The Annual Course of Month-to-Month Persistence in Climatic Anomalies*

Abstract

The annual march of month-to-month persistence in anomaly of temperature, precipitation, and mid-tropospheric flow pattern over the United States is examined for approximately the past decade. The data indicate a tendency for persistence in all three elements during all adjacent pairs of months except from April to May and from October to November when great and often abrupt transitions of long period regimes occur. These empirical findings are related to a “self-developmental” hypothesis presented by the author in a recent paper and designed to explain the evolution of climatic anomalies. An analysis of the year-to-year behavior of persistence suggests possible gradual secular trends which might be related to sunspots, but the evidence is inconclusive. Finally, persistence is related to zonal index, and here there is a suggestion that during the colder parts of the year low index periods are more persistent than high.