This study is an attempt to classify climatic regions of Korea based on the data of sunshine duration and to clarify the characteristics of sunshine for each divided regions. The data used in this study are the mean values of monthly and ten-daily sunshine duration, sunshine percentage, solar radiation and cloud amount obtained from 63 weather stations of the Korea Meteorological Administration during the period of 1974∼1993. The characteristics of annual change of sunshine percentage, annual duration of sunshine, percentage of sunshine, annual radiation, amount of cloud, days of sunshine percentage above 80% and days of sunless are investigated by the mean values of the stations belong to divided regions. The ward method of hierarchical cluster analysis is adopted to the analysis of data for the regional division. The results obtained in this study are summarized as follows.
(1) The sunshine regions of Korea can be divided into six regions of the central west, central east, south west, south east, Ullung-do and Cheju-do. These are strongly affected by the distribution of inclined slopes taking account of the topographic characteristics of Korea.
(2) Annual distribution shows the sunshine duration of 1777∼2287 hours, sunshine percentage of 40∼53%, solar radiation of 3469∼4637 MJ/㎡, cloud amount of 5.0∼6.1, days of sunshine percentage above 80% of 53∼116days and sunless days of 46∼71days.
(3) The types of annual change of sunshine percentages is classified with four types of minimum in July and maximum in October, minimum in July and maximum in December, high in May and October and low in July and January, high in May and November and low in June and January.
(4) The Iong-term trend of sunshine duration decrease in peninsula area but increase in island area and the long-term inclination of cloud amount is almost zero. The author believe this tendency is related to a pollutional turbidity than a cloud amount in inland area.

• 문영수(경산대학교 환경과학과) | Yung-Soo MOON