Regional climate simulations of summer rainfall over the Philippines

Abstract

Most simulations of global climate are performed by low spatial resolution models called general circulation models (GCMs) to avoid the huge computing expense normally incurred in running these models over time frames of the order of decades. In fact, predictions of global climate change and its impacts are largely taken from these coarsely resolved GCM results which are normally generated by powerful supercomputing platforms. While fairly accurate in representing the large scale planetary circulation of the atmosphere, these GCMs are unable to capture sub-GCM scale processes such as convective rainfall, clouds, and other such elements crucial to the forcing of climate. One of the greatest uncertainties in climate science today is in determining the regional impacts of a changing global climate. Hence, regional climate models are being developed and applied today to respond to this important gap in climate science.
In the last decade, regional climate simulations have been conducted for various parts of the globe. In eastern Asia, these have also been validated with actual observations and have been shown to perform adequately despite continued modifications in the physics ofthe different climate forcing mechanisms in the model itself.
We present here the first regional climate simulation of Philippine rainfall for the months of June, July, and August of 1994. The simulation shows the geographical distribution and temporal evolution of southwest monsoonal rainfall, among other things, over the archipelago.