HR: 0800h
AN: C31A-0282    [Abstracts]
TI: Enhanced Snow Cover Mapping on the Tibetan Plateau using NASA EOS Optical (MODIS) and Passive Microwave (AMSR-E) Remote Sensing Data
AU: * Armstrong, R L
EM: rlax@nsidc.org
AF: Cooperative Institute for Research in Environmental Sciences - National Snow and Ice Data Center, UCB 449 University of Colorado, Boulder, CO 80309
AU: Brodzik, M J
EM: brodzik@nsidc.org
AF: Cooperative Institute for Research in Environmental Sciences - National Snow and Ice Data Center, UCB 449 University of Colorado, Boulder, CO 80309
AU: Savoie, M H
EM: savoie@nsidc.org
AF: Cooperative Institute for Research in Environmental Sciences - National Snow and Ice Data Center, UCB 449 University of Colorado, Boulder, CO 80309
AU: Zhang, T
EM: tzhang@nsidc.org
AF: Cooperative Institute for Research in Environmental Sciences - National Snow and Ice Data Center, UCB 449 University of Colorado, Boulder, CO 80309
AU: Frauenfeld, O
EM: oliverf@nsidc.org
AF: Cooperative Institute for Research in Environmental Sciences - National Snow and Ice Data Center, UCB 449 University of Colorado, Boulder, CO 80309
AB: Snow cover on the Tibetan Plateau has been the focus of considerable attention since the inverse relationship between winter snow cover and the intensity of subsequent Indian summer monsoon rainfall was first suggested more than a century ago. However, the Tibetan Plateau typically receives only small snowfall amounts, often accompanied by strong winds. This results in a pattern of spatially intermittent, i.e. patchy, shallow snow cover. Over the past several decades both optical and passive microwave satellite data have been available to map snow on the Tibetan Plateau. However, the coarse resolution of these historical remote sensing data sets is often not capable of resolving the pattern of intermittent snow. The higher spatial resolution of the MODIS and AMSR-E data, however, provides an improved capability to more accurately characterize this patchy snow cover pattern. As background, we present the historical multi-sensor Northern Hemisphere snow products for the period 1978 to 2003. Snow cover climatologies derived from these optical and microwave data generally compare favorably and where they do not, a reasonable explanation exists. The single region over which these two data sets disagree is the Tibetan Plateau where the microwave data appear to consistently indicate more snow cover than the visible data. We offer several explanations for this which include: frozen ground, soil type, mixed pixels of frozen and unfrozen water, influence of a reduced atmospheric thickness and the application of non-representative station data for validation. The availability of the higher spatial resolution MODIS and AMSR-E data, and the blending of these data, allow new opportunities to investigate this apparent anomaly. The blending process incorporates MODIS data at approximately 5 km (0.05 deg.) with microwave-derived SWE at 25 km, resulting in a blended product that includes percent snow cover in the larger grid cell. Relationships between the percent area covered by snow as indicated by the MODIS data and the threshold for the appearance of snow as indicated by the passive microwave data are presented. Comparison of snow cover derived from MODIS, SSM/I and AMSR-E over the Tibetan Plateau provides an example of the higher spatial resolution of AMSR-E yielding more accurate snow extent maps.
DE: 3360 Remote sensing
DE: 1863 Snow and ice (1827)
DE: 1884 Water supply
DE: 1640 Remote sensing
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting