D-region positive and negative ion concentration and mobilities during the February 1979 eclipse

Abstract

Positive and negative ion concentrations and mobilities have been obtained from an analysis of Gerdien condenser measurements on rocket flights, A10.802-1 and A1O.802-2, during and after eclipse totality. The aerodynamic instrument calibration and the data analysis techniques are discussed. The measured concentrations on both flights were about 10 4 cm −3 in the altitude range, 45–80 km. These high concentrations at very low altitudes suggest that a relativistic electron precipitation event was occurring during the measurements. The ion concentration measurements along with electron density measurements made by other groups during the eclipse were used to calculate the negative ion: electron ratio, and the lumped parameter detachment rate. These results are compared with prior measurements during eclipse and solar proton events and code results. The analysis shows that the present negative ion model is incomplete. The reduced mobilities ( K 0) were also determined. The mobility distributions show that the heavy ions of both the positive and negative species dominate from 45 to 70 km. The data reveal more massive ions at higher al titudes than at low altitudes (1000 vs 300 a.m.u.) as well as possible evidence for multiply charged ions below about 60 km.