Upper-air density and temperature: some variations and an abrupt warming in the mesosphere

Measurements of upper-air densities and temperatures from 12 flights of the rocket-borne falling sphere are presented. They show little seasonal variation at 32° and 38° N, but large variations in a few winter days at 59°N. A low arctic density at 60 km results in a linear latitude density gradient of about 2 per cent per degree of latitude. Such a gradient was measured in a latitude survey. An abrupt warming at 45 km was detected at Fort Churchill in January 1958 and related to a warming of larger scope detected by balloons. The average air temperatures above Fort Churchill from January to March are warmer at 75 km and cooler from 50 to 30 km than at 32° to 38°N.