Abstract
The changes in the ionosphere during geomagnetic disturbances is one of the prominent Space Weather effects on the near-Earth environment. The character of these changes can differ significantly at different regions on the Earth. We studied ionospheric response to five geomagnetic storms of March 2012, using data of Total Electron Content (TEC) and F2-layer critical frequency (foF2) along the meridian of 70° W in the Northern Hemisphere. There are few ionosondes along this longitudinal sector: in Thule, Sondrestrom, Millstone Hill and Puerto Rico. The lacking foF2 values between the ionosondes were determined by using the experimental latitudinal dependences of the equivalent ionospheric slab thickness and TEC values. During geomagnetic storms, the following features were characteristic: (a) two-hours (or longer in one case) delay of the ionospheric response to disturbances, (b) the more prominent mid-latitude trough and (c) the sharper border of the EIA northern crest. During four storms of 7–17 March, the general tendency was the transition from negative disturbances at high latitudes to intense positive disturbances at low latitudes. During the fifth storm, the negative ionospheric disturbance controlled by O/N2 change was masked by the overall prolonged electron density increase during 21–31 March. The multiple correlation analysis revealed the latitudinal dependence of dominant Space Weather parameters’ impacts on foF2.
Highlights
Space Weather conditions influence on the ionosphere, whose state defines the reliability of operation of different technological systems [1,2]
Ionospheric response to geomagnetic disturbances depends on the latitude and can be estimated with two main ionospheric parameters: critical frequency of the F2-layer and vertical Total Electron
Τ was estimated according to Equations (1)–(4), for a further reconstruction of frequency of the F2-layer (foF2) values
Summary
Space Weather conditions influence on the ionosphere, whose state defines the reliability of operation of different technological systems [1,2]. Ionospheric response to geomagnetic disturbances depends on the latitude and can be estimated with two main ionospheric parameters: critical frequency of the F2-layer (foF2) and vertical Total Electron. Both foF2 and TEC characterize the state of the ionosphere and have common features, but are not interchangeable, as it was shown, for example, in References [3,4,5]. For a comprehensive diagnostics of the ionosphere, it is preferable to have information about the changes of both parameters. The networks of ionosondes that perform direct foF2 measurements have less spatial coverage if compared to the networks of Global Navigation Satellite System (GNSS) receivers that provide raw data for TEC calculation.
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