Comparison of Rainfall on the Japanese Islands and Their Adjacent Ocean

Abstract

Rainfall features of the Baiu season estimated from GMS IR images are investigated for the Japanese islands and their adjacent ocean for June 1989. The total monthly rainfall for the period is distributed in a band-like shape extending from west to east, showing its maximum on 35°N in the latitudinal section and a sudden decrease to the west of 130°E in the longitudinal section. The latitudinal distributions of rainfall relative to the Baiu front show almost the same shape with the maximum at 1.25° north of the front at the surface over both land and ocean, but the peak amount is larger over the island than that over the ocean. The temporal changes of rainfall are dominated by a period of synoptic scale for all regions over both land and ocean, and secondly, by a peak corresponding to daily variation observed only over the continent. The rainfall region moves eastward along the Baiu front with almost same phase speed of about 7.5° longitudes per 12 hours over almost all regions.