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  • Astronomy  (248)
  • Earth Resources and Remote Sensing  (238)
  • Engineering
  • General Chemistry
  • Life and Medical Sciences
  • 2005-2009  (502)
  • 1985-1989
  • 1950-1954
  • 2007  (502)
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  • 2005-2009  (502)
  • 1985-1989
  • 1950-1954
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  • 1
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    The increasing dominance of teams in production of knowledge (2007)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2007-04-14
    Description: We have used 19.9 million papers over 5 decades and 2.1 million patents to demonstrate that teams increasingly dominate solo authors in the production of knowledge. Research is increasingly done in teams across nearly all fields. Teams typically produce more frequently cited research than individuals do, and this advantage has been increasing over time. Teams now also produce the exceptionally high-impact research, even where that distinction was once the domain of solo authors. These results are detailed for sciences and engineering, social sciences, arts and humanities, and patents, suggesting that the process of knowledge creation has fundamentally changed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wuchty, Stefan -- Jones, Benjamin F -- Uzzi, Brian -- New York, N.Y. -- Science. 2007 May 18;316(5827):1036-9. Epub 2007 Apr 12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Northwestern Institute on Complexity (NICO), Northwestern University, Evanston, IL 60208, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17431139" target="_blank"〉PubMed〈/a〉
    Keywords: *Authorship ; Bibliometrics ; Biomedical Research/statistics & numerical data/trends ; Databases as Topic/statistics & numerical data ; Engineering ; Humanities ; *Knowledge ; *Patents as Topic ; Publishing/statistics & numerical data/*trends ; Research/statistics & numerical data/*trends ; Sociology ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Effect of Ducting on Radio Occultation Measurements: An Assessment Based on High-Resolution Radiosonde Soundings (2007)
    In:  Other Sources
    Details
    Publication Date: 2018-06-11
    Description: Recent studies have shown that the presence of elevated ducts in the lower atmosphere has an adverse effect on the inversion of GPS radio occultation data. The problem arises because the microwave refractivity within and below an elevated duct is no longer uniquely determined by the bending angle profile. Applying Abel inversion without a priori knowledge of the duct will introduce a negative bias in the retrieved refractivity profile within and below the duct. In this work, high vertical resolution radiosonde data are used to give a quantitative assessment of the characteristics and effects of ducts, including their frequency of occurrences, heights, and thicknesses at different latitudes and seasons. The negative bias from the Abel-retrieved refractivity profiles resulting from these ducts is also computed. The results give a strong indication that ducting in the lower troposphere is a frequent phenomenon over the tropics and midlatitudes. The ducts are shown to be predominantly caused by sharp changes in the vertical structure of water vapor. The majority of the ducts are found to be below 2 km, with a median duct layer thickness of about 100 m. The negative refractivity bias is shown to be largest below 2 km, with a median value of about 0.5-1% in the tropics and 0.2-0.5% in midlatitudes. The bias is about a factor of 2-3 smaller between 2 to 3 km and is negligible above 4 km.
    Keywords: Earth Resources and Remote Sensing
    Type: Radio Science; Volume 42
    Format: text
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  • 3
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    SIM Planetquest Science and Technology: A Status Report (2007)
    In:  Other Sources
    Details
    Publication Date: 2018-06-11
    Description: Optical interferometry will open new vistas for astronomy over the next decade. The Space Interferometry Mission (SIM-PlanetQuest), operating unfettered by the Earth's atmosphere, will offer unprecedented astrometric precision that promises the discovery of Earth-analog extra-solar planets as well as a wealth of important astrophysics. Results from SIM will permit the determination of stellar masses to accuracies of 2% or better for objects ranging from brown dwarfs through main sequence stars to evolved white dwarfs, neutron stars, and black holes. Studies of star clusters will yield age determinations and internal dynamics. Microlensing measurements will present the mass spectrum of the Milky Way internal to the Sun while proper motion surveys will show the Sun's orbital radius and speed. Studies of the Galaxy's halo component and companion dwarf galaxies permit the determination of the Milky Way's mass distribution, including its Dark Matter component and the mass distribution and Dark Matter component of the Local Group. Cosmology benefits from precision (1-2%) determination of distances to Cepheid and RR Lyrae standard candles. The emission mechanism of supermassive black holes will be investigated. Finally, radio and optical celestial reference frames will be tied together by an improvement of two orders of magnitude. Optical interferometers present severe technological challenges. The Jet Propulsion Laboratory, with the support of Lockheed Martin Advanced Technology Center (LM ATC) and Northrop Grumman Space Technology (NGST), has addressed these challenges with a technology development program that is now complete. The requirements for SIM have been satisfied, based on outside peer review, using a series of laboratory tests and appropriate computer simulations: laser metrology systems perform with 10 picometer precision; mechanical vibrations have been controlled to nanometers, demonstrating orders of magnitude disturbance rejection; and knowledge of component positions throughout the whole test assembly has been demonstrated to the required picometer level. Technology transfer to the SIM flight team is now well along.
    Keywords: Astronomy
    Type: Proceedings, SPIE; Volume 6693
    Format: text
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  • 4
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    Optical Measurement Center Status (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: Beginning in 2005, an optical measurement center (OMC) was created to measure the photometric signatures of debris pieces. Initially, the OMC was equipped with a 300 W xenon arc lamp, a SBIG 512 x 512 ST8X MEI CCD camera with standard Johnson filters, and a Lynx 6 robotic arm with five degrees of freedom. As research progressed, modifications were made to the equipment. A customized rotary table was built to overcome the robot s limitation of 180 degree wrist rotation and provide complete 360 degree rotation with little human interaction. This change allowed an initial phase angle (source-object-camera angle) of roughly 5 degrees to be adjusted to 7, 10, 15, 18, 20, 25, or 28 degrees. Additionally, the Johnson R and I CCD filters were replaced with the standard astronomical filters suite (Bessell R,I). In an effort to reduce object saturation, the two generic aperture stops were replaced with neutral density filters. Initially data were taken with aluminum debris pieces from the European Space Operations Centre ESOC2 ground test and more recently with samples from a thermal multi-layered insulation (MLI) commonly used on rocket bodies and satellites. The ESOC2 data provided light curve analysis for one type of material but many different shapes, including flat, bent, curled, folded, and torn. The MLI samples are roughly the same size and shape, but have different surfaces that give rise to interesting photometric light curves. In addition, filter photometry was conducted on the MLI pieces, a process that also will be used on the ESOC2 samples. While obtaining light curve data an anomalous drop in intensity was observed when the table revolved through the second 180 degree rotation. Investigation revealed that the robot s wrist rotation is not reliable past 80 degrees, thus the object may be at slightly different angles at the 180 degree transition. To limit this effect, the initial rotation position begins with the object s minimal surface area facing the camera.
    Keywords: Astronomy
    Type: Orbital Debris Quarterly News, Vol. 11, No. 3; 7
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  • 5
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    Optical Observations of GEO Debris with Two Telescopes (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: For several years, the Michigan Orbital DEbris Survey Telescope (MODEST), the University of Michigan s 0.6/0.9-m Schmidt telescope on Cerro Tololo Inter-American Observatory in Chile has been used to survey the debris population at GEO in the visible regime. Magnitudes, positions, and angular rates are determined for GEO objects as they move across the telescope s field-of-view (FOV) during a 5-minute window. This short window of time is not long enough to determine a full six parameter orbit so usually a circular orbit is assumed. A longer arc of time is necessary to determine eccentricity and to look for changes in the orbit with time. MODEST can follow objects in real-time, but only at the price of stopping survey operations. A second telescope would allow for longer arcs of orbit to obtain the full six orbital parameters, as well as assess the changes over time. An additional benefit of having a second telescope is the capability of obtaining BVRI colors of the faint targets, aiding efforts to determine the material type of faint debris. For 14 nights in March 2007, two telescopes were used simultaneously to observe the GEO debris field. MODEST was used exclusively in survey mode. As objects were detected, they were handed off in near real-time to the Cerro Tololo 0.9-m telescope for follow-up observations. The goal was to determine orbits and colors for all objects fainter than R = 15th magnitude (corresponds to 1 meter in size assuming a 0.2 albedo) detected by MODEST. The hand-off process was completely functional during the final eight nights and follow-ups for objects from night-to-night were possible. The cutoff magnitude level of 15th was selected on the basis of an abrupt change in the observed angular rate distribution in the MODEST surveys. Objects brighter than 15th magnitude tend to lie on a well defined locus in the angular rate plane (and have orbits in the catalog), while fainter objects fill the plane almost uniformly. We need to determine full six-parameter orbits to investigate what causes this change in observed angular rates. Are these faint objects either the same population of high area-to-mass (A/M) objects on eccentric orbits as discovered by the ESA Space Debris Telescope (Schildknecht, et al. 2004), or are they just normal debris from breakups in GEO?
    Keywords: Astronomy
    Type: Orbital Debris Quarterly News, Vol. 11, No. 3; 6-7
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  • 6
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    Hinode Observations of the Onset Stage of a Solar Filament Eruption (2007)
    In:  Other Sources
    Details
    Publication Date: 2018-06-12
    Description: We used Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT) filtergraph (FG) Stokes-V magnetogram observations, to study the early onset of a solar eruption that includes an erupting filament that we observe in TRACE EUV images. The filament undergoes a slow rise for at least 20min prior to its fast eruption and strong soft X-ray (SXR) flaring; such slow rises have been previously reported, and the new Hinode data elucidate the physical processes occurring during this period. XRT images show that during the slow-rise phase, an SXR sigmoid forms from apparent reconnection low in the sheared core field traced by the filament, and there is a low-level intensity peak in both EUV and SXRs during the slow rise. MDI and SOT FG Stokes-V magnetograms show that the pre-emption filament is along a neutral line between opposing-polarity enhanced network cells, and the SOT magnetograms show that these opposing fields are flowing together and canceling for at least six hours prior to eruption. From the MDI data we measured the canceling network fields to be approx. 40 G, and we estimated that approx. 10(exp 19)Mx of flux canceled during the five hours prior to eruption; this is only approx.5% of the total flux spanned by the eruption and flare, but apparently its tether-cutting cancellation was enough to destabilize the sigmoid field holding the filament and resulted in that field's eruption.
    Keywords: Astronomy
    Type: Publications of the Astronomical Society of Japan; Volume 59; S823-S829
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  • 7
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    An Overview of the CBERS-2 Satellite and Comparison of the CBERS-2 CCD Data with the L5 TM Data (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: CBERS satellite carries on-board a multi sensor payload with different spatial resolutions and collection frequencies. HRCCD (High Resolution CCD Camera), IRMSS (Infrared Multispectral Scanner), and WFI (Wide-Field Imager). The CCD and the WFI camera operate in the VNIR regions, while the IRMSS operates in SWIR and thermal region. In addition to the imaging payload, the satellite carries a Data Collection System (DCS) and Space Environment Monitor (SEM).
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 8
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    Future of Land Remote Sensing: What is Needed (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: A viewgraph presentation describing the future of land remote sensing and the new technologies needed for clear views of the Earth is shown. The contents include: 1) Viewing the Earth; 2) Multi-Imagery; 3) May Missions and Sensors; 4) What is Needed; 5) Things to Think About; 6) Global Land Remote Sensing in Landsat 7 Era; 7) Seasonality; 8) Cloud Contamination; 9) NRC Decadal Study; 10) Atmospheric Attenuation; 11) Geo-Registration; 12) Orthorectification Required; 13) Band Registration with OLI; and 14) Things to Do. A viewgraph presentation describing the future of land remote sensing and the new technologies needed for clear views of the Earth is shown. The contents include: 1) Viewing the Earth; 2) Multi-Imagery; 3) May Missions and Sensors; 4) What is Needed; 5) Things to Think About; 6) Global Land Remote Sensing in Landsat 7 Era; 7) Seasonality; 8) Cloud Contamination; 9) NRC Decadal Study; 10) Atmospheric Attenuation; 11) Geo-Registration; 12) Orthorectification Required; 13) Band Registration with OLI; and 14) Things to Do.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 9
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    AWiFS Radiometric Assessment (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: An assessment of the Advanced Wide Field Sensor (AWiFS) is presented. The contents include: 1) Overview of AWiFS sensor; 2) Description of University of Arizona approach; 3) Description of South Dakota State approach and results; 4) Description of Stennis Space Center approach and results; 5) Summary of results for all groups.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 10
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    GeoEye(TradeMark) Corporate Overview (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: This viewgraph presentation gives a corporate overview of GeoEye, the world's largest commercial remote sensing company. The contents include: 1) About GeoEye; 2) GeoEye Mission; 3) The Company; 4) Com,pany Summary; 5) U.S. Government Commitment; 6) GeoEye Constellation; 7) Other Imaging Resources; 8) OrbView-3 & OrbView-2; 9) OrbView-3 System Architecture; 10) OrbView-3; 11) OrbView-2; 12) IKONOS; 13) Largest Image Archive in the World; 14) GeoEye-1; 15) Best-In-Class Development Team; 16) Highest Performance Available in the Commercial Market; and 17) Key Themes
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 11
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    Cropland Classifications of Coincident TM and AWiFS Imagery (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Training and validation data is presented of approx. 100,000 acres fro about 200 randomly distributed area visits during the 2005 NASS Agricultural Survey.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 12
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    Radiometric Calibration Assessment of Commercial High Spatial Resolution Multispectral Image Products (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: This paper describes the results of commercial high spatial resolution sensors. The topics include: 1) Reflectance-based approach; 2) U of A test sites; 3) Test Site Selection; 4) Resort Living; 5) Aerosol parameters; 6) Surface reflectance retrieval; 7) Accuracy/precision; 8) Data sets; 9) June 23, 2005 for Ikonos; 10) QuickBird Results; 11) Ikonos results; 12) Orbview results; 13) Ikonos redux; and 14) Overall results.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 13
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    Monitoring and Assuring the Quality of Digital Aerial Data (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: This viewgraph presentation explains the USGS plan for monitoring and assuring the quality of digital aerial data. The contents include: 1) History of USGS Aerial Imaging Involvement; 2) USGS Research and Results; 3) Outline of USGS Quality Assurance Plan; 4) Other areas of Interest; and 5) Summary
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 14
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    Evaluating the Horizontal Accuracy of GeoEye OrbView-3 Orthorectified Products Over the Kaintuck Hollow, Missouri, Test Site (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Data collected and horizontal accuracy calculations of GeoEye OrbView-3 Orthorectified panchromatic imagery over the Kaintuch Hollow, Missouri test site is presented.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 15
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    The ASPRS Remote Sensing Industry Forecast: Phase II & III - Digital Sensor Compilation (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: In August 1999, ASPRS and NASA's (then) Commercial Remote Sensing Program (CRSP) entered into a 5-year Space Act Agreement (SAA), combining resources and expertise to: (a) Baseline the Remote Sensing Industry (RSI) based on GEIA Model; (b) Develop a 10-Year RSI market forecast and attendant processes; and (c) Provide improved information for decision makers.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 16
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    On-orbit Modulation Transfer Function (MTF) Measurements for IKONOS and QuickBird (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Point Spread Function is a method of evaluation the spatial resolution of an imaging system. It is also a measure of the spread of a single point of light. Modulation Transfer Function (MTF) is a measure of the spatial frequency response. It is often calculated from th point spread function (PSF). System response at the Nyquist frequency (or 0.5 cycle/pixel) is often used as a figure of merit
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 17
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    OrbView-3 Technical Performance Evaluation 2005: OV-3 Specifications (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The product specifications, geolocation accuracy, methodology, and test and evaluation are presented for Orbview-3.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 18
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    Poly-Pattern Compressive Segmentation of ASTER Data for GIS (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Pattern-based segmentation of multi-band image data, such as ASTER, produces one-byte and two-byte approximate compressions. This is a dual segmentation consisting of nested coarser and finer level pattern mappings called poly-patterns. The coarser A-level version is structured for direct incorporation into geographic information systems in the manner of a raster map. GIs renderings of this A-level approximation are called pattern pictures which have the appearance of color enhanced images. The two-byte version consisting of thousands of B-level segments provides a capability for approximate restoration of the multi-band data in selected areas or entire scenes. Poly-patterns are especially useful for purposes of change detection and landscape analysis at multiple scales. The primary author has implemented the segmentation methodology in a public domain software suite.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 19
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    Assessing Hurricane Katrina Damage to the Mississippi Gulf Coast Using IKONOS Imagery (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Hurricane Katrina hit southwestern Mississippi on August 29, 2005, at 10 a.m. CDT as a category 3 event with storm surges up to approximately 9 m and sustained winds of approximately 120 mph. The hurricane ravaged several coastal towns, destroying or severely damaging hundreds of homes. Hurricand Katrina deposited millions of tons of debris and caused severe damage to coastal forests. In response, several Federal agencies have been using a broad range of remotely sensed data (e.g., IKONOS) to aid damage assessment and disaster recovery efforts. This presentation discusses an effort to use IKONOS data for damage assessment, based on data collected over southwestern coastal Mississippi on September 2, 2005.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 20
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    Radiometric Characterization Results for the IKONOS Sensor (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The radiometric characterization results of the IKONOS sensor is presented.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 21
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    Medium Spatial Resolution Satellite Characterization (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: This project provides characterization and calibration of aerial and satellite systems in support of quality acquisition and understanding of remote sensing data, and verifies and validates the associated data products with respect to ground and and atmospheric truth so that accurate value-added science can be performed. The project also provides assessment of new remote sensing technologies.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 22
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    DigitalGlobe(TM) Incorporated Corporate and System Update (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: This viewgraph presentation describes a system update of Quickbird, the world's highest resolution commercial imaging satellite, operated by DigitalGlobe (TM) Incorporated. A satellite comparison of Quickbird, WorldView-60, and WorldView-110 is also presented.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 23
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    Small Satellite Constellations: The Future for Operational Earth Observation (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Nanosat, microsat and minisat are low-cost, rapid-response small-satellites built from advanced terrestrial technology. SSTL delivers the benefits of affordable access to space through low-cost, rapid response, small satellites designed and built with state-of-the-art COTS technologies by: a) reducing the cost of entry into space; b) Achieving more missions within fixed budgets; c) making constellations and formation flying financially viable; d) responding rapidly from initial concept to orbital operation; and e) bringing the latest industrial COTS component advances to space. Growth has been stimulated in constellations for high temporal revisit&persistent monitoring and military responsive space assets.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 24
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    Land Remote Sensing Overview (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: A general overview of the USGS land remote sensing program is presented. The contents include: 1) Brief overview of USGS land remote sensing program; 2) Highlights of JACIE work at USGS; 3) Update on NASA/USGS Landsat Data Continuity Mission; and 4) Notes on alternative data sources.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 25
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    Spatial Resolution Characterization for Aerial Digital Imagery (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: This viewgraph presentation reviews NASA and the U.S. Geological Survey (USGS)'s analysis of spatial characterization resolution for Aerial Digital Imagery.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 26
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    Viability of NLCD Products From IRS-P6, And From Landsat 7 Scan-gap Data (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: Landcover test on Salt Lake test site illustrates potential issues with AWiFS/LISS-III for classification of certain land cover classes (evergreen, shrub/scrub, woody wetlands, emergent wetlands). Canopy and impervious graphs of product differences from source indicate slightly lower overall accuracies (shorter peaks, wider bases) for AWiFS/LISS-III, compared to L5/L7. Inspection of individual products from canopy and impervious estimate tests revealed issues with combining AWifs quadrants, and similar but less severe effects with combining multiple dates of L7 scan gap data.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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  • 27
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    Crop Acreage Estimation: Landsat TM and Resourcesat-1 AWiFS Sensor Assessment of the Mississippi River Delta, 2005 (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: AWiFs data are appropriate for crop acreage estimation over large, spectrally homogenous, crop areas such as the Mid-West, the Delta and the Northern Great Plains. Regression and Kappa statistics for soybean, corn, cotton, rice and sorghum produced using both the Landsat TM and AWiFS data are very similar. AWiFS data appear to be a suitable alternative or supplement to Landsat TM data for production of NASS'Cropland Data Layer product.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Emerging Techniques for Vicarious Calibration of Visible Through Short Wave Infrared Remote Sensing Systems (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Autonomous Visible to SWIR ground-based vicarious Cal/Val will be an essential Cal/Val component with such a large number of systems. Radiometrically calibrated spectroradiometers can improve confidence in current ground truth data through validation of radiometric modeling and validation or replacement of traditional sun photometer measurement. They also should enable significant reduction in deployed equipment such as equipment used in traditional sun photometer approaches. Simple, field-portable, white-light LED calibration source shows promise for visible range (420-750 nm). Prototype demonstrated 〈0.5% drift over 10-40 C temperature range. Additional complexity (more LEDs) will be necessary for extending spectral range into the NIR and SWIR. LED long lifetimes should produce at least several hundreds of hours or more of stability, minimizing the need for expensive calibrations and supporting long-duration field campaigns.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Automated, per pixel Cloud Detection from High-Resolution VNIR Data (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: CASA is a fully automated software program for the per-pixel detection of clouds and cloud shadows from medium- (e.g., Landsat, SPOT, AWiFS) and high- (e.g., IKONOS, QuickBird, OrbView) resolution imagery without the use of thermal data. CASA is an object-based feature extraction program which utilizes a complex combination of spectral, spatial, and contextual information available in the imagery and the hierarchical self-learning logic for accurate detection of clouds and their shadows.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    NOAA's Use of High-Resolution Imagery (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: NOAA's use of high-resolution imagery consists of: a) Shoreline mapping and nautical chart revision; b) Coastal land cover mapping; c) Benthic habitat mapping; d) Disaster response; and e) Imagery collection and support for coastal programs.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Correction to Method of Establishing the Absolute Radiometric Accuracy of Remote Sensing Systems While On-orbit Using Characterized Stellar Sources (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The contents include: 1) Brief history of related events; 2) Overview of original method used to establish absolute radiometric accuracy of remote sensing instruments using stellar sources; and 3) Considerations to improve the stellar calibration approach.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Radiometric Characterization Results for the OrbView-3 Sensor (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Orbview-3 Sensor calibration summaries from the year 2004-2005 is presented.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    OrbView-3 Technical Performance Evaluation 2005: Modulation Transfer Function (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The Technical performance evaluation of OrbView-3 using the Modulation Transfer Function (MTF) is presented. The contents include: 1) MTF Results and Methodology; 2) Radiometric Calibration Methodology; and 3) Relative Radiometric Assessment Results
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Application of High Resolution Multispectral Imagery for Levee Slide Detection and Monitoring (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The objective is to develop methods to detect and monitor levee slides using commercially available high resolution multispectral imagery. High resolution multispectral imagery like IKONOS and QuickBird are suitable for detecting and monitoring levee slides. IKONOS is suitable for visual inspection, image classification and Tasseled Cap transform based slide detection. Tasseled Cap based model was found to be the best method for slide detection. QuickBird was suitable for visual inspection and image classification.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    NOAA's National Geodetic Survey Utilization of Aerial Sensors for Emergency Response Efforts (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Remote Sensing Division has a Coastal Mapping program and a Airport Survey program and research and development that support both programs. NOAA/NGS/RSD plans to acquire remotely sensed data to support the agency's homeland security and emergency response requirements.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    General Relativistic Radiative Transfer: Applications to Black-Hole Systems (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: We present general relativistic radiation transfer formulations which include opacity effects due to absorption, emission and scattering explicitly. We consider a moment expansions for the transfer in the presence of scattering. The formulation is applied to calculation emissions from accretion and outflows in black-hole systems. Cases with thin accretion disks and accretion tori are considered. Effects, such as emission anisotropy, non-stationary flows and geometrical self-occultation are investigated. Polarisation transfer in curved space-time is discussed qualitatively.
    Keywords: Astronomy
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    First X-ray Observations of the Young Pulsar J1357-6429 (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The first short Chandra and XMM-Newton observations of the young and energetic pulsar J1357-6429 provided strong indications of a tail-like pulsar-wind nebula associated with this object, as well as strong pulsations of its X-ray flux with a pulsed fraction above 40% and a thermal component dominating at lower photon energies (below 2 keV). The elongated nebular is very compact in size. about 1" x 1.5" and might be interpreted as a pulsar jet. The thermal radiation is most plausibly emitted from the entire neutron star surface of an effective temperature about 1 MK covered with a magnetized hydrogen atmosphere At higher energies the pulsar's emission is of a nonthermal (magnetospheric) origin, with a power-law spectrum of a photon index Gamma approx. equals 1.1. This makes the X-ray properties of PSR J1357-6429 very similar to those of the youngest pulsars J1119-6127 and Vela with a detected thermal radiation.
    Keywords: Astronomy
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    Detailed Physical Modeling Reveals the Magnetar Nature of a Transient Anomalous X-ray Pulsar (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: Anomalous X-ray Pulsars (AXPs) belong to a class of neutron stars believed to harbor the strongest magnetic fields in the universe, as indicated by their energetic bursts and their rapid spindowns. However, a direct measurement of their surface field strengths has not been made to date. It is also not known whether AXP outbursts result from changes in the neutron star magnetic field or crust properties. Here we report the first, spectroscopic measurement of the surface magnetic field strength of an AXP, XTE J1810-197, and solidify its magnetar nature. The field strength obtained from detailed spectral analysis and modeling is remarkably close to the value inferred from the rate of spindown of this source and remains nearly constant during numerous observations spanning over two orders of magnitude in source flux. The surface temperature, on the other hand, declines steadily and dramatically following the 2003 outburst of this source. Our findings demonstrate that heating occurs in the upper neutron star crust during an outburst and sheds light on the transient behaviour of AXPs.
    Keywords: Astronomy
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    X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) 〈 3 x 10(exp 25)/sq cm), local (〈 z 〉= 0.03), AGN sample. We find 9/22 low absorption (n(sub H) 〈 10(exp 23)/sq cm), simple power law model sources, where 4 of these sources have a statistically significant soft component. Among these sources, we find the presence of a warm absorber statistically significant for only one Seyfert 1 source, contrasting with the ASCA results of Reynolds (1997) and George et al. (1998), who find signatures of warm absorption in half or more of their Seyfert 1 samples at similar redshifts. Additionally, the remaining sources (13122) have more complex spectra, well-fit by an absorbed power law at E 〉 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.
    Keywords: Astronomy
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    An Active Subglacial Water System in West Antarctica Mapped from Space (2007)
    In:  Other Sources
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    Publication Date: 2018-06-06
    Description: Satellite laser altimeter elevation profiles from 2003 to 2006 collected over the lower parts of Whillans and Mercer ice streams, West Antarctica, reveal 14 regions of temporally varying elevation, which we interpret as the surface expression of subglacial water movement. Vertical motion and spatial extent of two of the largest regions are confirmed by satellite image differencing. A major, previously unknown subglacial lake near the grounding line of Whillans Ice Stream is obse~edto drain 2.0 cubic kilometers of water into the ocean over approx.3 years, while elsewhere a similar volume of water is being stored subglacially. These observations reveal a widespread, dynamic subglacial water system that may exert an important control on ice flow and mass balance.
    Keywords: Earth Resources and Remote Sensing
    Type: Science (ISSN 0036-8075); Volume 315; 1544-1548
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    Short GRB Prompt and Afterglow Correlations (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The Swift data set on short GRBs has now grown large enough to study correlations of key parameters. The goal is to compare long and short bursts to better understand similarities and differences in the burst origins. In this study we consider the both prompt and afterglow fluxes. It is found that the optical, X-ray and gamma-ray emissions are linearly correlated - stronger bursts tend to have brighter afterglows, and bursts with brighter X-ray afterglow tend to have brighter optical afterglow. Both the prompt and afterglow fluxes are, on average, lower for short bursts than for long. Although there are short GRBs with undetected optical emission, there is no evidence for "dark" short bursts with anomalously low opt/X ratios. The weakest short bursts have a low X-ray/gamma-ray ratio.
    Keywords: Astronomy
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    Improving Land-Surface Model Hydrology: Is an Explicit Aquifer Model Better than a Deeper Soil Profile? (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Land surface models (LSMs) are computer programs, similar to weather and climate prediction models, which simulate the storage and movement of water (including soil moisture, snow, evaporation, and runoff) after it falls to the ground as precipitation. It is not currently possible to measure all of the variables of interest everywhere on Earth with sufficient accuracy. Hence LSMs have been developed to integrate the available information, including satellite observations, using powerful computers, in order to track water storage and redistribution. The maps are used to improve weather forecasts, support water resources and agricultural applications, and study the Earth's water cycle and climate variability. Recently, the models have begun to simulate groundwater storage. In this paper, we compare several possible approaches, and examine the pitfalls associated with trying to estimate aquifer parameters (such as porosity) that are required by the models. We find that explicit representation of groundwater, as opposed to the addition of deeper soil layers, considerably decreases the sensitivity of modeled terrestrial water storage to aquifer parameter choices. We also show that approximate knowledge of parameter values is not sufficient to guarantee realistic model performance: because interaction among parameters is significant, they must be prescribed as a harmonious set.
    Keywords: Earth Resources and Remote Sensing
    Type: To appear in Geophysical Research Letters
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    Remote Sensing of Terrestrial Snow and Ice for Global Change Studies (2007)
    In:  Other Sources
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    Publication Date: 2018-06-06
    Description: Snow and ice play a significant role in the Earth's water cycle and are sensitive and informative indicators climate change. Significant changes in terrestrial snow and ice water storage are forecast, and while evidence of large-scale changes is emerging, in situ measurements alone are insufficient to help us understand and explain these changes. Imaging remote sensing systems are capable of successfully observing snow and ice in the cryosphere. This chapter examines how those remote sensing sensors, that now have more than 35 years of observation records, are capable of providing information about snow cover, snow water equivalent, snow melt, ice sheet temperature and ice sheet albedo. While significant progress has been made, especially in the last five years, a better understanding is required of the records of satellite observations of these cryospheric variables.
    Keywords: Earth Resources and Remote Sensing
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    The Energy-Dependent X-Ray Timing Characteristics of the Narrow Line Seyfert 1 MKN 766 (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766, obtained from combining data obtained during an XMM-Newton observation spanning six revolutions in 2005 with data obtained from an XMM-Newton long-look in 2001. The PSD shapes and rms-flux relations are found to be consistent between the 2001 and 2005 observations, suggesting the 2005 observation is simply a low-flux extension of the 2001 observation and permitting us to combine the two data sets. The resulting PSD has the highest temporal frequency resolution for any AGN PSD measured to date. Applying a broken power-law model yields break frequencies which increase in temporal frequency with photon energy. Obtaining a good fit when assuming energy-independent break frequencies requires the presence of a Lorentzian at 4.6 +/- 0.4 x 10(exp -4)Hz whose strength increases with photon energy, a behavior seen in black hole X-ray binaries. The cross-spectral properties are measured; temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time. Cross-spectral results are consistent with those for other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.
    Keywords: Astronomy
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    Does the Blazar Gamma-ray Spectrum Harden with Increasing Flux? - Analysis of Nine Years of EGRET Data (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) discovered gamma-ray emission from more than 67 blazars during its nine-year lifetime. We conducted an exhaustive search of the EGRET archives and selected all the blazars that were observed multiple times and were bright enough to enable a spectral analysis using standard powerlaw models. The sample consists of 18 flat-spectrum radio quasars (FSRQs), 6 low-frequency-peaked BL Lacs (LBLs) and 2 high-frequency-peaked BL Lacs (HBLs). We do not detect any clear pattern in'the variation of spectral index with flux. Some of the blazars do not show any statistical evidence for spectral variability. The spectrum hardens with increasing flux in a few cases. There is also evidence for a flux-hardness anticorrelation at lo\v fluxes in five blazars. The well observed blazars (3C 279,3C 273, PKS 0528-i-134, PKS 1622-297, PKS 0208- 512) do not show any overall trend in the long-term spectral dependence on flux, but the sample shows a mixture of hard and soft states. We observed spectral hysteresis at weekly timescales in all the three FSRQs for which data from flares lasting for 3 approx. 4 weeks were available. All three sources show a counterclockwise rotation despite the widely different flux profiles. Hysteresis in the spectral index vs. flux space has never been observed in FSRQs in gamma-rays at weekly timescales. itre analyze the observed spectral behavior in the context of various inverse-Compton mechanisms believed to be responsible for emission in the EGRET energy range. Our analysis uses the EGRET skymaps that were regenerated to include the changes in performance during the mission.
    Keywords: Astronomy
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    SWIFT Detects a remarkable Gamma-ray Burst, GRB 060514, that introduces a New Classification Scheme (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Gamma ray bursts (GFU3s) are known to come in two duration classes, separated at approx.2 s. Long bursts originate from star forming regions in galaxies, have accompanying supernovae (SNe) when near enough to observe and are likely caused by massive-star collapsars. Recent observations show that short bursts originate in regions within their host galaxies with lower star formation rates, consistent with binary neutron star (NS) or NS - black hole (BH) mergers. Moreover, although their hosts are predominantly nearby galaxies, no SNe have been so far associated with short GRBs. We report here on the bright, nearby GRB 060614 that does not fit in either class. Its approx.102 s duration groups it with long GRBs, while its temporal lag and peak luminosity fall entirely within the short GRB subclass. Moreover, very deep optical observations exclude an accompanying supernova, similar to short GRBs. This combination of a long duration event without accompanying SN poses a challenge to both a collapsar and merging NS interpretation and opens the door on a new GRB classification scheme that straddles both long and short bursts.
    Keywords: Astronomy
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    GRO J1655-40: Early Stages of the 2005 Outburst (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The black-hole X-ray binary transient GRO J1655-40 underwent an outburst beginning in early 2005. We present the results of our multi-wavelength observational campaign to study the early outburst spectral and temporal evolution, which combines data from X-ray (RXTE, INTEGRAL), radio (VLA) and optical (ROTSE, SMARTS) instruments. During the reported period the source left quiescence and went through four major accreting black hole states: low-hard, hard intermediate, soft intermediate and high-soft. We investigated dipping behavior in the RXTE band and compare our results to the 1996-1997 case, when the source was predominantly in the high-soft state, finding significant differences. We consider the evolution of the low frequency quasi-periodic oscillations and find that the frequency strongly correlates with the spectral characteristics, before shutting off prior to the transition to the high-soft state. We model the broad-band high-energy spectrum in the context of empirical models, as well as more physically motivated thermal and bulk-motion Comptonization and Compton reflection models. RXTE and INTEGRAL data together support a statistically significant high energy cut-off in the energy spectrum at approximately equal to 100 - 200 keV during the low-hard state. The RXTE data alone also show it very significantly during the transition, but cannot see one in the high-soft state spectra. We consider radio, optical and X-ray connections in the context of possible synchrotron and synchrotron self-Compton origins of X-ray emission in low-hard and intermediate states. In this outburst of GRO J1655-40, the radio flux does not rise strongly with the X-ray flux.
    Keywords: Astronomy
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    Muiti-Sensor Historical Climatology of Satellite-Derived Global Land Surface Moisture (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: A historical climatology of continuous satellite derived global land surface soil moisture is being developed. The data set consists of surface soil moisture retrievals from observations of both historical and currently active satellite microwave sensors, including Nimbus-7 SMMR, DMSP SSM/I, TRMM TMI, and AQUA AMSR-E. The data sets span the period from November 1978 through the end of 2006. The soil moisture retrievals are made with the Land Parameter Retrieval Model, a physically-based model which was developed jointly by researchers from the above institutions. These data are significant in that they are the longest continuous data record of observational surface soil moisture at a global scale. Furthermore, while previous reports have intimated that higher frequency sensors such as on SSM/I are unable to provide meaningful information on soil moisture, our results indicate that these sensors do provide highly useful soil moisture data over significant parts of the globe, and especially in critical areas located within the Earth's many arid and semi-arid regions.
    Keywords: Earth Resources and Remote Sensing
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    Seasonal Snow Extent and Snow Mass in South America Using SMMR and SSM/I Passive Microwave Data (1979-2003) (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-satellite and the Special Sensor Microwave Imagers (SSM/I) on board Defense Meteorological Satellite Program (DMSP) satellites. For the period from 1979-2003, both snow cover extent and snow depth (snow mass) were investigated during coldest months (May-September), primarily in the Patagonia area of Argentina and in Chile. Most of the seasonal snow in South America is in the Patagonia region of Argentina. Since winter temperatures in this region are often above freezing, the coldest winter month was found to be the month having the most extensive snow cover and also usually the month having the deepest snow cover as well. Sharp year-to-year differences were recorded using the passive microwave observations. The average snow cover extent for July, the month with the greatest average snow extent during the 25-year period of record, is 320,700 km(exp 2). In July of 1984, the average monthly snow cover was 701,250 km(exp 2) - the most extensive coverage observed between 1979 and 2003. However, in July of 1989, snow cover extent was only 120 km(exp 2). The 25-year period of record shows a sinusoidal like pattern, though there appears to be no obvious trend in either increasing or decreasing snow extent or snow mass between 1979 and 2003.
    Keywords: Earth Resources and Remote Sensing
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    Algorithm Development and Validation for Satellite-Derived Distributions of DOC and CDOM in the US Middle Atlantic Bight (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: In coastal ocean waters, distributions of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) vary seasonally and interannually due to multiple source inputs and removal processes. We conducted several oceanographic cruises within the continental margin of the U.S. Middle Atlantic Bight (MAB) to collect field measurements in order to develop algorithms to retrieve CDOM and DOC from NASA's MODIS-Aqua and SeaWiFS satellite sensors. In order to develop empirical algorithms for CDOM and DOC, we correlated the CDOM absorption coefficient (a(sub cdom)) with in situ radiometry (remote sensing reflectance, Rrs, band ratios) and then correlated DOC to Rrs band ratios through the CDOM to DOC relationships. Our validation analyses demonstrate successful retrieval of DOC and CDOM from coastal ocean waters using the MODIS-Aqua and SeaWiFS satellite sensors with mean absolute percent differences from field measurements of 〈 9 %for DOC, 20% for a(sub cdom)(355)1,6 % for a(sub cdom)(443), and 12% for the CDOM spectral slope. To our knowledge, the algorithms presented here represent the first validated algorithms for satellite retrieval of a(sub cdom) DOC, and CDOM spectral slope in the coastal ocean. The satellite-derived DOC and a(sub cdom) products demonstrate the seasonal net ecosystem production of DOC and photooxidation of CDOM from spring to fall. With accurate satellite retrievals of CDOM and DOC, we will be able to apply satellite observations to investigate interannual and decadal-scale variability in surface CDOM and DOC within continental margins and monitor impacts of climate change and anthropogenic activities on coastal ecosystems.
    Keywords: Earth Resources and Remote Sensing
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    Cooling of the North Atlantic by Saharan Dust (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Using aerosol optical depth, sea surface temperature, top-of-the-atmosphere solar radiation flux, and oceanic mixed-layer depth from diverse data sources that include NASA satellites, NCEP reanalysis, in situ observations, as well as long-term dust records from Barbados, we examine the possible relationships between Saharan dust and Atlantic sea surface temperature. Results show that the estimated anomalous cooling pattern of the Atlantic during June 2006 relative to June 2005 due to attenuation of surface solar radiation by Saharan dust remarkably resemble observations, accounting for approximately 30-40% of the observed change in sea surface temperature. Historical data analysis show that there is a robust negative correlation between atmospheric dust loading and Atlantic SST consistent with the notion that increased (decreased) Saharan dust is associated with cooling (warming) of the Atlantic during the early hurricane season (July- August-September).
    Keywords: Earth Resources and Remote Sensing
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    TRMM-TMI Satellite Observed Soil Moisture and Vegetation Density (1998-2005) Show Strong Connection with El Nino in Eastern Australia (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Spatiotemporal patterns in soil moisture and vegetation water content across mainland Australia were investigated from 1998 through 2005, using TRMMITMI passive microwave observations. The Empirical Orthogonal Function technique was used to extract dominant spatial and temporal patterns in retrieved estimates of moisture content for the top 1-cm of soil (theta) and vegetation moisture content (via optical depth tau). The dominant temporal theta and tau patterns were strongly correlated to El Nino/Southern Oscillation (ENSO) in spring (3 = 0.90), and to a progressively lesser extent autumn, summer and winter. The Indian Ocean Dipole (IOD) index also explained part of the variation in spring 8 and z. Cluster analysis suggested that the regions most affected by ENS0 are mainly located in eastern Australia. The results suggest that the drought conditions experienced in eastern Australia since 2000 an clearly expressed in these satellite observations have a strong connection with ENSO patterns.
    Keywords: Earth Resources and Remote Sensing
    Type: Submitted to Geophysical Research Letters (American Geophysical Union)
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    Variations of the Mid-IR Aromatic Features Inside and Among Galaxies (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We present the results of a systematic study of mid-IR spectra of Galactic regions, Magellanic H II regions, and galaxies of various types (dwarf, spiral, starburst), observed by the satellites ISO and Spitzer. We study the relative variations of the 6.2, 7.7, 8.6 and 11.3 micron features inside spatially resolved objects (such as M 82, M 51, 30 Doradus, M 17 and the Orion bar), as well as among 90 integrated spectra of 50 objects. Our main results are that the 6.2, 7.7 and 8.6 micron bands are essentially tied together, while the ratios between these bands and the 11.3 micron band varies by one order of magnitude. This implies that the properties of the PAHs are remarkably universal throughout our sample, and that the relative variations of the band ratios are mainly controlled by the fraction of ionized PAHs. In particular, we show that we can rule out the modification of the PAH size distribution as an explanation of these variations. Using a few well-studied Galactic regions (including the spectral image of the Orion bar), we give an empirical relation between the I(6.2)/I(11.3) ratio and the ionization/recombination ratio Go/n(sub e) x square root of(T(sub gas)). Finally, we discuss the physical interpretation of the I(6.2)/I(11.3) ratio, on galactic size scales.
    Keywords: Astronomy
    Type: To be submitted to Astrophysical Journal.
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    Eastern U.S. Continental Shelf Carbon Budget: Integrating Models,Data Assimilation, and Analysis (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The U.S. East Coast Continental Shelf (USECoS) project was initiated in 2004 with the overall goal of developing carbon budgets for Mid-Atlantic and South Atlantic regions of the eastern U.S. coast. We addressed this goal through a series of specific research questions that were designed to understand carbon inputs and fates in the two regions, dominant food web pathways for carbon cycling, and similarities/differences in carbon cycling in the two continental shelf systems. The USECoS project represents a major effort to simultaneously synthesize and integrate diverse data sets, field measurements, models, and modeling approaches. We expect that the type of approach taken here will result in more insight than would be possible if each component of the program moved forward independently. The primary significance of this project is in providing a strong quantitative basis for the development of future observational and modeling studies of carbon budgets of continental shelf systems. A strong aspect of the USECoS project is the integration of modeling and extensive physical, chemical, and biological data sets, which provides an opportunity for modeling and data analyses to inform one another from the outset. This research is particularly germane to NASA's carbon cycle research focus and coastal research initiative and the U.S. Climate Change Research Program, all of which support the goals of the North American Carbon Program. We highlight primary approaches that have been used, and some of the challenges and results that have come from interactions among our team of investigators. The global scale and interdisciplinary nature of the science questions that we now face in Earth Science are such that integrated teams of investigators are needed to address them.
    Keywords: Earth Resources and Remote Sensing
    Type: To be submitted to Oceanography.
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    A Catalog of Galaxy Clusters Observed by XMM-Newton (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Images and the radial profiles of the temperature, abundance, and brightness for 70 clusters of galaxies observed by XMM-Newton are presented along with a detailed discussion of the data reduction and analysis methods, including background modeling, which were used in the processing. Proper consideration of the various background components is vital to extend the reliable determination of cluster parameters to the largest possible cluster radii. The various components of the background including the quiescent particle background, cosmic diffuse emission, soft proton contamination, and solar wind charge exchange emission are discussed along with suggested means of their identification, filtering, and/or their modeling and subtraction. Every component is spectrally variable, sometimes significantly so, and all components except the cosmic background are temporally variable as well. The distributions of the events over the FOV vary between the components, and some distributions vary with energy. The scientific results from observations of low surface brightness objects and the diffuse background itself can be strongly affected by these background components and therefore great care should be taken in their consideration.
    Keywords: Astronomy
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    Differential Radiometers Using Fabry-Perot Interferometric Technique for Remote Sensing of Greenhouse Gases (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: A new type of remote sensing radiometer based upon the Fabry-Perot interferometric technique has been developed at NASA's Goddard Space Flight Center and tested from both ground and aircraft platform. The sensor uses direct or reflected sunlight and has channels for measuring column concentration of carbon dioxide at 1570 nm, oxygen lines sensitive to pressure and temperature at 762 and 768 nm, and water vapor (940 nm). A solid Fabry-Perot etalon is used as a tunable narrow bandpass filter to restrict the measurement to the gas of interest's absorption bands. By adjusting the temperature of the etalon, which changes the index of refraction of its material, the transmission fringes can be brought into nearly exact correspondence with absorption lines of the particular species. With this alignment between absorption lines and fringes, changes in the amount of a species in the atmosphere strongly affect the amount of light transmitted by the etalon and can be related to gas concentration. The technique is applicable to different chemical species. We have performed simulations and instrument design studies for CH4, "Cot isotope, and CO detection. Index Terms- Absorbing media, Atmospheric measurements, Fabry-Perot interferometers, Optical interferometry, Remote sensing.
    Keywords: Earth Resources and Remote Sensing
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    Correlated Temporal and Spectral Variability (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the Xray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and review briefly what they tell us about the physical states of the systems.
    Keywords: Astronomy
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    SN 1987A after 18 Years: Mid-Infrared GEMINI and SPITZER Observations of the Remnant (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We present high resolution 11.7 and 18.3 micron mid-IR images of SN 1987A obtained on day 6526 since the explosion with the Thermal-Region Camera and Spectrograph (T-ReCS) attached to the Gemini South 8m telescope. The 11.7 micron flux has increased significantly since our last observations on day 6067. The images clearly show that all the emission arises from the equatorial ring (ER). Nearly contemporaneous spectra obtained on day 6184 with the MIPS at 24 micron, on day 6130 with the IRAC in 3.6- 8 micron region, and on day 6190 with the IRS in the 12-37 micron instruments on board the Spitzer Space Telescope's show that the emission consists of thermal emission from silicate dust that condensed out in the red giant wind of the progenitor star. The dust temperature is 1662(sup +18) (sub -12) K, and the emitting dust mass is (2.6(sup +2.0 (sub -1.4)) x 10 (exp -6) M(solar). Lines of [Ne II] 12.82 micron and [Ne III] 15.56 pm are clearly present in the Spitzer spectrum, as well as a weak [Si II] 3 34.8 micron line. We also detect two lines near 26 micron which we tentatively ascribe to [Fe II] 25.99 pm and [0 IV] 25.91 micron. Comparison of the mid-IR Gemini 11.7 micron image with X-ray images obtained by Chandra, UV-optical images obtained by HST, and radio synchrotron images obtained by the ATCA show generally good correlation of the images across all wavelengths. Because of the limited resolution of the mid-IR images we cannot uniquely determine the location. or heating mechanism of the dust giving rise to the emission. The dust could be collisionally heated by the X-ray emitting plasma, providing a unique diagnostic of plasma conditions. Alternatively, the dust could be radiatively heated in the dense UV-optical knots that are overrun by the advancing supernova blast wave. In either case the dust-to-gas mass ratio in the circumstellar medium around the supernova is significantly lower than that in the general interstellar medium of the LMC, suggesting either a low condensation efficiency in the wind of the progenitor star, or the efficient destruction of the dust by the SN blast wave. Overall, we are witnessing the interaction of the SN blast wave with its surrounding medium, creating an environment that is rapidly evolving at all wavelengths. Continuous multiwavelength observations of SN 1987A such as these provide unique snapshots of the very early evolution of supernova remnants.
    Keywords: Astronomy
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    Gamma-Ray Bursts in the Swift Era (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: GRB research has undergone a revolution in the last two years. The launch of Swift, with its rapid slewing capability, has greatly increased the number and quality of GRB localizations and X-ray and optical afterglow lightcurves. Over 160 GRBs have been detected, and nearly all that have been followed up with the on-board narrow field telescopes. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations from ground based observatories, which have given host identifications and redshifts. Theoretical models for short GRB progenitors have, for the first time, been placed on a sound foundation. The hosts for the short GRBs differ in a fundamental way from the long GRB hosts: short GRBs tend to occur in non-star forming galaxies or regions, whereas long GRBs are strongly concentrated within star forming regions. Observations are consistent with a binary neutron star merger model, but other models involving old stellar populations are also viable. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at zeta approx. 5-6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova. The prospects for future progress are excellent given the 〉10 year orbital lifetime of the Swift satellite.
    Keywords: Astronomy
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    Suzaku Observation of Two Ultraluminous X-ray Sources in NGC 1313 (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: TA study was made of two ultraluminous X-ray sources (ULXs) in the nearby faceon, late-type Sb galaxy NGC 1313 using data from Suzaku, the 5th Japanese X-ray satellite. Within the 90 ks observation, both sources named X-1 and X-2 exhibited luminosity change by about 50%. The o.4-10keV X-ray luminosity was measured. For X-1, the spectrum exhibited a strong power-law component with a high energy cutoff which is thought to arise from strong Comptonization by a disk corona, suggesting the source was in a very high state. Absorption line features with equivalent widths of 40-80 eV found at 7.00 keV and 7.8 keV in the X-1 spectrum support the presence of a highly ionized plasma and a high mass accretion rate on the system. The spectrum of X-2 in fainter phase is presented by a multicolor disk blackbody model.
    Keywords: Astronomy
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    Performance of the Anti-Coincidence Detector on the GLAST Large Area Telescope (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The Anti-Coincidence Detector (ACD), the outermost detector layer in the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT), is designed to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly-charged relativistic particles, but must also have a low probability for self-veto of high-energy gammas by backplash radiation from interactions in the LAT calorimeter. Simulations and tests demonstrate that the ACD meete its design requirements. The performance of the ACD has remained stable thrugh stand-alone environmental testing, shipment across the U.S. installation onto the LAT, shipment back across the U.S., LAT environmental testing, and shipment to Arizona. As part of the fully-assembled GLAST observatory, the ACD is being readied for final testing before launch.
    Keywords: Astronomy
    Type: AIP Conference Proceedings (The First GLAST Symposium) (ISSN 0094-243X); Volume 921; 588-589
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    Global Aerosol Optical Models and Lookup Tables for the New MODIS Aerosol Retrieval over Land (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Since 2000, MODIS has been deriving aerosol properties over land from MODIS observed spectral reflectance, by matching the observed reflectance with that simulated for selected aerosol optical models, aerosol loadings, wavelengths and geometrical conditions (that are contained in a lookup table or 'LUT'). Validation exercises have showed that MODIS tends to under-predict aerosol optical depth (tau) in cases of large tau (tau greater than 1.0), signaling errors in the assumed aerosol optical properties. Using the climatology of almucantur retrievals from the hundreds of global AERONET sunphotometer sites, we found that three spherical-derived models (describing fine-sized dominated aerosol), and one spheroid-derived model (describing coarse-sized dominated aerosol, presumably dust) generally described the range of observed global aerosol properties. The fine dominated models were separated mainly by their single scattering albedo (omega(sub 0)), ranging from non-absorbing aerosol (omega(sub 0) approx. 0.95) in developed urban/industrial regions, to neutrally absorbing aerosol (omega(sub 0) approx.90) in forest fire burning and developing industrial regions, to absorbing aerosol (omega(sub 0) approx. 0.85) in regions of savanna/grassland burning. We determined the dominant model type in each region and season, to create a 1 deg. x 1 deg. grid of assumed aerosol type. We used vector radiative transfer code to create a new LUT, simulating the four aerosol models, in four MODIS channels. Independent AERONET observations of spectral tau agree with the new models, indicating that the new models are suitable for use by the MODIS aerosol retrieval.
    Keywords: Earth Resources and Remote Sensing
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    Comparison of Measurements and FluorMOD Simulations for Solar Induced Chlorophyll Fluorescence and Reflectance of a Corn Crop under Nitrogen Treatments [SIF and Reflectance for Corn] (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The FLuorescence Explorer (FLEX) satellite concept is one of six semifinalist mission proposals selected in 2006 for pre-Phase studies by the European Space Agency (ESA). The FLEX concept proposes to measure passive solar induced chlorophyll fluorescence (SIF) of terrestrial ecosystems. A new spectral vegetation Fluorescence Model (FluorMOD) was developed to include the effects of steady state SIF on canopy reflectance. We used our laboratory and field measurements previously acquired from foliage and canopies of corn (Zea mays L.) under controlled nitrogen (N) fertilization to parameterize and evaluate FluorMOD. Our data included biophysical properties, fluorescence (F) and reflectance spectra for leaves; reflectance spectra of canopies and soil; solar irradiance; plot-level leaf area index; and canopy SIF emissions determined using the Fraunhofer Line Depth principal for the atmospheric telluric oxygen absorption features at 688 nm (O2-beta) and 760 nm (O2-alpha). FluorMOD simulations implemented in the default "look-up-table" mode did not reproduce the observed magnitudes of leaf F, canopy SIF, or canopy reflectance. However, simulations for all of these parameters agreed with observations when the default FluorMOD information was replaced with measurements, although N treatment responses were underestimated. Recommendations were provided to enhance FluorMOD's potential utility in support of SIF field experiments and studies of agriculture and ecosystems.
    Keywords: Earth Resources and Remote Sensing
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    Cosmic Ray Electron Science with GLAST (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Cosmic ray electrons at high energy carry information about their sources, their definition in local magnetic fields and their interactions with the photon fields through which they travel. The spectrum of the particles is affected by inverse Compton losses and synchrotron losses, the rates of which are proportional to the square of the particle's energy making the spectra very steep. However, GLAST will be able to make unique and very high statistics measurements of electrons from approx. 20 to approx. 700 GeV that will allow us to search for anisotropies in anival direction and spectral features associated with some dark matter candidates. Complementary information on electrons of still higher energy will be required to see effects of possible individual cosmic ray sources.
    Keywords: Astronomy
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    SOFIA: Stratospheric Observatory for Infrared Astronomy (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: This viewgraph presentation reviews the Stratospheric Observatory for Infrared Astronomy (SOFIA). The contents include: 1) Heritage & History; 2) Level 1 Requirements; 3) Top Level Overview of the Observatory; 4) Development Challenges; and 5) Highlight Photos.
    Keywords: Astronomy
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    Operational Use of Remote Sensing within USDA (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: A viewgraph presentation of remote sensing imagery within the USDA is shown. USDA Aerial Photography, Digital Sensors, Hurricane imagery, Remote Sensing Sources, Satellites used by Foreign Agricultural Service, Landsat Acquisitions, and Aerial Acquisitions are also shown.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Access and Availability of Resourcesat-1 AWiFS Data for Agriculture (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: AWiFS data has elements for successful applications in agriculture. Low prices, rapid delivery, aquisition planning, and global coverage.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Accuracy Analysis on Large Blocks of High Resolution Images (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: Although high altitude frequencies effects are removed at the time of basic image generation, low altitude (Yaw) effects are still present in form of affinity/angular affinity. They are effectively removed by additional parameters. Bundle block adjustment based on properly weighted ephemeris/altitude quaternions (BBABEQ) are not enough to remove the systematic effect. Moreover, due to the narrow FOV of the HRSI, position and altitude are highly correlated making it almost impossible to separate and remove their systematic effects without extending the geometric model (Self-Calib.) The systematic effects gets evident on the increase of accuracy (in terms of RMSE at GCPs) for looser and relaxed ground control at the expense of large and strong block deformation with large residuals at check points. Systematic errors are most freely distributed and their effects propagated all over the block.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    Geolocation Accuracy Evaluations of OrbView-3, EROS-A, and SPOT-5 Imagery (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: This viewgraph presentation evaluates absolute geolocation accuracy of OrbView-3, EROS-A, and SPOT-5 by comparing test imagery-derived ground coordinates to Ground Control Points using SOCET set photogrammetric software.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    NGA Commercial Imagery Overview (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: A general overview of The National Geospatial Intelligence Agency (NGA) Commercial Imagery is presented.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    High Quality - High Resolution, Rapid Revisit Wide Area Coverage EO Data Service (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: DMC data is actively used in a wide range of international commercial and government applications that benefit from the combination of high resolution, rapid revisit, spectral bands and coverage.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the 2006 Civil Commercial Imagery Evaluation Workshop; SSTI-2220-0104
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    The Physical Nature of Polar Broad Absorption Line Quasars (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: It has been shown based on radio variability arguments that some BALQSOs (broad absorption line quasars) are viewed along the polar axis (o rthogonal to accretion disk) in the recent article of Zhou et a. Thes e arguments are based on the brightness temperature, T(sub b) exceedi ng 10(exp 12) K which leads to the well-known inverse Compton catastr ophe unless the radio jet is relativistic and is viewed along its axi s. In this letter, we expand the Zhou et al sample of polar BALQSOs u sing their techniques applied to SDSS DR5. In the process, we clarify a mistake in their calculation of brightness temperature. The expanded sample of high T(sub b) BALQSOS, has an inordinately large fraction of LoBALQSOs (low ionization BALQSOs). We consider this an important clue to understanding the nature of the polar BALQSOs. This is expec ted in the polar BALQSO analytical/numerical models of Punsly that pr edicted that LoBALQSOs occur when the line of sight is very close to the polar axis, where the outflow density is the highest.
    Keywords: Astronomy
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    The Hinode(Solar-B)Mission: An Overview (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: The Hinode satellite (formerly Solar-B) of the Japan Aerospace Exploration Agency's Institute of Space and Astronautical Science (ISAS/JAXA) was successfully launched in September 2006. As the successor to the Yohkoh mission, it aims to understand how magnetic energy is transferred from the photosphere to the upper atmospheres and resulting in explosive energy releases. Hinode is an observatory style mission, with all the instruments being designed and built to work together to address the science aims. There are three instruments onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer (EIS), and the X-ray Telescope (XRT). This paper overviews the mission, including the satellite, the scientific payload and operations. It will conclude with discussions on how the international science community can participate in the analysis of the mission data.
    Keywords: Astronomy
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    Policy Document on Earth Observation for Urban Planning and Management: State of the Art and Recommendations for Application of Earth Observation in Urban Planning (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: A policy document on earth observation for urban planning and management resulting from a workshop held in Hong Kong in November 2006 is presented. The aim of the workshop was to provide a forum for researchers and scientists specializing in earth observation to interact with practitioners working in different aspects of city planning, in a complex and dynamic city, Hong Kong. A summary of the current state of the art, limitations, and recommendations for the use of earth observation in urban areas is presented here as a policy document.
    Keywords: Earth Resources and Remote Sensing
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    Prompt and Afterglow Emmision Properties of Gamma-ray Bursts with Spectroscopically Identified Supernovae (2007)
    In:  Other Sources
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    Publication Date: 2018-06-12
    Description: We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425,030329,031203, and 060218) that were spectroscopically found to be associated with Type IC supernovae and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution and estimate the total energy budget based on broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and subrelativistic form. The result is a global portrait of the effects of the physical processes responsible for producing long-soft GRBs. In particular, we find that the values of the energy released in mildly relativistic out8ows appears to have a sigruficantly smaller scatter than those found in highly relativistic ejecta. This is consistent with a picture in which the energy released inside the progenitor star is roughly standard, while the fracti
    Keywords: Astronomy
    Type: The Astrophysical Journal; Volume 654; 385-402
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    Methods for Characterizing Fine Particulate Matter Using Satellite Remote-Sensing Data and Ground Observations: Potential Use for Environmental Public Health Surveillance (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: 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.
    Keywords: Earth Resources and Remote Sensing
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    The Prospects for X-ray Polarimetry and its Potential use for Understanding Neutron Stars (2007)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: We review the state of the art for measuring the X-ray polarization of neutron stars. We discuss how valuable precision measurements of the degree and position angle of polarization as a function of energy and, where relevant, of pulse phase, would provide deeper insight into the details of the emission mechanisms. We then review the current state of instrumentation and its potential for obtaining relevant data. Finally, we conclude our discussion with some opinions as to future directions.
    Keywords: Astronomy
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    Aquarius: An Instrument to Monitor Sea Surface Salinity from Space (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: Aquarius is a combined passive/active L-band microwave instrument that is being developed to map the salinity field at the surface of the ocean from space. The data will support studies of the coupling between ocean circulation, global water cycle, and climate. Aquarius is part of the Aquarius/SAC-D mission, which is a partnership between the U.S. (National Aeronautics and Space Administration) and Argentina (CONAE). The primary science objective of this mission is to monitor the seasonal and interannual variation of the large-scale features of the surface salinity field in the open ocean with a spatial resolution of 150 km and a retrieval accuracy of 0.2 psu globally on a monthly basis.
    Keywords: Earth Resources and Remote Sensing
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); Volume 45; No. 7; 2040-2050
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    X-ray Variability Characteristics of the Narrow line SEYFERT 1 MKN 766 I: Energy Dependent Timing Properties (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766 obtained from a six-revolution XMM-Newton observation in 2005. The resulting PSDs, which have highest temporal frequency resolution for an AGN PSD to date, show breaks which increase in temporal frequency as photon energy increases; break frequencies differ by an average of approx.0.4 in the log between the softest and hardest bands. The consistency of the 2001 and 2005 observations variability properties, namely PSD shapes and the linear rms-flux relation, suggests the 2005 observation is simply a low-flux extension of the 2001 observation. The coherence function is measured to be approx.0.6-0.9 at temporal frequencies below the PSD break, and is lower for relatively larger energy band separation; coherence also drops significantly towards zero above the PSD break frequency. Temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time: lags increase towards longer time scales and as energy separation increases. Cross-spectral properties are the thus consistent with previous measurements for Mkn 766 (Vaughan & Fabian 2003) and other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.
    Keywords: Astronomy
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    Swift/BAT and RXTE Observations of the Peculiar X-ray Binary 4U 2206+54 - Disappearance of the 9.6 Day Modulation (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Observations of the high-mass X-ray binary 4U 2206+54 with the Swift Burst Alert Telescope (BAT) do not show modulation at the previously reported period of 9.6 days found from observations made with the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Instead, the strongest peak in the power spectrum of the BAT light curve occurs at a period of 19.25+/-0.08 days, twice the period found with the RXTE ASM. The maximum of the folded BAT light curve is also delayed compared to the maximum of the folded ASM light curve. The most recent ASM data folded on twice the 9.6 day period show 'similar morphology to the folded BAT light curve. This suggests that the apparent period doubling is a recent secular change rather than an energy-dependent effect. The 9.6 day period is thus not a permanent strong feature of the light curve. We suggest that the orbital period of 4U 2206+54 may be twice the previously proposed value.
    Keywords: Astronomy
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    The Anti-Coincidence Detector for the GLAST Large Area Telescope (2007)
    In:  CASI
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    Publication Date: 2018-08-10
    Description: This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of -8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.
    Keywords: Astronomy
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    High Efficiency Plastic Scintillator Detector with Wave-Length Shifting Fiber Readout for the GLAST Large Area Telescope (2007)
    In:  CASI
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    Publication Date: 2018-08-10
    Description: This paper describes the design and performance studies of the scintillator tile detectors for the Anti-Coincidence Detector (ACD) of the Large Area Telescope (LAT) on the Gamma ray Large Area Space Telescope (GLAST), scheduled for launch in early 2008. The scintillator tile detectors utilize wavelength shifting fibers and have dual photomultiplier tube (PMT) readout. The design requires highly efficient and uniform detection of singly charged relativistic particles over the tile area and must meet all requirements for a launch, as well as operation in a space environment. We present here the design of three basic types of tiles used in the ACD, ranging in size from approx.450 sq cm to approx.2500 sq cm, all 1 cm thick, with different shapes, and with photoelectron yield of approx. 20 photoelectrons per minimum ionizing particle (mip) at normal tile incidence, uniform over the tile area. Some tiles require flexible clear fiber cables up to 1.5 m long to deliver scintillator light to remotely located PMT.
    Keywords: Astronomy
    Type: Meeting held on Oct. 1-5, 2007 in Moscow, Russia. To appear in the Journal of Nuclear Instruments and Methods, Elsevier
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    Closed Loop, DM Diversity-based, Wavefront Correction Algorithm for High Contrast Imaging Systems (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: High contrast imaging from space relies on coronagraphs to limit diffraction and a wavefront control systems to compensate for imperfections in both the telescope optics and the coronagraph. The extreme contrast required (up to 10(exp -10) for terrestrial planets) puts severe requirements on the wavefront control system, as the achievable contrast is limited by the quality of the wavefront. This paper presents a general closed loop correction algorithm for high contrast imaging coronagraphs by minimizing the energy in a predefined region in the image where terrestrial planets could be found. The estimation part of the algorithm reconstructs the complex field in the image plane using phase diversity caused by the deformable mirror. This method has been shown to achieve faster and better correction than classical speckle nulling.
    Keywords: Astronomy
    Type: Optics Express; Volume 15; Issue 19; 12338-12343
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    Encounter of the Ulysses Spacecraft with the Ion Tail of Comet McNaught (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: Comet McNaught was the brightest comet observed from Earth in the last 40 years. For a period of five days in early 2007 February, four instruments on the Ulysses spacecraft directly measured cometary ions and key properties of the interaction of the comet's ion tail with the high-speed solar wind from the polar regions of the Sun. Because of the record-breaking duration of the encounter, the data are unusually comprehensive. O3(+) ions were detected for the first time in a comet tail, coexisting with singly charged molecular ions with masses in the range 28-35 amu. The presence of magnetic turbulence and of ions with energies up to approximately 200 keV indicate that at a distance of approximately 1.6 AU from the comet nucleus, the ion tail McNaught had not yet reached equilibrium with the surrounding solar wind.
    Keywords: Astronomy
    Type: The Astrophysical Journal; Volume 667; 1262-1266
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    Precise Determination of the Zero-Gravity Surface Figure of a Mirror without Gravity-Sag Modeling (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: The zero-gravity surface figure of optics used in spaceborne astronomical instruments must be known to high accuracy, but earthbound metrology is typically corrupted by gravity sag. Generally, inference of the zero-gravity surface figure from a measurement made under normal gravity requires finite-element analysis (FEA), and for accurate results the mount forces must be well characterized. We describe how to infer the zero-gravity surface figure very precisely using the alternative classical technique of averaging pairs of measurements made with the direction of gravity reversed. We show that mount forces as well as gravity must be reversed between the two measurements and discuss how the St. Venant principle determines when a reversed mount force may be considered to be applied at the same place in the two orientations. Our approach requires no finite-element modeling and no detailed knowledge of mount forces other than the fact that they reverse and are applied at the same point in each orientation. If mount schemes are suitably chosen, zero-gravity optical surfaces may be inferred much more simply and more accurately than with FEA.
    Keywords: Astronomy
    Type: Applied Optics (ISSN 0003-6935); Volume 46; No. 31; 7670-7678
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    The Local Stellar Velocity Field via Vector Spherical Harmonics (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: We analyze the local field of stellar tangential velocities for a sample of 42,339 nonbinary Hipparcos stars with accurate parallaxes, using a vector spherical harmonic formalism.We derive simple relations between the parameters of the classical linear model (Ogorodnikov-Milne) of the local systemic field and low-degree terms of the general vector harmonic decomposition. Taking advantage of these relationships, we determine the solar velocity with respect to the local stars of (V(sub X), V(sub Y), V(sub Z)) = (10.5, 18.5, 7.3) +/- 0.1 km s(exp -1) not for the asymmetric drift with respect to the local standard of rest. If only stars more distant than 100 pc are considered, the peculiar solar motion is (V(sub X), V(sub Y), V(sub Z)) = (9.9, 15.6, 6.9) +/- 0.2 km s(exp -1). The adverse effects of harmonic leakage, which occurs between the reflex solar motion represented by the three electric vector harmonics in the velocity space and higher degree harmonics in the proper-motion space, are eliminated in our analysis by direct subtraction of the reflex solar velocity in its tangential components for each star...
    Keywords: Astronomy
    Type: The Astronomical Journal; Volume 134; 367-375
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    Aerosol Source Plume Physical Characteristics from Space-based Multiangle Imaging (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: Models that assess aerosol effects on regional air quality and global climate parameterize aerosol sources in terms of amount, type, and injection height. The multiangle imaging spectroradiometer (MISR) aboard NASA's Terra satellite retrieves total column aerosol optical thickness (AOT), and aerosol type over cloud-free land and water. A stereo-matching algorithm automatically retrieves reflecting-layer altitude wherever clouds or aerosol plumes have discernable spatial contrast, with about 500-m accuracy, at 1.1-km horizontal resolution. Near-source biomass burning smoke, volcanic effluent, and desert dust plumes are observed routinely, providing information about aerosol amount, particle type, and injection height useful for modeling applications. Compared to background aerosols, the plumes sampled have higher AOT, contain particles having expected differences in Angstrom exponent, size, single-scattering albedo, and for volcanic plume and dust cloud cases, particle shape. As basic thermodynamics predicts, thin aerosol plumes lifted only by regional winds or less intense heat sources are confined to the boundary layer. However, when sources have sufficient buoyancy, the representative plumes studied tend to concentrate within discrete, high-elevation layers of local stability; the aerosol is not uniformly distributed up to a peak altitude, as is sometimes assumed in modeling. MISR-derived plume heights, along with meteorological profile data from other sources, make it possible to relate radiant energy flux observed by the moderate resolution imaging spectroradiometer (MODIS), also aboard the Terra spacecraft, to convective heat flux that plays a major role in buoyant plume dynamics. A MISR climatology of plume behavior based on these results is being developed.
    Keywords: Earth Resources and Remote Sensing
    Type: Journal of Geophysical Research; Volume 112
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    A Laboratory Demonstration of the Capability to Image an Earth-like Extrasolar Planet (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: The detection and characterization of an Earth-like planet orbiting a nearby star requires a telescope with an extraordinarily large contrast at small angular separations. At visible wavelengths, an Earth-like planet would be 1 times 10-10 times fainter than the star at angular separations of typically 0.1 arcsecond or less. There are several proposed space telescope systems that could, in principle, achieve this. Here we report a laboratory experiment that reaches these limits. We have suppressed the diffracted and scattered light near a star-like source to a level of 6 times 10-10 times the peak intensity in individual coronagraph images. In a series of such images, together with simple image processing, we have effectively reduced this to a residual noise level of about 0.1 times 10-10. This demonstrates that a coronagraphic telescope in space could detect and spectroscopically characterize nearby exoplanetary systems, with the sensitivity to image an 'Earth-twin' orbiting a nearby star.
    Keywords: Astronomy
    Type: Nature; Volume 446; 771-773
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    Highly Collimated Jets and Wide-angle Outflows in HH 46/47: New Evidence from Spitzer Infrared Images (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: We present new details of the structure and morphology of the jets and outflows in HH 46/47 as seen in Spitzer infrared images from IRAC and MIPS, reprocessed using the 'HiRes' deconvolution technique. HiRes improves the visualization of spatial morphology by enhancing resolution (to subarcsecond levels in IRAC bands) and removing the contaminating side lobes from bright sources. In addition to sharper views of previously reported bow shocks, we have detected (1) the sharply delineated cavity walls of the wide-angle biconical outflow, seen in scattered light on both sides of the protostar, (2) several very narrow jet features at distances approximately 400 AU to approximately 0.1 pc from the star, and (3) compact emissions at MIPS 24 m with the jet heads, tracing the hottest atomic/ionic gas in the bow shocks. Together the IRAC and MIPS images provide a more complete picture of the bow shocks, tracing both the molecular and atomic/ionic gases, respectively. The narrow width and alignment of all jet-related features indicate a high degree of jet collimation and low divergence (width of approximately 400 AU increasing by only a factor of 2.3 over 0.2 pc). The morphology of this jet, bow shocks, wide-angle outflows, and the fact that the jet is nonprecessing and episodic, constrain the mechanisms for producing the jet's entrained molecular gas, and origins of the fast jet, and slower wide-angle outflow.
    Keywords: Astronomy
    Type: The Astrophysical Journal; Volume 668; L159-L162
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    P/2006 HR30 (Siding Spring): A Low-activity Comet in Near-Earth Space (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: The low cometary activity of P/2006 HR30 (Siding Spring) allowed a unique opportunity to study the nucleus of a periodic comet while near perihelion. P/2006 HR30 was originally targeted as a potential extinct comet, and we measured spectral reflectance and dust production using long-slit CCD spectroscopy and wide-field imaging obtained at the Palomar Mountain 200 inch telescope on 2006 August 3 and 4. The dust production Afp = 19.7 +/- 0.4 cm and mass-loss rate Q(dust) 4.1 +/- 0.1 kg/sec of the comet were approximately 2 orders of magnitude dust less than 1P/Halley at similar heliocentric distance. The VRI colors derived from the spectral reflectance were compared to Kuiper Belt objects, Centaurs, and other cometary nuclei. We found that the spectrum of P/2006 HR30 was consistent with other comets. However, the outer solar system bodies have a color distribution statistically distinct from cometary nuclei. It is our conjecture that cometary activity, most likely the reaccretion of ejected cometary dust, tends to moderate and mute the visible colors of the surface of cometary nuclei.
    Keywords: Astronomy
    Type: The Astrophysical Journal Letters, 662: L47-L50, 2007 June 10; Volume 662; L47 - L50
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    Ultraviolet Observations of Phoebe from the Cassini UVIS (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: Observations of Saturn's distant moon Phoebe were made at far-ultraviolet (FUV) (1100-1900 A) and extreme-ultraviolet (EUV) (600-1100 A) wavelengths by the Cassini Ultraviolet Imaging Spectrograph (UVIS) during the Cassini spacecraft flyby on June 11, 2004. These are the first UV spectra of Phoebe and the first detection of water ice on a Solar System surface using FUV wavelengths. The characteristics of water ice in the FUV are presented, and Hapke models are used to interpret the spectra in terms of composition and grain size; the use of both areal and intimate mixing models is explored. Non-ice species used in these models include carbon, ice tholin, Triton tholin, poly-HCN and kerogen. Satisfactory disk-integrated fits are obtained for intimate mixtures of approx.10% H2O plus a non-ice species. Spatially resolved regions of higher (approx.20%) and lower (approx.5%) H2O ice concentrations are also detected. Phoebe does not display any evidence of volatile activity. Upper limits on atomic oxygen and carbon are 5 x 10(exp 11) and 2 x 10(exp 12) atoms/sq. cm, respectively, for solar photon scattering. The UVIS detection of water ice on Phoebe, and the ice amounts detected, are consistent with IR measurements and contribute to the evidence for a Phoebe origin in the outer Solar System rather than in the main asteroid belt.
    Keywords: Astronomy
    Type: Icarus; Volume 193; Issue 2; 323-333
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    The Albedo Dichotomy of Iapetus Measured at UV Wavelengths (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: The dramatic hemispheric dichotomy in albedo displayed by Saturn's moon Iapetus has intrigued astronomers for centuries. Here we report on far-ultraviolet observations of Iapetus' bright and dark terrains from Cassini. We compare the reflectance spectra of Iapetus's dark terrain, Hyperion and Phoebe and find that both Phoebe and Hyperion are richer in water ice than Iapetus' dark terrain. Spectra of the lowest latitudes of the dark terrain display the diagnostic water ice absorption feature; water ice amounts increase within the dark material away from the apex (at 90 deg W longitude, the center of the dark leading hemisphere), consistent with thermal segregation of water ice. The water ice in the darkest, warmest low latitude regions is not expected to be stable and may be a sign of ongoing or recent emplacement of the dark material from an exogenic source.
    Keywords: Astronomy
    Type: Icarus; Volume 193; 344-351
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    Distribution of Aboveground Live Biomass in the Amazon Basin (2007)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: The amount and spatial distribution of forest biomass in the Amazon basin is a major source of uncertainty in estimating the flux of carbon released from land-cover and land-use change. Direct measurements of aboveground live biomass (AGLB) are limited to small areas of forest inventory plots and site-specific allometric equations that cannot be readily generalized for the entire basin. Furthermore, there is no spaceborne remote sensing instrument that can measure tropical forest biomass directly. To determine the spatial distribution of forest biomass of the Amazon basin, we report a method based on remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 plot measurements of forest biomass distributed over the basin. A decision tree approach was used to develop the spatial distribution of AGLB for seven distinct biomass classes of lowland old-growth forests with more than 80% accuracy. AGLB for other vegetation types, such as the woody and herbaceous savanna and secondary forests, was directly estimated with a regression based on satellite data. Results show that AGLB is highest in Central Amazonia and in regions to the east and north, including the Guyanas. Biomass is generally above 300Mgha(sup 1) here except in areas of intense logging or open floodplains. In Western Amazonia, from the lowlands of Peru, Ecuador, and Colombia to the Andean mountains, biomass ranges from 150 to 300Mgha(sup 1). Most transitional and seasonal forests at the southern and northwestern edges of the basin have biomass ranging from 100 to 200Mgha(sup 1). The AGLB distribution has a significant correlation with the length of the dry season. We estimate that the total carbon in forest biomass of the Amazon basin, including the dead and below ground biomass, is 86 PgC with +/- 20% uncertainty.
    Keywords: Earth Resources and Remote Sensing
    Type: Global Change Biology; Volume 13; No. 4; 816-837
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    Detector Arrays for the James Webb Space Telescope Near-Infrared Spectrograph (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The James Webb Space Telescope's (JWST) Near Infrared Spectrograph (NIRSpec) incorporates two 5 micron cutoff (lambda(sub co) = 5 microns) 2048x2048 pixel Teledyne HgCdTe HAWAII-2RG sensor chip assemblies. These detector arrays, and the two Teledyne SIDECAR application specific integrated circuits that control them, are operated in space at T approx. 37 K. In this article, we provide a brief introduction to NIRSpec, its detector subsystem (DS), detector readout in the space radiation environment, and present a snapshot of the developmental status of the NIRSpec DS as integration and testing of the engineering test unit begins.
    Keywords: Astronomy
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    The Impacts of Bowtie Effect and View Angle Discontinuity on MODIS Swath Data Gridding (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We have analyzed two effects of the MODIS viewing geometry on the quality of gridded imagery. First, the fact that the MODIS scans a swath of the Earth 10 km wide at nadir, causes abrupt change of the view azimuth angle at the boundary of adjacent scans. This discontinuity appears as striping of the image clearly visible in certain cases with viewing geometry close to principle plane over the snow of the glint area of water. The striping is a true surface Bi-directional Reflectance Factor (BRF) effect and should be preserved during gridding. Second, due to bowtie effect, the observations in adjacent scans overlap each other. Commonly used method of calculating grid cell value by averaging all overlapping observations may result in smearing of the image. This paper describes a refined gridding algorithm that takes the above two effects into account. By calculating the grid cell value by averaging the overlapping observations from a single scan, the new algorithm preserves the measured BRF signal and enhances sharpness of the image.
    Keywords: Earth Resources and Remote Sensing
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    Blazar Gamma-Rays, Shock Acceleration, and the Extragalactic Background Light (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The observed spectra of blazars, their intrinsic emission, and the underlying populations of radiating particles are intimately related. The use of these sources as probes of the extragalactic infrared background, a prospect propelled by recent advances in TeV-band telescopes, soon to be augmented by observations by NASA's upcoming Gamma-Ray Large Area Space Telescope (GLAST), has been a topic of great recent interest. Here, it is demonstrated that if particles in blazar jets are accelerated at relativistic shocks, then GAMMA-ray spectra with indices less than 1.5 can be produced. This, in turn, loosens the upper limits on the near infrared extragalactic background radiation previously proposed. We also show evidence hinting that TeV blazars with flatter spectra have higher intrinsic TeV GAMMA-ray luminosities and we indicate that there may be a correlation of flatness and luminosity with redshift.
    Keywords: Astronomy
    Type: Submitted to The Astrophysical Journal.
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    Construction of a Penrose Diagram for a Spatially Coherent Evaporating Black Hole (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: A Penrose diagram is constructed for an example black hole that evaporates at a steady rate as measured by a distant observer, until the mass vanishes, yielding a final state Minkowski space-time. Coordinate dependencies of significant features, such as the horizon and coordinate anomalies, are clearly demonstrated on the diagram. The large-scale causal structure of the space-time is briefly discussed.
    Keywords: Astronomy
    Type: To be submitted to Classical and Quantum Gravity
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    Physical and Radiative Characteristics and Long Term Variability of the Okhotsk Sea Ice Cover (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Much of what we know about the large scale characteristics of the Okhotsk Sea ice cover comes from ice concentration maps derived from passive microwave data. To understand what these satellite data represents in a highly divergent and rapidly changing environment like the Okhotsk Sea, we analyzed concurrent satellite, aircraft, and ship data and characterized the sea ice cover at different scales from meters to tens of kilometers. Through comparative analysis of surface features using co-registered data from visible, infrared and microwave channels we evaluated how the general radiative and physical characteristics of the ice cover changes as well as quantify the distribution of different ice types in the region. Ice concentration maps from AMSR-E using the standard sets of channels, and also only the 89 GHz channel for optimal resolution, are compared with aircraft and high resolution visible data and while the standard set provides consistent results, the 89 GHz provides the means to observe mesoscale patterns and some unique features of the ice cover. Analysis of MODIS data reveals that thick ice types represents about 37% of the ice cover indicating that young and new ice represent a large fraction of the lice cover that averages about 90% ice concentration, according to passive microwave data. A rapid decline of -9% and -12 % per decade is observed suggesting warming signals but further studies are required because of aforementioned characteristics and because the length of the ice season is decreasing by only 2 to 4 days per decade.
    Keywords: Earth Resources and Remote Sensing
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    The Suzaku Observation of NGC 3516: Complex Absorption and the Broad and Narrow Fe K Lines (2007)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We present results from a 150 ksec Suzaku observation of the Seyfert 1 NGC 3516 in October 2005. The source was in a relatively highly absorbed state. Our best-fit model is consistent with partial covering by a lowly-ionized absorber with a column density near 5x10(exp 22) cm(exp -2) and with a covering fraction 96-100 percent. Narrow K-shell absorption features due to He- and H-like Fe confirm the presence of a high-ionization absorbing component as well. A broad Fe K(alpha) diskline is required in all fits, even after the complex absorption is taken into account; an additional partial-covering component is an inadequate substitute for the continuum curvature associated with the broad line. The narrow Fe Ka line at 6.4 keV is resolved, yielding a velocity width commensurate with the optical Broad Line Region. The strength of the Compton reflection hump suggests a contribution mainly from the broad Fe line origin. We include in our model soft band emission lines from He- and H-like ions and radiative recombination lines, consistent with photo-ionization, though a small contribution from collisional ionization is possible.
    Keywords: Astronomy
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    Laboratory-Based BRDF Calibration of Radiometric Tarps (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The current study provides the remote sensing community with important high accuracy laboratory-based BRDF calibration of radiometric tarps. The results illustrate the dependence of tarps' weft and warp threads orientation on BRDF. The study was done at incident angles of 0deg, 10deg, and 30deg; scatter zenith angles from 0deg to 60deg, and scatter azimuth angles of 0deg, 45deg, 90deg, 135deg, and 180deg. The wavelengths were 485nm, 550nm, 633nm and 800nm. The dependence is well defined at all measurement geometries and wavelengths. It can be as high as 8% at 0deg incident angle and 2% at 30deg incident angle. The fitted BRDF data show a very small discrepancy from the measured ones. New data on the forward and backscatter properties of radiometric tarps is reported. The backward scatter is well pronounced for the white samples. The black sample has well pronounced forward scatter. The BRDF characterization of radiometric tarps can be successfully extended to other structured surface fabric samples. The results are NIST traceable.
    Keywords: Earth Resources and Remote Sensing
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