Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

The Carolina slate belt is a 10- to 50- kilometer-wide zone of 350- to 600- million-year-old volcanic and sedimentary rocks
extending from Georgia to Virginia. An older group of heterogeneous volcanic rocks is unconformably overlain by an extensive
unit of rhyodacitic to dacitic rocks. These units were intruded by granitic to dioritic complexes which resulted in hornfels and
hydrothermally altered rocks ranging from quartz-sericite to nearly pure quartz. Gold and silver deposits and pyrophyllite deposits
are associated with the hydrothermally altered rocks, particularly along northeast-trending shear zones. Mineral resource studies
in the slate belt are complicated by the complex geology, deep weathering of bedrock, and dense vegetation cover over much of
the area. to augment conventional geologic mapping and mineral resource studies in the area the U. S. Geological Survey has been
evaluating the use of LANDSAT images and, more recently, Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) data for
mapping spectral reflectance variations in the forest canopy that might be related to altered, potentially mineralized rocks. Previous
analysis of a December 1, 1981, LANDSAT Multispectral Scanner (MSS) image showed good spatial correspondence
between known areas of hydrothermally altered, commonly mineralized rocks and pixels derived by thresholding a principal component
image. Field studies showed that most of these areas are topographically high and have a forest community of principally
Quercus prinus (chestnut oak) and subordinate Pinus virginiana (Virginia pine) and Acer rubrum (red maple). The understory is
typically open with patches of Vaccinium sp. (blueberry). Analyses of LANDSAT Thematic Mapper images recorded on November
9, 1982, and also 1988, which is near the peak of autumn colors, essentially duplicated the earlier MSS results. However, in
both of these studies, numerous areas underlain by unaltered silicic volcanics also showed as anomalies, reducing the effectiveness
of the LANDSAT-image maps for mineral resource studies. Initial analysis of AVIRIS images recorded on June 26, 1996, indicates
that chestnut oak growing on highly siliceous altered rocks can be distinguished from the chestnut-oak canopy on unaltered silicic
volcanic rocks, as well as from the background canopy on other unaltered lithologic units. Calibration of 10 scenes of AVIRIS
data was accomplished by using a modified version of the Atmosphere Removal Program (ATREM), and a laboratory spectrum
representing a spectrally uniform plowed field. A matched-filter algorithm was used to map anomalous and background canopies
in the 0.49 to 1.3 micrometer region. The resulting anomalous-class image was thresholded to retain only the highest digital numbers
and, hence, the best matches to the AVIRIS canopy reference spectrum. The main difference between anomalous and background
canopy spectra is weaker intensity of the 0.96 and 1.19 micrometer water absorption features in the anomalous canopy
spectra. AVIRIS spectra of chestnut-oak canopy growing on unaltered silicic volcanic rocks are similar to those that characterize
other background forest types. Soil analyses indicate that nutrients are anomalously low in residual samples representing the silicified
altered areas. The spatial agreement with known hydrothermally silicified bedrock situated along the 10-scene strip of AVI-
RIS data is very high with no known omissions, except where forests have been cut or replanted. Two areas of silicified rocks were
identified in this study that had not been previously documented. A few areas that were initially erroneously identified as being
underlain by silicified rocks were eliminated subsequently by reprocessing these scenes using additional AVIRIS reference spectra.
Author
Infrared Imagery; Canopies (Vegetation); Deciduous Trees; Foliage; Timber Identification; Spectral Reflectance; Forests
20000064905 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA USA
Analysis of Interferometric Radar Data in a Queensland, Australia Tropical Rain Forest
Hensley, Scott, Jet Propulsion Lab., California Inst. of Tech., USA; Rodriquez, Ernesto, Jet Propulsion Lab., California Inst. of
Tech., USA; Chapin, Elaine, Jet Propulsion Lab., California Inst. of Tech., USA; Accad, Arnon, Jet Propulsion Lab., California
Inst. of Tech., USA; [1999]; 14p; In English; PIERS 99, 23 Mar. 1999, Pasadena, CA, USA; No Copyright; Avail: CASI; A03,
Hardcopy; A01, Microfiche
The radar flies at 8000 m (24000 ft) above the ground and collects data in swath about 10 km wide. The radar simultaneously
collects data from multiple frequencies and is capable of making interferometric radar measurements.
Derived from text
Radar Data; Rain Forests; Data Acquisition; Radar Measurement
20000067675 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA USA
Potential Applications of Satellite Based Low Frequency Microwave Measurements of Snow and Ice
West, Richard D., Jet Propulsion Lab., California Inst. of Tech., USA; [2000]; 1p; In English; No Copyright; Avail: Issuing Activity;
Abstract Only
In this presentation we will examine some potential applications of low frequency microwave radar and radiometer data to
remote sensing of snow and ice conditions over land. We focus on the following low frequency bands; L-band (1.28 GHz), S-band
(2.69 GHz), and C-band (5.0 GHz). to predict the effect of snow cover on microwave emission, we need to characterize the dielectric
properties of the snow in terms of important physical parameters such as snow density, temperature, and wetness. For the case
of dry snow, we use an empirical mixing formula which gives the effective complex permittivity of snow as a function of density,
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