Diurnal variation of winter F region ionosphere for solar minimum at both Zhongshan Station, Antarctica, and Svalbard Station, Arctic

Abstract

Diurnal variation features of wintertime F2 peak electron density (NmF2) representative for solar minimum at both Zhongshan station, Antarctica, and Svalbard station are compared and analyzed. Both stations are located around cusp latitude and are almost on the same geomagnetic meridian plane in both hemispheres. For quiet time period, typical NmF2 diurnal variation features at Svalbard station show double peaks with a decrease of NmF2 around magnetic local noon (∼UT + 3 h); NmF2 diurnal variation at Zhongshan station shows one major peak around magnetic local noon (∼UT + 1.75 h), followed by a sharp decrease of NmF2, and a subpeak around 1500 UT. Simulation results of the high-latitude ionospheres in both hemispheres agree well with observations at both stations. It is found that the major difference of NmF2 variation between both stations can be explained by the unique location of each station relative to the sunlit demarcation line during the day. For quiet time period, photoionization from lower latitude contributes to the major peak of NmF2 in the diurnal variation at Zhongshan station, while the interaction between horizontal convection and auroral precipitation is the main cause for NmF2 variation at Svalbard station. For active time period, both stations show the increase of NmF2 due to transportation of higher plasma density from lower latitudes on the dayside with the expansion of the polar cap and the additional ionization from soft-precipitating electrons.