Estimated relations between main gas components during strong and moderate geomagnetic disturbances over a period of decreasing and minimum solar activity

The method previously put forward by the authors has been exploited to estimate the main gas components [O]/[N 2] and [O 2]/[O] at the atmospheric reference level (120 km) during strong and moderate geomagnetic disturbances over a period of decreasing and minimum solar activity (2003-2005). Experimental data on electron density obtained by a digisonde at the station Irkutsk (52° N, 104° E) during the said period have been used. These estimations significantly differ from the corresponding values obtained with the MSIS-86 model. This confirms the necessity of correcting the model to describe disturbed conditions of the Irkutsk region.