Auroral studies with a chain of meridian‐scanning photometers: 1. Observations of proton and electron aurora in magnetospheric substorms

Abstract

A chain of sensitive meridian‐scanning photometers and all‐sky cameras was operated during two new moon periods in 1978 to observe auroral proton and electron precipitation patterns with high time resolution (30 s). The latitude range was from 59.5° to 73.3° N (invariant) with Churchill, Manitoba, as the northernmost of three stations. Intensity plots on a latitude‐time scale were prepared, and from these, 14 auroral substorms over a broad range of local times were selected for analysis. Data from a widely spaced array of auroral zone and low‐latitude magnetometers were used to determine substorm onset times and longitude sectors. Representative meridian intensity profiles of Hβλ4861 and OI λ5577 were then assembled as a function of invariant latitude and local magnetic time to obtain a synthetic model of a typical substorm. It is found that the data are better ordered when the local magnetic time scale for the individual substorms is shifted so as to place the substorm origins at local magnetic midnight. While the results are in general agreement with earlier observations, the quantitative nature of the present data base leads to a more objective proton substorm model.