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Vibrationally excited molecular nitrogen plays an important role in the F region ionosphere. It increases the loss rate of the dominant ion O+ and reduces the electron concentration in the F region of the ionosphere. In this paper, we use a theoretical numerical ionospheric model to study the effect of on the ionosphere during four time periods, each including both geomagnetically quiet and storm disturbed periods, with considering and without considering the role of in the numerical ionospheric model. The four periods simulated are (1) May 14–20, 1997; (2) May 1–10, 1998; (3) June 11–15, 1990 and (4) April 6–10, 2000. By Comparing the simulated results with the observational ones, it is shown that has a significant effect on the ionosphere during high solar activity years. While for the low solar activity years, the role played by is very limited, much less than that in high solar activity years. It is also shown that for the high solar activity years, when constructing an ionospheric physical model, one must take into account not only for geomagnetically disturbed period but also for quiet period. Moreover, it is found that the effect of on the ionospheric electron density distribution depends on the vibrational temperature Tv adopted. When taking the value of Tn as Tv(where Tn is the background neutral temperature) the simulated result, compared with the observation one, is not as good as that when Tv is calculated by the steady state analytical solution. Moreover, our simulation results show that, for high solar activity years, the effect of on the distribution of ionospheric electron concentration is to reduce the electron density for the altitudes above 150km, while its effect on the electron density below 150km is very small. The F2 layer peak height hmF2 is not affected very much by . |
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