HR: 09:45h
AN: H31M-08    [Abstracts]
TI: The Amazon Water Budget as Diagnosed by ERA40
AU: * Fernandes, K
EM: kfernandes@eas.gatech.edu
AF: Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340, United States
AU: Fu, R
EM: fu@eas.gatech.edu
AF: Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340, United States
AU: Betts, A
EM: akbetts@aol.com
AF: Atmospheric Research, 58 Hendee Lane, Pittsford, VT 05763, United States
AB: The ERA40 surface water budget is evaluated by comparing to observed precipitation (P), streamflow/runoff (R), and evapotranspiration (ET) for the period of 1980-2001 in the Amazon River basin. ERA40 precipitation shows an overall agreement with observations in annual and interannual scales, although the seasonal cycle shows a clear precipitation low bias during the wet season. Rainfall distribution on sub-basin scale disagrees with observations by as much as 30%. ERA40 rain rates compare to those estimated by TRMM at the 2.5o spatial resolution indicating interception loss may not account for the 25% underestimation of runoff (R) in annual scale, although it remains unclear whether the ERA40 rain rate agrees with observation at the scales of convective rainfall. ET in ERA40 appears to be higher than observations by as much as 30%. The residual of precipitation and runoff (P-R) in ERA40 generally agrees with observations. Thus the large scale surface water budget could provide a realistic annual ET, but soil moisture nudging appears to cause overestimation of annual ET. The seasonal scale analysis however, shows that soil moisture nudging is necessary to provide realistic ET during the dry season. This is because ERA40 provides only 45 mm surplus of P-R relative to ET during the wet season, whereas the deficit in the dry season is almost four times greater. This low bias in wet season soil moisture recharge may be caused by the underestimation of wet season rainfall in ERA40.
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 3337 Global climate models (1626, 4928)
DE: 3374 Tropical meteorology
SC: Hydrology [H]
MN: 2007 Fall Meeting