THE IMPORTANCE OF NEW CHEMICAL SOURCES FOR THE HOT OXYGEN GEOCORONA

Exothermic reactions involving metastable neutrals and ions were recen tly proposed as sources of hot oxygen atoms in addition to the classic al O-2(+) and NO+ dissociative recombination. The Boltzmann equations for thermal and nonthermal populations of O atoms are solved with a Mo nte Carlo stochastic simulation method. It is shown that the calculate d energy distribution functions of O atoms are significantly in nonequ ilibrium in the transition region between the thermosphere and the exo sphere. It is found that the inclusion of additional sources leads to stronger dis turbances of the energy distribution function and, as a c onsequence, increases the nonthermal fraction of hot O atoms. The vari ation of the vertical distribution of hot O between solar maximum and minimum conditions is also evaluated and shows good agreement with the available experimental evidence.