On the Mutual Relation between Stratosphere and Troposphere during Periods of Stratospheric Warmings in Winter

Abstract

An investigation of tropospheric conditions before and after pronounced stratospheric midwinter warmings indicates an interdependence of developments in the two atmospheric regions. The eleven northern hemisphere winters which have been investigated show that every two years the behavior of the stratosphere is similar as regards the location of the initial warming, direction of movement of systems, and subsequent response of the troposphere. Every second year the midwinter warmings begin in the stratosphere above the eastern United States and Canada, as illustrated in the published examples from 1957 and 1963. During the alternate years of the cycle the warmings originate over central and eastern Europe. In this paper the emphasis has been placed on this type of warming. The tropospheric circulation patterns before each warming of this kind are analogous, and the warming is followed after about ten days by a blocking situation at sea level. It is likely that there is a connection between the 26-month cycle in the stratospheric winds in the tropics and the cycle in the stratospheric warnings.