ALBERT

Description: The Long Valley Caldera located in the eastern Sierra Nevada (California) shows new signs of volcanic activity. This renewed activity is expressed by gas emissions, hydrothermal activity and frequent earthquakes. Analysis of the gas composition regarding the percentage biogenic carbon and the He-3/He-4 ratio revealed that the gas source is the magma body approximately 7 km beneath the Long Valley Caldera. The gas from the magma body surfaces not only via the fumaroles but also emerges along geological faults. Some of the spots where gas surfaces are marked by dead or stressed trees. Other spots may not yet be identified. It is only recently known, from research at 'Vulcano Island' in southern Italy, that volcanoes release abundant carbon dioxide from their flanks as diffuse soil emanations. Mammoth Mountain seems to behave in a similar manner. The research described in this paper is designed to determine whether AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) can be used to identify areas of volcanic gas emissions.

Description: The NASA/JPL AIRSAR/TOPSAR instruments have the capability of collecting fully polarimetric radar data at three wavelengths (C, L and P-Bands) and dual antenna interferometry at C-Band, and more recently L-Band. In order to understand frequency and baseline dependent scattering effects in vegetated regions repeat pass interferometry data was collected for two vegetated regions in 1993. Portage Lake, Maine is a primarily coniferous forested region with some clear cutting from logging activities in the region. The second site at Innisfail, Australia borders a tropical rain forest and is situated adjacent to some major clear cut regions and banana plantations. Preliminary analysis of repeat pass data collected in these areas shows that the smaller the wavelength the greater the temporal decorrelation between passes, the longer the wavelength the greater the penetration depth for some types of vegetation canopy, yet for some vegetation canopy types, in particular for a banana plantation there appears to be no frequency dependent penetration into the canopy.

Description: The objectives of the study are: (1) Analysis of SIR-C/X-SAR response to soil moisture, vegetation and surface roughness and development of an algorithm to retrieve these parameters; (2) Combination of the visible and near-infrared data and the SIR-C/X-SAR data to improve the range and accuracy of vegetation classification; (3) Testing of theoretical models for microwave propagation with SIR-C/X-SAR and microwave radiometric measurements over rough surfaces; and (4) Evaluation of a water balance model using SIR-C/X-SAR derived soil moisture values and other ancillary data. Progress, significant results and future plans are presented.

Description: Progress, significant results, publications and future plans are discussed in relation to the following objectives: (1) To model, experimentally characterize, and verify penetration phenomena in hyperarid and vegetated regions using the SIR-C/X-SAR multiparameter radar system and groundbased receivers; (2) To invert measured radar backscatter as a function of frequency and polarization in terms of geophysical parameters of the surface, subsurface and vegetation canopy such as surface roughness, subsurface geomorphology, or tree height and density; and (3) To display subsurface and within-canopy features in an image format, thus easing the interpretability of the results.

Description: Progress, significant results and future plans are discussed relating to the following objectives: (1) Ecosystem characterization using SIR-C/X-SAR and AirSAR data; (2) Improving radar backscatter models for forest canopies; and (3) Using SAR measurements and models with forest ecosystem models to improve inferences of ecosystem attributes and processes.

Description: Progress and future plans regarding the following objectives are presented: (1) Test differential radar interferometry as a new monitoring technique for remote sensing of a forest site, a farm site, and a desert site; and (2) Generate topographic maps of test sites from radar data.

Description: The progress, results and future plans regarding the following objectives are presented: (1) Determine and compare soil moisture patterns within one or more humid watersheds using SAR data, ground-based measurements, and hydrologic modeling; (2) Use radar data to characterize the hydrologic regime within a catchment and to identify the runoff producing characteristics of humid zone watersheds; and (3) Use radar data as the basis for scaling up from small scale, near-point process models to larger scale water balance models necessary to define and quantify the land phase of GCM's (Global Circulation Models).

Description: The NASA/JPL AIRSAR/TOPSAR instruments have the capability of collecting fully polarimetric radar data at three wavelengths (C, L, and P-bands) and dual antenna interferometry at C-band, and more recently, L-band. In order to understand frequency and baseline dependent scattering effects in vegetated regions, repeat pass interferometry data was collected for two vegetated regions in 1993. Portage Lake, Maine is a primarily coniferous forested region with some clear cutting from logging activities in the region. The second site at Innisfail, Australia borders a tropical rain forest and is situated adjacent to some major clear cut regions and banana plantations. Preliminary analysis of repeat pass data collected in these areas shows that the smaller the wavelength the greater the temporal decorrelation between passes, the longer the wavelength the greater the penetration depth for some types of vegetation canopy, yet for some vegetation canopy types, in particular for a banana plantation, there appears to be no frequency dependent penetration into the canopy.

Description: Biomass burning is an important process on the Earth at the local, regional and global scales. To investigate issues related to biomass burning, a range of remotely acquired data were measured as part of the NASA Smoke Cloud Aerosol and Radiation experiment in Brazil, 1995. As part of this experiment, images of calibrated spectral radiance from 400 to 2500 nm at 10 nm intervals were acquired by AVIRIS. To investigate the expression of biomass fires in AVIRIS spectra, a model of the upwelling radiance from a burning fire was developed. This spectral model accounts for four components in the 20 by 20 m AVIRIS spatial resolution element. These are: (1) the atmospheric path radiance, (2) the solar reflected radiance from unburnt vegetation and soil, (3) the apparent temperature and area of a primary fire, and (4) the apparent temperature and area of a secondary fire. A nonlinear least squares spectral fitting algorithm was developed to invert this model for the AVIRIS spectra. The derived biomass burning parameters from this algorithm are presented for AVIRIS spectral images acquired over Cuiaba, Brazil on 25 August 1995.

Description: Since 1980 the Long Valley Caldera in the eastern Sierra Nevada (California) has shown signs of renewed volcanic activity. Frequent earthquakes, a re-inflation of the caldera, hydrothermal activity and gas emissions are the outer symptoms of this renewed activity. In 1990 and 1991 several areas of dying trees were found around Mammoth Mountain. The cause of the die off of the trees was first sought in the persistent drought in the preceding years. However, the trees died regardless of age and species. Farrar et al. (1995) started a soil-gas survey in 1994 in the dead-tree areas and found carbon dioxide concentrations ranging from 30 to 96% at soil depths between 30 and 60 cm. CO2 concentrations in the atmosphere are usually around 0.03% and in the soil profile CO2 levels do commonly not exceed 4 to 5%. Although not much is known about the effect of high levels of carbon dioxide in the soil profile on roots, it is most likely that the trees are dying due to oxygen deprivation: the CO2 drives the oxygen out of the soil. So far, four sites of dead trees have been mapped around Mammoth Mountain. The two largest dying trees sites are located near Horseshoe Lake and near Mammoth Mountain Main Lodge covering approximately an area of 10 and 8 ha respectively. Analysis of the gas composition regarding the He-3/He-4 ratio and the percentage biogenic carbon reveals the source of the gas: the magma body beneath the Long Valley Caldera. Until recently it was not known that volcanoes release abundant carbon dioxide from their flanks as diffuse soil emanations. As a result of the magma gas emission around Mammoth Mountain there is an excellent sequence of dead trees, stressed trees, healthy trees and bare soil surfaces. This research site provides excellent opportunities to: (1) Study the capabilities of imaging spectrometry to map stressed (and dead) pine and fir species; (2) Study methods to separate the vivid vegetation, stressed vegetation and dead vegetation from the soil background of glacial deposits and crystalline rocks. The dead tree areas are located on the flanks of Mammoth Mountain (N:37 deg 37' 45" and W:119 deg 02' 05") at an elevation between 2600 and 3000 meters. The area is covered by an open type of Montane Forest. The dominant tree species are Lodgepole Pine (Pinus contorta), the Red Fir (Abies magnifica) and the Jeffrey Pine (Pinus jeffreyi). The soil surface near Horseshoe Lake is generally fairly bright. The surface is covered by glacial deposits (till) consisting mainly of weathered granitic rocks.