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 anomali...