Ionospheric effects in the Doppler frequency shift on the storm sudden sommencement

  The geophysical manifestations of 6 strong G3-G5 magnetic storms were analyzed for the period from December 2023 to October 2024. Each storm is characterized by a Storm Sudden Commencement (SSC), which appears under a sharply increased speed of the solar wind  and dense accelerated solar wind streams interact with the Earth's magnetosphere. The ionospheric response to an SSC event is investigated. Solar wind parameters are obtained from NASA's Advanced Composition Explorer (ACE) satellite, which is located approximately 1.5 million kilometers from Earth, near the Lagrange point L1 in the Sun-Earth system. An induction magnetometer IMS-008 with a sampling frequency of 66 Hz was used in this work. Measurements of the XYZ components of the geomagnetic field were made using a LEMI-008 fluxgate magnetometer of the geomagnetic observatory of the Institute of Ionosphere (https://ionos.kz/geomagnetic-observatory), geographic coordinates (43.10ºN; 76.57ºE). Doppler measurements of the signal reflected from the ionosphere were carried out on inclined radio paths with a sampling frequency of 25 Hz, using signals from radio broadcast transmitters located in China, Kyrgyzstan and Kuwait [1].

The impulse impact of interplanetary shock waves on the magnetosphere and the processes of interaction of the magnetosphere with the ionosphere are traced. A Doppler ionosonde has determined the beginning of the ionosphere's reaction to the pulsed action of interplanetary shock waves. The delay in the appearance of disturbances in the DFS (time constant of the ionospheric reaction) averaged 45-107 seconds. The high temporal resolution and sensitivity of the induction magnetometer IMS-008 for recording the sudden onset of magnetic storms is demonstrated, and an advanced response relative to the response recorded by the fluxgate magnetometer LEMI-008 is revealed.

1. Salikhov, N.; Shepetov, A.;Pak, G.; Saveliev, V.; Nurakynov, S.; Ryabov, V.; Zhukov, V.  A PLL Based Doppler Method Using an SDR-Receiver for Investigation of Seismogenic and Man-Made Disturbances in the Ionosphere. Geosciences 2024, 14, 192. https:// doi.org/10.3390/geosciences14070192

This research was funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan, grant number AP19678127 ”Development of the methods for geophysical fields monitoring in the lithosphere-atmosphere-ionosphere-magnetosphere system in a seismically hazardous region of Northern Tien Shan”.