Plasmaspheric plumes: CRRES observations

CRRES plasma wave receiver density data were used to study the distribution and properties of dense plasmaspheric-like plasma observed outside the plasmapause. Our study indicates that outer plasmaspheric structure, often called plasmaspheric plumes, blobs, or detached plasma regions exist at all local times under all levels of geomagnetic activity. Of the 549 CRRES orbits that had at least one clearly defined plasmapause, 201 (or 36.6%) had plasmaspheric-like density structures at higher L shells than the plasmapause. Most of the occurrence of plasmaspheric-like plasma observed by CRRES was in the noon-to-dusk sector and was observed following moderate geomagnetic activity.