P2.33
Interannual Variations in HIRS Observations of the Temperature Inversion over the Antarctic Plateau
Steven A. Ackerman, CIMSS/Univ. of Wisconsin, Madison, WI; and R. Frey and J. Key
Radiance measurements from satellites provide the best means of routinely monitoring global climate parameters. Global analysis of cloud amounts, types and optical properties using satellite measurements have been developed and are currently operational. The large negative differences in brightness temperatures at 11 and 6.7 microns (BT11-BT6.7) observed over the polar high-altitude plateaus in winter result from the presence of a strong temperature inversion, consistent with theory and physical expectations. Detecting the presence of this surface inversion is important, as the energy exchanges at a snow-ice surface are dominated by radiative processes. During winter conditions, the magnitude of the longwave net radiation balance is largely driven by the presence or absence of clouds. For cloud-free conditions the net infrared flux is large and is directed away from the surface, thus causing the cooling of the lower layers of the atmospheres. This radiative cooling plays an important role in the formation of cold air masses which may develop into downslope katabatic winds. Five years of HIRS/2 observations over Antarctica allow us to map out the extent and strength of this surface inversion and it interannual variability.
Poster Session 2, Climatology and Long-term Satellite Studies
Monday, 15 October 2001, 2:15 PM-4:00 PM
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