Estimates of plasma wave amplitudes in the turbulent high‐latitude E region using electron temperature measurements

Abstract

The excitation of unstable waves by large perpendicular currents in the high‐latitude E region is a well‐known phenomenon and has been documented experimentally. It has been found recently that the unstable waves heat the E region plasma to produce easily detectable effects on the electron temperature (increases up to 1000°K have been measured). The present paper offers a refinement of previous plasma heating rate calculations by including finite Larmor radius effects in the heating rate expressions and by selecting values for the parallel wave vectors that are more appropriate for the E region plasma. As was done previously, we use a quasi‐linear theory to estimate the amount of heating going into the electron gas. Since it is based on measured electron temperature values, the amount of heating is the same as found previously. However, the heating rate is now described as a function of the saturation amplitude of the unstable waves. As a result, we are able to estimate the level of turbulence in the plasma from a measurement of the electron temperature. By using Chatanika radar measurements, we infer the presence of mean density fluctuation levels of the order of 2–4% when perpendicular currents are well above threshold values.