Investigation of South American Land/Atmosphere Interactions Using the Regional Eta/ssib Model
Fernando
Henrique
De Sales, University of California Los Angeles, fsales@ucla.edu
(Presenting)
Yongkang
Xue, University of California Los Angeles, yxue@geog.ucla.edu
The NCEP Eta model coupled with a biosphere model, SSiB, was set up over the South American continent to study the role of land/atmosphere interactions in the South American hidrometeorology and regional climate predictability. NCEP Reanalysis and NCEP GCM output were used as initial and lateral boundary conditions for 3-month regional integrations. Sea surface temperature, sea ice concentration and snow cover were updated daily during the simulation.
Results were compared to GCM and Reanalysis data as well as to observation to evaluate the dynamic downscaling of the regional climate model in regional hydrometeorological study. To understand the predictability, a series of sensitivity studies has been designed to explore the role of variety of factors in water cycle simulations. These factors include domain size, horizontal resolution, different lateral boundary conditions and different convective scheme.
Preliminary results indicate the regional model was able to capture most of the features of precipitation distribution over Brazil as well as to improve atmosphere circulation simulations when compared to the GCM results and reanalysis data. Although rainfall magnitudes were not perfectly reproduced, the model properly simulated the maximum precipitation region over the southern part of Brazil and the dry areas elsewhere during the dry season period.
The study shows the importance of a regional model and the proper land surface processes representation in the South American rainfall simulation and the role of more realistic boundary condition description in predicting its regional climate.
Submetido por Fernando Henrique De Sales em 15-MAR-2004