Response of the High-latitude Upper Mesosphere to Energetic Electron Precipitation

We carried out a statistical study on the effects of strong geomagnetic activity on the mesopause over the auroral region from 2002 to 2018. When the auroral electrojet index increased significantly, the energetic electron precipitation from the Medium Energy Proton and Electron Detector was enhanced by several multiples of 10 for the 55 degrees-70 degrees geomagnetic latitude band. The temperatures measured by the Sounding of the Atmosphere using Broadband Emission Radiometry instrument increased immediately in the mesopause region, together with a descent of the mesopause of about 0.5-2 km. Due to the depth that the precipitation can affect, we conclude that the mesopause is mainly influenced by electrons in the energy range 30-100 keV. The maximum temperature increment at 95 km can reach 4 K and the delay of the response can be up to 1 day. In general, we find that the temperatures significantly respond to the electron precipitation at as low as 93 km, within the mesopause region in most of a year.