Thermospheric molecular oxygen

Thermospheric studies to date have relied heavily on model values of O2 concentration, which are in turn indirectly derived. This paper reports the results of a comparison of a large data base of directly measured O2 concentrations with the concentrations obtained from the MSIS model atmosphere. For concentrations of 10 billion/cu cm the direct measurements are larger than the model values by up to 50%. For concentrations of 100 million/cu cm the measured values are in agreement with the model to within 10%. A comparison is made of the computed major thermospheric species by using both the MSIS and the measured O2 concentrations. The impact is largest in the odd nitrogen species NO, N(S-4), and N(+), where the difference in concentration can be as much as 70%, and also on O2(+).