Identification and Classification of Heavy Rainfall Areas and Their Characteristic Features in Japan

Abstract

 We propose a new procedure for the objective identification and classification of heavy rainfall areas (HRAs) to advance the understanding of mesoscale convective systems (MCSs) in Japan. The distributions of accumulated precipitation amounts are evaluated from the radar/raingauge-analyzed precipitation amounts and characteristic features of HRAs are examined. The HRAs extracted during the warm season (April–November) in 2009-2018 are classified into four types (e.g., linear-stationary, linear, stationary, and others) from their morphological features and temporal variations. HRAs are frequently distributed on the Pacific sides of eastern and western Japan; 80 % of HRAs appeared from June to September and 60 % of the HRAs were observed in association with stationary fronts and tropical cyclones. Approximately 80 % of those HRAs of the linear-stationary type corresponded to typical elongated and stagnated MCSs, as has been suggested in previous studies.