Summer precipitation–SST relationship on different time scales in the northern tropical Indian Ocean and western Pacific

Abstract

The time-lag relationship between precipitation and sea surface temperature (SST) variations depends upon the time scale. The present study compares the relationship between precipitation and SST variations on three time scales (synoptic, intraseasonal, and interannual) during boreal summer in the North Indian Ocean and the western North Pacific region. On interannual time scale, higher SST is followed by more rain rate in the Arabian Sea, but less rain rate in the Philippine Sea. On intraseasonal and synoptic time scales, higher SST precedes more rain rate. It is shown that the precipitation perturbation following the SST perturbation is more robust in the Philippine Sea on interannual and intraseasonal variations and less robust in the Arabian Sea on synoptic variations. The increase of rain rate perturbation leads to a decrease of SST on all the three time scales. The SST change in response to precipitation perturbation is more robust in the Philippine Sea and the South China Sea than in the Arabian Sea and the Bay of Bengal on interannual and intraseasonal variations. The correlation between intraseasonal precipitation and SST variations tends to be stronger when SST is above than below 29 °C in the South China Sea and the Philippine Sea. The correlation between intraseasonal precipitation perturbation and precipitation-induced SST change displays a decrease with total rain rate in the Arabian Sea and the Bay of Bengal.