Influence of High-Resolution SST on Early Summer Surface Air Temperature in Japan in Downscaling Experiments

Abstract

This study evaluated the effects of sea surface temperature (SST) resolution on dynamically downscaled daily surface air temperature (Tsrf) in the Kanto region during early summer. Two downscaling experiments and one additional experiment were conducted using different SST datasets for the months of June and July over a 10-year period. The results demonstrated that the Tsrf difference in the Kanto region between the high-resolution SST experiment (Run-H) and the low-resolution SST experiment (Run-C) correlates positively with the difference in surrounding SST. The impact of SST difference depends on the wind direction and speed. By comparing the results with observations at meteorological stations, the number of days with warm Tsrf bias in Run-C significantly reduces in Run-H, but the number of days with cold Tsrf bias still remains. These results suggest that SST resolution influences the downscaled Tsrf reproducibility over land, and it is worthwhile to pay attention to coastal SST.