Plasma Temperatures in the Topside Ionosphere

Abstract:

In the topside ionosphere during the daytime, the thermal electrons are directly heated by photoelectron fluxes from the local and conjugate hemispheres. The heat is lost primarily through collisions with the ions, with the loss rate being dependent on the ion mass. Likewise the ions are heated by collisions with the electrons and lost primarily through conduction to lower altitudes. In this work we examine the ion and electron temperatures in the topside ionosphere during daytime observed by the DMSP F15 satellite. The variations of electron and ion temperature with plasma density and composition indicate how the heat is exchanged between the different constituent ions and role played by solar zenith angle and solar activity. We find that the electron and ion temperatures depend upon the topside ionospheric composition which determines the extent to which H⁺ acts as an intermediary for heat exchange between the electrons and the O⁺. The SAMI2 model is utilized to calculate the temperature difference between the O⁺ and H⁺ ions that is inferred from the observations.