Persistent Anomalies of the Extratropical Northern Hemisphere Wintertime Circulation: Geographical Distribution and Regional Persistence Characteristics
We have studied the geographical and regional persistence characteristics of wintertime Northern Hemisphere 500 mb height anomalies, focusing particular attention on the behavior of strong anomalies that persist beyond the durations associated with synoptic-scale variability (“persistent anomalies”). We have also examined the persistence characteristics of certain dominant regional patterns of low-frequency variability. There are three major regions for the occurrence of persistent anomalies: the North Pacific to the south of the Aleutians, the North Atlantic to the southeast of Greenland, and from the northern Soviet Union northeastward to over the Arctic Ocean. These regions have relatively high numbers of both persistent positive anomaly and persistent negative anomaly cases. For moderate magnitudes and durations, the numbers of positive and negative cases in each region are about the same; however, for larger magnitudes and longer durations, the number of positive cases exceeds the correspond... Abstract We have studied the geographical and regional persistence characteristics of wintertime Northern Hemisphere 500 mb height anomalies, focusing particular attention on the behavior of strong anomalies that persist beyond the durations associated with synoptic-scale variability (“persistent anomalies”). We have also examined the persistence characteristics of certain dominant regional patterns of low-frequency variability. There are three major regions for the occurrence of persistent anomalies: the North Pacific to the south of the Aleutians, the North Atlantic to the southeast of Greenland, and from the northern Soviet Union northeastward to over the Arctic Ocean. These regions have relatively high numbers of both persistent positive anomaly and persistent negative anomaly cases. For moderate magnitudes and durations, the numbers of positive and negative cases in each region are about the same; however, for larger magnitudes and longer durations, the number of positive cases exceeds the correspond...