ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Springer Verlag Göttingen, Germany 10.1007/s00585-997-1422-2 The effect of vibrationally excited nitrogen on the low-latitude ionosphere Jenkins B. 1 Bailey G. J. 1 Ennis A. E. 1 Moffett R. J. 1 Upper Atmosphere Modelling Group, School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK 30 11 1997 15 11 1422 1428 Copyright: © 1997 B. Jenkins et al. 1997 © European Geosciences Union 1997 This article is available from https://angeo.copernicus.org/articles/15/1422/1997/angeo-15-1422-1997.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/15/1422/1997/angeo-15-1422-1997.pdf

The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O<sup>+</sup> ions are converted to NO<sup>+</sup> ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest effect being at the location of the equatorial trough.