HR: 14:35h
AN: H23F-04    [Abstracts]
TI: How Do Precipitation, Evapotranspiration, and Runoff Contribute to Layered Soil Moisture Memory? - Results from A Climate Simulation
AU: * Wu, W
EM: wwu@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-0340 United States
AU: Dickinson, R E
EM: robted@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-0340 United States
AB: Previous studies have suggested that soil moisture memory is mainly controlled by four distinct factors: (i) nonstationarity (seasonality) in the atmospheric forcing, such as precipitation and net radiation; (ii) the effect of ET in removing soil moisture and hence its memory; (iii) the analogous dependence of runoff; and (iv) feedback of soil moisture on precipitation. The latter depends on how ET and runoff are partitioned between removal from the rooting zone soil column and from smaller stores located at or near the surface. This study quantifies the time scales over which these controls act globally using a 50-year climate simulation from CCM3-CLM. Our major findings are: a) soil moisture memory in warm climates can be at least several times longer for drier conditions than while it is sufficiently rainy; b) under wet conditions, the time scales of soil moisture appear to be controlled by temperature-dependent climatic demand but for drier conditions, appear to depend largely on increasing time scales for the coupling of soil moisture to ET and especially runoff; c) the longer soil moisture memory in deeper soil layers appears to respond and feedback to longer atmospheric variability.
DE: 3322 Land/atmosphere interactions
DE: 1833 Hydroclimatology
DE: 1866 Soil moisture
DE: 1655 Water cycles (1836)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting