scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Coupling between the stratosphere, mesosphere and ionosphere during the major
stratospheric warming of January 2009
Shepherd Marianna 1 , Alexander Simon 2 , Cho Young-Min 1 , Shepherd Gordon 1
1 Centre for Research in Earth and Space Science, York University, 2 Australian Antarctic Division
Temperature and electron density data from the COSMIC GPS-RO satellite constellation together with
temperatures from the MLS-Aura satellite in the Arctic are used to study the response of the
mesosphere/ lower thermosphere (MLT) and ionosphere to changes in the stratosphere during the
major sudden stratospheric warming (SSW) event from January 2009. Ground-based observations of
hydroxyl and O2(0,1) Atmospheric band airglow emission rates and rotational temperatures are also
considered. In the low to mid-stratosphere (15-40 km) eastward wave activity was significantly
reduced during the early part of the 2008-09 winter and immediately prior to the major SSW. A
westward wave with zonal wavenumber two, with distinct peaks at 22 km and 35 km and period of
~16-24 days, as well as a stationary wave two were associated with the 2009 major SSW. In the MLT
region at the time of the SSW the airglow emissions and the temperatures appear depleted and
decreased, followed by an enhancement of the airglow emission rates during the SSW recovery phase,
while the temperatures returned to their pre-event state. The analysis has shown atomic oxygen
depletion by a factor of ~ 5 during the SSW which lasted about 5 days. During the SSW recovery
phase the atomic oxygen volume mixing ratio giving rise to the observed O2 (0,1) airglow emission
rates increased by a factor of 3.5 from its pre-SSW level and 17 times from the peak of the SSW.
Perturbations in the OH and O2(0,1) airglow layers with periods of 4-, 6-, 8- and 12-h indicate nonlinear
interaction between zonally symmetric semidiurnal tides and planetary waves. These
perturbations are followed into the ionosphere and compared with the planetary wave signatures
observed in the stratosphere and mesosphere examining the dynamical coupling between these
atmospheric regions.