SA34A-01
Stratospheric Sudden Warming Effects on the Upper Thermosphere
Wednesday, 16 December 2015: 16:00
2016 (Moscone West)
Yosuke Yamazaki1, Michael J Kosch1,2 and John T Emmert3, (1)University of Lancaster, Physics, Lancaster, United Kingdom, (2)South African National Space Agency, Hermanus, South Africa, (3)U.S. Naval Research Laboratory, Space Science Division, Washington, DC, United States
Abstract:
It has been controversial whether a stratospheric sudden warming (SSW) event has any measurable impact on the upper thermosphere. In this study, we use long-term records of the global average thermospheric total mass density derived from satellite orbital decay data during 1967-2013. This enables, for the first time, a statistical investigation of the thermospheric density response to SSW events. A superposed epoch analysis of 37 SSW events reveals a density reduction of 3-7% at 250-575 km around the time of polar vortex weakening. The temperature perturbation is estimated to be -7.0 K at 400 km. We suggest enhanced wave forcing from the lower atmosphere as a possible cause for the density reduction observed during SSWs.
