Abstract:
An integrated campaign “Suryagrahan-2019” with multi-institutional support was conducted by launching a series of radiosondes/ozonesondes over 6-different locations in India along with the operation of ST/MST radars and launching of RH-200 rockets during the annular solar eclipse of 26 December 2019. We present the eclipse-induced changes in the thermal structure, dynamics and trace gases in the lower and middle atmosphere. One of the novel findings is the formation of three step-like isothermal structures in the lower stratosphere with a layer height of 1.4, 2.5, and 4 km, which is attributed to the adiabatic compression and expansion of the air parcel. These structures have both warming and cooling effect of the order of ±6 K. A significant increase of ozone by 20% in post-eclipse scenario between 29 and 32 km is observed over Cochin. Strong downdrafts of ∼−0.25 m s −1 are observed between 12 and 16 km during the eclipse event, which is attributed to the atmospheric compression due to the sudden cooling during the eclipse event. Due to the changes in thermal structure, the atmospheric circulation changes are observed in the meridional wind. During the maximum obscuration, there is a sudden decrease in near-surface and boundary layer ozone by 12–15 ppbv. The present study reiterates that the eclipse-induced perturbations depend on the local time of the eclipse event and place of observations. It is envisaged that the results discussed in the study will improve our understanding of the eclipse induced perturbations in the Earth's atmosphere.
