AN EVALUATION OF THE SPATIAL AND INTERANNUAL VARIABILITY OF TROPICAL PRECIPITATION AS SIMULATED BY GCMS

Precipitation is one of the most din?cult variables to Data simulate i n a General Circulation Model and arguably one of the most important. The Atmospheric Model Intercomparison Project (AMIP) provides an oppor tunity to examine the simulation of precipitation in a wide array of m odels. Monthly precipitation fields produced by a subset of 19 current ly available AMIP model experiments are evaluated for the tropical reg ion using a land-only observed dataset for the period 1980-1988. The m odels show large variations in their ability to reproduce observed tro pical precipitation, although spatial correlations indicate that some of the models simulate the pattern of observed precipitation fields fa irly well. The correlations are strongest during boreal winter (DJF) a nd weakest during the boreal summer (JJA). Comparison between model an d observed precipitation time series for two Central Pacific locations show that most models are unable to reliably reproduce interannual pr ecipitation variability in this region.