THE WARMING OF THE UPPER STRATOSPHERE IN FEBRUARY 1966 AND THE ASSOCIATED STRUCTURE OF THE MESOSPHERE

Abstract

A major warming above the 10-mb level in February 1966 is described with the aid of rocket data from high-latitude stations at Heiss Island (81° N.) and Churchill (59° N.), together with high-level radiosonde reports from Berlin, Germany. At Heiss Island a temperature increase of 85°C is deduced at an altitude of 32 km, preceded by a record wind of nearly 400 kt (at 39 km), verified through thermal wind computations. Extraordinary vertical motions reaching 60 cm sec?1 are calculated from the thermodynamic equation. The warming is shown to have been similar to major warmings of the lower stratosphere in several respects, including the occurrence of 1) high winds related to pressure-gradient intensification several days before the peak temperature and 2) upward vertical motion in high latitudes in response to strong horizontal advection. Rocket soundings extending to the mesopause indicate the occurrence of warming to a height of at least 70 km. The mesospheric data further suggest that prior to warming events the upper polar mesosphere is characteristically cold, in accord with radiative calculations for winter. However, the mesospheric analysis is hampered by poor sampling, and an improved program of observation is needed to clarify the full structure of ?stratospheric? warmings.