HR: 0830h
AN: C41B-0968    [PDF]
TI: Monitoring Mountain Snow Pack Evolution using Near Surface Optical and Thermal Properties
AU: * Lampkin, D J
EM: dlampkin@hwr.arizona.edu
AF: University of Arizona Department of Geography and Regional Development, Harvill Hall, Tucson, AZ 85721 United States
AU: Yool, S
EM: yool@skydog.geog.arizona.edu
AF: University of Arizona Department of Geography and Regional Development, Harvill Hall, Tucson, AZ 85721 United States
AB: Variability in regional climate can affect snow covered area, amount, and timing of yields. Monitoring is particularly important in the semi-arid western United States. In order to assess the impact of regional climate variability on water resources, there is a need for improved assessment of changes in snow pack properties as they indicate the degree and timing of snow pack melt. Detecting the evolution and spatial distribution of surface melt requires extracting diagnostic information about the evolving spring time snow pack using retrieved radiative surface information from satellites. We have examined a theoretical approach for monitoring the state of the snow pack using surface indicators such as visible reflectance and temperature. This was accomplished through the development of a Near Surface Moisture Index (NMSI), which models relative moisture through construction of a feature space using visible band and a thermal band. A simple analytical RT model for computing directional hemispherical reflectance and emissivity derived from the delta-eddington approximation to the equation of radiative transfer was used to produce the NMSI. Snow near surface grain size could be a proxy for characterizing the evolution of surface conditions during ablation periods. Modeled reflectance and emissivity, as a function of grain size, over MODIS channels 4, 6, and thermal band passes were used to produce the NMSI feature space constructed from the Normalized Difference Snow Index (NDSI) on the adscissa and brightness temperature (Tb) on the ordinate. As grain size increases, the dynamic range or sensitivity of NDSI is reduced, with saturation occurring approximately around 400-450�m grain radius. Tb for various grain sizes at fixed kinetic temperatures at 245, 250, 255, 260, 265, and 273 Kelvin and ndsi as a function of grain size were used to construct a theoretical NMSI feature space. An index from such a feature space may be designed considering than an optimal index would be constructed with isolines situated perpendicular to the displacement features within the modeled feature space. Displacement vectors ideally are indicative of the change in the surface snow pack through an increase in NDSI and Tb. Field data of snow surface and depth properties will be used to confirm if such an approach would be viable for monitoring snow pack evolution from combined TERRA/AQUA daily MODIS acquisitions during the melt season.
DE: 1640 Remote sensing
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting