L-dependent energetic electron precipitation and mid-latitudeDregion ion pair production profiles

Abstract

Energetic electron precipitation at middle latitudes is at times intense enough to contribute significantly to the ionization of the ionospheric D region. The observed fluxes are often latitude dependent. This L‐dependent precipitation may give rise to a latitude variation in the free electron density at L region heights. Specifically, low‐altitude satellite measurements show that the electron environment on L shells which connect to the atmosphere at D region heights above the ionospheric research stations operated by the Ionosphere Research Laboratory at University Park, Pennsylvania, and the Communications Research Centre at Ottawa, Canada, may be very different. Although the present study is not very extensive and does not cover all seasons, it shows that for a number of cases, precipitating electrons were observed over Ottawa but not over University Park. The resulting difference in D region ionization rates due to the additional ionization source at Ottawa may be important in light of the apparent conflict between D region density profiles derived at the two stations. Owing to lack of relevant information, it was assumed in an earlier intercomparison of electron density profiles measured simultaneously at University Park and Ottawa that no such difference existed. Our data show that it may be important to have simultaneous knowledge also of the electron precipitation versus latitude in order to resolve questions relating to the accuracy of the wave interaction and partial reflection techniques used at the University Park and Ottawa sites, respectively, for obtaining the electron density profile.

Ionospheric Profiles for Predicting Nighttime VLF/LF Propagation, Determination of an Effective (Exponential) Model for Use in Design and Deployment of Resources for Communication and Navigation

“…If the location and extent of particle precipitation could be determined on each of the nights for which two profiles were required, the calculations could be made with a latitudinally varying ionospheric model. Lacking such detailed data, the NOSC ten-frequency sounder data collected on flights 6 and 7 (fig 14) have been analyzed with an empricially derived latitude variation of h' that is consistent with the satellite data (ref 18,19). This is the only path so analyzed because it is essentially along a magnetic meridian and is therefore an ideal one from which to derive the h' latitude variation.…”