HR: 08:10h
AN: H31E-01 INVITED     [Abstracts]
TI: The role of antecedent soil moisture on variability of the North American Monsoon System
AU: Zhu, C
EM: chunmei@hydro.washington.edu
AF: Department of Civil & Environmental Engineering, University of Washington, Seattle, WA 98195, United States
AU: Qian, Y
EM: Yun.Qian@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999 Richland, WA 99352, Richland, WA 99352, United States
AU: Leung, R
EM: Ruby.Leung@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999 Richland, WA 99352, Richland, WA 99352, United States
AU: Gochis, D
EM: gochis@ucar.edu
AF: Research Applications Laboratory, The National Center for Atmospheric Research, P.O. Box 3000 Boulder, CO 80307-3000, Boulder, CO 80307-3000, United States
AU: Cavazos, T
EM: tcavazos@cicese.mx
AF: Department of Physical Oceanography, Centro de Investigacion Cientifica de Educacion Superior de Ensenada, Ensenada, Mexico, Centro de Investigacion Cientifica de Educacion Superior de Ensenada, Ensenada, Mexico
AU: * Lettenmaier, D P
EM: dennisl@u.washington.edu
AF: Department of Civil & Environmental Engineering, University of Washington, Seattle, WA 98195, United States
AB: We evaluate the influence of soil moisture anomalies on the timing and strength of North American Monsoon system (NAMS) precipitation through analysis of retrospective data sets including off-line simulations with the Variable Infiltration Capacity (VIC) land surface model, and through coupled model simulations using the MM5 mesoscale climate model coupled with the VIC land surface scheme. The role of land surface conditions on variations in monsoon precipitation in the Arizona-New Mexico and northwestern Mexico subregions of the North American Monsoon region are evaluated. The retrospective data analysis shows that soil moisture memory can propagate winter precipitation anomalies, and hence land surface cooling, through the dry spring season and into early summer. The effect is greater in NW Mexico where the monsoon begins earlier than in the southwestern U.S. We further investigate this land surface feedback mechanism through a set of coupled model runs using MM5/VIC. These coupled runs are consistent with the previous off-line runs to the extent that the VIC land surface scheme is the basis for soil moisture prediction in both. MM5/VIC control runs together with a set of sensitivity experiments in which soil moisture is prescribed to field capacity, wilting point and VIC soil moisture climatology, respectively, during pre-monsoon seasons (April-June) are used to examine the influence of antecedent (above-normal, below-normal and normal) soil moisture on pre-monsoon (May and June) surface temperature. Surface temperature, and its contrast with sea surface temperature, is a key driver of the onset of the NAMS. These experiments are intended to better understand the role of land-atmosphere feedbacks on the NAMS by testing a range of land surface and climate conditions in the coupled modeling environment.
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1847 Modeling
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2007 Joint Assembly