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 seasons (April–November) in 2009 – 2018 are classified into four types (e.g., linear-stationary, linear, stationary, and others) based on their morphological features and temporal variations. HRAs are frequently observed 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 suggested in previous studies.