Midlatitude neutral thermosphere density and temperature measurements

Abstract

An ensemble of six independent aeronomy experiments was launched from Wallops Island, Virginia on March 2, 1966, at 1300 EST.Two Bayard-Alpert ionization gauges, similar to those on the Explorer 17 satellite, were flown to measure neutral atmospheric density and temperature.However, the Bayard-Alpert gauges appear to have pumped or adsorbed virtually all of the atmospheric atomic oxygen (0) to which they were exposed, and thus measured only the molecular nitrogen (N2), molecular oxygen (02), and helium (He), in the region from 150 km to'450 km altitude.Deduced N2 number densities (1.9 x 10 lo, 3.5 x lo7, and 1.9 x lo5 particles ~m -~ at 150lun, 300km, and 450km respectively) agree with nearly simultaneous measurements obtained from a neutral mass spectrometer and a solar EUV extinction experiment.Previous N2 measurements from Thermosphere Probes, obtained under similar solar and geomagnetic conditions, agree well with these data.An exospheric temperature near 875K was determined for the 1300 hour local solar time atmosphere.The 0 pumping, presumably by initially oxygen free surfaces in the Bayard-Alpert gauges, is discussed and contrasted to the oxygen processed surfaces in the magnetron gauges flown on the Explorer 17 and 32 satellites, which apparently did not pump the ambient 0.