Environmental stability for afternoon rain events in the Kanto Plain in summer

Abstract

The environmental stability for afternoon rain events over theKanto Plain in summer was investigated. The AMeDAS data wereused to extract the hot, sunny days under synoptically undisturbedconditions, and the gridded mesoscale analysis data that cover thesouthern Kanto Plain were used to examine the difference of thecharacteristics of environmental stability among no-rain, rain, andstrong-rain events in the afternoon by calculating commonly usedstability indices and parameters. A statistical analysis by t-teststatistic was conducted to determine the significance of the differentfeatures of the stability parameters among the events. Amongthe parameters, K-index indicated the highest significance level.The analyses on the difference of temperature and humidity ateach height among the events indicated that the temperatures andmoistures at low to middle levels clearly distinguish the stabilityconditions for the afternoon rain events. It is strongly suggestedthat colder temperature at middle levels and higher humidity atlow to middle levels are favorable conditions for the developmentof stronger rains in the afternoon.