Role of thermospheric winds on the generation of F-region irregularities over Indonesian sector during the solar minimum year 2020.

Analysis of ionosonde observations over Chumpon (10.7°N, 99.4°E, 3.3° Mag. Lat.) and Kototabang (0.2° S, 100.3° E, 10° S Mag. Lat.) during the low solar activity year 2020 reveals that the occurrence of post-sunset spread-F maximises during winter (November-February), whereas that of post-midnight spread-F maximises during summer (May-August). The thermospheric winds observed by the Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) on board the Ionospheric Connection Explorer (ICON) satellite over the Indonesian longitudes (95°E-115°E) are investigated to determine their impact on the generation of spread-F. The thermospheric winds at equatorial and low latitudes (10°N) are strongly eastward (> 50 m/s) around post-sunset hours (∼19:00 LST) in winter and equinox. The strong eastward wind is present only around midnight hours (after 22:00 LST) in summer. However, the zonal wind does not appear to contribute to the generation of plasma bubbles. The ICON-MIGHTI meridional wind at low latitude (10°N) is observed to be equatorward throughout the day during summer. Compared to the post-sunset hours, the intensity of trans -equatorial wind is stronger on the windward side (60–70 m/s) than on the leeward side (10–20 m/s) during midnight hours. The component of the equatorward meridional wind along the magnetic field lines can lift the F-layer to higher heights on the windward side leading to a net decrease in the field line-integrated Pedersen conductivity thereby increasing the growth rate of the Rayleigh Taylor instability that can result in the generation of post-midnight spread F. [ABSTRACT FROM AUTHOR]