Results of stratwarm campaign during winter of 1985-86

Abstract

The effect of high latitude stratospheric warmings on low latitude middle atmosphere during the winter of 1985-86 has been studied on the basis of experiments conducted under Indo-soviet Collaborative Programme. During this winter, two ‘minor’ warmings occurred in the high latitude middle atmosphere during mid-January and mid-February. The occurrence of cooling in the stratosphere and the lower mesosphere over Thumba simultaneously with the first warming event over the high latitudes has been observed. The second minor warming event is found to be associated with a cooling in the middle stratosphere over Thumba. A warming in the upper stratosphere and the lower mesosphere is observed over Thumba in the weakening stage of the second warming event. In association with the minor warmings over the high latitudes, there were short-period (i) strengthening of the easterly shear and weakening of the westerly shear in the high latitude stratosphere and lower mesosphere, and (ii) strengthening of the westerly shear in the lower mesosphere and of easterly shear in the upper stratosphere and the middle stratosphere over the two tropical stations.