HR: 16:00h
AN: H34D-01 INVITED    [Abstracts]
TI: Atmospheric Moisture Demand Under Global Warming
AU: * Dai, A
EM: adai@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, United States
AB: Warming near the surface increases the water vapor holding capacity of the air. Since the vapor saturation level or relative humidity in the air is fairly stable on annual to longer time scales, this would lead to increased atmospheric demand for water vapor if other things being equal. However, accompanying changes in surface wind speed and solar radiation can alter this general trend under global warming at least on regional scales. Decreasing trends in pan evaporation from the 1950s- early 1990s over many parts of the continents suggest that recent warming did not play a dominant role in determining atmospheric demand of water vapor over many areas. In this talk, I will examine historical data for trends in surface humidity, wind speed, and solar radiation and their implications for potential evapotranspiration over global land. I may also discuss climate-model simulated changes in evapotranspiration if time permits.
DE: 1630 Impacts of global change (1225)
DE: 1655 Water cycles (1836)
DE: 1818 Evapotranspiration
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
SC: Hydrology [H]
MN: 2007 Fall Meeting