Mesosphere and Lower Thermosphere Temperature Responses to the May 2024 Mother's Day Storm

The storm-time temperature difference with respect to its quiet-time expectation (ΔT) in the mesosphere and lower thermosphere were studied during the extreme storms on 2024 Mother's Day and 2003 Halloween Day. The storm-time ΔT were determined by performing daily zonal running mean on the temperature profiles in the ascending and descending nodes separately. The storm-time ΔT had peak values of ≥25 K and extended downward to ∼100 km globally. Above 105 km, the global mean ΔT had values of ≥20 K in the early morning and of ≥15 K in the late afternoon during storm-time. At high latitudes, the storm-time ΔT was larger in the late afternoon than in the early morning. This is opposite to that at middle and low latitudes. Adiabatic warming/cooling caused by the heating-induced circulation changes outside of the auroral oval is likely responsible for the local time and latitude dependence of the storm-time ΔT.