Thermospheric damping response to sheath-enhanced geospace storms
Article first published online: 15 APR 2013
©2013. American Geophysical Union. All Rights Reserved.
Geophysical Research Letters
Volume 40, Issue 7, pages 1263–1267, 16 April 2013
How to Cite
2013), Thermospheric damping response to sheath-enhanced geospace storms, Geophys. Res. Lett., 40, 1263–1267, doi:10.1002/grl.50197., , , , , , , and (
- Issue published online: 27 APR 2013
- Article first published online: 15 APR 2013
- Accepted manuscript online: 28 JAN 2013 05:01PM EST
- Manuscript Accepted: 24 JAN 2013
- Manuscript Revised: 22 JAN 2013
- Manuscript Received: 20 NOV 2012
- M-I-T coupling;
- auroral particles
 We show evidence that solar wind density enhancements and pressure pulses can lead to intense low-energy particle precipitation and an associated, but unexpected, damping of thermospheric density response. Ground-based indices, used as proxies for thermospheric energy deposition, fail to capture these interactions in forecasting algorithms. Superposed epoch comparison of a group of poorly specified neutral density storms suggests an event-chain of (1) multi-hour, pre-storm solar wind density enhancement, followed by solar wind dynamic pressure pulses that trigger excess low-energy particle flux to the upper atmosphere; (2) enhanced production of thermospheric Nitric Oxide (NO) by precipitating particles and storm heating; (3) NO infrared cooling and damping of the thermosphere; and (4) mis-forecast of neutral density. In the control storms, these features are absent or muted. We discuss the roles of solar wind pre-conditioning and solar cycle dependency in the problem storms. These problem neutral-density storms reveal an element of “geo-effectiveness” that highlights competition between hydrodynamic aspects of the solar wind and other interplanetary drivers.