Reaction of region F1 of the ionosphere to disturbances in October and November 2003 (analysis from Irkutsk digisonde measurements)

The ionosphere response at heights of 120-220 km to geomagnetic disturbances in October and November 2003 caused strongly pronounced decreases in electron density within this range of heights is considered. For this disturbed period, using the method suggested by authors midday variations of the relative content of atomic and molecular oxygen at a height of 120 km were estimated. The estimation was made using the ionosphere measurements carried out in ISTP SB RAS in 2003-2006 with digital ionosonde. The comparison of the values with those from MSIS-86 model showed that our estimations during days of disturbances were two times less. The study continues research into the field of using ionosphere measurements for estimating the thermosphere gas composition at heights below the maximum of F2 layer.