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

Abstract

We consider the ionospheric response at heights of 120–220 km to geomagnetic disturbances in October and November 2003, which caused a strongly pronounced decrease in the electron content in the noted height range. For this disturbance period, using a technique of the authors, midday variations of the relative content of atomic and molecular oxygen at a height of 120 km were estimated. This estimation was performed with the help of ionospheric measurements (by a digital ionosonde) conducted at the Institute of Solar-Terrestrial Physics of the Russian Academy of Sciences from 2003 to 2006. Comparison of these values with similar values from the mass spectrometer-incoherent scatter (MSIS)-86 model showed that our estimates during disturbance days were two times less. This study continues research into the field of using ionospheric measurements to estimate the relative gas composition of the thermosphere at heights below the maximum of the F2 layer.