Banded electrostatic emissions observed by the CRRES Plasma Wave Experiment

Abstract

A survey of banded electrostatic emissions observed by the Plasma Wave Experiment on the recently launched spacecraft “CRRES” is presented with an emphasis on the relation of the frequency of the highest intensity waves to multiples of the local electron cyclotron frequency. Because one of its goals is a first look at the CRRES high‐frequency electric field data, all the data discussed in this paper were taken in the first 8 months after launch. During this time, emissions are detected chiefly in the postmidnight quadrant of the magnetosphere between L=3.5 and L=7. We confirm that high‐intensity emissions are confined to within a few degrees of the magnetic equator. The emissions presented here are all measured below the electron plasma frequency, and we find they generally favor the upper part of the gyroharmonic interval. When ECH emissions are detected both near and far from the equator on the same orbit, it is generally true that a broad band of the same relative frequency emissions are excited in both locations. The difference is that near the equator, a few frequency channels measure much higher intensities. When we compare with one model for convective growth, we find that the observed spectra may not be consistent with predicted ones.