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

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Mesospheric/lower thermospheric winds and tides at low, middle, and high latitudes
during the CAWSES Global Tidal Campaign observations in 2005-2010
Singer Werner 1 , Batista P.P. 2 , Oberheide Jens 3 , Grieger Norbert 1 , Nakamura Takuji 4 , Hoffmann
Hoffmann 1 , Buriti R.A. 5 , Riggin Dennis 6 , Mitchell N.J. 7 , Ramkumar Geetha 8 , Schmidt Hauke 9
1 Leibniz Institute of Atmospheric Physics, Kuehlungsborn, Germany, 2 National Space Research
Institute-INPE, Sao Jose dos Campos, SP, Brazil, 3 Physics Department, University of Wuppertal,
Wuppertal, Germany, 4 National Institute of Polar Research, Tokyo, Japan, 5 Universidade Federal
de Campina Grande, Paraiba, Brazil, 6 Northwest Research Associates, Boulder, CO, USA, 7 Centre
for Space, Atmospheric & Oceanic Science, University of Bath, Bath, UK, 8 Space Physics
Laboratory, Vikram Sarabhai Space Centre, Trivandrum, India, 9 Max-Planck-Institute of
Meteorology, Hamburg, Germany
Winds at mesospheric/lower thermospheric altitudes between 80 and 100 km and
temperatures around 90 km are derived from all-sky meteor radar observations at latitudes
between 22°S and 69°N. Wind tides are determined using 4-d, 10-d, and 60-d composite days.
The seasonal variability of mean winds, diurnal, semi-diurnal, and ter-diurnal tides is
presented. In addition, the seasonal variation of the migrating tides at 22°S has been derived
using radar observations at three sites well separated in longitude (Learmonth, 114°E;
Rarotonga, 200°E; Cachoeira Paulista, 315°E). The radar observations of the diurnal tidal
signatures at 22°S are characterised by a strong longitudinal variability in good agreement
with the results of the global circulation model HAMMONIA (HAMburg Model of the
Neutral and Ionized Atmosphere). Comparisons are made between the tidal wind fields
obtained from meteor radar observations and by superposing the tidal components from
satellite analyses (TIMED). Both data sets are in good agreement and show that satellite and
ground based observations are consistent with each other. The depicted strong longitudinal
variability at 22°S is also seen in the reconstructed tidal wind fields of the HAMMONIA
model.
The dynamical response of the MLT region on solar activity phenomena is presented for
severe solar proton events in October 2003, January 2005, and December 2006 with a reversal
of the meridional winds down to about 75 km and a moderate reduction of zonal winds.
Particular attention is devoted to the events in 2003 and 2005 in respect to enhanced
turbulence related with changes of the background wind field and gravity wave propagation.