HR: 17:45h
AN: H44A-08    [Abstracts]
TI: Influence of Precipitation Assimilation on Regional Climate Simulations Over North America
AU: * Roads, J
EM: jroads@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0224 United States
AU: Nunes, A
EM: anunes@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0224 United States
AB: A continuous assimilation of the "observed" precipitation was performed over North America from 1986-1996 with a regional climate model bounded by the National Centers for Environmental Prediction/ Dept. of Energy (NCEP/DOE) Reanalysis II (RII). Using observed daily rain rates over the continental United States, and the global reanalysis precipitation fields over the rest of the model domain, including Mexico, we attempted to bring the regional climate model-produced precipitation close to the "observed" precipitation by adjusting the specific humidity. This adjustment technique works well with sophisticated convection schemes, including the Relaxed Arakawa-Schubert used in our regional simulations. We then compared the precipitation assimilation (PA) simulation to a control regional climate simulation to see whether PA had a positive influence on other climate processes and variables. In general PA improved surface features over the central and eastern US. In particular, the 2-m specific humidity and the 10-m horizontal wind fields had less bias and stronger correlation with corresponding variables from the North American Regional Reanalysis (NARR) than the control simulation. Evaporation and sensible patterns were also improved. Although the PA soil moisture was relatively low in comparison to NARR, which had a different land surface scheme, the PA soil moisture was correlated better than the control, suggesting that PA may eventually be useful for initializing regional climate forecasts. Analysis of the impact of PA on tropospheric features are beginning will be presented at the meeting.
DE: 1833 Hydroclimatology
DE: 3354 Precipitation (1854)
SC: Hydrology [H]
MN: Fall Meeting 2005