On the Annual Cycle of Central South-West Asia precipitation in GCMs: an Analysis of AMIP Simulation Results
Abstract
This study evaluates simulations of precipitation patterns over the Central South-West Asia region (25-40N and 45-75E) by using results from the Atmospheric Model Inter-comparison Project (AMIP). Annual and monthly spatial precipitation fields produced by a subset of 13 currently available AMIP model experiments are evaluated for the region and compared with GPCC (Global Precipitation Climatology Centre) monthly precipitation data for the period of 1979-2001. GPCC precipitation data are available with 0.5 degree resolution and correlate with observational precipitation data with a correlation factor of 0.953. The models show large variations in their ability to capture the seasonal precipitation, although spatial correlations indicate that some of the models simulate the pattern of GPCC precipitation fields fairly well. Some models cannot capture the convective precipitation in the region that occurs during spring (March-April) and fall (Sept-Oct). Relative to the GPCC data most of the models predicted well in winter whereas some models cannot adequately capture the summer (monsoon) precipitation which enters the domain from east. On the spatial scales of the selected region, there is little consistent evidence that points to any specific feature as an indicator of model performance. None of the obvious candidates such as horizontal resolution, convective closure schemes, or land surface schemes are reliable discriminators of a models ability to simulate precipitation accurately. Horizontal resolution effects are apparent in the inter-mountain region, where high resolution models do better that low resolution models. However, there is not enough evidence to produce reliable simulation on this basis. Correlation coefficients of observed precipitation with model output can be improved by using ensemble averaged precipitation from several models.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.H33E0918M
- Keywords:
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- 1626 GLOBAL CHANGE / Global climate models