Modeling the behavior of hot oxygen ions

Abstract. Photochemical processes in the upper atmosphere are known to create significant amounts of energetic oxygen atoms or “hot O”. In this research we simulate the effects of ionized hot oxygen, hot O+, on the ionosphere. We find that hot O+ is not able to maintain a temperature substan-tially above the ambient ion temperature at most altitudes, the exception being around the F-region ion density peak. However, the thermalization of hot O+, due to Coulomb col-lisions, represents an important heating process for the ambi-ent ions. A time-dependent, fluid-kinetic model of the iono-sphere (TRANSCAR) is used to self-consistently simulate hot O+ by considering it to be a separate species from O+. A Maxwellian neutral hot O population having characteristics consistent with current knowledge is added to TRANSCAR. The production of the hot O+ is then computed by consid-ering ion charge exchange with the neutral hot O population that we have assumed. Loss of hot O+ results from these charge exchange reactions and from reactions with molecu-lar atoms