This study is a part of the APCC-PAGASA Regional Prediction System (APCC-PRePS) project, aimed at providing valuable high-resolution seasonal forecasts using downscaling techniques. In the first year of the APCC-PRePS project, 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.

On the whole, there is no single model that outperforms the others in all aspects of simulated climate. 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. The RegCM simulates erroneous meridional flows, which causes difficulties in reproducing the climate of the Philippines.

1. INTRODUCTION

2. APCC-PRePS PROJECT

3. DATA AND METHODOLOGY

3.1 Models

3.2 Experimental Design

4. RESEARCH RESULTS

4.1 Climatological Features and Mean Biases

4.2 Interannual Variability

4.3 ENSO-Related Features

5. SUMMARY AND DISCUSSION

6. FUTURE PLANS

REFERENCES

TABLES AND FIGURES