Summer-day auroral-zone atmospheric-structure measurements from 100 to 210 kilometers

Abstract

The density and pressure of the atmosphere from 100 to 210 kilometers above Fort Churchill, Manitoba, Canada, were determined from the IGY NN3.13F Aerobee-Hi rocket flight on July 29, 1957, at 4:00 p.m., CST. Two magnetic cold-cathode ionization gages were used to measure pressure and pressure changes on the side of the rolling rocket. Excellent agreement was obtained (a) between both gages throughout flight, and (b) between ascent and descent measurements. Measured pressures in the region from 100 to 120 kilometers were corrected for a residual gas pressure of approximately 2×10−5 mm Hg. An ambient pressure of 10−4 mm Hg was obtained at 107 kilometers. The derived pressure of 4×10−6 mm Hg at 210 kilometers is an order of magnitude greater than the corresponding 1951 values measured at the White Sands Proving Ground, New Mexico. Densities were measured from 125 to 210 kilometers. The density value of 6×10−7 gm/m3 at 210 kilometers is five times greater than the 1951 measurement, while at 140 kilometers the difference is a factor of two. Scale heights (RT/Mg) were derived from the measured pressure and density data vs altitude, using the hydrostatic equation. The scale-height value obtained at 210 kilometers was 95 kilometers, and the scale-height gradient from 190 to 210 kilometers was 0.1 km/km.