Solar cycle variation of thermospheric NO: A model sensitivity study.

The one-dimensional numerical model, which simulates diurnal and solar cycle variations of nitric oxide (NO), is examined on whether it may reproduce the NO profiles observed with rockets at various phases of solar activity. The model result is highly dependent on the adopted rate coefficients of the reactions N(4S)+O2→NO+O and N(2D)+O→N(4S)+O. The laboratory data on these rate coefficients seem to be incompatible with the observed variation in NO profiles. The variation in the thermospheric NO may affect the thermal structure of the thermosphere. A calculation of the thermospheric temperature shows that the observed NO profiles modify the thermopause temperature by -200K at solar maximum, and that they are consistent with the variation of the thermospheric temperature.