Statistical Comparison of the CIR- and CME- Induced Geomagnetic Activity Effects on Lower Thermospheric Temperature

Abstract:

During geomagnetic storms, high-latitude electric fields and auroral precipitation are greatly enhanced resulting in a large amount of energy and momentum being deposited into the coupled mesosphere-thermosphere-ionosphere system, which changes the neutral temperature, composition, winds, and ionospheric electron densities. A recent study of the storm effects on neutral temperature during the 2013 St. Patrick’s storm with satellite data shows that the temperature enhancement occurs at the altitudes lower than 100 km in both hemispheres. In this paper, we conduct statistical comparisons of storm time temperature response to the coronal mass ejection (CME) versus corotating interaction region (CIR) storms from 2003 to 2013 using the temperature measurements from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. We illustrate that storm time warming occurs in the MLT region at middle to high latitudes in both hemispheres in response to both the CME and CIR storms; the temperature enhancement is larger and extended to lower altitudes during the CME storms, whereas the storm time warming lasts longer during CIR storms. These results demonstrate that although the CIR storms have smaller maximum energy input compared to the CME storms, their effects on the MLT region are just as significant due to their long durations, and understanding their behavior and impact is of great importance.