Division of seasons in a year

Abstract

Seasons in mid-latitude area are the results of change in latitudinal distribution of incomming solar radiation. To identify the fact in every year, following procedures are adopted for two years 2005 and 2010.1.Pressure distributions around Japan are divided based on JMA ASAS surface charts. 2.Then seasons are determined on the timescale of pentad. The criteria for change of season are arranged from 10-years mean of the last decade of the last century.