Heavy Rainfalls Associated With Frontal Depression in Asian Subtropical Humid Region (II) Mesoscale Features of Precipitation, Radar Echoes and Stratification

摘要

A subtropical frontal depression brought heavy rainfalls over western Japan on June 27, 1972. In the present study, we intend to describe the mesoscale features of precipitation over the depression with relation to air-mass stratification and circulation. The echo band along the trailing portion of front brought intense convective rainfalls. The area of unstable air (saturated, -∂θe/∂p--12°K/400mb) was localized around the echo band. There was 1-3 hours time lag between the generation of strong instability and onset of heavy rainfalls. The area of maximum rainfalls shifted northward -30km from the area of maximum instability. Radar observation indicated the suppression of weak echoes around strong echoes. The stability change associated with the release of instability is evaluated by cumulus parameterization scheme and heat energy budget calculation.