Characteristics of a stable auroral red arc event

Abstract

An intense (∼2.2 kR) stable auroral red (SAR) arc was observed on October 23, 1981 by the Dynamics Explorer 1 and 2 satellites as well as by a ground‐based scanning photometer operated by the Pacific Northwest Laboratory at Battelle Observatory in Richland, Washington, providing a unique series of nearly simultaneous measurements. The DE satellites provided in‐situ electric field and particle measurements at altitudes of about 850 km and 6000 km along approximately the same flux tube as well as in‐situ electron temperature and density measurements at 850 km for this red arc. These measurements along with ground‐based determination of arc position and intensity allowed a comprehensive analysis of the arc. Calculations of the electron heating rate and temperature which result from the observed precipitating electron flux at the arc location indicate that the heat required to establish the necessary and observed ionospheric electron temperatures is provided by the extrapolated low energy electron particle flux. The available data does not provide sufficient information to uniquely determine the energy source for this flux.