HR: 11:05h
AN: C12A-04    [Abstracts]
TI: Snowmelt over the Greenland and Antarctica ice sheets from spaceborne radiometric data: extreme events and updated trends
AU: * Tedesco, M
EM: mtedesco@umbc.edu
AF: NASA Goddard Space Flight Center, NASA GSFC, Greenbelt, MD 20771, United States
AU: * Tedesco, M
EM: mtedesco@umbc.edu
AF: University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States
AB: Being able of observing melt extent and duration over ice sheets is fundamental for understanding how they are contributing to current sea level rise and affecting Earth's energy budget. With a surface size about 1.5 times the size of the U.S., Antarctica contains 90 percent of Earth's fresh water, making it the largest potential source of sea level rise. At the other pole, Greenland is the Earth's largest island with a total surface of about 2.2 square million km2 (slightly more than three time the size of Texas), representing another large potential source of sea level rise. Generally, some of the liquid water from snowmelt flows into the ocean, directly contributing to sea level rise while other might percolate at the bottom of the ice sheet, enhancing glacier sliding by lubricating the ice/bedrock interface. Also, after melting, snow changes its properties of absorbing and reflecting the energy irradiated by the sun, with melted/refrozen snow absorbing up to four times more energy than fresh/unthawed snow, strongly affecting Earth's energy budget. In Antarctica, snowmelt on ice shelves surface can lead to melt ponds, with meltwater filling small cracks and eventually causing larger fractures in the ice shelves, which act as brakes for glaciers and keep warmer marine air away from glaciers. Melting and surface temperature are strongly related and, therefore, knowledge of melting distribution and duration is extremely important to understand the spatial distribution of surface temperature over those places where ground measurements are sparse and difficult in view of the harsh conditions and remote locations. The Special Sensor Microwave Imager radiometer (SSM/I) aboard the Defense Meteorological Satellite Program's satellites (DMPS) provides daily measurements of brightness temperatures at several microwave frequencies. Microwave data have the great advantage of not being affected by sun or clouds presence and, differently from visible data, can detect melting occurring below the surface. In this study, results regarding melting over both the Greenland and Antarctica ice sheets derived from 19.35 GHz SSM/I brightness temperatures updated to 2007 are reported. Extreme melting events during the observation period and updated trends and anomalies for both melt extent and index (e.g., melting days x melting area) are reported. Results are obtained from different approaches and preliminarily compared with ground observations for validation purposes.
DE: 0740 Snowmelt
SC: Cryosphere [C]
MN: 2007 Fall Meeting