Seasonal and latitudinal variations of air density in the mesosphere (30 to 80 kilometers)

Abstract

Abstract : The results of a statistical analysis of mesosphere data, together with four other soundings are given. The lowest densities are found in winter in arctic latitudes. At 65 km, the mean winter density is 60% of the mean summer density. The seasonal variation in mid-latitudes is relatively small, amounting to less than 5% below 50 km, with a maximum of 13% at 66 km. The latitudinal gradient is greatest in winter, and greatest at around 65 km. The gradient is directed northward from mid-latitudes, in the AMOUNT OF 2% per degree of latitude (at 65 km), and there is a smaller gradient directed equatorward from mid-latitudes. At mid-latitudes, the standard deviation of density varies from 4% (of the mean density) at 30 km to about 20% near 60 km, remaining nearly constant up to the top of the mesosphere. In arctic latitudes, the standard deviation varies from 11% at 30 km to a maximum of about 40% near 60 km, decreasing to about 30% at 80 km.