Rocket Observations of the Structure of the Mesosphere

Abstract

Pressure, density, temperature and wind measurements in the upper stratosphere and in the mesosphere resulted from a total of 53 rocket-grenade soundings conducted during the period 1960?1965. Most of the soundings were performed over North America (Wallops Island, 38N and Churchill, 59N) but some results were also obtained over the tropical Atlantic (Ascension Island, 8S) and over Northern Europe (Kronogard, 66N). Soundings were carried out simultaneously at these sites and were coordinated with soundings measing similar parameters over other areas of the globe. Seasonal and latitudinal variations in the structure and circulation of this region of the atmosphere were derived from the results. Stratosphere temperatures vary with season and latitude in accordance with solar heating rates and with established circulation models. Temperatures above 65 km are substantially warmer in winter than in summer. Average seasonal temperature differences are about 40K at 80 km. They are very pronounced at midlatitudes (Wallops Island) and become even more extreme at high latitudes where in summer mesopause temperatures as low as 140K were observed. Maximum stratopause temperatures were observed during late winter-early summer. At Wallops Island these maxima of about 280K coincided with the period of transition from winter to summer circulation. Temperature profiles for all seasons at all sites intersect between 60 and 65 km at a temperature range of 230 to 240K. The strong westerly flow in winter shows two pronounced cores, one persistent throughout the winter just above the stratopause, the other somewhat weaker and less persistent near 75 km. Deviations from the zonal flow indicate the existence of meteorological circulation cells on a synoptic scale with the average meridional flaw at Churchill strongly from the north during both summer and winter and at Wallops Island somewhat weaker from the south during the winter.