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At least 343 records · Page 19

Spectrophotometry of the 1.5-micron window of Jupiter.

The limb darkening of the 1.5-micron region and the variations of ammonia and methane absorptions over the Jovian belts, zones, and spots are studied on the basis of high-resolution infrared spectrometric data obtained for 86 areas on the Jovian surface. It is shown that the absorptions increase with increasing air mass between the equator and the poles, that they decrease linearly with increasing air mass between the central meridian and the limbs, and that the absorptions over the South Tropical Zone are greater and those over the Great Red Spot are smaller than the absorptions for other features. An ammonia absorption map of the planet is plotted for the period April-June, 1970.

Binder, A. B.↗

Task 1: Water Depth Management, 1388

The author has identified the following significant results. ERTS-1 MSS data taken on October 10, 1972, of the Little Bahama Bank are being used to demonstrate the use of ERTS-1 data for mapping of shallow water features for the purpose of upgrading world navigation charts. Marked reflectance differences occur for the shallow water areas in bands 4, 5, and 6. Digital processing of two adjacent data tapes within the ERTS-1 frame covering an area of about 40 by 40 miles has been completed. Correlation of depth measurements to 5 meters has been successful. A mathematical model for depth measurements using ratio of voltages in band 4 and 5 has been successfully developed and is being tested for accuracy. Additional studies for areas near Puerto Rico and in northern Lake Michigan will be undertaken. Satellite data will also provide geographical evidence for verifying existence or nonexistence of doubtful shoal waters now appearing on world charts and considered to be hazardous to shipping.

Polcyn, F. C.↗

ERTS-1 applications in hydrology and water resources

After having been in orbit for less than one year, the Earth Resources Technology Satellite (ERTS-1) has shown that it provides very applicable data for more effective monitoring and management of surface water features over the globe. Mapping flooded areas, snowcover, and wetlands and surveying the size, type, and response of glaciers to climate are among the specific areas where ERTS-1 data were applied. In addition the data collection system has proven to be a reliable tool for gathering hydrologic data from remote regions. Turbidity variations in lakes and rivers were also observed and related to shoreline erosion, industrial plant effluent, and overall water quality.

Salomonson, V. V.↗

Calculations of water depth from ERTS-MSS data

ERTS-1 MSS data taken on October 10, 1972 of the Little Bahama Bank are being used to demonstrate the use of ERTS-1 data for mapping of shallow water features for the purpose of upgrading world navigation charts. Marked reflectance differences occur for the shallow water areas in Bands 4, 5, and 6. Digital processing of two adjacent data tapes within the ERTS frame covering an area of about 40 by 40 miles has been completed. Correlation of depth measurements to 5 meters has been successful. A mathematical model for depth measurements using ratio of voltages in Band 4 and 5 has been successfully developed and is being tested for accuracy. Additional studies for areas near Puerto Rico and in Northern Lake Michigan will be undertaken. Satellite data will also provide geographical evidence for verifying existence or nonexistence of doubtful shoal waters now appearing on world charts and considered to be hazardous to shipping.

Polcyn, F. C.↗

Science considerations for an orbital radar mapping mission to Venus

A radar mapping mission to Venus is under consideration by NASA for the 1980s. The science objectives of the mission are to determine the geologic history of the planet; map the major topographic features and provide limited detailed geologic and terrain analysis of potential probe landing sites. Because of the thick Venusian atmosphere, a synthetic-aperture side-looking radar system has been selected as the most practical remote sensing instruments to use. Topographic data are the most useful for achieving the science goals of the mission. The radar system variables and mission parameters must be specified to maximize topographic data returns while being compatible with engineering and cost restraints. A baseline imaging resolution of 100 meters, with ability to obtain some higher-resolution coverage, is acceptable. Total planet coverage is desirable but the primary science objectives can be achieved if at least one entire hemisphere is imaged.

Wychgram, D. C.↗

Active microwave remote sensing of earth/land, chapter 2

Geoscience applications of active microwave remote sensing systems are examined. Major application areas for the system include: (1) exploration of petroleum, mineral, and ground water resources, (2) mapping surface and structural features, (3) terrain analysis, both morphometric and genetic, (4) application in civil works, and (5) application in the areas of earthquake prediction and crustal movements. Although the success of radar surveys has not been widely publicized, they have been used as a prime reconnaissance data base for mineral exploration and land-use evaluation in areas where photography cannot be obtained.

Source record↗

Characteristics of Antarctic sea ice as determined by satellite-borne microwave imagers

The electrically scanning microwave radiometers on Nimbus 5 (wavelengths of 1.55 cm) and Nimbus 6 (wavelengths of 0.81 cm) produce images with a resolution of about 30 km. Weekly maps of sea ice coverage are generated, showing the percent of open water in each 2.5 x 2.5 degree cell. More detailed studies of the dynamics and thermodynamics of the sea ice and its interaction with the ocean and the atmosphere are carried out, using 3-day average pseudo-color images and maps of ice boundaries. Features of the Antarctic ice discerned from microwave images are discussed, and the important features of Antarctic currents are illustrated.

Zwally, H. J.↗

Application of aerial photography to water-related programs in Michigan

Aerial photography and information system technology were used to generate information required for the effective operation of three water-related programs in Michigan. Potential mosquito breeding sites were identified from specially acquired low altitude 70 mm color photography for the city of Lansing; the inventory identified 35% more surface water areas than indicated on existing field maps. A comprehensive inventory of surface water sources and potential access sites was prepared to assist fire departments in Antrim County with fire truck water-recharge operations. Remotely-sensed land cover/use data for Windsor Township, Eaton County, were integrated with other resource data into a computer-based information system for regional water quality studies. Eleven thematic maps focusing on landscape features affecting non-point water pollution and waste disposal were generated from analyses of a four-hectare grid-based data file containing land cover/use, soils, topographic and geologic (well-log) data.

Enslin, W. R.↗

Satellite geological and geophysical remote sensing of Iceland

The author has identified the following significant results. The ERTS imagery has sufficient resolution to map, from MSS color composites, areas of altered ground caused by high temperature geothermal activity at the Namafjall, Torfajokull, and Reykjanes geothermal areas. The major axes of the fallout pattern of tephra from the May - July 1970 volcanic eruption from Hekla Volcano can be mapped where sufficient depth of deposition was present to seriously affect the normal vegetation. Lava flows from the 1961 volcanic eruption at Askja; some of the lava flows from the 1947-48 eruption, and and all of the lava flows from the 1970 eruption at Hekla; and the areas covered by tephra and lava from the 1973 eruption on Heimaey could be delineated. Low sun angle imagery of less than 10 deg of snow covered terrain was particularly valuable in mapping structural and volcanic features concealed beneath glacial ice in the active volcanic zones of Iceland.

Williams, R. S., Jr.↗

Nationwide forestry applications program: Procedure 1 applicability to rangeland classification

The author has identified the following significant results. An assumption that short prairie grass and salt grass could be differentiated on aircraft photographs was inaccurate for the Weld County site. However, rangeland could be differentiated using procedure 1 from LACIE. Estimates derived from either random or systematic sampling were satisfactory. Level 1 features were separated and mapped, and proportions were estimated with accompanying confidence statements.

Reeves, C. A.↗

Phobos transit of Mars as viewed by the Viking cameras

A Viking orbiting spacecraft successfully obtained pictures of the martian satellite Phobos with Mars in the background. This is the first time that a single picture was obtained from a spacecraft which contained both a planet and a moon and had significant surface detail visible on both. The region of Mars below Phobos included volcanoes in the Tharsis Montes region. These pictures showed Phobos to be smaller than previously thought. The image of Phobos can be used as a control point to determine the map coordinates of surface features on Mars.

Duxbury, T. C.↗

Study of the fluctuations in the cosmic X-ray background

The emerging picture indicates that neither the total cosmic X-ray background (CXB) flux nor the fluctuations are completely dominated by any single class of sources. Quasars clearly contribute a substantial fraction of the total flux while galaxy cluster X-ray sources and galactic nuclear activity also make nonnegligible contributions. It appears that from the large angular scale CXB galaxy correlations that no class of relatively low liminosity X-ray sources associated with galaxies can play a major role in supplying the total flux. The origin of the fluctuations looks more complex. It is hard to avoid the conclusion that the NGP-SGP difference and some other features of the CXB map are associated with the local anisotropy in the galactic distribution (the local supercluster). It also appears reasonable to some suppose that at least some large angular structures in the CXB are due to emission from hot galactic halo gs.

Turner, E. L.↗

High-Resolution Subsurface-Interface Radar

Homomorphic deconvolution signal processing enhances information obtained in high-resolution soil-depth measurements by radar. Proposed technique is expected to increase accuracy with which soil-layer depths are gaged. Intended use with subsurface-interface radar sounding, in which subsurface features of soils are mapped.

Steinway, W. J.↗

Analysis of MAGSAT and surface data of the Indian region

Techniques and significant results of an analysis of MAGSAT and surface data of the Indian region are described. Specific investigative tasks included: (1) use of the multilevel data at different altitudes to develop a model for variation of magnetic anomaly with altitude; (2) development of the regional model for the description of main geomagnetic field for the Indian sub-continent using MAGSAT and observatory data; (3) development of regional mathematical model of secular variations over the Indian sub-continent; and (4) downward continuation of the anomaly field obtained from MAGSAT and its combination with the existing observatory data to produce a regional anomaly map for elucidating tectonic features of the Indian sub-continent.

Agarwal, G. C.↗

Seismic properties of the crust and uppermost mantle of North America

Seismic refraction profiles for the North American continent were compiled. The crustal models compiled data on the upper mantle seismic velocity (P sub n), the crustal thickness (H sub c) and the average seismic velocity of the crystalline crust (V sub p). Compressional wave parameters were compared with shear wave data derived from surface wave dispersion models and indicate an average value for Poisson's ratio of 0.252 for the crust and of 0.273 for the uppermost mantle. Contour maps illustrate lateral variations in crustal thickness, upper mantle velocity and average seismic velocity of the crystalline crust. The distribution of seismic parameters are compared with a smoothed free air anomaly map of North America and indicate that a complidated mechanism of isostatic compensation exists for the North American continent. Several features on the seismic contour maps also correlate with regional magnetic anomalies.

Braile, L. W.↗

SIR-B analysis of the Precambrian shield of Sudan and Egypt: Penetration studies and subsurface mapping

A shuttle imaging radar-B (SIR-B) study is proposed for the Precambrian shield in southeast Egypt and northeast Sudan in an area east of the Nile. The phenomenon of radar penetration of thin, dry eolian/alluvial cover is to be confirmed and quantified. The penetration phenomenon is to be used to map structural and lithologic features. Field work to be done in conjunction with image acquisition is discussed.

Dixon, T. H.↗