Intercomparison of Regional Climate Models for Summer Climate over the Philippines

The purpose of this study is to evaluate the performance of regional climate models and investigate their characteristics in simulating the climate of the Philippines. Dynamical downscaling was carried out by the WRF, RegCM, and GRIMs-RMP with the same horizontal resolution and domain for May-June-July-August from 1986 to 2010. The results were evaluated by APHRODITE and ERA-Interim in terms of climatological mean, interannual variability, and ENSO-related features.

The results show that the WRF is capable of reproducing the climatological mean with a certain cold bias and spatial distributions of surface temperature. The GRIMs significantly underestimates surface temperature due to a poor representation of topography, but interannual variabilities are reasonably reproduced. Rainfall anomalies in association with ENSO are well captured in the WRF simulations, despite simulated regional circulations that are weaker than observations. On the contrary, the GRIMs shows exaggerated circulations and a slightly northward flow in the low-level wind, resulting in a northward precipitation band. Although the RegCM simulates erroneous meridional flows, ENSO effect in boreal summer is represented.

On the whole, there is no single model that outperforms the others in all aspects of simulated climate. However, these results can be helpful to select the most appropriate model for operational system of the Philippines.