Evaluation of electron and ion densities in the middle atmosphere from rocket-borne blunt probes

Abstract

Detailed consideration has been given to the determination of electron number densities from conductivity data gathered by rocket-borne blunt probes in the middle atmosphere, and the intercomparison of these electron densities with those derived from other diagnostics. A definition of the difficulty of electron density determination from rocket-borne probes is presented. Also, the procedures for the determination of ion densities from blunt probe data in the middle atmosphere are critically evaluated. General aspects of particle collection by supersonic probes are compared with those of subsonic probes. It is noted that strong (× 10) compression regions will form in front of supersonic probes at altitudes up to 100 km, and the altered electron attachment rates could significantly affect indicated electron and negative ion concentrations. A summary of new analysis for determining electron densities from negative conductivities taken with a subsonic blunt probe is presented and the analysis is applied to data on several days where intercomparisons are possible. Blunt probe data from 31 January 1972 and 5 December 1972 (WI), † † (WI) Wallops Island, VA (38°N, 76°W). and 2 October 1975 and 29 September 1977 (WSMR) ‡ are reduced to predict electron density profiles. In the region of intercomparison, there is general agreement in the electron density predictions. The indications of electron density at altitudes below 70 km are new, and predict a region of moderately enhanced densities down to 45 km.