THE STATISTICAL STUDY OF EAST HEMISPHERE 500 HPA CLOSED CYCLONE

Based on 10-year(1981-1990) historical weather maps(prepared by Beijing Meteorolo gical Center),the statistical study of East Hemisphere 500 hPa closed cyclone is presented.The results indicate that the frequency of cyclones has inter-annual variability and inter-monthly change.The closed cyclones are concentrated on two large areas: Asian East Coast-West Pacific and East Europe.The center of the firstarea shifts to a more western position in the summer than in the other seasons and its frequency increases.The frequency distribution of cyclone center heights appears in a two-peak type.The cyclone life cycle is longer than that of blocking high.The deep cyclones tend to appearin the regions of A sia-European mid-high latitude and West Pacific.The intensely devoloped cyclones appearin the region of West Pacific.The cyclones in Asia have two pathes:the northwestern and the western.