Regional characteristics of contribution of atmospheric fronts to heavy rainfall in boreal summer over Japan, Northwestern Pacific

Abstract

In this study, we use a long-term gridded dataset of daily precipitation and atmospheric fronts delineated on weather maps of Japan, the Northwestern Pacific, to identify rainfalls influenced by fronts within heavy rainfall periods occurring from June to August. We clarify the relationship between daily precipitation and the distance to fronts. The analytical targets are heavy rain events that occur for approximately four days each season. In the areas from Northwestern Kyushu to Western Tohoku, facing the Sea of Japan, the amount of precipitation from heavy rain events occurring within 500 km of fronts accounts for at least 80% of all heavy rain events. This is the same for the number of heavy rain events as well. Specifically, in Northwestern Kyushu, the amount of precipitation and the number of heavy rain events occurring within 200 km of fronts account for approximately 70% of all heavy rain events.