Variation of electron loss rate due to recombination processes in the upper ionospheric D-region plasma after a solar X-ray flare: a study case

In this paper, we study electron loss rate resulting from recombination processes in the upper part of the ionospheric D-region after being influenced by a solar X-ray flare activity. We analyse the altitude and time dependences of the governing plasma electron loss rate and its spatial and temporal derivatives. The presented numerical modelling is based on data recorded through remote sensing of the lower ionosphere utilizing the reflected very low-frequency radio signal emitted by the DHO transmitter in Germany and received in Belgrade, Serbia. Ionospheric parameters were calculated by a procedure based on a comparison of the observed changes in the signal amplitude and phase with their values modelled by the Long-Wave Propagation Capability numerical model. We consider the time period after influence of the solar X-ray flare of the class C8.8 occurred on 5 May, 2010 between 11:37 UT and 11:58 UT with the maximum at 11:52 UT. Due to the same tendencies of the D-region plasma parameters variation, the obtained conclusions can be extended and generalized to any solar X-ray flare. Graphic Abstract)