describing damage and other effects and interpreted them to obtain modified Mercalli intensities at over 300 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. These maps reveal several interesting features. Significant sediment-induced amplification is suggested at a number of locations around the Gulf of Kachchh and in other areas along rivers, within deltas, or on coastal alluvium. The overall distribution of intensities also reveals extremely efficient wave propagation throughout the subcontinent: the earthquake was felt at distances as large as 2400 km and caused light damage at distances upwards of 700 km. This is consistent with earlier theoretical and observational results suggesting that higher mode surface waves (Lg waves) will propagate efficiently in intraplate crust, which forms a relatively uniform, high-Q waveguide. We use fault rupture parameters inferred from teleseismic data to predict ground motions at distances of 0-1000 km. We convert the predicted peak ground acceleration (PGA) values to MMI using a relationship between MMI and PGA that assigns MMI based on the average effects in a region. The predicted MMI's are typically lower by 1-2 units than the estimated values. We discuss two factors that probably account for this discrepancy: 1) a tendency for media accounts to focus on the most dramatic damage, rather than

  18. Effects of Hyperfine Mixing of Rydberg-ground molecular potentials in Rb

    NASA Astrophysics Data System (ADS)

    Maclennan, Jamie; Ramos, Andira; Thaicharoen, Nithiwadee; Raithel, Georg

    2016-05-01

    Rydberg molecules formed by the scattering between a ground-state atom and a Rydberg electron can offer new insight into the nature of atomic interactions and molecular structure. Shallow bound states that arise from hyperfine-induced mixing of singlet and triplet channels have recently been predicted and observed for P-states in Cs and S-states in 87 Rb. Here we present progress toward characterizing Rb (nD + 5 S1/2) molecules, including a comparison of the hyperfine-mixing effects between the two isotopes (85 Rb and 87 Rb).

  19. Visual observations of historical lake trout spawning grounds in western Lake Huron

    USGS Publications Warehouse

    Nester, Robert T.; Poe, Thomas P.

    1987-01-01

    Direct underwater video observations were made of the bottom substrates at 12 spawning grounds formerly used by lake trout Salvelinus namaycush in western Lake Huron to evaluate their present suitability for successful reproduction by lake trout. Nine locations examined north of Saginaw Bay in the northwestern end of the lake are thought to provide the best spawning habitat. The substrate at these sites consisted of angular rough cobble and rubble with relatively deep interstitial spaces (a?Y 0.5 m), small amounts of fine sediments, and little or no periphytic growth. Conditions at the three other sampling locations south of Saginaw Bay seemed much less suitable for successful reproduction based on the reduced area of high-quality substrate, shallow interstitial spaces, high infiltration of fine sediments, and greater periphytic growth.

  20. Ground-based IR observation of oxygen isotope ratios in Venus's atmosphere

    NASA Astrophysics Data System (ADS)

    Iwagami, N.; Hashimoto, G. L.; Ohtsuki, S.; Takagi, S.; Robert, S.

    2015-08-01

    The oxygen isotope ratios 17O/16O and 18O/16O in Venus's atmosphere were measured simultaneously by ground-based IR spectroscopy. The CO2 absorption lines in the 2648 cm-1 (for 17O/18O) and 4582 cm-1 (for 18O/16O) regions were observed using the IRTF/CSHELL spectrometer. The deviations of the isotope fractions are found to be δ17O=+92±158‰ and δ18O=-42±85‰ as compared to the terrestrial standard (HITRAN 2012) where the uncertainties include both random and systematic errors. Such combination agrees with the Earth-Moon fractionation line within the errors. This is consistent to the fact that the proto-Venus matter was also well mixed with the proto-Earth-Moon matter.

  1. Follow-up observations of Planck cold clumps with ground-based telescopes.

    NASA Astrophysics Data System (ADS)

    Liu, Tie

    2015-08-01

    Stars form in dense regions within molecular clouds, called pre-stellar cores (PSCs), which provide information on the initial conditions in the process of star formation. The low dust temperature (<14 K) of Planck cold clumps/cores makes them likely to be pre-stellar objects or at the very initial stage of protostellar collapse. We are conducting a legacy survey of Planck cold clumps with the JCMT, the TRAO 14-m, the KVN and TianMa 65-m telescopes. We aim to statistically study the initial conditions of star formation and cloud evolution in various kinds of environments. We have conducted some pilot observations with ground-based telescopes (JCMT, IRAM, PMO 14m, APEX, Mopra, Effelsberg 100 m, CSO and SMA). I will discuss the progress and the plans of this internationally collaborating project.

  2. 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

  3. Ground-based observations of comets, the Jupiter plasma Torus, and Io

    NASA Technical Reports Server (NTRS)

    Scherb, Frank; Roesler, Fred L.

    1991-01-01

    Aspects of cometary and magnetospheric physics were investigated by means of ground-based astronomical spectroscopy. High-throughput, dual-etalon Fabry-Perot spectrometers were used to obtain very high resolution spectra of atomic, molecular, and ionic emission lines from the diffuse gases and plasmas associated with comets and the Jupiter plasma torus. The Fabry-Perot spectrometers were also used with a charge coupled device (CCD) camera to obtain images of these extended emission sources in individual spectral lines at high spectral resolution. A new program using the McMath solar-stellar spectrograph to observe emission lines from Io was recently initiated. The McMath spectrograph has a high resolution mode which allows the detection of narrow, relatively faint emission lines superimposed on Io's reflected solar spectrum.

  4. 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.

  5. 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.

  6. Ground deformation near Gada ‘Ale Volcano, Afar, observed by radar interferometry

    NASA Astrophysics Data System (ADS)

    Amelung, Falk; Oppenheimer, Clive; Segall, P.; Zebker, H.

    2000-10-01

    Radar interferometric measurements of ground-surface displacement using ERS data show a change in radar range, corresponding to up to 12 cm of subsidence near Gada ‘Ale volcano in northern Afar, Ethiopia, that occurred between June 1993 and May 1996. This is the area of lowest topography within the Danakil Depression (-126 m). Geodetic inverse modeling and geological evidence suggest a volcanic origin of the observed deformation; it was probably caused by a combined process of magma withdrawal from a larger reservoir and normal faulting. There is no evidence of subaerial eruption. This is the only identifiable deformation event during June 1993-October 1997 in the 80 km long Erta ‘Ale volcanic range, indicating surprising inactivity elsewhere in the range.

  7. Direct observation of the hyperfine transition of ground-state positronium.

    PubMed

    Yamazaki, T; Miyazaki, A; Suehara, T; Namba, T; Asai, S; Kobayashi, T; Saito, H; Ogawa, I; Idehara, T; Sabchevski, S

    2012-06-22

    We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-Pérot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be A = 3.1(-1.2)(+1.6) × 10(-8) s(-1) for the first time, which is in good agreement with the theoretical value of 3.37 × 10(-8) s(-1). PMID:23004598

  8. 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.

  9. 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.

  10. A method for retrieving the cumulus entrainment rate from ground based observations

    NASA Astrophysics Data System (ADS)

    Wagner, Timothy J.

    2011-12-01

    The entrainment of drier environmental air into cumulus clouds affects the impact that these clouds have on the environment by modifying their radiative, microphysical, and thermodynamic characteristics. Entrainment is a difficult parameter to observe directly, and heretofore has been obtained from occasional aircraft penetrations. To increase the number of cumulus entrainment rate observations under a wide range of atmospheric conditions, an algorithm for retrieving the cumulus entrainment rate from ground-based remote sensing observations has been developed. This algorithm, called the Entrainment Rate In Cumulus Algorithm (ERICA), uses the suite of instruments at the Southern Great Plains (SGP) site of the United States Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility as inputs into a Gauss-Newton optimal estimation scheme. The forward model in this algorithm is the Explicit Mixing Parcel Model (EMPM), a cloud parcel model that treats entrainment as a series of discrete mixing events. Output from EMPM is used to calculate quantities that can be observed from the surface, including effective radius and liquid water path. The entrainment rate in EMPM is adjusted iteratively until the modeled output converges to the observations. Sensitivity testing and error and information content analysis show that ERICA is a robust method for obtaining accurate estimates of entrainment rate without the drawbacks of aircraft observations. Results from a three-month trial of ERICA show significant variability of the entrainment rate of clouds in a single day and from one day to the next. The mean value from this analysis corresponds well with prior knowledge of the entrainment rate.

  11. The Department of Defense energy vulnerabilities: Potential problems and observations

    NASA Astrophysics Data System (ADS)

    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. 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.

  13. 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.

  14. Multiple ground-based and satellite observations of global Pi 2 magnetic pulsations

    SciTech Connect

    Yumoto, K. ); Takahashi, K. ); Sakurai, T. ); Sutcliffe, P.R. ); Kokubun, S. ); Luehr, H. ); Saito, T. ); Kuwashima, M. ); Sato, N. )

    1990-09-01

    Four Pi 2 magnetic pulsations, observed on the ground at L = 1.2-6.9 in the interval from 2,300 UT on May 22 to 0300 UT on May 23, 1985, provide new evidence of a global nature of Pi 2 pulsations in the inner (L {approx lt} 7) region of the magnetosphere bounded by the plasma sheet during quiet geomagnetic conditions. In the present study, magnetic data have been collected from stations distributed widely both in local time and in latitude, including conjugate stations, and from the AMPTE/CCE spacecraft located in the magnetotail. On the basis of high time resolution magnetic field data, the following characteristics of Pi 2 have been established: horizontal components, H and D, of the Pi 2 oscillate nearly antiphase and in-phase, respectively, between the high- and low-altitude stations in the midnight southern hemisphere. Both the H and D components of the Pi 2 have nearly in-phase relationships between the nightside and the dayside stations at low latitude. The Pi 2 amplitude is larger at the high-latitude station and decreases toward lower latitudes. The dominant periods of the Pi 2 are nearly identical at all stations. Although a direct coincidence between spacecraft-observed and ground-based global Pi 2 events does not exist for these events, the Pi 2 events are believed to be a forced field line oscillation of global scale, coupled with the magnetospheric cavity resonance wave in the inner magnetosphere during the substorm expansive phase.

  15. Combining satellite precipitation and long-term ground observations for hydrological monitoring in China

    NASA Astrophysics Data System (ADS)

    Zhang, Xuejun; Tang, Qiuhong

    2015-07-01

    Satellite real-time precipitation enables hydrological monitoring in China where the near-real-time ground observations are not readily available. However, the inconsistency between the real-time satellite precipitation and gauge-based retrospective data may introduce large systematic bias in near-real-time hydrological monitoring. Here we attempted to integrate the Tropical Rainfall Measuring Mission (TRMM) real-time precipitation (3B42RTV7) into a 62 year gauge-based retrospective product, the IGSNRR (Institute of Geographical Sciences and Natural Resources Research) dataset through matching their cumulative probability functions toward a near-real-time hydrological monitoring consistent with the long-term retrospective simulations. A nearly 11 year period from March 2000 to December 2010 was taken as the training period to establish the satellite-gauge precipitation relationship, which was employed in the period of 2011-2013 to evaluate the performance of the adjustment. The results show that the adjusted 3B42RTV7 matches well with IGSNRR precipitation, while the unadjusted data tend to overestimate precipitation. Forced by the adjusted 3B42RTV7, the Variable Infiltration Capacity model can reproduce the IGSNRR-derived hydrographs and high/low flows better than the model forced by the unadjusted data. The percentiles of the adjusted hydrological estimates in the 62 year estimates from IGSNRR are used for near-real-time assessment of hydrological extremes. The hydrological monitoring assisted by the adjusted satellite precipitation, which enables the employment of the long-term ground observations, is able to capture more detailed drought information than that before adjustment. Our experiment suggests that the satellite real-time precipitation, after adjustment, can generate the current hydrological conditions which can be directly compared with the long-term climatology, and thus facilitates near-real-time diagnosis and detection of hydrological extremes.

  16. 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

  17. 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.

  18. The ground-state potential energy curve of the radium dimer from relativistic coupled cluster calculations

    NASA Astrophysics Data System (ADS)

    Teodoro, Tiago Quevedo; Haiduke, Roberto Luiz Andrade; Dammalapati, Umakanth; Knoop, Steven; Visscher, Lucas

    2015-08-01

    The potential energy curve for the ground-state of radium dimer (Ra2) is provided by means of atomic and molecular relativistic coupled cluster calculations. The short-range part of this curve is defined by an equilibrium bond length of 5.324 Å, a dissociation energy of 897 cm-1, and a harmonic vibrational frequency of 20.5 cm-1. The asymptotic behavior at large interatomic distances is characterized by the van der Waals coefficients C6 = 5.090 × 103, C8 = 6.978 × 105, and C10 = 8.786 × 107 atomic units. The two regions are matched in an analytical potential to provide a convenient representation for use in further calculations, for instance, to model cold collisions between radium atoms. This might become relevant in future experiments on ultracold, optically trapped, radioactive radium atoms that are used to search for a permanent electric dipole moment.

  19. CVRQD ab initio ground-state adiabatic potential energy surfaces for the water molecule.

    PubMed

    Barletta, Paolo; Shirin, Sergei V; Zobov, Nikolai F; Polyansky, Oleg L; Tennyson, Jonathan; Valeev, Edward F; Császár, Attila G

    2006-11-28

    The high accuracy ab initio adiabatic potential energy surfaces (PESs) of the ground electronic state of the water molecule, determined originally by Polyansky et al. [Science 299, 539 (2003)] and called CVRQD, are extended and carefully characterized and analyzed. The CVRQD potential energy surfaces are obtained from extrapolation to the complete basis set of nearly full configuration interaction valence-only electronic structure computations, augmented by core, relativistic, quantum electrodynamics, and diagonal Born-Oppenheimer corrections. We also report ab initio calculations of several quantities characterizing the CVRQD PESs, including equilibrium and vibrationally averaged (0 K) structures, harmonic and anharmonic force fields, harmonic vibrational frequencies, vibrational fundamentals, and zero-point energies. They can be considered as the best ab initio estimates of these quantities available today. Results of first-principles computations on the rovibrational energy levels of several isotopologues of the water molecule are also presented, based on the CVRQD PESs and the use of variational nuclear motion calculations employing an exact kinetic energy operator given in orthogonal internal coordinates. The variational nuclear motion calculations also include a simplified treatment of nonadiabatic effects. This sophisticated procedure to compute rovibrational energy levels reproduces all the known rovibrational levels of the water isotopologues considered, H(2) (16)O, H(2) (17)O, H(2) (18)O, and D(2) (16)O, to better than 1 cm(-1) on average. Finally, prospects for further improvement of the ground-state adiabatic ab initio PESs of water are discussed. PMID:17144700

  20. Ground observations of high-latitude Pc3-4 ULF waves

    NASA Astrophysics Data System (ADS)

    Howard, T. A.; Menk, F. W.

    2005-04-01

    A detailed study has been undertaken of Pc3-4 waves recorded on the ground with the IMAGE magnetometer array (56° < Λ < 76°) during January and March 1998. We focus only on daytime events exhibiting high coherence (>0.6) across the entire station array. Most of these had well-defined wave packet appearance in time series records and a clear peak in power spectra. Their occurrence and frequency suggest the waves are generated by the upstream ion-cyclotron resonance mechanism, with no evidence of generation by the Kelvin-Helmholtz instability. For each event the amplitude, phase, coherence, ellipticity, azimuth angle, and degree of polarization across the ground array were examined. The coherence length, azimuthal wave number, and hence the apparent wave propagation velocity were thus determined, with emphasis on the precision and significance of these measurements. It was found that these daytime Pc3-4 pulsations usually have maximum amplitude near the magnetopause projection, meridional coherence lengths of order 1.5-2.0 × 103 km, and low azimuthal wave numbers during morning hours, averaging around -4.0 (indicating westward propagation). Over 80% of events propagated poleward and westward, with average equivalent ground velocity of 41 km/s N43°W for the H component. About 24-30% of the events are higher harmonics of field line resonances. There is no evidence that the remaining events arise from cavity modes or localized modulated electron precipitation. The observations instead suggest a mechanism involving mode coupling and field-guided propagation. In this model, fast mode waves in the Pc3-4 range entering near the subsolar point propagate earthward and due to the inhomogeneity of the magnetosphere couple to the field-guided Alfvén mode. At certain latitudes, standing oscillations are established at harmonics of the local resonant frequency, while at other latitudes traveling waves convey energy to low altitudes. The expected L dependence of wave power

  1. High-speed video observations of natural cloud-to-ground lightning leaders - A statistical analysis

    NASA Astrophysics Data System (ADS)

    Campos, Leandro Z. S.; Saba, Marcelo M. F.; Warner, Tom A.; Pinto, Osmar; Krider, E. Philip; Orville, Richard E.

    2014-01-01

    The aim of this investigation is to analyze the phenomenology of positive and negative (stepped and dart) leaders observed in natural lightning from digital high-speed video recordings. For that intent we have used four different high-speed cameras operating at frame rates ranging from 1000 or 11,800 frames per second in addition to data from lightning locating systems (BrasilDat and NLDN). All the recordings were GPS time-stamped in order to avoid ambiguities in the analysis, allowing us to estimate the peak current of and the distance to each flash that was detected by one of the lightning locating systems. The data collection was done at different sites in south and southeastern of Brazil, southern Arizona and South Dakota, USA. A total of 62 negative stepped leaders, 76 negative dart leaders and 29 positive leaders were recorded and analyzed. From these data it was possible to calculate the two-dimensional speed of each observed leader, allowing us to obtain its statistical distribution and evaluate whether or not it is related to other characteristics of the associated flash. In the analyzed dataset, the speeds of positive leaders and negative dart leaders follow a lognormal distribution at the 0.05 level (according to the Shapiro-Wilk test). We have also analyzed how the two-dimensional leader speeds change as they approach ground through two different methodologies. The speed of positive leaders showed a clear tendency to increase while negative dart leaders tend to become slower as they approach ground. Negative stepped leaders, on the other hand, can either accelerate as they get closer to ground or present an irregular development (with no clear tendency) throughout their entire development. For all the three leader types no correlation has been found between the return stroke peak current and the average speed of the leader responsible for its initiation. We did find, however, that dart leaders preceded by longer interstroke intervals cannot present

  2. 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

  3. 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.

  4. 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.

  5. 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. PMID:16783916

  6. Satellite and ground-based observations of a fading transpolar arc

    SciTech Connect

    Pellinen, R.J.; Koskinen, H.E.J.; Pulkkinen, T.I. ); Murphree, J.S. ); Rostoker, G. ); Opgenoorth, H.J. )

    1990-05-01

    Satellite and ground-based observations of the end phase of a transpolar arc event on September 25, 1986, are presented. The event was recorded by the UV imager of the Viking spacecraft during the time period from 2000 to 2110 UT. The transpolar arc was formed during a period of more than one hour of northward directed interplanetary magnetic field B{sub Z}. The arc started to fade when the IMF turned southward and a localized brightening of the auroral oval west of its nightside foot point was observed. Within a few minutes the activation was strongly enhanced. Magnetic disturbances below the activation were relatively weak, but at the EISCAT magnetometer stations a counterclockwise rotating equivalent current system, which can be interpreted as due to an upward directed filamentary field-aligned current, was observed to last about 10 min. The magnetic disturbance was fairly stable and did not move across the magnetometer chain during its existence. EISCAT observed a clear enhancement of E region electron density after 2100 UT, which was not associated with hard precipitation, as indicated by the absence of riometer absorption over Scandinavia. The EISCAT scan data on ionospheric horizontal ion drift velocity showed a localized region of eastward drift just north of Tromsoe, in agreement with the magnetometer recordings. Also the postmidnight auroral oval was brightened in a wide longitudinal range, and a weak westward current was observed flowing in the ionosphere by Soviet magnetometers below the bright region of the oval. Though the magnetic signatures below the activation west of the foot point indicate a cablelike upward field-aligned current, the authors do not interpret the phenomenon as a substorm.

  7. Fine spectral structures in Jovian decametric radio emission observed by ground-based radio telescope.

    NASA Astrophysics Data System (ADS)

    Panchenko, M.; Brazhenko, A. I.; Shaposhnikov, V. E.; Konovalenko, A. A.; Rucker, H. O.

    2014-04-01

    Jupiter with the largest planetary magnetosphere in the solar system emits intense coherent non-thermal radio emission in a wide frequency range. This emission is a result of a complicated interaction between the dynamic Jovian magnetosphere and energetic particles supplying the free energy from planetary rotation and the interaction between Jupiter and the Galilean moons. Decametric radio emission (DAM) is the strongest component of Jovian radiation observed in a frequency range from few MHz up to 40 MHz. This emission is generated via cyclotron maser mechanism in sources located along Jovian magnetic field lines. Depending on the time scales the Jovian DAMexhibits different complex spectral structures. We present the observations of the Jovian decametric radio emission using the large ground-based radio telescope URAN- 2 (Poltava, Ukraine) operated in the decametric frequency range. This telescope is one of the largest low frequency telescopes in Europe equipped with high performance digital radio spectrometers. The antenna array of URAN-2 consists of 512 crossed dipoles with an effective area of 28 000m2 and beam pattern size of 3.5 x 7 deg. (at 25 MHz). The instrument enables continuous observations of the Jovian radio during long period of times. Jovian DAM was observed continuously since Sep. 2012 (depending on Jupiter visibility) with relatively high time-frequency resolution (4 kHz - 100ms) in the broad frequency range (8-32MHz). We have detected a big amount of the fine spectral structures in the dynamic spectra of DAM such as trains of S-bursts, quasi-continuous narrowband emission, narrow-band splitting events and zebra stripe-like patterns. We analyzed mainly the fine structures associated with non-Io controlled DAM. We discuss how the observed narrowband structures which most probably are related to the propagation of the decametric radiation in the Jupiter's ionosphere can be used to study the plasma parameters in the inner Jovian magnetosphere.

  8. Ground-water levels in observation wells in Oklahoma, 1967-68

    USGS Publications Warehouse

    Bingham, R.H.

    1969-01-01

    The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. This report has been prepared primarily to present water-level records of wells not included in the Federal network. However, for the sake of completeness it includes water-level records of Federal wells that either have been or will be published in water-supply papers since 1955. This report, which contains water-level records for the 2-year period (1967-68), is the fifth in a series presenting water-level records for all permanent observations wells in Oklahoma. The first report, published in 1963, contains water-level records for the 2-year period of (1961-62); the second report, published in 1964, contains water-level records for the 2-year period (1961-62); the third report, published in 1965, contains water-level records for the 2-year period (1963-64); and the fourth report contains water-level records for

  9. Ground-water levels in observation wells in Oklahoma, 1965-66

    USGS Publications Warehouse

    Hart, D.L., Jr.

    1967-01-01

    The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. This report has been prepared primarily to present water-level records of wells not included in the Federal network. However, for the sake of completeness it includes water-level records of Federal wells that either have been or will be published in water-supply papers since 1955. This report, which contains water-level records for the 2-year period (1965-66), is the fourth in a series presenting water-level records for all permanent observations wells in Oklahoma. The first report, published in 1963, contains water-level records for the 2-year period of (1961-62); the second report, published in 1964, contains water-level records for the 2-year period (1961-62); and the third report, published in 1965, contains water-level records for the 2-year period (1963-64). (available as photostat copy only)

  10. 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.

  11. 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.

  12. Documentation of potential for surface faulting related to ground-water withdrawal in Las Vegas Valley, Nevada

    USGS Publications Warehouse

    Holzer, Thomas L.

    1978-01-01

    Leveling data collected in Las Vegas Valley are compatible with the interpretation that ongoing land-surface displacements related to ground-water withdrawal may be precursory to fault offset of the land surface. Zones of potential faulting intersect regions of intense urban development. The degree of risk and the potential economic consequences from possible surface faulting cannot be assessed adequately without additional data and analysis of the relation between surface faulting and ground-water withdrawal.

  13. On the potential role of SSS observations on ENSO prediction

    NASA Astrophysics Data System (ADS)

    Ballabrera, J.; Murtugudde, R.; Busalacchi, A. J.

    2003-04-01

    Multiple regression analysis is used here to construct statistical prediction models for the El Niño/Southern Oscillation (ENSO) to explore the potential impact of monitoring Pacific Ocean sea surface salinity (SSS) on prediction of equatorial Pacific sea surface temperature. This study, one of the first focusing on the direct role of SSS in ENSO predictions, is motivated by proposed missions for remote sensing of SSS. A forward stepwise method is used to extract significant predictors of the Niño-3 sea surface temperature (SST) index from observed monthly anomalies of tropical SST, SSS, sea level, freshwater flux, and components of the wind stress. The results indicate that sea surface salinity monitoring would have small impact on the statistical nowcast (reconstruction) of ENSO, but a potential role in the 6-12 month forecasts. Correlation maps show two regions of high correlation: an equatorial region (between 170E-160W), and an off-equatorial region (between 170E-140W and 5S-20S). Short lag correlations display the negative relationship between the warm phase of ENSO with negative equatorial SSS anomalies related with the increase of local rainfall. Such an equatorial negative correlation coexists with an area of positive correlations off-the equator. The region with positive correlations moves eastward as the lag increases, reaching the geographical limit of the SSS observations at six months lag. The region of negative correlation moves northward and becomes weaker as the lag increases (it is non-significant for 9-months lag). For lags longer than 9 months, significant positive correlations are found south of the equator (5S-10S). At these lags, positive salinity anomalies have the potential to modify the subsurface stratification of the western Pacific as they are subducted westward. Thus, the availability of continuous remotely sensed SSS data might add considerably to ENSO predictions at longer lead-time, as a result of SSS induced changes in the

  14. Rosetta in context: Ground-based observations of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Snodgrass, C.

    2014-04-01

    collaboration with the large and enthusiastic community of amateur comet observers, especially in 2015 when the comet is brighter (see also talks in the proamsessions at EPSC). The comet has been recovered (in late February 2014), with early indications from VLT photometry suggesting that activity had indeed already started beyond 4 AU from the Sun, as predicted[1]. Its activity level, as measured by the dust brightness, will be followed all year and used to make further predictions about the future activity. The comet is observable until November 2014 using large telescopes (primarily in the Southern hemisphere), and is getting brighter as it approaches the Sun. In addition to photometric observations, visible wavelength spectroscopy will be attempted during 2014, to constrain gas emissions. Polarimetric observations and high resolution imaging with the HST are also proposed. A wide range of observational techniques and wavelength ranges will be covered by the campaign in 2015 as the comet reaches perihelion. I will present an update on the ground-based observation campaign in support of the Rosetta mission, the current status of various observation programmes at the time of the EPSC conference, and results on the 2014 activity of the comet, for comparison with early Rosetta results. I will also discuss how well the 2014 observations match with our earlier predictions, and make an assessment of how active the comet appears to be relative to previous orbits. I will also describe what further observations are planned in 2015, and how these will support the primary 'escort' phase of the mission.

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Pettersen, C.; Bennartz, R.; Kulie, M. S.; Merrelli, A. J.; Shupe, M. D.; Turner, D. D.

    2015-12-01

    Multi-instrument, ground-based measurements provide unique and comprehensive datasets of the atmosphere for a specific location over long periods of time and resulting data compliments 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 2010-2013. 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 four years of summer season isolated ice signature in the high-frequency microwave channels.

  17. 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.

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

    DOE PAGESBeta

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

    2016-04-15

    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 gm–2 or less, themore » 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. As a result, 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.« less

  19. 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.

  20. 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.

  1. Wide cusp/llbl ground observations by twin high-latitude auroral monitors.

    NASA Astrophysics Data System (ADS)

    Massetti, S.; Candidi, M.; Cerulli-Irelli, P.; Orsini, S.

    2003-04-01

    Northern dayside auroral emission associated with cusp/LLBL plasma precipitation has been monitored for many year by means of all-sky cameras from the Svalbard, sometimes by joining meridian-scanning-photometer (MSP) observations from Svalbard and/or Greenland. The typical altitude of the dayside red auroras (about 250-300km) usually means a field-of-view of roughly 1000km of diameter, about 45° of magnetic longitude, corresponding to 3 hours MLT. Taking into account the cusp displacements driven by IMF variations, this implies that for a prolonged period of time only in few occasions the cusp/LLBL auroral signatures (from 2/3 to 8 hours wide) fit entirely within the field-of-view of a single imager. In the past, this fact has reduced the possibility of comparison between optical ground observations and data from satellites (DMSP, Polar, Cluster, FAST). Starting from the present 2002/2003 winter season, we have the opportunity to combine cusp/LLBL optical observations from two digital imagers located in Ny-Ålesund (Svalbard) and Daneborg (Greenland), at about the same magnetic latitude. Our twin monitors have contiguous field-of-views and allow the monitoring of the dayside auroral activity over about 80° of magnetic longitude, equivalent to about 5/6 hours MLT. In the present study, we show a preliminary analysis of the first campaign of observations, concerning both the dayside cusp/LLBL phenomena and the substorm-related poleward expansion of the auroral oval.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Ionospheric scintillations at Guilin detected by GPS ground-based and radio occultation observations

    NASA Astrophysics Data System (ADS)

    Zou, Yuhua

    2011-03-01

    The occurrence of ionospheric scintillations with S4 ⩾ 0.2 was studied using GPS measurements at Guilin, China (25.29°N, 110.33°E; geomagnetic: 15.04°N, 181.98°E), a station located near the northern crest of the equatorial anomaly. The results are presented for data collected from January 2009 to March 2010. The results show that nighttime amplitude scintillations only took place in February and March of the considered years, while daytime amplitude scintillations occurred in August and December of 2009. Nighttime amplitude scintillations, observed in the south of Guilin, always occurred with phase scintillations, TEC (Total Electron Content) depletions, and ROT (Rate Of change of TEC) fluctuations. However, TEC depletions and ROT fluctuations were weak during daytime amplitude scintillations, and daytime amplitude scintillations always took place simultaneously for most of the GPS satellites which appeared over Guilin in different azimuth directions. Ground-based GPS scintillation/TEC observations recorded at Guilin and signal-to-noise-ratio (SNR) measurements obtained from GPS-COSMIC radio occultation indicate that nighttime and daytime scintillations are very likely caused by ionospheric F region irregularities and sporadic E, respectively. Moreover, strong daytime amplitude scintillations may be associated with the plasma density enhancements in ionospheric E region caused by the Perseid and Geminid meteor shower activities.

  7. 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.

  8. ULF cusp pulsations: Diurnal variations and interplanetary magnetic field correlations with ground-based observations

    SciTech Connect

    McHarg, M.G.; Olson, J.V.; Newell, P.T.

    1995-10-01

    In this paper the authors establish the Pc 5 magnetic pulsation signatures of the cusp and boundary regions for the high-latitude dayside cusp region. These signatures were determined by comparing spectrograms of the magnetic pulsations with optical observations of particle precipitation regions observed at the cusp. The ULF pulsations have a diurnal variation, and a cusp discriminant is proposed using a particular narrow-band feature in the pulsation spectrograms. The statistical distribution of this pattern over a 253-day period resembles the statistical cusp description using particle precipitation data from the Defense Meterological Satellite Program (DMSP). The distribution of the ground-based cusp discriminant is found to peak 1 hour earlier than the DMSP cusp distribution. This offset is due to the interplanetary magnetic field (IMF) being predominantly negative B{sub y} for the period when the data were collected. The authors find the diurnal variations so repeatable that only three main categories have statistically different IMF distributions. The identification of the signatures in the magnetic spectrograms of the boundary regions and central cusp allows the spectrogram to be used as a {open_quotes}time line{close_quotes} that shows when the station passed under different regions of the dayside oval. 36 refs., 11 figs., 1 tab.

  9. Observation of the Bottomonium Ground State in the Decay Y(3S) to ynb

    SciTech Connect

    Aubert, B.

    2008-07-11

    The authors report the results of a search for the bottomonium ground state {eta}{sub b}(1S) in the photon energy spectrum with a sample of (109 {+-} 1) million of {Upsilon}(3S) recorded at the {Upsilon}(3S) recorded at the {Upsilon}(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. They observe a peak in the photon energy spectrum at E{sub {gamma}} = 921.2{sub -2.8}{sup +2.1}(stat) {+-} 2.4(syst) MeV with a significance of 10 standard deviations. They interpret the observed peak as being due to monochromatic photons from the radiative transition {Upsilon}(3S) {yields} {gamma} {eta}{sub b}(1S). This photon energy corresponds to an {eta}{sub b}(1S) mass of 9388.9{sub -2.3}{sup +3.1}(stat) {+-} 2.7(syst) MeV/c{sup 2}. The hyperfine {Upsilon}(1S)-{eta}{sub b}(1S) mass splitting is 71.4{sub -3.1}{sup +2.3}(stat) {+-} 2.7(syst) MeV/c{sup 2}. The branching fraction for this radiative {Upsilon}(3S) decay is estimated to be (4.8 {+-} 0.5(stat) {+-} 1.2(syst)) x 10{sup -4}.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Temporal and spatial variations of pulsating auroras obtained from ground-based observations at Poker Flat Research Range: Initial result

    NASA Astrophysics Data System (ADS)

    Nishiyama, T.; Sakanoi, T.; Miyoshi, Y.; Kataoka, R.; Katoh, Y.; Asamura, K.; Sato, M.; Okano, S.

    2011-12-01

    Pulsating Aurora(PA) is characterized by the periodically changing emission amplitudes with the rectangular pulses of a few seconds to a few tens of seconds [e.g., Oguti et al., 1981; Yamamoto, 1988]. PAs tend to appear in the recovery phase of substorm between postmidnight and dawn sector. The horizontal size of PAs are known to be 10-200 km, based on the optical observations. Recently, some ground-satellite coordinated observations suggested the generation mechanisms of PAs as a result of pitch angle scatterings due to whistler mode chorus waves and/or the electron cyclotron harmonics[Nishimura et al., 2010; Liang et al., 2010]. Time-varying field aligned potential was also suggested by Sato et al. [2004]. The dominant mechanisms and the origin of the periodicity remain unclear. Ground-based all-sky observations have been made for a long time, although they were not enough for a quantitative discussion about small-scale characteristics of PAs such as the shapes and dynamics due to their limited spatial resolutions. The fast temporal variations of intensity known as quasi-3Hz modulations, which was reported by a number of rocket/satellite observations about precipitating electrons[e.g., Sandahl et al., 1980], has been hardly discussed in detail using the ground instruments because of the limited temporal resolutions and sensitivities. We have carried out ground-based observations using a suit of instruments, consisting of an EMCCD camera, an all-sky video camera, a photometer, and a search coil magnetometer covering the frequency range of ELF-VLF. We installed the instruments at Poker Flat Research Range between November 2010 and March 2011. Our EMCCD camera has narrow field of view corresponding to 100km × 100km at altitude of 110 km and high sampling rate up to 100 frames per second. An initial analysis result of event on March 4th 2011 around 1100UT revealed two important features of PAs in small scale. One is PAs in the FOV can be categorized into three

  15. Potential Seasonal Predictability of Water Cycle in Observations and Reanalysis

    NASA Astrophysics Data System (ADS)

    Feng, X.; Houser, P.

    2012-12-01

    Identification of predictability of water cycle variability is crucial for climate prediction, water resources availability, ecosystem management and hazard mitigation. An analysis that can assess the potential skill in seasonal prediction was proposed by the authors, named as analysis of covariance (ANOCOVA). This method tests whether interannual variability of seasonal means exceeds that due to weather noise under the null hypothesis that seasonal means are identical every year. It has the advantage of taking into account autocorrelation structure in the daily time series but also accounting for the uncertainty of the estimated parameters in the significance test. During the past several years, multiple reanalysis datasets have become available for studying climate variability and understanding climate system. We are motivated to compare the potential predictability of water cycle variation from different reanalysis datasets against observations using the newly proposed ANOCOVA method. The selected eight reanalyses include the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP/NCAR) 40-year Reanalysis Project (NNRP), the National Centers for Environmental Prediction-Department of Energy (NCEP/DOE) Reanalysis Project (NDRP), the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-year Reanalysis, The Japan Meteorological Agency 25-year Reanalysis Project (JRA25), the ECMWF) Interim Reanalysis (ERAINT), the NCEP Climate Forecast System Reanalysis (CFSR), the National Aeronautics and Space Administration (NASA) Modern-Era Retrospective Analysis for Research and Applications (MERRA), and the National Oceanic and Atmospheric Administration-Cooperative Institute for Research in Environmental Sciences (NOAA/CIRES) 20th Century Reanalysis Version 2 (20CR). For key water cycle components, precipitation and evaporation, all reanalyses consistently show high fraction of predictable variance in the tropics, low

  16. Observations and stochastic modelling of strong ground motions for the 2011 October 23 Mw 7.1 Van, Turkey, earthquake

    NASA Astrophysics Data System (ADS)

    Akinci, Aybige; Antonioli, Andrea

    2013-03-01

    The 2011 October 23 Van earthquake occurred at 13:41 local time in Eastern Turkey with an epicentre at 43.36oE, 38.76oN (Kandilli Observatory Earthquake Research Institute (KOERI)), 16 km north-northeast of the city of Van, killing around 604 people and leaving thousands homeless. This work presents an overview of the main features of the seismic ground shaking during the Van earthquake. We analyse the ground motion characteristics of the mainshock in terms of peak ground acceleration (PGA), peak ground velocity (PGV) and spectral accelerations (SA, 5 per cent of critical damping). In order to understand the characteristics of the ground motions induced by the mainshock, we also study the site response of the strong motion stations that recorded the seismic sequence. The lack of seismic recordings in this area imposes major constraints on the computation of reliable seismic hazard estimates for sites in this part of the country. Towards this aim, we have used a stochastic method to generate high frequency ground motion synthetics for the Mw 7.1 Van 2011 earthquake. The source mechanism of the Van event and regional wave propagation parameters are constrained from the available and previous studies. The selected model parameters are then validated against recordings. We also computed the residuals for the ground motion parameters in terms of PGA and PGV at each station and the model parameter bias by averaging the residuals over all the stations. The attenuation of the simulated ground motion parameters is compared with recent global and regional ground motion prediction equations. Finally, since it has been debated whether the earthquake of November 9 was an aftershock of the October 23 earthquake, we examine whether static variation of Coulomb stress could contribute to the observed aftershock triggering during the 2011 Van Lake sequence. Comparison with empirical ground motion prediction illustrated that the observed PGA data decay faster than the global

  17. 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.

  18. Decomposition of Pyruvic Acid on the Ground-State Potential Energy Surface.

    PubMed

    da Silva, Gabriel

    2016-01-21

    A potential energy surface is reported for isomerization and decomposition of gas-phase pyruvic acid (CH3C(O)C(O)OH) in its ground electronic state. Consistent with previous works, the lowest energy pathway for pyruvic acid decomposition is identified as decarboxylation to produce hydroxymethylcarbene (CH3COH), with overall barrier of 43 kcal mol(-1). This study discovers that pyruvic acid can also isomerize to the α-lactone form with a barrier of only 36 kcal mol(-1), from which CO elimination can occur at 49 kcal mol(-1) above pyruvic acid. An additional novel channel is identified for the tautomerisation of pyruvic acid to the enol form, via a double H-shift mechanism. The barrier for this process is 51 kcal mol(-1), which is around 20 kcal mol(-1) lower than the barrier for conventional keto-enol tautomerization via a 1,3-H shift transition state. Rate coefficients are calculated for pyruvic acid decomposition through RRKM theory/master equation simulations at 800-2000 K and 1 atm, showing good agreement with the available experimental data. The dissociation of vibrationally excited pyruvic acid produced through photoexcitation and subsequent internal conversion to the ground state is also modeled under tropospheric conditions and is seen to produce appreciable quantities of CO (∼1-4%) in addition to CH3COH via the dominant CO2 loss channel. PMID:26587666

  19. 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

  20. 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.

  1. Joint Cassini, Galileo and Ground-Based Infrared Observations of Jupiter's Atmosphere

    NASA Astrophysics Data System (ADS)

    Orton, G.; Fisher, B.; Barnard, L.; Edberg, S.; Martin, T.; Spilker, L.; Tamppari, L.; Ustinov, E.; Harrington, J.; Conrath, B.; Gierasch, P.; Deming, D.; Flasar, F. M.; Kunde, V.; Achterberg, R.; Bjoraker, G.; Brasunas, J.; Carlson, R.; Jennings, D.; Nixon, C.; Pearl, J.; Romani, P.; Samuelson, R.; Simon-Miller, A.; Smith, M.; Abbas, M.; Ade, P.; Barucci, A.; Bezard, B.; Courtin, R.; Coustenis, A.; Gautier, D.; Lellouch, E.; Marten, A.; Calcutt, S.; Irwin, P.; Read, P.; Taylor, F.; Owen, T.; Cesarsky, C.; Ferrari, C.; Meyer, J. P.; Travis, L.; Coradini, A.; Prangee, R.; Grossman, K.; Spencer, J.

    2001-11-01

    During the simultanous Galileo and Cassini encounter with Jupiter in December, 2000, and January, 2001, data on its atmosphere were obtained simultaneously by (1) Galileo's Photopolarimeter-Radiometer (PPR) at 27 microns, (2) Cassini's Composite Infrared Spectrometer (CIRS) between 7 and 16 microns, and (3) ground-based imaging from the NASA IRTF between 5 and 24 microns. These data sets mapped temperature structure, minor and trace constituent abundances and the NH3 condensate cloud field. Features observed by the three sets of data included the Great Red Spot (GRS), the merged white oval ``BA'', and 5-micron hot spots. In addition, the IRTF data provided (a) contextual information for planetary-scale and regional phenomena, such as thermal waves and polar airmasses, as well as (b) a study of the evolution of various phenomena. The GRS remains the coldest feature in Jupiter's upper troposphere at temperate or equatorial latitudes, and it is consistent with an upwelling cyclonic vortex. A warm region remains semi-permanently associated with it to the south. Little thermal variability is detectable that can be associated with the 5-micron hot spots. Jupiter exhibits seasonal variability in its stratosphere, and the ``quasiquadrennial oscillation'' of the last 12 years dominates the time variability of the stratosphere. Greater than normal abundances of NH3 gas are associated with regions of substantial cloudiness. The meridional variability of zonally averaged para-H2 abundances is similar to that observed by Voyager IRIS at Jupiter; it is more abundant in the Great Red Spot than in surrouding regions. Implications of these and other observations will be discussed. This work was supported by NASA grants to JPL, GSFC and Cornell, as well as the Galileo and Cassini projects.

  2. 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.

  3. The volatile composition of comet 103P/Hartley 2 from ground-based radio observations

    NASA Astrophysics Data System (ADS)

    Gicquel, Adeline; Milam, S. N.; Remijan, A. J.; Chuang, Y.; Kuan, Y.; Coulson, I. M.; Villanueva, G.; Charnley, S. B.; Cordiner, M. M.

    2013-10-01

    103P/Hartley 2 (103P) is a Jupiter-family comet which has a short orbital period (6.5 years) and perihelion at 1.06 AU. 103P was discovered on 4 June 1984 by Malcolm Hartley at the Siding Spring Observatory and has been frequently observed over the 20 years following its discovery, both by ground-based and space telescopes. Observation from 1991 and 1997 indicated a maximum water production rate of 3 x 10^28 molecules/s. 103P passed perihelion on 28 October 2010 at q = 1.059 AU. It made an exceptional close approach to the Earth just before perihelion on 21 October 2010 at Δ = 0.12 AU. On UT 2010 November 4.58, the comet was visited by NASA’s EPOXI spacecraft with a flyby at 700 km. As part of an ongoing investigation to establish the contribution of the natal molecular cloud from which the solar system was formed to primitive materials and comets, we have been conducting observations toward the comet 103P to determine taxonomy and cosmogonic quantities, such as the ortho:para ratio and isotope ratios. Here we report detections of HCN, H2CO, CS, and OH and upper limits on HNC and DCN toward comet 103P, using the Arizona Radio Observatory Kitt Peak 12m (12m) and submillimeter telescopes (SMT), the James Clerk Maxwell Telescope (JCMT) and the Greenbank Telescope (GBT). From these data physical parameters such as temperature, column densities, and production rates have been determined toward comet 103P. The ortho:para ratio has been derived from H2CO. We used the JCMT data to compute the D/H ratio from DCN and HCN. Here we present our analysis and discuss the origin of volatiles in cometary material.

  4. 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.

  5. Validation of NH3 satellite observations by ground-based FTIR measurements

    NASA Astrophysics Data System (ADS)

    Dammers, Enrico; Palm, Mathias; Van Damme, Martin; Shephard, Mark; Cady-Pereira, Karen; Capps, Shannon; Clarisse, Lieven; Coheur, Pierre; Erisman, Jan Willem

    2016-04-01

    Global emissions of reactive nitrogen have been increasing to an unprecedented level due to human activities and are estimated to be a factor four larger than pre-industrial levels. Concentration levels of NOx are declining, but ammonia (NH3) levels are increasing around the globe. While NH3 at its current concentrations poses significant threats to the environment and human health, relatively little is known about the total budget and global distribution. Surface observations are sparse and mainly available for north-western Europe, the United States and China and are limited by the high costs and poor temporal and spatial resolution. Since the lifetime of atmospheric NH3 is short, on the order of hours to a few days, due to efficient deposition and fast conversion to particulate matter, the existing surface measurements are not sufficient to estimate global concentrations. Advanced space-based IR-sounders such as the Tropospheric Emission Spectrometer (TES), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) enable global observations of atmospheric NH3 that help overcome some of the limitations of surface observations. However, the satellite NH3 retrievals are complex requiring extensive validation. Presently there have only been a few dedicated satellite NH3 validation campaigns performed with limited spatial, vertical or temporal coverage. Recently a retrieval methodology was developed for ground-based Fourier Transform Infrared Spectroscopy (FTIR) instruments to obtain vertical concentration profiles of NH3. Here we show the applicability of retrieved columns from nine globally distributed stations with a range of NH3 pollution levels to validate satellite NH3 products.

  6. Ground satellite observations of Pc 1 magnetic pulsations in the plasma trough

    SciTech Connect

    Hansen, H.J.; Fraser, B.J.; Menk, F.W.

    1995-05-01

    An analysis of concurrent Pc 1 pulsation activity (0.2-0.6 Hz) recorded on the ground at Mawson, Antarctica (70{degrees}S magnetic latitude (MLAT); 19{degrees}E magnetic longitude (MLONG); L=8), and on board the Viking polar-orbiting satellite, when the spacecraft was located near apogee (13.5x10{sup 3} km) from 50-77{degrees} MLAT above the northern ionosphere, shows that simultaneous pulsation were observed only when Viking`s conjugate point was within 60-70{degrees}S MLAT and 30{degrees}E-33{degrees}W MLONG, an extent of about 1000 km in latitude and 1700 km in longitude. Spectral analysis confirms that the waves responsible for these pulsations are electromagnetic ion cyclotron (EMIC) waves that have propagated to the spacecraft and ground from the geomagnetic equator. For the intervals when the waves were on field lines above and equatorward of Mawson, convective EMIC wave modeling shows wave growth is dominant below the equatorial He{sup +} gyrofrequency. Waves generated on field lines poleward of Mawson exhibit frequencies above the equatorial He{sup +} gyrofrequency. These propagate to Mawson, most likely through a purely proton plasma rather than a multi-ion environment. Frequency shifts in the Pc 1 activity at Mawson appear to be directly linked to solar wind velocity and flux variations measured by IMP 8. For certain intervals these linked observations are consistent with an interpretation based on the velocity and flux changes altering the radial position of the magnetopause through pressure balance considerations. This, in turn, changes the magnitude of the ambient magnetic field in the equatorial plasma trough and consequently the ion gyrofrequency and EMIC growth rate. The changes in the temperature anisotropy and energy of the resonant ions in the plasma trough, which are causing the Pc 1 emission changes, are associated with the entry of dayside Pc 3-5 pulsation energy into the dayside magnetosphere. 47 refs., 13 figs., 1 tab.

  7. 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

  8. First geophysical observations in Sahara by ground-based Lidar and CALIPSO

    NASA Astrophysics Data System (ADS)

    Cuesta, J.; Edouart, D.; Flamant, P. H.; Flamant, C.

    2006-12-01

    Saharan dust 3D spatial distribution and optical/microphysical properties are essential in understanding of Saharan desert radiative budget. Dust properties influence Saharan heat low deepening which, in turn, is believed to affect climate, particularly the West African Monsoon. Moreover, the Saharan desert regroups the world largest dust sources. In order to improve our current knowledge on Saharan dust as well as Saharan heat low dynamics, a new synergetic approach of a ground-based platform TReSS (Transportable Remote Sensing Station) and CALIPSO satellite has been implemented. TReSS has been deployed in Tamanrasset (Algeria) from February to November 2006, in the framework of the AMMA experience. TReSS is an autonomous and high-performance system designed to observe radiative and structural properties of aerosol layers and clouds, as well as atmospheric boundary layer (ABL) dynamics. The TReSS payload includes a multi-wavelength elastic/Raman backscatter Mini-Lidar, a sun-photometer and two IR radiometers. Retrieval of aerosol extinction and backscatter coefficient profiles includes several new techniques. Firstly, a new "Two-stream" lidar inversion method has been developed which independently retrieves aerosol extinction and backscatter coefficients profiles, therefore providing the proportionality coefficient or "lidar ratio" with altitude. Observations of two opposite-aiming backscatter lidar systems are combined: CALIOP (CALIPSO) and the Mini-Lidar (TReSS). This presentation provides a comparison between Two-stream inverted CALIPSO level 1 data and climatological data. Secondly, nexus between aerosol vertical distribution and optical/microphysical properties is investigated through a new "Lidar & Almucantar synergy" method. It combines vertical information contained in backscatter Lidar soundings and column-integrated aerosol optical/microphysical properties retrieved by sun photometer "Almucantar" inversion. This new algorithm provides a unique

  9. Correlations between potentials and observables in the NN interaction

    NASA Astrophysics Data System (ADS)

    Pauss, F.; Mathelitsch, L.; Côté, J.; Lacombe, M.; Loiseau, B.; Vinh Mau, R.

    1981-08-01

    We study the effects of the components of the soft-core and velocity-dependent Paris nucleon-nucleon potential on the scattering observables for laboratory energies, TL, between 10 and 350 MeV. Knowledge of these correlations is useful to indicate constraints on components of the nucléon-nucléon force. The velocity-dependent component, attractive at low energy and repulsive at high energy, plays a role at all energies. The polarisation P, the depolarisation D and the parameters Dt, A, R, CKP and CNN are good tests for the tensor, spin-orbit and, to a smaller extent, quadratic spin-orbit forces. The isovector tensor force contribution is important at low energy and that of the isovector spin-orbit at high energy. The isoscalar tensor force effect is large at all energies and that of the isoscalar spin-orbit force rather small. The potential without quadratic spin-orbit term reproduces well the experimental data for TL < 150 MeV.

  10. Hubble flows and gravitational potentials in observable Universe

    SciTech Connect

    Eingorn, Maxim; Zhuk, Alexander E-mail: ai.zhuk2@gmail.com

    2012-09-01

    In this paper, we consider the Universe deep inside of the cell of uniformity. At these scales, the Universe is filled with inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies), which disturb the background Friedmann model. We propose mathematical models with conformally flat, hyperbolic and spherical spaces. For these models, we obtain the gravitational potential for an arbitrary number of randomly distributed inhomogeneities. In the cases of flat and hyperbolic spaces, the potential is finite at any point, including spatial infinity, and valid for an arbitrary number of gravitating sources. For both of these models, we investigate the motion of test masses (e.g., dwarf galaxies) in the vicinity of one of the inhomogeneities. We show that there is a distance from the inhomogeneity, at which the cosmological expansion prevails over the gravitational attraction and where test masses form the Hubble flow. For our group of galaxies, it happens at a few Mpc and the radius of the zero-acceleration sphere is of the order of 1 Mpc, which is very close to observations. Outside of this sphere, the dragging effect of the gravitational attraction goes very fast to zero.

  11. 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.

  12. An over view of ground-based electromagnetic observations addressed to seismo- electromagnetism in Japan

    NASA Astrophysics Data System (ADS)

    Nagao, T.

    2007-12-01

    Almost all through the human history, electromagnetic (EM) phenomena associated with earthquakes (EQ) have been repeatedly reported. Especially 1995 Kobe earthquake brought a great impact to the earthquake prediction studies in Japan. After this devastating event, Science and Technology Agency (STA) decided to initiate five year programs of Earthquake Frontier Program which included RIKEN/NASDA's subprograms. Both subprograms addressed to the short-term earthquake prediction research by using the electromagnetic methods, and the main objective was to attain comprehensive understanding of the pre-, co- and post seismic EM phenomena related to EQs. Both projects produced many appraisable results. However, there is still a long way to go, physics of DC to ULF/ELF signal generation/transmission and so on. We now consider that EQ related EM signals may be classified into two major groups. One is EM signals supposedly emitted from the focal zone and the other is anomalous transmission of EM waves over the epicentral region. Of-course, to establish the science of seismo-EM phenomena, we need continued efforts to collect and accumulate more data on one hand and to advance basic physics on the other. In the presentation, we briefly summarize the current status of ground-based EM measurements from ULF to VHF ranges in Japan (DC-ULF geoelectric potential difference, ULF, ELF and VLF three-component magnetic, VLF, LF and VHF anomalous transmission of radio waves, etc.) and propose the future direction (tactics) of EQ- related EM study in Japan.

  13. Space borne GPM dual-frequency radar simulation from high resolution ground radar observations.

    SciTech Connect

    Rose, C. R.; Chandrasekar, V.

    2004-01-01

    The Global Precipitation Measurement (GPM) mission is dedicated to improving the understanding of the global water cycle by measuring and mapping precipitation throughout the globe. The core GPM satellite will incorporate two separate precipitation radars: one operating at Ku-band (13.6 GHz) and the other at Ka band (35.6 GHz). Each radar beam will be steered such that they both point to the same location in the atmosphere. The main purpose of the dual-frequency radar system is to resolve the DSD in precipitation as well as discriminate between rain and ice. With the two beams collocated on the same precipitation volume, new algorithms are being developed to reliably es timate attenuation and rain rate. Any algorithm is based on models of precipitation. In addition, the GPM system assumes collocated beams and matched resolu tion volumes. Electromagnetic and microphysical models have been developed based on ground-based dual-frequency radar data at S-band to simulate Ku- and Ka-band results for comparison with the new GPM algorithms. This paper evaluates the dual-frequency inversion algorithm with synthesized S-band and known perfect data and presents results. Results show the expected performance of the new dual-precipitation radar algorithms with the potential for guiding algorithm and system improvements.

  14. 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.

  15. Use of Ground Imagery to Study Wood Raft and Ice Dynamics in Fluvial Systems: Potential and Challenges.

    NASA Astrophysics Data System (ADS)

    Benacchio, V.; Piegay, H.; Buffin-Belanger, T. K.; Vaudor, L.; Michel, K.

    2014-12-01

    Automatic cameras allow acquisition of large amounts of information at high resolution in both temporal and spatial dimensions, with a roughly close range. Recently, ground cameras have been used to study the morphological evolution of fluvial environments (e.g. bank erosion, bar mobility, braided pattern changes) or to quantify components of fluvial dynamics (e.g. flow velocity, wood transport or river ice development). As the amount of information increases, automation of the data processing becomes essential, but many challenges arise to improve features detection, taking into account light contrasts, shadow and reflection, or to calculate surfaces and volumes from image orthorectification. This study illustrates the high potential of ground cameras to observe and quantify rapid, stochastic or complex events in fluvial systems and the numerous challenges we have to face. In order to automatically monitor such key fluvial processes, two ground cameras were installed. The first one was placed on the Genissiat dam (Rhône River, France) focusing on the reservoir where pieces of wood are trapped, creating a large raft. The objective is to survey wood raft area over time as a surrogate of the basin wood production. The second camera was installed along the St Jean River (Gaspesia, Québec) focusing on a pool section. The objective here is to characterize the evolution of ice cover, in terms of growing rate and ice types. The snowy environment is particularly challenging because of brightness or fairly homogeneous radiometric conditions amongst ice types. In both cases, remote sensing technics, especially feature based classification are used. Radiometric and texture indexes are used to discriminate both wood and water and ice types.

  16. 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.

  17. Ground-Based Observations of Io's Volcanos in Support of the Galileo Mission

    NASA Astrophysics Data System (ADS)

    Spencer, J. R.; Stansberry, J. A.; Dumas, C.; Vakil, D.

    1996-09-01

    We have obtained frequent 1.7--4.8 mu m observations of Io's volcanic thermal emission in 1995 and 1996, from the NASA IRTF on Mauna Kea and from Lowell Observatory. In 1995 there were several dramatic volcanic events, including major outbursts on the leading hemisphere in March and September 1995; one of Loki's periodic brightenings during the Fall of 1995, in the months before the Galileo Io flyby; and three high-temperature events of a few weeks' duration (in late March, July, and August) on the Jupiter-facing hemisphere. In contrast, intensive monitoring in 1996 has shown no bright volcanic events at all between early February and mid-August. High-quality IRTF observations in June 1996, near the time of the first Galileo images at the "G1" encounter, provided fluxes and locations for up to 11 faint hot spots on the Jupiter-facing hemisphere. Due to the loss of Galileo G1 NIMS and PPR Io observations, these and other ground-based observations provided our only information on Io's volcanic thermal emission at the time that the Galileo images were taken. Notable features of the volcanic emission at the G1 encounter included the following: (i) Loki's thermal emission was at the faint end of its normal range. Its 3.5 mu m flux was about 6 GW mu m(-1) str(-1) , compared to about 34 GW mu m(-1) str(-1) at the time of the Voyager 1 flyby (Pearl and Sinton 1982), and about 70 GW mu m(-1) str(-1) during the winter 1991 Loki brightening (Spencer et al. 1994). (ii) No 3.5 mu m emission was seen from Ra Patera, the site of a plume seen by Galileo, with an upper flux limit of about 1 GW mu m(-1) str(-1) . This suggests that the current Ra plume eruption is from a low-temperature source: cooler than 370 K for a source diameter of 20 km, for example. (iii) A small burst of thermal emission from Surt, with a 3.5 mu m flux of 5 GW mu m(-1) str(-1) , was seen in early and late June. Surt is not normally a site of detectable emission in groundbased observations, though it may have

  18. Tropospheric nitrogen dioxide column retrieval based on ground-based zenith-sky DOAS observations

    NASA Astrophysics Data System (ADS)

    Tack, F. M.; Hendrick, F.; Pinardi, G.; Fayt, C.; Van Roozendael, M.

    2013-12-01

    A retrieval approach has been developed to derive tropospheric NO2 vertical column amounts from ground-based zenith-sky measurements of scattered sunlight. Zenith radiance spectra are observed in the visible range by the BIRA-IASB Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument and analyzed by the DOAS technique, based on a least-squares spectral fitting. In recent years, this technique has shown to be a well-suited remote sensing tool for monitoring atmospheric trace gases. The retrieval algorithm is developed and validated based on a two month dataset acquired from June to July 2009 in the framework of the Cabauw (51.97° N, 4.93° E) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). Once fully operational, the retrieval approach can be applied to observations from stations of the Network for the Detection of Atmospheric Composition Change (NDACC). The obtained tropospheric vertical column amounts are compared with the multi-axis retrieval from the BIRA-IASB MAX-DOAS instrument and the retrieval from a zenith-viewing only SAOZ instrument (Système d'Analyse par Observations Zénithales), owned by Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). First results show a good agreement for the whole time series with the multi-axis retrieval (R = 0.82; y = 0.88x + 0.30) as well as with the SAOZ retrieval (R = 0.85; y = 0.76x + 0.28 ). Main error sources arise from the uncertainties in the determination of tropospheric and stratospheric air mass factors, the stratospheric NO2 abundances and the residual amount in the reference spectrum. However zenith-sky measurements have been commonly used over the last decades for stratospheric monitoring, this study also illustrates the suitability for retrieval of tropospheric column amounts. As there are long time series of zenith-sky acquisitions available, the developed approach offers new perspectives with regard to the use of observations from the NDACC

  19. 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

  20. 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.

  1. Ground-Based Observations of Saturn's North Polar Spot and Hexagon.

    PubMed

    Sanchez-Lavega, A; Lecacheux, J; Colas, F; Laques, P

    1993-04-16

    Ground-based observations of two conspicuous features near the north pole of Saturn, the polar vortex and the hexagonal wave structure, were made from July 1990 to October 1991, 10 years after their discovery. During this period the polar spot drifted in longitude, relative to system III, by -0.0353 degrees per day on average. Superimposed on this mean motion, the spot also underwent short-term rapid excursions in longitude of up to approximately 14 degrees at rates of up to approximately 1 degrees per day. The spot also exhibited irregular variations in its latitude location. A combination of these data together with those obtained by Voyager 1 and 2 in 1980 and 1981 shows that the spot drifted -0.0577 degrees per day for the 11-year interval from 1980 to 1991. The large lifetime of both features indicates that they are insensitive to the strong variations in the seasonal heating of the cloud layers in the upper polar atmosphere. PMID:17838249

  2. Monitoring Ground Deformation in Taiyuan Basin (China) with PS-InSAR and Continuous GPS Observation

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Liao, Mingsheng; Zhang, Lu; Balz, Timo; Yuan, Peng; Qin, Changwei

    2014-11-01

    Since the late 1950s, several areas of the Taiyuan basin have undergone accelerated ground subsidence and have developed associated fracturing and faulting. Through a combined analysis of GPS position time series from 2009.3438 to 2013.3109 for 5 reference stations and thousands of observations of InSAR persistent scatterers using ENVISAT-ASAR images from 2009.0849 to 2010.7150, we determine that the maximum subsidence rate at the study area is 80 mm/yr. Taiyuan city subsided at a rate of 15-20 mm/yr, in contrast to previous studies in the last decade of the 20th Century suggesting that the subsidence have become stabilized. Comparison to the independent GPS data indicates RMS agreement between the two techniques of 5.7 mm/yr. The main cause of subsidence is due to the long-term overexploitation of groundwater and coal-mining, so that our results could provide scientific evidence to improve the management of groundwater and coal exploitation in this area.

  3. 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.

  4. High Resolution Observations of Drop Size Distribution for GPM Ground Validation

    NASA Technical Reports Server (NTRS)

    Gatlin, Patrick N.; Petersen, W. A.; Carey, L. D.; Wingo, M. T.; Tokay, A.; Bringi, V. N.; Thurai, M.; Wolff, D. B.; Phillips, D. W.

    2012-01-01

    During the Mid-latitude Continental Convective Cloud Experiment (MC3E), NASA's GPM GV Disdrometer and Radar Observations of Precipitation (DROP) Facility deployed an array of disdrometers and rain gauges in northern Oklahoma to sample, with high resolution, the drop size distribution for use in development of precipitation retrieval algorithms for the GPM core satellites. The DROP Facility instruments deployed during MC3E consisted of 16 autonomous Parsivel units, 5 two-dimensional video disdrometers (2dvds), a vertically pointing K band radar, and 32 tipping bucket rain gauges. There were several rainfall events during MC3E in which rain drops exceeding 6 mm in diameter were recorded. The disdrometer array revealed large rain drops with diameters exceeding 6 mm and 8 mm during two separate stratiform and convective rainfall events, respectively. The NPOL radar, which was scanning in high resolution RHI mode (every 40 sec) over the disdrometer array during the stratiform event, indicated a 1 km thick bright band with a differential reflectivity column of 2-3 dB extending below the melting layer to the surface where the large drops were recorded by the 2dvds. These large drops are important for GPM since they can have a great impact upon satellite precipitation retrieval, especially near the ground and below heavy convective rainfall cores where satellites have had problems depicting the rainfall.

  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-based observations of Saturn's north polar SPOT and hexagon

    NASA Astrophysics Data System (ADS)

    Sanchez-Lavega, A.; Lecacheux, J.; Colas, F.; Laques, P.

    1993-04-01

    Ground-based observations of two conspicuous features near the north pole of Saturn, the polar vortex and the hexagonal wave structure, were made from July 1990 to October 1991, 10 yrs after their discovery. During this period the polar spot drifted in longitude, relative to system III, by -0.0353 deg/day on average. Superimposed on this mean motion, the spot also underwent short-term rapid excursions in longitude of up to about 14 deg at rates of up to about 1 deg/day. The spot also exhibited irregular variations in its latitude location. A combination of these data together with those obtained by Voyager 1 and 2 in 1980 and 1981 shows that the spot drifted -0.0577 deg/day for the 11-yr interval from 1980 to 1991. The large lifetime of both features indicates that they are insensitive to the strong variations in the seasonal heating of the cloud layers in the upper polar atmosphere.

  7. Comparison Of Dawn, Hubble Space Telescope, And Ground-based Observations Of Vesta: What We Learned So Far?

    NASA Astrophysics Data System (ADS)

    Reddy, Vishnu; Li, J.; Le Corre, L.; Russell, C. T.; Scully, J. E. C.; Becker, K. J.; Park, R.; Gaskell, R.; Gaffey, M. J.; Nathues, A.

    2012-10-01

    NASA’s Dawn spacecraft observations of asteroid Vesta have revealed a surface that shows highest diversity in albedo, color and composition than any asteroid visited by a spacecraft so far. Ground-based and HST observations of Vesta showed hemispherical and rotational variations attributed to igneous and impact processes that have shaped Vesta’s surface since its formation. Here we compare interpretation of Vesta’s rotation period, pole position, albedo, topography, color and compositional properties from ground-based telescopes, HST and Dawn. Our goal is to provide ground truth for prior observations and help identify the limits of ground/HST-based studies of asteroids. We also present HST and Dawn albedo and color maps of Vesta in the Claudia (used by the Dawn team) and IAU (similar to Thomas et al. 1997) coordinate systems. These maps should help observers orient themselves and identify compositional and albedo features from prior studies. We have linked several albedo features identified on HST maps to morphological features on Vesta using Dawn Framing Camera data. Rotational spectral variations observed from ground-based studies are also consistent with those observed by Dawn. While past interpretation of some of these features was tenuous, they were reasonable for the limitations set by the data and our knowledge of Vesta and HED meteorites at that time. Our analysis shows ground-based and HST observations are critical for our understanding of small bodies and provide valuable support ongoing and future spacecraft missions. This research was supported by NASA Dawn Participating Scientist Program Grant NNX10AR22G-DAVPS, and NASA Planetary Geology and Geophysics Grant NNX07AP73G.

  8. Saturn's Hydrocarbon Emission from Ground-based and Cassini/CIRS Observations

    NASA Astrophysics Data System (ADS)

    Hesman, Brigette E.; Jennings, D. E.; Sada, P. V.; Bjoraker, G. L.; Simon-Miller, A. A.; Nixon, C. A.; Boyle, R. J.; McCabe, G. H.

    2007-10-01

    Hydrocarbons in the upper atmosphere of Saturn are known, from Voyager and early Cassini results, to vary in emission intensity with latitude. Of particular interest is the marked increase in temperature and hydrocarbon line intensity near the South Pole (Greathouse et al. 2005, Orton and Yanamandra-Fisher, 2005, Flasar et al. 2005). Latitudinal variations in hydrocarbon abundances can be determined from measurements of hydrocarbon emission lines using temperatures derived from Cassini's Composite InfraRed Spectrometer (CIRS). Latitudinal, temporal, and vertical variations of stratospheric hydrocarbons provide constraints on dynamics, seasonal climate models, and photochemical models. In an effort to monitor temporal and latitudinal variations of hydrocarbons in Saturn's southern hemisphere we are conducting a ground-based campaign using Celeste, an infrared (5-25 μm) high-resolution (<0.1 cm-1) cryogenic grating spectrometer. From 2005 to 2007, we have been mapping lines of ethane and acetylene at the McMath-Pierce telescope at Kitt Peak, AZ and the NASA Infrared Telescope Facility at Mauna Kea, HI. These observations are complemented by the Cassini CIRS hydrocarbon observations. Specifically, Celeste measurements at the IRTF in October 2006 are being combined with 3cm-1 spectral resolution CIRS measurements to infer molecular abundances for each species in the 1-10 mbar region across the southern hemisphere of Saturn. These results will be presented. This research was supported by a NASA Postdoctoral Program Fellowship appointment conducted at the Goddard Space Flight Center. This research is currently supported by the NASA Planetary Astronomy Program. References: Flasar et al., (2005) Science 307, 1247. Greathouse et al., (2005) Icarus 177, 18 Orton and Yanamandra-Fisher, (2005) Science 307, 696.

  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. 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

  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. 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).

  13. WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team

    NASA Astrophysics Data System (ADS)

    Robertson, Brant

    The Wide-Field InfraRed Survey Telescope (WFIRST) holds tremendous promise as a space observatory for extragalactic astrophysics beyond cosmological surveys. The WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team will identify the most pressing and scientifically compelling Guest Investigator and Guest Observer projects with WFIRST to address a range of exciting outstanding issues in galaxy formation, from the epoch of reionization to galaxy-galaxy lensing, the discovery of exotic supernovae and luminous active galaxies, and charting the chemical evolution of galaxies. The identified EXPO GI projects will help maximize the scientific return of the WFIRST cosmological surveys, and supply innovative ideas and methods for archival research that leverages the WFIRST dataset. The EXPO team will also evaluate the science payoff of translating previous successful space telescope surveys to the era of WFIRST, helping us to realize the full power of WFIRST for extragalactic astronomy through the competed GO programs. The WFIRST-EXPO team consists of world-wide experts in designing and executing space-based extragalactic programs, multi-object spectroscopic campaigns in the optical and infrared, and theoretical modeling of galaxy formation, exotic supernovae, and reionization. In support of WFIRST before Critical Design Review, WFIRST-EXPO will 1) develop and publicly release tools to generate mock catalogs for planning extragalactic astrophysics investigations with the HLS (GI) and GO community programs, 2) simulate images for modeling medium- and ultra-deep extragalactic GO programs, 3) develop and publicly release work flows for planning and evaluating the science return of potential extragalactic GI/GO programs, 4) perform case studies of medium- and ultra-deep imaging and spectroscopic GO/GI programs, 5) evaluate WFIRST design choices that influence extragalactic science return, and 6) serve as liaisons to James Webb Space Telescope, Large

  14. 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

  15. 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. PMID:24912224

  16. The ground-state potential energy curve of the radium dimer from relativistic coupled cluster calculations.

    PubMed

    Teodoro, Tiago Quevedo; Haiduke, Roberto Luiz Andrade; Dammalapati, Umakanth; Knoop, Steven; Visscher, Lucas

    2015-08-28

    The potential energy curve for the ground-state of radium dimer (Ra2) is provided by means of atomic and molecular relativistic coupled cluster calculations. The short-range part of this curve is defined by an equilibrium bond length of 5.324 Å, a dissociation energy of 897 cm(-1), and a harmonic vibrational frequency of 20.5 cm(-1). The asymptotic behavior at large interatomic distances is characterized by the van der Waals coefficients C6 = 5.090 × 10(3), C8 = 6.978 × 10(5), and C10 = 8.786 × 10(7) atomic units. The two regions are matched in an analytical potential to provide a convenient representation for use in further calculations, for instance, to model cold collisions between radium atoms. This might become relevant in future experiments on ultracold, optically trapped, radioactive radium atoms that are used to search for a permanent electric dipole moment. PMID:26328843

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  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. 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.

  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. Temporal Variations of Yellowstone Ground Deformation, 2004-2011, from Geodetic Observations and Magmatic Source Modeling

    NASA Astrophysics Data System (ADS)

    Chang, W.; Smith, R. B.; Farrell, J.; Puskas, C.

    2011-12-01

    In mid-2004, GPS and InSAR measurements of Yellowstone revealed the initiation of accelerated uplift of the Yellowstone caldera, with maximum rates of ~7 cm/yr near the Sour Creek resurgent dome in the northeastern caldera. From mid-2006 to 2010, the ground uplift rates declined in two distinct phases: in 2006-2009 from 7 to 5 cm/yr in the northeast caldera and from 4 to 2 cm/yr in the southwest, and in 2009-2010 to 2 cm/yr and 0.5 cm/yr at the same areas. Elastic dislocation modeling of the GPS and InSAR data suggest that magmatic intrusions at 7- 10 km beneath the caldera have been responsible for the uplift, and that a decreasing rate of magmatic replenishment from beneath the northeast caldera and an increase of seismic moment release can plausibly account for reduced rates of caldera uplift. Furthermore, geodetic measurements, including three campaign-mode GPS surveys from 2008 to 2010, revealed that the caldera-wide vertical motion reverted to subsidence in 2010, with an average rate of 2-3 cm/yr (see the attached figure). The initiation of the reversal in vertical deformation was coincident with the occurrence of a large earthquake swarm (a total moment of ~3×1022 dyne-cm) that occurred in January 2010 at the northwestern caldera boundary. With new geodetic measurements in 2011, we expect to present key information for decadal-scale observations and modeling of the Yellowstone caldera deformation that provide insight on temporal variations in the context of Yellowstone magma reservoir replacement and transport.

  6. 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.

  7. Exploring light rain in the trades as observed by satellite- and ground-based remote sensing

    NASA Astrophysics Data System (ADS)

    Burdanowitz, Jörg; Nuijens, Louise; Klepp, Christian; Stevens, Bjorn

    2013-04-01

    Satellite climatologies are usually expected to have difficulties to properly capture light rain from shallow marine clouds due to limited spatiotemporal resolution. In order to evaluate this, ground-based radar data from the RICO (Rain in Cumulus clouds over the Ocean) campaign is compared with rainfall estimates of three different satellite climatologies over the subtropical North Atlantic. In particular, these satellite products are the Hamburg Ocean Atmosphere Parameters and fluxes from Satellite data (HOAPS), the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and the Global Precipitation Climatology Project (GPCP). Different footprint sizes and temporal resolutions among the used satellite products require an up-scaling of the data to facilitate a fair comparison. Apart from that, recent micro rain radar data from the Barbados Cloud Observatory (BCO) is analyzed to further explore the nature of light rain over the subtropical ocean at a higher temporal resolution. In the trades, the dominance of light rain, i.e. low rain intensities, is ubiquitous as previously observed in several field studies. However, some of them even seem to be conservative in their estimation of light rain contribution to total rainfall according to recent BCO measurements. For active and passive satellite sensors the light rain detection still remains a challenging task. However, as main result, satellite products showed to be partly able to resolve light rain events from shallow clouds during RICO. HOAPS detects most and GPCP least of them while TMPA performs similarly to HOAPS. But along a mean trade-wind trajectory starting at the Canaries, TMPA detects less light rainfall compared to HOAPS, especially in the Caribbean region. Currently collected ship-based rain data sets will be used to further evaluate the performance of HOAPS and TMPA over larger areas of the subtropical Atlantic.

  8. Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; O'Connor, E. J.; Komppula, M.; Korhonen, K.; Pfüller, A.; Giannakaki, E.; Wood, C. R.; Bauer-Pfundstein, M.; Poikonen, A.; Karppinen, T.; Lonka, H.; Kurri, M.; Heinonen, J.; Moisseev, D.; Asmi, E.; Aaltonen, V.; Nordbo, A.; Rodriguez, E.; Lihavainen, H.; Laaksonen, A.; Lehtinen, K. E. J.; Laurila, T.; Petäjä, T.; Kulmala, M.; Viisanen, Y.

    2013-08-01

    The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds, and Trace gases Research InfraStructure Network (ACTRIS); a Ka-band Doppler cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, POLLYXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (European Aerosol Research Lidar Network to Establish an Aerosol Climatology). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We carried out two inter-comparison campaigns to investigate the Doppler lidar performance. The aims of the campaigns were to compare the backscatter coefficient and retrieved wind profiles, and to optimise the lidar sensitivity through adjusting the telescope focus and data-integration time to ensure enough signals in low-aerosol-content environments. The wind profiles showed good agreement between different lidars. However, due to inaccurate telescope focus setting and varying receiver sensitivity, backscatter coefficient profiles showed disagreement between the lidars. Harsh Finnish winters could pose problems, but, due to the built-in heating systems, low ambient temperatures had no, or only a minor, impact on the lidar operation: including scanning-head motion. However, accumulation of snow and ice on the lens has been observed, which can lead to formation of a water/ice layer thus attenuating the signal inconsistently

  9. 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

  10. 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

  11. 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.

  12. 73P/Schwassmann-Wachmann 3-B observed from the optical ground station

    NASA Astrophysics Data System (ADS)

    Ho, T.-M.; Schulz, R.; Erd, C.; Martin, D.; Oosterbroek, T.; Peacock, A.; Stankov, A.; Stuewe, J.; Verhoeve, P.

    2008-01-01

    Aims:In 2006 comet 73P/Schwassmann-Wachmann 3, which split in 1995 into five pieces, approached the Sun again with a swarm of new fragments. The same year in May, the conglomerate of sub-fragments from the original fragment B was observed with the S-Cam3 instrument mounted on the 1-m ESA Optical Ground Station (OGS) telescope in Tenerife, Spain. With a total FOV of ~876 km × 730 km and a spatial resolution of ~73 km/pixel, the S-Cam3 observations provided the possibility to examine dust fragmentation processes, as well as dust and gas outflow, within the first few hundred kilometres of the sub-fragment surfaces. Methods: The superconducting camera, S-Cam3, is an ultra-fast photon counting camera developed by ESA. Cooled to ~0.3 K, its sensitive superconducting tunnel junction sensors detect single photons, measuring their arrival time to accuracies of microseconds and determining its crude wavelength. The camera is also essentially noise-free except for sky background photons. Thus S-Cam3 essentially provides high-speed, low-resolution spectra between 395 nm and 1052 nm with a resolution of ~35 nm at 500 nm wavelength. Results: The images acquired show three intensity maxima that were identified as most likely from the B fragment itself and two clusters of sub-fragments 253 km and 896 km away from fragment B. Furthermore we could see spatial intensity variations on short time scales (2-4 min), indicating the varying dust and gas emission of “subnuclei”. The gas and dust profiles do not show an inverse radial distribution (1/r) in all flow directions, but rather a clear deviation from a free radial outflow. This most likely is due to the gas outflow of one cluster of sub-fragments hitting the outflow of the other cluster. In other words, the material is expanding from one cluster into the other. In addition, the dust particles continue to fragment.

  13. 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

  14. A simple methodology to calibrate local meltrate function from ground observation in absence of density measurements

    NASA Astrophysics Data System (ADS)

    Mariani, Davide; Guyennon, Nicolas; Maggioni, Margherita; Salerno, Franco; Romano, Emanuele

    2015-04-01

    Snowpack melting can represent a major contribution to the seasonal variability of the surface and ground water budget at basin scale: the snow pack, acting as a natural reservoir, stores water during the winter season and releases it during spring and summer. The radiative budget driving the melting process depends on numerous variables that may be affected by the ongoing climatic changes. As a result, a shift in time during the spring and summer discharge may significantly affect surface water management at basin scale. For this reason, a reliable model able to quantitatively describe the snow melting processes is very important also for management purposes. The estimation of snow melt rate requires a full energy (mass) balance snowpack assessment. The limited availability of necessary data often does not allow implementing a radiative (mass) balance model. As an alternative we propose here a simple methodology to reconstruct the daily snowmelt and associated melt rate function based only on solid precipitation, air mean temperature and snowpack depth measurements, while snow density observations are often missing. The model differentiates between the melting and the compaction processes based on a daily mean temperature threshold (i.e. above or below the freezing point) and the snowpack state. The snow pack is described as two-layer model, each of them considers its own depth and density. The first one is a fresh snow surface layer whose density is a constant parameter. It is modulated by the daily snowfall/melting budget or it can be compacted and embedded within the second layer. The second one is the ripe snow, whose density is a weighted average with depths of antecedent snowpack and possible first layer contribution. The two snow layers allow starting the fusion by the snowpack's top where the density is lower, while much water is released when the ripe snow starts melting during the late melting season. Finally, we estimate the associated degree-day and

  15. 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.

  16. Ground state of the holes localized in II-VI quantum dots with Gaussian potential profiles

    NASA Astrophysics Data System (ADS)

    Semina, M. A.; Golovatenko, A. A.; Rodina, A. V.

    2016-01-01

    We report on a theoretical study of the hole states in II-IV quantum dots of spherical and ellipsoidal shapes, described by smooth potential confinement profiles that can be modeled by Gaussian functions in all three dimensions. The universal dependencies of the hole energy, g factor, and localization length on the quantum dot barrier height, as well as the ratio of effective masses of the light and heavy holes are presented for the spherical quantum dots. The splitting of the fourfold degenerate ground state into two doublets is derived for anisotropic (oblate or prolate) quantum dots. Variational calculations are combined with numerical ones in the framework of the Luttinger Hamiltonian. Constructed trial functions are optimized by comparison with the numerical results. The effective hole g factor is found to be independent of the quantum dot size and barrier height and is approximated by a simple universal expression depending only on the effective mass parameters. The results can be used for interpreting and analyzing experimental spectra measured in various structures with quantum dots of different semiconductor materials.

  17. 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.

  18. 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). PMID:25966923

  19. A new ``spectroscopic'' potential energy surface for formaldehyde in its ground electronic state

    NASA Astrophysics Data System (ADS)

    Yachmenev, Andrey; Yurchenko, Sergei N.; Jensen, Per; Thiel, Walter

    2011-06-01

    We report a new "spectroscopic" potential energy surface (PES) of formaldehyde (H212C16O) in its ground electronic state, obtained by refining an ab initio PES in a least-squares fitting to the experimental spectroscopic data for formaldehyde currently available in the literature. The ab initio PES was computed using the CCSD(T)/aug-cc-pVQZ method at 30 840 geometries that cover the energy range up to 44 000 cm-1 above equilibrium. Ro-vibrational energies of formaldehyde were determined variationally for this ab initio PES by means of the program TROVE [Theoretical ROtation-Vibration Energies; S. N. Yurchenko, W. Thiel, and P. Jensen, J. Mol. Spectrosc. 245, 126 (2007)], 10.1016/j.jms.2007.07.009. The parameter values in the analytical representation of the PES were optimized in fittings to 319 ro-vibrational energies with J = 0, 1, 2, and 5. The initial parameter values in the fittings were those of the ab initio PES, the ro-vibrational eigenfunctions obtained from this PES served as a basis set during the fitting process, and constraints were imposed to ensure that the refined PES does not deviate unphysically from the ab initio one in regions of configuration space not sampled by the experimental data. The resulting refined PES, referred to as H2CO-2011, reproduces the available experimental J ⩽ 5 data with a root-mean-square error of 0.04 cm-1.

  20. 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.

  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

    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

  3. 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…

  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 Real-Aperture Radar Interferometry: Techniques and Potential for Measurement of mm-Scale Motion

    NASA Astrophysics Data System (ADS)

    Werner, C. L.; Wiesmann, A.; Kos, A.; Caduff, R.; Strozzi, T.; Wegmüller, U.

    2011-12-01

    Ground-based radar interferometry is an emerging geodetic imaging technology that has been applied to measurement of landslides, rockfalls, glaciers, and mines. Geo-technical observations have been performed of infrastructure including bridges and dams. Compared with spaceborne radar systems, ground-based observations have advantages with respect to the selection of the imaging geometry to optimize visibility and sensitivity to deformation, shorter repeat intervals for monitoring rapidly moving features, and higher sensitivity to motion along the line-of-sight (LOS) due to the shorter wavelength and potential for averaging of multiple observations. The GPRI instrument developed by Gamma Remote Sensing is an FM-CW radar operating at 17.2 GHz (λ: 17.4 mm) with a range resolution of 90 cm along the line of sight and an operational range from 20 meters to 16 km. The GPRI is a real-aperture instrument using a 2.06 m long waveguide antenna to generate a fan-beam that is 0.4 x 35 degrees. During data acquisition, the radar performs a rotary scan of the scene at a programmable rate between 0.5 and 10 degrees/sec. Azimuth resolution is linearly proportional to slant range with a value of 7m at 1 km distance. Differential motion of 8.71 mm results in 2PI radians of measurable phase between observations. The GPRI incorporates two receivers enabling simultaneous interferometric observation with a vertical baseline variable between 25 and 60 cm. The single transmitting antenna and 2 receiving antennas are mounted parallel to one another on a rigid tower attached to a rotary positioner. An internal GPS receiver provides a time and frequency reference permitting simultaneous operation of multiple GPRI systems. The GPRI operates in four possible data acquisition modes permitting a wide range of applications. The first mode is the simultaneous interferometric mode using the upper and lower receiving antennas. The interferometric phase can be used to derive an elevation model

  7. Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; O'Connor, E. J.; Komppula, M.; Korhonen, K.; Pfüller, A.; Giannakaki, E.; Wood, C. R.; Bauer-Pfundstein, M.; Poikonen, A.; Karppinen, T.; Lonka, H.; Kurri, M.; Heinonen, J.; Moisseev, D.; Asmi, E.; Aaltonen, V.; Nordbo, A.; Rodriguez, E.; Lihavainen, H.; Laaksonen, A.; Lehtinen, K. E. J.; Laurila, T.; Petäjä, T.; Kulmala, M.; Viisanen, Y.

    2014-05-01

    The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds and Trace gases Research InfraStructure Network (ACTRIS); a Ka band cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, PollyXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (the European Aerosol Research Lidar Network). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We performed two inter-comparison campaigns to investigate the Doppler lidar performance, compare the backscatter signal and wind profiles, and to optimize the lidar sensitivity through adjusting the telescope focus length and data-integration time to ensure sufficient signal-to-noise ratio (SNR) in low-aerosol-content environments. In terms of statistical characterization, the wind-profile comparison showed good agreement between different lidars. Initially, there was a discrepancy in the SNR and attenuated backscatter coefficient profiles which arose from an incorrectly reported telescope focus setting from one instrument, together with the need to calibrate. After diagnosing the true telescope focus length, calculating a new attenuated backscatter coefficient profile with the new telescope function and taking into account calibration, the resulting attenuated backscatter profiles all showed good agreement with each other. It was thought that harsh Finnish

  8. Ground-based observations of the fair weather vertical current response to solar disturbances

    NASA Astrophysics Data System (ADS)

    Elhalal, G.; Yair, Y.; Harrison, R.; Nicoll, K.; Price, C. G.; Yaniv, R.

    2013-12-01

    The Global atmospheric Electric Circuit (GEC) is a conceptual model that represents the observed variable and quasi-static electrical properties of the atmosphere in the Earth-ionosphere cavity. The DC component of the GEC is typified by an average potential difference of 250 kV between the upper and lower conducting layers of the surface and ionosphere, leading to a near-surface electric field (Ez) of potential gradient ~130 V m-1, and a steady downward-flowing fair-weather current density (Jz) of ~2 pA m-2. By separation the steady global circuit current from short-term fluctuations, Jz provides information on local and global conductivity changes due to aerosols, air-pollution and solar activity. This talk will present evidence for the effects of geomagnetic storms and sub-storms on the fair weather vertical current, based on results from continuous measurements of Jz conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35'N, 34°45'E) with the GDACCS instrument (Bennett and Harrison, 2008). We studied 3 coronal mass ejections (CMEs), which included solar proton events (SPE) on 26.09.11, 24.10.11 and 08.03.12. In all three events, fluctuations in Jz increased by an order of magnitude compared to normal fair weather conditions. The dynamic spectrum of the increased fluctuations exhibit peaks in the Pc5 frequency range. Similar low frequency characteristics occur during periods of enhanced solar wind proton density. During the 24.10.11 event, the periods of increased fluctuations in Jz lasted for 7 hours and coincided with fluctuations of the inter-planetary magnetic field (IMF) that were detected by the ACE satellite. The observed current density fluctuations occurred at a period when Bz<0 and when it was highly variable, suggesting the possibility for magnetic reconnection with ensuing changes in ionospheric properties. These low-latitude observations probably represent a response of the GEC to the solar induced geomagnetic sub-storms, perhaps arising

  9. Observation of Muon Excess at Ground Level in Relation to Gamma-Ray Bursts Detected from Space

    NASA Astrophysics Data System (ADS)

    Augusto, C. R. A.; Navia, C. E.; de Oliveira, M. N.; Tsui, K. H.; Nepomuceno, A. A.; Kopenkin, V.; Sinzi, T.; Atri, D.

    2015-05-01

    In this paper we examine the possibility of the ground observation of the gigaelectronvolt counterparts associated with the Monitor of All-sky X-ray Image transient event (trigger 58072727) and the Swift GRB140512A event. In both cases, there was a muon excess with a statistical significance above 4σ. The coordinates of the events were located in the field of view (FOV) of the Tupi muon telescopes at the time of the occurrence. Since 2013 August, the Tupi experiment has been operating a new extended array of five muon telescopes, located at ground level at (22\\buildrel{\\circ}\\over{.} 9S,43\\buildrel{\\circ}\\over{.} 2W, 3 m above sea level). This location coincides with the South Atlantic Anomaly central region. We consider a hypothesis that the muon excess could be due to photonuclear reactions in the Earth’s atmosphere induced by gamma rays with energies above 10 GeV. We describe a data analysis for candidate events identified by internally triggered (by the Tupi experiment) as well as untriggered (dependent on external observations) modes of search. In light of the Fermi LAT (\\gt 100 MeV) gamma-ray bursts (GRBs) catalog, we examine the possibility of the ground observation of similar transient events within the FOV of the extended Tupi array and perform a systematic analysis of the Tupi data. Using a Monte Carlo simulation, we discuss the experimental conditions that allow the detection of signals from GRBs at ground level.

  10. 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.

  11. Ground-water levels in observation wells in Oklahoma, 1980-82

    USGS Publications Warehouse

    Goemaat, Robert L.; Mize, Lionel D.; Spiser, Dannie E.

    1983-01-01

    In the 1980-82 Climatic Years, the U. S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, collected ground-water level data in Oklahoma from 1,122 sites in 77 counties. This report presents this data.

  12. 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)

  13. 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.

  14. Intended long-term permafrost monitoring in Austria: Observations from eight years (2006-2014) of ground temperature monitoring in the Tauern Range, Central Austria

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas; Lintschnig, Michèle

    2015-04-01

    At present permafrost monitoring in Austria is carried out by several institutions at some 20 sites in the Austrian Alps. However, so far this monitoring is not coordinated and institutionalised in terms of monitoring strategy, organization, data management and funding. Within the currently running permAT project such an institutionalization is in progress. Permafrost in the Austrian mountains is rather warm and hence sensitive to present climate change. Consequently permafrost conditions and changes are of increasing importance also for the public. Therefore, it is evident that a coordinated and institutionalised long-term monitoring of ground temperature in Austria is essential for permafrost understanding and people's safety. In this contribution we present up to eight years of field data from nine different study sites in Austria. All sites are located in the highest mountain range in Austria, the Tauern Range (maximum elevation 3798 m asl) covering some 9000 km² of the national territory. The nine different study sites are located between latitude 46°55' to 47°22' and longitude 12°44' to 14°41'. Altogether 57 ground temperature monitoring sites have been installed in 2006 and 2007 at the nine study sites using one- (at 23 sites) and three-channel (at 34 sites) miniature temperature dataloggers produced by GeoPrecision, Germany. Therefore, more than 120 ground temperature data series are available from between the ground surface to maximum depths of 2.75 m. The 57 monitoring sites range from 1922 to 3002 m asl in elevation and consider flat terrain as well as step rock walls. All slope aspects are adequately considered. Relevant research questions we intend to address in this contribution include (a) general ground thermal conditions in 2006-2014, (b) the influence of different substrates and aspects on ground temperatures, (c) potential permafrost occurrence, (d) changes or stable conditions during the observation period, (e) regional pattern, and (f

  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. A possible explanation for the inconsistency between the Giotto grain mass distribution and ground-based observations

    NASA Technical Reports Server (NTRS)

    Perry, C. H.; Green, S. F.; Mcdonnell, J. A. M.

    1988-01-01

    Giotto measured the in situ Halley dust grain mass distribution with 2 instruments, Particle Impact Analyzer and Dust Impact Detection System (DIDSY), as well as the total intercepted mass from the deceleration of the spacecraft (Giotto Radio-Science Experiment, GRE). Ground based observations made shortly before encounter have fluxes much higher than would be predicted from Giotto data. It is concluded that Giotto DIDSY and GRE data represent observations of dust originating from a narrow track along the nucleus. They are consistent with ground based data, if assumptions are made about the level of activity along this track. The actual size distribution that should be used for modeling of the whole coma should not include the large mass excess actually observed by Giotto. Extrapolation of the small grain data should be used, since for these grains the velocity dispersion is low and temporal changes at the nucleus would not affect the shape of the mass distribution.

  17. Validation of five years (2003-2007) of SCIAMACHY CO total column measurements using ground-based spectrometer observations

    NASA Astrophysics Data System (ADS)

    de Laat, A. T. J.; Gloudemans, A. M. S.; Schrijver, H.; Aben, I.; Nagahama, Y.; Suzuki, K.; Mahieu, E.; Jones, N. B.; Paton-Walsh, C.; Deutscher, N. M.; Griffith, D. W. T.; de Mazière, M.; Mittermeier, R. L.; Fast, H.; Notholt, J.; Palm, M.; Hawat, T.; Blumenstock, T.; Hase, F.; Schneider, M.; Rinsland, C.; Dzhola, A. V.; Grechko, E. I.; Poberovskii, A. M.; Makarova, M. V.; Mellqvist, J.; Strandberg, A.; Sussmann, R.; Borsdorff, T.; Rettinger, M.

    2010-10-01

    This paper presents a validation study of SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) carbon monoxide (CO) total column measurements from the Iterative Maximum Likelihood Method (IMLM) algorithm using ground-based spectrometer observations from twenty surface stations for the five year time period of 2003-2007. Overall we find a good agreement between SCIAMACHY and ground-based observations for both mean values as well as seasonal variations. For high-latitude Northern Hemisphere stations absolute differences between SCIAMACHY and ground-based measurements are close to or fall within the SCIAMACHY CO 2σ precision of 0.2 × 1018 molecules/cm2 (∼10%) indicating that SCIAMACHY can observe CO accurately at high Northern Hemisphere latitudes. For Northern Hemisphere mid-latitude stations the validation is complicated due to the vicinity of emission sources for almost all stations, leading to higher ground-based measurements compared to SCIAMACHY CO within its typical sampling area of 8° × 8°. Comparisons with Northern Hemisphere mountain stations are hampered by elevation effects. After accounting for these effects, the validation provides satisfactory results. At Southern Hemisphere mid- to high latitudes SCIAMACHY is systematically lower than the ground-based measurements for 2003 and 2004, but for 2005 and later years the differences between SCIAMACHY and ground-based measurements fall within the SCIAMACHY precision. The 2003-2004 bias is consistent with previously reported results although its origin remains under investigation. No other systematic spatial or temporal biases could be identified based on the validation presented in this paper. Validation results are robust with regard to the choices of the instrument-noise error filter, sampling area, and time averaging required for the validation of SCIAMACHY CO total column measurements. Finally, our results show that the spatial coverage of the ground

  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 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.

  19. 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.

  20. 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

  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. Full configuration interaction pseudopotential determination of the ground-state potential energy curves of Li2 and LiH

    NASA Astrophysics Data System (ADS)

    Maniero, Angelo M.; Acioli, Paulo H.

    A full configuration interaction (CI) with a norm-conserving pseudopotential procedure to determine potential energy surfaces is proposed. Analysis of the potentiality and the possible sources of inaccuracies of the methodology is given in terms of its application to the generation of the ground-state potential energy curves of the LiH and Li2 molecules. The vibrational energy levels were obtained using the discrete variable representation. The agreement between our results and those from Rydberg-Klein-Ress-derived potentials is very good. The extension of this procedure to larger systems is straightforward.

  3. Statistical Retrieval of Thin Liquid Cloud Microphysical Properties Using Ground-Based Infrared and Microwave Observations

    NASA Astrophysics Data System (ADS)

    Marke, Tobias; Löhnert, Ulrich; Ebell, Kerstin; Turner, David D.

    2016-04-01

    In this study, liquid water cloud microphysical properties are retrieved by exploiting passive remote sensing techniques in the microwave and infrared spectral regime. Liquid water clouds are highly frequent in various climate regimes and play a significant role in terms of interaction with radiation. Small perturbations in the amount of liquid water contained in the cloud can cause large variations in the radiative fluxes. This effect enhances for thin clouds with a low liquid water path (LWP), which requires accurate retrieval information on the cloud properties. Retrieving low LWP values using the microwave spectral regime reveals large relative errors, whereas the potential for infrared methods is high. Therefore robust and computationally low demanding synergistic retrievals based on a multivariate regression and a neural network are derived to estimate LWP and cloud effective radius. While the regression-type synergy retrievals are strongly influenced by the nonlinearities of saturating signals in the infrared regime for higher LWP, the neural network retrieval is able to retrieve LWP and cloud effective radius with a higher accuracy than the single instrument retrievals. This is achieved by examining synthetic observations in the low LWP range. Furthermore, the performance of the retrievals is assessed in a radiative closure study for the downwelling shortwave flux, using measurements of a microwave radiometer, a broadband infrared radiometer and a spectrally highly resolved Atmospheric Emitted Radiance Interferometer (AERI).

  4. 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).

  5. 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.

  6. ESTIMATION OF POTENTIAL EVAPOTRANSPIRATION FROM MERGED CERES and MODIS OBSERVATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate and timely estimates of potential evapotranspiration (ET) and knowledge of their spatial and temporal distribution are essential for agriculture and water resource management as well as for understanding the impacts of climate variability on terrestrial systems. Because of the paucity and i...

  7. Ground-water levels in observation wells in Oklahoma, period of record to March 1985

    USGS Publications Warehouse

    Goemaat, Robert L.; Mize, Lionel D.; Madaj, Ambrose J.; Spiser, Dannie E.

    1986-01-01

    During the 1984-85 climatic years, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources, collected ground-water level data in Oklahoma from 1,018 sites in 76 of the State's 77 counties. This report is a compilation of all available data through March 1985 for each well currently in the network. Some of the data were collected as early as 1937.

  8. Ground-satellite observation of Pc 4 pulsations by MAGDAS/CPMN and ETS-VIII geosynchronous orbit satellite

    NASA Astrophysics Data System (ADS)

    Ikeda, A.; Yumoto, K.; Koga, K.; Obara, T.; Baishev, D. G.; Shevtsov, B. M.; Uozumi, T.; Abe, S.; Shishime, A.

    2011-12-01

    Electromagnetic pulsations in ULF range have been studied extensively using ground and satellite observations. However, how Pc 4 pulsations (6.7-22.2 mHz) propagate from the magnetosphere to the ground is not fully understand. Especially the propagation to low latitudes is unclear. We examined data obtained by the ETS-VIII satellite at the geosynchronous orbit (G.M.Lat. -12 degree, G.G.Lon. 146.0 degree) (Koga et al., 2010). We also analyzed ground data of MAGDAS/CPMN (Yumoto and the MAGDAS Group, 2006). The ground data were obtained at high-latitude CHD station (G.M.Lat. 64.9 degree, G.M.Lon. 212.7 degree) and at low-latitude KUJ station (G.M.Lat. 26.1 degree, G.M.Lon. 203.0 degree). The magnetic longitudes of these ground stations are almost same as that of the ETS-VIII. Pc 4 events at ETS-VIII were selected by an automated routine using FFT method which was developed by Takahashi and Ukhorskiy (2007). These Pc 4 events were classified into 2 types. One type is a poloidal Pc 4, in which Hp (northward) component is dominant. Another type is a toroidal mode, in which Hn (eastward) component is dominant. About 10 % of the poloidal/toroidal Pc 4 pulsations, the peak frequency is identical with that of ground Pc 4 pulsations, and the coherence between pulsations observed aboard ETS-VII and on the ground stations is high at the peak frequencies. Thus, about 10 % of the poloidal/toroidal Pc 4 in the magnetosphere can be concluded to transmit to high-latitude ground stations as well as low-latitude stations. For such Pc 4 events, H (horizontal northward) and D (horizontal eastward) components at CHD showed higher amplitude (delta(H)/delta(Hn) = 6.8, delta(H)/delta(Hp) = 10.8, delta(D)/delta(Hn) = 6.8, delta(D)/delta(Hp) = 7.4) than that at the geosynchronous orbit. On the other hand, H and D components at KUJ was attenuated considerably (delta(H)/delta(Hn) = 0.66, delta(H)/delta(Hp) = 0.89, delta(D)/delta(Hn) = 0.35, delta(D)/delta(Hp) = 0.37).

  9. 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

  10. Observational constraints in scalar tensor theory with tachyonic potential

    SciTech Connect

    Farajollahi, Hossein; Salehi, Amin; Shahabi, Asieh E-mail: a.salehi@guilan.ac.ir

    2011-10-01

    We study the dynamics of the scalar tensor cosmological model in the presence of tachyon field. In an alternative approach, in two exponential and power law form of the scalar field functions in the model, field equations are solved by simultaneously best fitting the model parameters with the most recent observational data. This approach gives us an observationally verified interpretation of the dynamics of the universe. We then discuss the best fitted of equation of state parameter, the statefinder parameters and the reconstructed scalar field in the model.

  11. Ground state of rotating ultracold quantum gases with anisotropic spin—orbit coupling and concentrically coupled annular potential

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Tan, Ren-Bing; Du, Zhi-Jing; Zhao, Wen-Yu; Zhang, Xiao-Fei; Zhang, Shou-Gang

    2014-07-01

    Motivated by recent experimental realization of synthetic spin—orbit coupling in neutral quantum gases, we consider the quasi-two-dimensional rotating two-component Bose—Einstein condensates with anisotropic Rashba spin—orbit coupling subject to concentrically coupled annular potential. For experimentally feasible parameters, the rotating condensate exhibits a variety of rich ground state structures by varying the strengths of the spin—orbit coupling and rotational frequency. Moreover, the phase transitions between different ground state phases induced by the anisotropic spin—orbit coupling are obviously different from the isotropic one.

  12. Ground-state and quenched-state properties of a one-dimensional interacting lattice gas in a random potential

    SciTech Connect

    Fonk, Y.; Hilhorst, H.J.

    1987-12-01

    The authors determine the zero-temperature properties of a one-dimensional lattice gas of particles that interact via a nearest neighbor exclusion potential and are subject to a random external field. The model is a special limiting case of the random field Ising chain. We calculate (1) the energy and density of the ground state as well as the local energy-density correlation and (2) the pair correlation function. The latter calculation gives access to all higher order correlations. The structure factor is shown to be a squared Lorentzian. The authors also compare the ground state to the quenched state obtained by sequentially filling the lowest available energy levels.

  13. 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.

  14. 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.

  15. Propagation mechanism of daytime Pc 3-4 pulsations observed at synchronous orbit and multiple ground-based stations

    NASA Technical Reports Server (NTRS)

    Yumoto, K.; Saito, T.; Akasofu, S.-I.; Tsurutani, B. T.; Smith, E. J.

    1985-01-01

    Observational data obtained during the last two decades show that the amplitude of daytime Pc 3-4 magnetic pulsations is controlled by the solar wind conditions. The high degree of correlation between the solar wind parameters and Pc 3-4 pulsations in the dayside magnetosphere suggests that the ultimate cause of the daytime Pc 3-4 pulsations must be the interaction of the solar wind with the earth's magnetosphere. The present paper is concerned with details regarding the control of the properties of the Pc 3-4 pulsations by the solar wind parameters, taking into account observations made at multiple ground-based stations. It is attempted to establish the relation between the daytime Pc 3-4 pulsations at the ground stations and the compressional Pc 3-4 waves in the magnetosphere. Attention is given to the most probable propagation mechanism of the daytime Pc 3-4 pulsations in the magnetosphere.

  16. Propagation mechanism of daytime Pc 3-4 pulsations observed at synchronous orbit and multiple ground-based stations

    SciTech Connect

    Yumoto, K.; Saito, T.; Akasofu, S.-I.; Tsurutani, B.T.; Smith, E.J.

    1985-07-01

    Observational data obtained during the last two decades show that the amplitude of daytime Pc 3-4 magnetic pulsations is controlled by the solar wind conditions. The high degree of correlation between the solar wind parameters and Pc 3-4 pulsations in the dayside magnetosphere suggests that the ultimate cause of the daytime Pc 3-4 pulsations must be the interaction of the solar wind with the earth's magnetosphere. The present paper is concerned with details regarding the control of the properties of the Pc 3-4 pulsations by the solar wind parameters, taking into account observations made at multiple ground-based stations. It is attempted to establish the relation between the daytime Pc 3-4 pulsations at the ground stations and the compressional Pc 3-4 waves in the magnetosphere. Attention is given to the most probable propagation mechanism of the daytime Pc 3-4 pulsations in the magnetosphere. 59 references.

  17. Observation of a metallic ground state of Sn/Ge(111)-3×3 at 4 K

    NASA Astrophysics Data System (ADS)

    Morikawa, Harumo; Jeong, Sukmin; Yeom, Han Woong

    2008-12-01

    The Sn/Ge(111)-3×3 surface was investigated by scanning tunneling microscopy/spectroscopy (STM/STS) at low temperature, for which a triangular Mott-Hubbard ground state was suggested recently. Our detailed STM/STS observation at 77 K combined with ab initio calculations unambiguously determines its atomic structure as the one-up two-down model with one third of Sn adatoms lifted upward from the flat 3×3 layer. The surface is metallic due to the partially filled dangling bonds on the down adatoms. On cooling down to 4 K, another 3×3 phase with a distinct but still metallic electronic structure was observed. The Mott-Hubbard ground state with an undistorted 3×3 structure is denied.

  18. Estimating the CO2 mitigation potential of horizontal Ground Source Heat Pumps in the UK

    NASA Astrophysics Data System (ADS)

    Garcia-Gonzalez, R.; Verhoef, A.; Vidale, P. L.; Gan, G.; Chong, A.; Clark, D.

    2012-04-01

    By 2020, the UK will need to generate 15% of its energy from renewables to meet our contribution to the EU renewable energy target. Heating and cooling systems of buildings account for 30%-50% of the global energy consumption; thus, alternative low-carbon technologies such as horizontal Ground Couple Heat Pumps (GCHPs) can contribute to the reduction of anthropogenic CO2 emissions. Horizontal GCHPs currently represent a small fraction of the total energy generation in the UK. However, the fact that semi-detached and detached dwellings represent approximately 40% of the total housing stocks in the UK could make the widespread implementation of this technology particularly attractive in the UK and so could significantly increase its renewable energy generation potential. Using a simulation model, we analysed the dynamic interactions between the environment, the horizontal GCHP heat exchanger and typical UK dwellings, as well as their combined effect on heat pump performance and CO2 mitigation potential. For this purpose, a land surface model (JULES, Joint UK Land Environment Simulator), which calculates coupled soil heat and water fluxes, was combined with a heat extraction model. The analyses took into account the spatio-temporal variability of soil properties (thermal and hydraulic) and meteorological variables, as well as different horizontal GCHP configurations and a variety of building loads and heat demands. Sensitivity tests were performed for four sites in the UK with different climate and soil properties. Our results show that an installation depth of 1.0m would give us higher heat extractions rates, however it would be preferable to install the pipes slightly deeper to avoid the seasonal influence of variable meteorological conditions. A value of 1.5m for the spacing between coils (S) for a slinky configuration type is recommended to avoid thermal disturbances between neighbouring coils. We also found that for larger values of the spacing between the coils

  19. 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

  20. 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.

  1. Automated ground-water monitoring with Robowell: case studies and potential applications

    NASA Astrophysics Data System (ADS)

    Granato, Gregory E.; Smith, Kirk P.

    2002-02-01

    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/

  2. 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/.

  3. Sound propagation over soft ground without and with crops and potential for surface transport noise attenuation.

    PubMed

    Bashir, Imran; Taherzadeh, Shahram; Shin, Ho-Chul; Attenborough, Keith

    2015-01-01

    Growing demand on transportation, road, and railway networks has resulted in increased levels of annoyance from road traffic. Optimized use of green surfaces in combination with vegetation may be desirable as a method for reducing the noise impact of road traffic in urban and rural environments. Sound propagation over soft ground and through crops has been studied through outdoor measurements at short and medium ranges and through predictions. At lower frequencies, ground effect is dominant, and there is little or no attenuation due to crops. At higher frequencies above 3-4 kHz, the attenuation in crops is dominant. It was also found that the ground effects and the influence of crops can be treated independently and can be added to obtain the total effect. Sound attenuation by crops is the result of multiple scattering between the stems and leaves, loss of coherence, and viscous and thermal losses due to foliage. The major contribution is associated with viscous and thermal losses. A model for sound attenuation by vegetation is proposed. Insertion losses for a typical road traffic noise source have been calculated that result either by replacing hard ground with different types of acoustically soft ground or by growing crops along the road sides. PMID:25618047

  4. 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.

  5. Investigation of the adiabatic assumption for estimating cloud micro- and macrophysical properties from satellite and ground observations

    NASA Astrophysics Data System (ADS)

    Merk, D.; Deneke, H.; Pospichal, B.; Seifert, P.

    2016-01-01

    Cloud properties from both ground-based as well as from geostationary passive satellite observations have been used previously for diagnosing aerosol-cloud interactions. In this investigation, a 2-year data set together with four selected case studies are analyzed with the aim of evaluating the consistency and limitations of current ground-based and satellite-retrieved cloud property data sets. The typically applied adiabatic cloud profile is modified using a sub-adiabatic factor to account for entrainment within the cloud. Based on the adiabatic factor obtained from the combination of ground-based cloud radar, ceilometer and microwave radiometer, we demonstrate that neither the assumption of a completely adiabatic cloud nor the assumption of a constant sub-adiabatic factor is fulfilled (mean adiabatic factor 0.63 ± 0.22). As cloud adiabaticity is required to estimate the cloud droplet number concentration but is not available from passive satellite observations, an independent method to estimate the adiabatic factor, and thus the influence of mixing, would be highly desirable for global-scale analyses. Considering the radiative effect of a cloud described by the sub-adiabatic model, we focus on cloud optical depth and its sensitivities. Ground-based estimates are here compared vs. cloud optical depth retrieved from the Meteosat SEVIRI satellite instrument resulting in a bias of -4 and a root mean square difference of 16. While a synergistic approach based on the combination of ceilometer, cloud radar and microwave radiometer enables an estimate of the cloud droplet concentration, it is highly sensitive to radar calibration and to assumptions about the moments of the droplet size distribution. Similarly, satellite-based estimates of cloud droplet concentration are uncertain. We conclude that neither the ground-based nor satellite-based cloud retrievals applied here allow a robust estimate of cloud droplet concentration, which complicates its use for the study of

  6. 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.

  7. Potentials and constraints of different types of soil moisture observations for flood simulations in headwater catchments

    NASA Astrophysics Data System (ADS)

    Bronstert, A.; Creutzfeldt, B.; Graeff, T.; Hajnsek, I.; Heistermann, M.; Itzerott, S.; Jagdhuber, T.; Kneis, D.; Lück, E.; Reusser, D.; Zehe, E.

    2012-04-01

    Flood generation in mountainous headwater catchments is governed by rainfall intensities, by the spatial distribution of rainfall and by the state of the catchment prior to the rainfall, e.g. by the spatial pattern of the soil moisture, groundwater conditions, and possibly snow. The work presented here explores the limits and potentials of measuring soil moisture with different methods and in different scales and their potential use for flood simulation. These measurements were obtained in 2007 and 2008 within a comprehensive multi-scale experiment in the Weisseritz headwater catchment in the Ore-Mountains, Germany. The following technologies have been applied jointly thermogravimetric method, Frequency Domain Reflectometry (FDR) sensors, Spatial-Time Domain Reflectometry (STDR) cluster, Ground Penetrating Radar (GPR), airborne polarimetric synthetic aperture radar (polarimetric-SAR) and Advanced Synthetic Aperture Radar (ASAR) based on the satellite Envisat. We present exemplary soil measurement results, with spatial scales ranging from point scale, via hillslope and field scale to the catchment scale. Only the Spatial-TDR cluster was able to record continuous data. The other methods are limited to the date of over flights (airplane and satellite) or measurement campaigns on the ground. At a first glance, using soil moisture data to initiate better flood modelling (including flood forecasts) seems to be a rather straight forward approach. However, this approach bears several problems regarding the operational use of such data and the model parameterisation: 1) A main constraint is that the observation of spatially distributed soil moisture and the subsequent data processing are still far from an operational stage because continuous or quasi-continuous air-borne observation and processing of soil moisture is not available; 2) remote soil moisture sensors observe only a quite shallow soil depths, which are of restricted relevance for flood generation and water

  8. 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

  9. The spatio-spectral localization approach to modeling VTEC by integrating ground GPS observations and satellite altimetry data

    NASA Astrophysics Data System (ADS)

    Farzaneh, Saeed; Sharifi, Mohammad Ali

    2015-04-01

    The upper part of the Earth atmosphere is important for ground-based and satellite radio communication and navigation. It consists of free electrons and ions, mainly ionized by solar radiation. Free electrons, in the ionosphere, have a strong impact on the propagation of radio waves. When the signals pass through the ionosphere, both their group and phase velocity are disturbed. The effect is in first approximation proportional to TEC along the signal path and inversely proportional to the frequency squared. Several space geodetic techniques such as satellite altimetry, LEO satellite and Very Long Baseline Interferometry (VLBI) can be used for modeling the total electron content. In this study the combination of the data from ground GPS observation over west part of USA and from the altimetry mission Jason-2 is performed on the normal equation level in least-square producer and the least-squares variance component estimation is applied to consider the different accuracy levels of the observations. The integrated ionosphere model is expected to be more accurate and reliable than the results derived by the ground GPS observation over the oceans. Keywords: Slepian function, LS-VCE, satellite altimetry, GPS, local ionospheric modeling

  10. Fine structure of breakup development inferred from satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Kornilova, T. A.; Kornilov, I. A.; Kornilov, O. I.

    2008-05-01

    More than 60 breakups, including weak activations of the pseudo-breakup type, moderate breakups, and events of very strong auroral activity, were analyzed using ground-based TV data, together with satellite auroral images. We studied the fine subvisual details of spatial and temporal dynamics of active auroral forms and surrounding diffuse luminosity, both in the longitudinal and latitudinal directions of the TV camera field of view. For all types of breakups a close interconnection of auroral activity was found across and along the auroral oval.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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., Jr.; 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

  16. HiRISE observations of potential MSL landing sites

    NASA Astrophysics Data System (ADS)

    Griffes, J. L.; Grant, J.; McEwen, A.; Golombek, M.; HiRISE Team

    2007-12-01

    The Mars Reconnaissance Orbiter's (MRO) High Resolution Imaging Science Experiment (HiRISE) began acquiring data in the fall of 2006. Some of the images of the past year of operations include support for the 2009 Mars Science Laboratory (MSL) potential landing sites, which were proposed at the first landing site workshop in October of 2006. There are 28 proposed sites that were prioritized at the first workshop and they are located across elevations and latitudes ranging from -6 km to approximately +1 km, and 29.3°N to 48.5°S respectively. These sites emphasize a range of science themes including mineralogy (i.e. phyllosilicates, sulfates, or hematite), layered materials, or presence of fluvial, erosional or depositional landforms. Each site was originally proposed with a 20 km landing ellipse in an area that appeared smooth and flat in pre-HiRISE images. Many of the sites are "go to" sites where there is a proposed landing ellipse adjacent to a nearby science target of interest. HiRISE has acquired images at ~30 cm/pixel for all the proposed sites, including a few additional images of the northern hemisphere landing ellipses at low sun, used to better constrain the distribution of slopes at small scales. Each HiRISE image is approximately 6 km wide by at least 10 km long and includes a 1.2 km-wide blue-green and NIR swath down the middle of the image. For each HiRISE footprint, there is also a co-located Context Image (CTX) and CRISM hyperspectral image. The HiRISE images show a variety of landforms at high resolution, such as layered deposits, dunes, channels, ridges, rocks, polygonal terrain and craters. Each of these sites will be extensively studied to assess the safest landing site, as well as what is best suited to achieving mission science objectives. The acquired images have been released to the PDS and are available to all interested parties, including MSL project and science advocates for the purpose of characterizing potential hazards to safe landing

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Observation of Nonspreading Wave Packets in an Imaginary Potential

    SciTech Connect

    Stuetzle, R.; Goebel, M.C.; Hoerner, Th.; Kierig, E.; Mourachko, I.; Oberthaler, M.K.; Efremov, M.A.; Fedorov, M.V.; Yakovlev, V.P.; Leeuwen, K.A.H. van; Schleich, W.P.

    2005-09-09

    We propose and experimentally demonstrate a method to prepare a nonspreading atomic wave packet. Our technique relies on a spatially modulated absorption constantly chiseling away from an initially broad de Broglie wave. The resulting contraction is balanced by dispersion due to Heisenberg's uncertainty principle. This quantum evolution results in the formation of a nonspreading wave packet of Gaussian form with a spatially quadratic phase. Experimentally, we confirm these predictions by observing the evolution of the momentum distribution. Moreover, by employing interferometric techniques, we measure the predicted quadratic phase across the wave packet. Nonspreading wave packets of this kind also exist in two space dimensions and we can control their amplitude and phase using optical elements.

  2. 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.

  3. U.S. border patrol potential applications of internetted unattended ground sensors

    NASA Astrophysics Data System (ADS)

    Eaton, Wilbur W., Jr.; Schatzmann, Larry A.

    1997-07-01

    The U.S. Border Patrol monitors the traffic on the Mexican/U.S. Border, the Canadian/U.S. Border and along some coastal areas. Measures have been taken to reduce or eliminate illegal immigration and smuggling. An automated border surveillance sub-system based on the DARPA Internetted Unattended Ground Sensors Program is discussed.

  4. Hydrology of the solid waste burial ground as related to potential migration of radionuclides, Idaho National Engineering Laboratory

    USGS Publications Warehouse

    Barraclough, Jack T.; Robertson, J.B.; Janzer, V.J.; Saindon, L.G.

    1976-01-01

    A study was made (1970-1974) to evaluate the geohydrologic and geochemical controls on subsurface migration of radionuclides from pits and trenches in the Idaho National Engineering Laboratory (INEL) solid waste burial ground and to determine the existence and extent of radionuclide migration from the burial ground. A total of about 1,700 sediment, rock, and water samples were collected from 10 observation wells drilled in and near the burial ground of Idaho National Engineering Laboratory, formerly the National Reactor Testing Station (NRTS). Within the burial ground area, the subsurface rocks are composed principally of basalt. Wind- and water-deposited sediments occur at the surface and in beds between the thicker basalt zones. Two principal sediment beds occur at about 110 feet and 240 feet below the land surface. The average thickness of the surficial sedimentary layer is about 15 feet while that of the two principal subsurface layers is 13 and 14 feet, respectively. The water table in the aquifer beneath the burial ground is at a depth of about 580 feet. Fission, activation, and transuranic elements were detected in some of the samples from the 110- and 240-foot sedimentary layers. (Woodard-USGS)

  5. Investigation on the real-time prediction of ground motions using seismic records observed in deep boreholes

    NASA Astrophysics Data System (ADS)

    Miyakoshi, H.; Tsuno, S.

    2013-12-01

    The present method of the EEW system installed in the railway field of Japan predicts seismic ground motions based on the estimated earthquake information about epicentral distances and magnitudes using initial P-waves observed on the surface. In the case of local earthquakes beneath the Tokyo Metropolitan Area, however, a method to directly predict seismic ground motions using P-waves observed in deep boreholes could issue EEWs more simply and surely. Besides, a method to predict seismic ground motions, using S-waves observed in deep boreholes and S-wave velocity structures beneath seismic stations, could show planar distributions of ground motions for train operation control areas in the aftermath of earthquakes. This information is available to decide areas in which the emergency inspection of railway structures should be performed. To develop those two methods, we investigated relationships between peak amplitudes on the surface and those in deep boreholes, using seismic records of KiK-net stations in the Kanto Basin. In this study, we used earthquake accelerograms observed in boreholes whose depths are deeper than the top face of Pre-Neogene basement and those on the surface at 12 seismic stations of KiK-net. We selected 243 local earthquakes whose epicenters are located around the Kanto Region. Those JMA magnitudes are in the range from 4.5 to 7.0. We picked the on-set of P-waves and S-waves using a vertical component and two horizontal components, respectively. Peak amplitudes of P-waves and S-waves were obtained using vertical components and vector sums of two horizontal components, respectively. We estimated parameters which represent site amplification factors beneath seismic stations, using peak amplitudes of S-waves observed in the deep borehole and those on the surface, to minimize the residuals between calculations by the theoretical equation and observations. Correlation coefficients between calculations and observations are high values in the range

  6. 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.

  7. Observation and Prediction of Dynamic Ground Strains, Tilts and Torsions Caused by the M6.0 2004 Parkfield, California, Earthquake and Aftershocks Derived From UPSAR Array Observations

    NASA Astrophysics Data System (ADS)

    Spudich, P.; Fletcher, J. B.

    2008-12-01

    The September 28, 2004, Parkfield, California, earthquake (Mw 6.0) and four aftershocks (Mw 4.7 - 5.1) were recorded on 12 accelerograph stations of the UPSAR seismic array, an array of three-component accelerographs occupying an area of about 1 square km located 8.8 km from the San Andreas fault. Peak horizontal acceleration and velocity at UPSAR during the mainshock were 0.45 g and 0.27 m/s, 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 predicted peak velocity from the Boore-Atkinson (2007) ground motion prediction relation scaled by a phase velocity of 1 km/s, 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 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.

  8. 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

  9. Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

    NASA Astrophysics Data System (ADS)

    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.

  10. A New Ground-Based Carbon Monoxide Radiometer for Observing the Dynamics of the Arctic Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Ryan, Niall; Palm, Mathias; Notholt, Justus

    2015-04-01

    The dynamical properties of the middle atmosphere must largely be derived from interpretation of observed chemical tracer data, predominantly from measurements by ground-based or satellite-borne instruments. Carbon monoxide (CO) is a well-suited tracer for polar middle atmosphere dynamics: during polar winter, the chemical reactions involving the gas are negligible due to lack of sunlight and the gas exhibits strong vertical and horizontal gradients. Ground-based measurements of the atmosphere are increasingly important for making long-term records of atmospheric composition and, because of the likely upcoming gap in satellite measurements, are needed to intercompare past and future satellite instruments. This contribution presents a new ground-based millimeter wave radiometer, CORAM, that is designed to measure radiation, at ~230 GHz, emitted during rotational transitions of CO. CORAM will be housed at the APIWEV station in Ny Alesund, Spitsbergen (79° N), an ideal location for observing middle atmosphere dynamics from inside and outside the polar vortex, and make continuous CO observations in the High-Arctic. The observations from CORAM will be used for validation of the polar dynamics in atmospheric models, and to investigate the short-term variability of polar middle atmosphere dynamics. Used in combination with measurements in Kiruna, Sweden (68° N), information about the CO gradient across the polar vortex edge can also be recovered. I will describe the new instrument and inversion technique, and present the ability of the observation system operating in a High-Arctic location. I will show the sensitivity of the system to CO concentrations in the altitude range of approximately 40-80 km with a preliminary error analysis using optimal estimation, and the effect of inversion nonlinearities on CO trend analysis.

  11. Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations

    NASA Astrophysics Data System (ADS)

    Titova, E. E.; Kozelov, B. V.; Demekhov, A. G.; Manninen, J.; Santolik, O.; Kletzing, C. A.; Reeves, G.

    2015-08-01

    We report on simultaneous spacecraft and ground-based observations of quasiperiodic VLF emissions and related energetic-electron dynamics. Quasiperiodic emissions in the frequency range 2-6 kHz were observed during a substorm on 25 January 2013 by Van Allen Probe-A and a ground-based station in the Northern Finland. The spacecraft detected the VLF signals near the geomagnetic equator in the night sector at L = 3.0-4.2 when it was inside the plasmasphere. During the satellite motion toward higher latitudes, the time interval between quasiperiodic elements decreased from 6 min to 3 min. We find one-to-one correspondence between the quasiperiodic elements detected by Van Allen Probe-A and on the ground, which indicates the temporal nature of the observed variation in the time interval between quasiperiodic elements. Multi-component measurements of the wave electric and magnetic fields by the Van Allen Probe-A show that the quasiperiodic emissions were almost circularly right-hand polarized whistler mode waves and had predominantly small (below 30°) wave vector angles with respect to the magnetic field. In the probable source region of these signals (L about 4), we observed synchronous variations of electron distribution function at energies of 10-20 keV and the quasiperiodic elements. In the pause between the quasiperiodic elements pitch angle distribution of these electrons had a maximum near 90°, while they become more isotropic during the development of quasiperiodic elements. The parallel energies of the electrons for which the data suggest direct evidence of the wave-particle interactions is in a reasonable agreement with the estimated cyclotron resonance energy for the observed waves.

  12. 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.

  13. 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.

  14. Observations of total electron content perturbations on GPS signals caused by a ground level explosion

    NASA Astrophysics Data System (ADS)

    Fitzgerald, T. Joseph

    1997-05-01

    We have measured perturbations of electron density in the ionosphere caused by a ground level explosion with an energy release of 2 kt (8.5 × 1012 J) using transmissions from Global Positioning System (GPS) satellites to monitor integrated electron density. The frequencies of the transmissions were 1575.42 MHz (L1) and 1227.60 MHz (L2). The detected perturbation showed a maximum excursion of 0.14 TEC units and had a duration of 80 s beginning at 565 s after the explosion. The acoustic disturbance necessary to produce such a perturbation is well modeled as an N wave with a dimension of 35 km and a relative amplitude of 12% propagating radially at a speed of 0.7 km/s. The majority of the TEC perturbation occurred at an altitude of approximately 200 km.

  15. Surface/subsurface observation and removal mechanisms of ground reaction bonded silicon carbide

    NASA Astrophysics Data System (ADS)

    Yao, Wang; Zhang, Yu-Min; Han, Jie-cai; Zhang, Yun-long; Zhang, Jian-han; Zhou, Yu-feng; Han, Yuan-yuan

    2006-01-01

    Reaction Bonded Silicon Carbide (RBSiC) has long been recognized as a promising material for optical applications because of its unique combination of favorable properties and low-cost fabrication. Grinding of silicon carbide is difficult because of its high hardness and brittleness. Grinding often induces surface and subsurface damage, residual stress and other types of damage, which have great influence on the ceramic components for optical application. In this paper, surface integrity, subsurface damage and material removal mechanisms of RBSiC ground using diamond grinding wheel on creep-feed surface grinding machine are investigated. The surface and subsurface are studied with scanning electron microscopy (SEM) and optical microscopy. The effects of grinding conditions on surface and subsurface damage are discussed. This research links the surface roughness, surface and subsurface cracks to grinding parameters and provides valuable insights into the material removal mechanism and the dependence of grind induced damage on grinding conditions.

  16. 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.

  17. 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

  18. Observation of a bipolar cloud-to-ground flash containing one first positive stroke followed by three negative strokes

    NASA Astrophysics Data System (ADS)

    Lu, G.; Tian, Y.; Wang, Z.; Zhang, H.; Jiang, R.; Liu, M.; Sun, Z.; Qie, X.

    2014-12-01

    We report the high-speed (3,200 fps) observation of a bipolar cloud-to-ground flash with one first positive stroke followed by three subsequent negative strokes that all transferred charge to ground through the same channel. The inception of this flash was barely captured with the high-speed camera, indicating an onset near the cloud base, which allows us to investigate the possible mechanism for its occurrence. The examination of multi-disciplinary data recorded for this event, including high-speed imagery, slow and fast E-field change, broadband (3-300 kHz) magnetic fields, and surface static electric field, indicates that this flash could have initiated from a relatively large positive charge center near the cloud base (which caused a sustained negative surface electric field at the observation site); the preliminary breakdown pulse train has the same polarity as the pulse of leading positive return stroke. The positive leader propagated downward at an average speed of 1×105 m s-1, culminating a positive stroke with a continuing current of ~70 ms about 120 ms after the flash onset. The ascendance of upward negative leaders into the middle negative cloud charge region, as stimulated by a sequence of K processes that drew negative charge elsewhere at the cloud base, probably resulted in the polarity reversal of charge transfer to ground.

  19. 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

  20. 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.

  1. Ground based observations of the Cascades2 sounding rocket ionosphere - characterization and interpretation

    NASA Astrophysics Data System (ADS)

    Hampton, D. L.; Stenbaek-Nielsen, H. C.; Dahlgren, H.; Ivchenko, N. V.; Nicolls, M. J.; Lynch, K. A.; Mella, M. R.; Kintner, P. M.; Lundberg, E. T.; Lessard, M.; Jones, S.

    2009-12-01

    In support of the Cascades2 program (see Lynch et al. this session) multiple ground-based observatories were recording the auroral conditions on March 20, 2009. In addition to standard all-sky cameras at Poker Flat, Fort Yukon, Kaktovik and Toolik Lake, and meridian spectrographs at Poker Flat, Fort Yukon and Kaktovik, two sets of narrow-field cameras were deployed to Kaktovik and Toolik Lake specifically for the experiment. The Poker Flat Incoherent Scatter Radar (PFISR) was collecting ion and electron density, temperature and velocity profiles in the upleg region of the rocket trajectory. The geomagnetic conditions on March 20, 2009 showed very low activity prior to 10 UT, with a single narrowly defined arc nearly overhead at Fort Yukon (magnetic latitude ~67.3). At 10:15 the arc intensified, and split and showed increased activity with the active arcs drifting northward of Kaktovik (magnetic latitude ~70.8) as the rocket payload overflew the region at 11:10 to 11:15 UT. The increased activity produced only moderate currents with the ground magnetometers at Kaktovik and Fort Yukon recording 150 nT deflection in H. For a significant portion of the flight the rocket overflies a region where arcs are often not aligned along magnetic E-W which is consistent with alfvenic aurora associated with Poleward Boundary Intensifications. We present the characteristics of the ionosphere and auroral emissions along the trajectory of the rocket and how they correlate to the precipitation data recorded by the Cascades2 payload.

  2. 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.

  3. 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.

  4. 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).

  5. 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.

  6. Biogeographic patterns in below-ground diversity in New York City's Central Park are similar to those observed globally

    PubMed Central

    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

    2014-01-01

    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. PMID:25274366

  7. 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.

  8. 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 c