An Analysis of Persistence of 500 hPa Pentad Mean Height Anomalies for the Northern Hemisphere Summer
北半球夏季５００hPa候平均高度场异常持续性的分析

Both of the persistent anomaly criterion and the Rotated Principal Component (RPC) analysis were applied to 500 hPa pentad mean height data for the Northern Hemisphere Summer during 1951-1986 to diagnose the characteristics of geographical distribution and duration of persistent anom-alies of the Northern Hemisphere summertime circulation. The results show that the localities of high-loading centers of the first 11 RPCs basically coincide with those of the high frequency regions where the persistent anomalies occur. The persistence of pentad mean circulation anomalies is little higher than the Marckov Chain, but some seasonal abnormalities often comprise reoccurrences of the persistent anomalies with short breaks, and the subtropic systems are important components of the persistent anomalies for the Summertime.