Energy Input and Dissipation in the Ionosphere-Thermosphere (IT) System

Abstract:

AFRL

The long-held view of energy input and dissipation into the IT system says that the primary region in which dynamic and electrodynamic processes occur is the auroral zone. Recent observations have indicated that this may not be completely true. The dominant form of energy input to the IT system is electromagnetic, and not particle precipitation. Poynting flux measured on DMSP spacecraft during storms indicates that energy can be deposited at all local times (LTs) in both hemispheres at polar latitudes as well as in the auroral zones. One major effect of this energy input is Joule heating of the ionosphere and thermosphere. We have analyzed the ion temperature measured by DMSP for a number of storms. During storm main phases, the increase in ion temperature maximizes at polar latitudes. We have processed neutral densities from CHAMP, GRACE and GOCE which show localized Joule heating at extremely high latitudes in both hemispheres. We conclude that energy input and dissipation occurs in the polar cap as well as in the auroral zones. Our results require a re-examination of the processes by which energy can enter the IT system, as well as where and how energy is transferred to ions and neutrals