Convection Effect in the Surface Atmosphere of Solar Eclipses of March 20, 2015, and June 10, 2021

Abstract

The parameters of geophysical fields and numerous parameters of the Earth–atmosphere–ionosphere–magnetosphere system significantly change during a solar eclipse (SE). In particular, the planet surface temperature decreases, the convection and turbulent processes slow down, and the air temperature near the ground reduces. The inhomogeneous structure of the surface air layer notably changes, and the role of temperature fluctuations in this layer and, consequently, the role of fluctuations in the air refractive index shrink. The purposes of this work are to analyze the observations of solar limb quivering during the two last partial SE that took place near the city of Kharkiv on March 20, 2015, and June 10, 2021, and the estimates of the statistical parameters governing air convection. The SE effects in the surface air layer were observed with the optical AFR-2 chromospheric-photospheric telescope at the V.N. Karazin Kharkiv National University Astronomical Observatory 70 km to southeast of Kharkiv. The quivering of the solar limb was measured on the days of SEs (March 20, 2015, and June 10, 2021) and on the reference days in order to determine the basic parameters of the atmospheric convection. The variations in the convection parameters are qualitatively similar to variations in illumination of the Earth’s surface and in the air temperature in the surface air layer. In the summertime, all convection parameters are a factor of ~2 higher than in the springtime. The SE effect on atmospheric convection was considerably weaker on June 10, 2021, than on March 20, 2015, because of insignificant magnitude of the former SE (0.11 vs. 0.54) and the clouds which screened the solar disk, which appreciably suppressed atmospheric convection. The comparative study of convection during seven SEs in 1999–2021 has shown that the magnitude of the effect strongly depends on the season, local time, cloud thickness, the tropospheric weather, and the magnitude of a solar eclipse.