Measurements of atmospheric composition near 400 km
Document ID: 347
Philbrick, C. Russell1
McIsaac, J R1
1 Air Force Cambridge Research Laboratories, Bedford, Massachusetts, USA
Presented: Space Research XII - Akademie-Verlag
Berlin, 1972
Abstract
Measurements near 400 km altitude of atmospheric composition and density on the circular, polar-orbiting OV3-6 satellite have shown marked departure from atmospheric models. The results have shown that the molecular species constitute a much larger percentage of the atmosphere near local sunset than near local noon. Near local sunset (from observations made in December 1967), the N2 to O concentration ratio is a few percent and near local noon (March 1968), the ratio is a few tenths of 1 % or less. The results would indicate that the temperature maximum is near local sunset; however, the measurements indicate a broad density maximum between 1400 and 1600 hours. The results show that diffusive equilibrium models must be reconsidered with regard to dynamics and heating sources of the atmosphere. In addition, the measurements exhibit a significant minimum in the density of each of the species in a large percentage of the orbits near equatorial latitudes.