Geospace storm effects on August 5-6, 2019

Geospace storms are the synergistically interacting magnetic storms, ionospheric storms, atmospheric storms, and the storms in an electric field of magnetospheric, ionospheric, and atmospheric origins. Geospace storms are very diverse, and no two of them behave exactly the same. Therefore, studying the effects of each new storm becomes an urgent task for us. Such research will reveal both the general laws and individual characteristics of storm processes. The purpose of this paper is to present general information about the geospace storm, the results of the analysis of features of magnetic and ionospheric storms. To analyze the magnetic environment, we used the measurement results of magnetic field fluctuations in the range from 1 s to 1000 s, performed at the Magnetometric Observatory of V. N. Karazin Kharkiv National University, and variations of three components of the geomagnetic field, performed at the Low-frequency observatory of the IRA NASU. We analyzed the ionospheric environment using multi-frequency multi-path measurements performed at Harbin Engineering University (China) and also the data of ionosonde. The main results of the work are as follows. An increase in the main parameters of the solar wind on August 5, 2019, led to a geospace storm, which was mainly observed on August 5 and 6, 2019. The main phase of the magnetic storm took place on August 5, 2019, from 06:00 a.m. to 08:30 a.m. The recovery phase lasted at no less than 4 days. The magnetic storm shows significant variations of all components of the geomagnetic field, and there is an increase by order of magnitude of the oscillations’ level of the geomagnetic field in the range from 400 s to 950 s. During the ionospheric storm, significant disturbances occurred in the F region of the ionosphere. The E-region of the ionosphere remained weakly perturbed. The ionospheric storm has severely affected the Doppler spectra of radio waves in the 5 – 10 MHz frequency range. The Doppler spectra are significantly broadened, and the Doppler frequency shift and its quasi-periodic change with a period of 20–40 minutes and a duration of 120–240 minutes have taken place. The quasi-periodic variations of the Doppler frequency shift are due to quasi-periodic variations in the electron concentration, and the amplitude of their relative perturbations varied from 3% to 16%. On one of these paths, the amplitude of the Doppler frequency shift reached 0.7 Hz. And in this case, the amplitude of the relative perturbations of the electron concentration could reach 80 - 90%. In addition, the ionospheric storm little affected the signal amplitude on most radio paths.