Ionosphere, D and E regions

Abstract

The most notable contributions to our understanding of the D and E regions of the ionosphere made during the period from 1967 to 1971 have come through the following developments: the determination of the ionic composition of the ionosphere through the use of mass spectrometers flown on sounding rockets; the measurement of electron density profiles under a wide range of conditions, at various latitudes, hours, and seasons, during eclipses and winter anomalies with probes in combination with radio receivers for propagation measurements flown on sounding rockets; the measurement of the concentration of several important minor species in the mesosphere and lower thermosphere, such as NO, O2(a1 Δg), and Na; the explosive outburst of laboratory measurements of rate constants for reactions between electrons, ions, and molecules of atmospheric interest. These developments have been accompanied by some significant successes and some significant failures in theoretical studies attempting to reconcile the measurements.

Monte Carlo simulation ofDregion sampling

“…The importance of possible contamination by the payload surface and disturbance by the merged shock layer is difficult to estimate owing to the multitude of processes that could occur and the incomplete knowledge of the reaction cross sections and the actual D region composition, although this situation is improving rapidly, and more detailed calculations may soon be feasible. There are certainly fragile species there, such as positive ions com-bined with water molecules [Narcisi and Roth, 1970;Narcisi et al, 1972;Thomas, 1971] and other molecules [Keller and Beyer, 1971], negative ions and their hydrates [Donahue, 1971;Narcisi et d., 1971Narcisi et d., , 1972Arnold et al, 1971], and probably neutral cluster molecules. The actual abundance of these species could easily be masked by reactions occurring in the nonequilibrium situation of D region sampling.…”