Secular changes in occurrence of summer circulation types in the Far East

The first (1946-58) and third (1976-85) periods have a similar tendency in that low index circulation types are prevalent, which result in hot summer as well as the first type of cool summer. Low index circulation types are inclined to continue for several pentads, and remarkably high or low temperatures are frequently observed in these periods. The second period (1959-75) have an opposite tendency in that high index circulation types are prevalent. The circulation types are inclined to change under a zonal flow pattern, especially in the transitional stage between high and low temperature types that are frequently recognized. -from Author