Extended Abstract (120K)14B.1
Onset of the rainy season over Tropical Brazil in Observationsand A general Circulation Model Simulation
Brant Liebmann, NOAA/CIRES/CDC, Boulder, CO; and D. Allured, A. Seth, and S. J. Camargo
Onset of the rainy season over South America is examined using runs from an ensemble of general circulation models (GCMs), run with observed sea surface temperatures (SSTs) and compared to observations. The onset climatology and its progression as well as the intra-ensemble variability will be discussed. Of particular interest is the interannual variability of onset and its relationship to the rainy season total and to SST. Previous observations indicate that the timing of onset is well-correlated with seasonal totals if onset occurs in the season of interest. Further, in some parts of the Amazon basin the timing of onset is strongly related to anomalous SST, as are seasonal totals. However, the post-onset rain rate is not well-correlated with SST. Thus it is hypothesized that the influence of SST on seasonal totals is through its influence on the timing of onset. The known skill of a GCM in reproducing the observed seasonal rainfall variability when run with realistic SSTs will be examined to determine whether it is consistent with observations.
Session 14B, Climate Processes in the Americas and Eastern Pacific II (Parallel with Sessions 14A, 14C, and 14D)
Thursday, 2 May 2002, 2:00 PM-3:15 PM
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