HR: 0800h
AN: GC21A-0143 [Abstracts]
TI: Evaluation of Orographic Effect on Surface Climate with WRF Climate Model
AU: * Huang, Y
EM: yhuang@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst
Drive, Atlanta, GA 30332-0340,
AU: Dickinson, R E
EM: robted@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst
Drive, Atlanta, GA 30332-0340,
AU: Shaikh, M
EM: shaikh@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst
Drive, Atlanta, GA 30332-0340,
AB:
Over high altitude regions, surface observations are scarce and representations of atmospheric and terrestrial
flux exchanges can be poor in global models. This study evaluates the statistical dependence of various surface
climate properties, such as temperature, moisture and winds on orographic elevation using the Weather and
Research Forecast model (WRF). Our study region is the Tibetan Plateau where the elevation is greater than
3000m. Both seasonal and diurnal elevation dependences are analyzed and compared with global model
simulations. The lapse rate of surface temperature is found to be smaller in the summer and larger in the winter,
while opposite seasonality is seen for water vapor, likely due to the high surface moisture availability in the
summer. The surface winds increase with altitude and has relatively larger gradients in all seasons except the
summer. As for the diurnal cycle, the temperature decreases largely with elevation in the afternoon, probably due
to the heating at the surface during daytime compared to the relatively stable conditions during the night and
morning time within the planetary boundary layer. Water vapor shows a similar cycle as temperature; however,
horizontal winds do not have a significant cycle. By testing the different cumulus and planetary boundary
parameterizations available in the WRF model, it is found only small differences in their derived dependences,
e.g., the orographic effect on surface temperature varies at most by 15 percent. The orographic effects from the
regional simulations are generally in line with that of a global model.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1637 Regional climate change
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting