Sensitivity of Heavy Precipitation to coastal SST near the Kuroshio: A Case Study in the Sea of Japan area on early July, 2018

Previous studies have examined the atmospheric responses to the Kuroshio sea surface temperature (SST) front using high-resolution satellite-derived SST and numerical modeling. However, cloud contamination is problematic in producing high-resolution infrared-based SST data. Temporal and spatial optimal interpolation is often used for constructing high-resolution gap-free SST products, and the performance in satellite-derived SST at the coastal area is lower when compared with offshore waters due to the limitation of sampling coverage.

Here, we examine the difference in the representation of SST near coastal areas among satellite-derived SST products and their impacts on heavy precipitation. In the present study, we focus the influence of SSTs in vicinity of the Kuroshio south of the Bungo Channel between Kyushu and Shikoku Islands on a heavy precipitation event that occurred over the western part of Japan’s largest island on early July, 2018, using a regional atmospheric model WRF. Results show that when SSTs with warmer (cooler) bias are prescribed in WRF simulations, the position of intense convective precipitation area is shifted on southward (northward) side, under prevailing southerlies over the Bungo Channel.