Daytime optical investigation of the equatorial mesopause energetics in the context of equatorial MLTI coupling: recent results

Abstract

First experimental evidences for the mesopause energetic changes in context of (a) counter electrojet (CEJ); (b) solar flare; and (c) solar eclipse in the equatorial mesopause region using a daytime optical photometer are presented. The photometer has been operated in a scanning mode to probe the thermosphere and mesopause regions simultaneously in north-south direction over Trivandrum (8.5°N; 77°E; dip lat. 0.5°N). The striking features observed are (i) enhancement in the wave activity as seen in the mesopause temperature, during the eclipse, (ii) cooling of the mesopause during the equatorial electrojet (EEJ) reversal and (iii) decrease in mesopause temperature during a flare. These observations are discussed to highlight the vertical coupling of the mesopause with thermosphere-ionosphere region, mainly through neutral dynamics.