Comment on angeo-2022-15

Abstract

The paper deals with the variations in the Doppler spectra and in the relative amplitudes of the signals observed at oblique incidence over the People’s Republic of China (PRC) during the partial solar eclipse of 5–6 January 2019 and on reference days. The observations were made using the multifrequency multiple path radio system for sounding the ionosphere at oblique incidence. The receiver system is located at the Harbin Engineering University campus, PRC, and 14 HF broadcasting station transmitters are used for taking measurements along the Lintong/Pucheng to Harbin, Hwaseong to Harbin, Chiba/Nagara to Harbin, Hailar/Nanmen to Harbin, Beijing to Harbin (three paths), Goyang to Harbin, Ulaanbaatar/Khonkhor to Harbin, Yakutsk to Harbin (two paths), Shijiazhuang to Harbin, Hohhot to Harbin, and Yamata to Harbin radio wave propagation paths. The specific feature of this partial solar eclipse was that it occurred during local time morning with a geomagnetic disturbance (Kp = 3–) in the background. The response of the ionosphere to the solar eclipse have been inferred from temporal variations in the Doppler spectra, the Doppler shift, and in the signal relative amplitude. The partial solar eclipse was found to be associated by Doppler spectrum broadening, up to ±1.5 Hz, alternating sign Doppler shift variations, up to ±0.5 Hz, in the main ray, and by quasi-periodic Doppler shift changes. The relative amplitude of electron density disturbances in the 15 min period atmospheric gravity wave field and in the 4–5 min period infrasound wave field is estimated to be 1.6–2.4 % and 0.2–0.3 %, respectively. The estimates of a maximum decrease in the electron density are in agreement with the observations.