The Use of Satellite Data for Archaeology : An Overview of NASA's Experience
No abstract available
satellites↗
Engineering topics
Evans, Diane
Publications and source records attributed to Evans, Diane.
JPL's Role in Advancing Earth System Science to Meet the Challenges of Climate and Environmental Change
Objective 2.1.1: Improve understanding of and improve the predictive capability for changes in the ozone layer, climate forcing, and air quality associated with changes in atmospheric composition. Objective 2.1.2: Enable improved predictive capability for weather and extreme weather events. Objective 2.1.3: Quantify, understand, and predict changes in Earth s ecosystems and biogeochemical cycles, including the global carbon cycle, land cover, and biodiversity. Objective 2.1.4: Quantify the key reservoirs and fluxes in the global water cycle and assess water cycle change and water quality. Objective 2.1.5: Improve understanding of the roles of the ocean, atmosphere, land and ice in the climate system and improve predictive capability for its future evolution. Objective 2.1.6: Characterize the dynamics of Earth s surface and interior and form the scientific basis for the assessment and mitigation of natural hazards and response to rare and extreme events. Objective 2.1.7: Enable the broad use of Earth system science observations and results in decision-making activities for societal benefits.
Earth observations↗
Remote Sensing for Climate and Environmental Change
Remote sensing is being used more and more for decision-making and policy development. Specific examples are: (1) Providing constraints on climate models used in IPCC assessments (2) Framing discussions about greenhouse gas monitoring (3) Providing support for hazard assessment and recovery.
Environmental Change↗
Eyes on the Earth the Critical Role of Satellites in Understanding Our Environment
No abstract available
Evans, Diane↗
Climate Change and Neotectonic History of Northwestern China
The progress, results and future plans for the following objectives are presented: (1) To compare the types, rates, and magnitudes of surficial modification processes that have operated in Northwest China and the Southwestern U.S.; (2) To quantify and understand the basis of the remote sensing signatures of these processes to allow extrapolation from field sites to regional maps and to allow comparisons between widely separated arid regions; (3) To use the resulting chronologies to help define the temporal and spatial distribution of continental climate changes; and (4) Determine the ages of movements on some of the active faults in Northwestern China.
Farr, Tom G.↗
(abstract) The SIR-C/X-SAR Mission
The Shuttle Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) is a cooperative experiment between the National Aeronautics and Space Administration (NASA), the German Space Agency (DARA), and the Italian Space Agency (ASI). The experiment is the next evolutionary step in NASA's Spaceborne Imaging Radar (SIR) program that began with the Seasat SAR in 1978, and continued with SAR -A in 1981 and SAR-B in 1984. The program will eventually lead to the Earth Observing System (EOS) SAR later in this decade. SIR-C will provide increased capability over Seasat, SIR-A, and SIR-B by acquiring polarimetric images simultaneously at two microwave frequencies: L-band (wavelength 24 cm) and C-band (wavelength 6 cm). X-SAR will operate at X-band (wavelength 3 cm) with VV polarization, resulting in a three-frequency capability. Because radar backscatter is most strongly influenced by objects comparable in size to the radar wavelength, this multifrequency capability will provide information about the Earth's surface over a wide range of scales not discernable with single-frequency experiments. The polarimetric data will yield quantitative information about the surface geometric structure, vegetation dielectric properties, and surface discontinuities. The first SIR-C/X-SAR flight is planned for early in 1994, with two subsequent flights in different seasons to enable data aquisition under different environmental conditions. SIR-C/X-SAR will collect data for a period of 6 to 9 days during each flight. The instrument will be flown in a 57(deg) inclination orbit with a nomimal orbit altitude of 215 km. This altitude will result in a slightly drifting orbit. The latest status of the SIR-C/X-SAR mission and instrument design, science activities, and expected results will be presented.
SIR-C/XSAR radar backscatter surface geometric str↗
Approach to derivation of SIR-C science requirements for calibration
Many of the experiments proposed for the forthcoming SIR-C mission require calibrated data, for example those which emphasize (1) deriving quantitative geophysical information (e.g., surface roughness and dielectric constant), (2) monitoring daily and seasonal changes in the Earth's surface (e.g., soil moisture), (3) extending local case studies to regional and worldwide scales, and (4) using SIR-C data with other spaceborne sensors (e.g., ERS-1, JERS-1, and Radarsat). There are three different aspects to the SIR-C calibration problem: radiometric and geometric calibration, which have been previously reported, and polarimetric calibration. The study described in this paper is an attempt at determining the science requirements for polarimetric calibration for SIR-C. A model describing the effect of miscalibration is presented first, followed by an example describing how to assess the calibration requirements specific to an experiment. The effects of miscalibration on some commonly used polarimetric parameters are also discussed. It is shown that polarimetric calibration requirements are strongly application dependent. In consequence, the SIR-C investigators are advised to assess the calibration requirements of their own experiment. A set of numbers summarizing SIR-C polarimetric calibration goals concludes this paper.
Dubois, Pascale C.↗
Approach to derivation of SIR-C science requirements for calibration
A study undertaken to determine SIR-C (Shuttle Imaging Radar-C) science requirements for polarimetric calibration is described. A model describing the effect of miscalibration is presented, followed by a description of specific experiments and the resulting requirements levied on the system. The effects of miscalibration on some commonly used measures which can be extracted from SAR (synthetic aperture radar) data are also discussed. It is concluded that polarimetric calibration requirements are strongly application-dependent, and that a compromise must be made to maximize the domain of application of the data without prohibitive cost. Data summarizing SIR-C polarimetric calibration goals are also presented.
Dubois, Pascale↗
Multisensor classification of sedimentary rocks
A comparison is made between linear discriminant analysis and supervised classification results based on signatures from the Landsat TM, the Thermal Infrared Multispectral Scanner (TIMS), and airborne SAR, alone and combined into extended spectral signatures for seven sedimentary rock units exposed on the margin of the Wind River Basin, Wyoming. Results from a linear discriminant analysis showed that training-area classification accuracies based on the multisensor data were improved an average of 15 percent over TM alone, 24 percent over TIMS alone, and 46 percent over SAR alone, with similar improvement resulting when supervised multisensor classification maps were compared to supervised, individual sensor classification maps. When training area signatures were used to map spectrally similar materials in an adjacent area, the average classification accuracy improved 19 percent using the multisensor data over TM alone, 2 percent over TIMS alone, and 11 percent over SAR alone. It is concluded that certain sedimentary lithologies may be accurately mapped using a single sensor, but classification of a variety of rock types can be improved using multisensor data sets that are sensitive to different characteristics such as mineralogy and surface roughness.
Evans, Diane↗
The Spaceborne Imaging Radar program: SIR-C - The next step toward EOS
The NASA Shuttle Imaging Radar SIR-C experiments will investigate earth surface and environment phenomena to deepen understanding of terra firma, biosphere, hydrosphere, cryosphere, and atmosphere components of the earth system, capitalizing on the observational capabilities of orbiting multiparameter radar sensors alone or in combination with other sensors. The SIR-C sensor encompasses an antenna array, an exciter, receivers, a data-handling network, and the ground SAR processor. It will be possible to steer the antenna beam electronically, so that the radar look angle can be varied.
Evans, Diane↗