Extreme Enhancements of Electron Temperature in Low Latitude Topside Ionosphere During the October 2016 Storm

We use the in-situ observations of DMSP and SWARM satellites to report the changes of the topside ionospheric electron temperature during the October 2016 storm. Electron temperature in the afternoon sector dramatically increases in low latitudes in the recovery phase of the storm. Furthermore, the temperature enhancements have an obvious dependence on longitude and are mainly centralized around 100 degrees-150 degrees E in different satellite observations. The temperature enhancements attain more than 2,000 K at 840 km and 1,500 K at 450 km around the magnetic equator. The decrease in the electron-ion collision cooling rate, resulting from the lessened topside electron density, could not fully explain the temperature enhancement. At the same time, the electron densities in crests of the equatorial ionization anomaly are suppressed drastically at 100 degrees-150 degrees E, which cause a less heat conduction effect from the equatorial topside ionosphere to low altitudes via magnetic field lines and heat the topside ionospheric electron temperature. Further analysis indicates that dayside westward disturbance dynamo electric field presents a significant longitude structure and is a primary driver for the topside ionospheric temperature enhancement during the storm.

Automated summary

This study reports the changes in topside ionospheric electron temperature during the October 2016 storm using in-situ observations from DMSP and SWARM satellites. The results show a dramatic increase in electron temperature in the afternoon sector of low latitudes during the recovery phase of the storm. The temperature enhancements have a clear dependence on longitude, concentrated mainly around 100 degrees-150 degrees E.