Variability in planetary, gravity and tidal waves in the MLT in response to sudden stratospheric warming events: radar observations, model simulations and satellite observations
Y.J. Orsolini1,4, P. J. Espy2,4, R. E. Hibbins2,4, V. Limpasuvan3
1 Norwegian Institute for Air Research (NILU), Kjeller, Norway
2 Norwegian University of Science and Technology (NTNU), Trondheim, Norway3
3 Coastal Carolina University, Conway, SC, USA
4 Birkeland Centre for Space Science, University of Bergen, Norway
We use the Super Dual Auroral Radar Network (SuperDARN) in the northern hemisphere and the SkiYMET all-sky meteor radar located at Trondheim, Norway (63.4°N,10.5°E), in conjunction with model simulations and satellite observations to study planetary, gravity and tidal waves in the mesosphere and lower thermosphere (MLT) region. The SuperDARN radar network spans a limited range of latitudes around 60°N over nearly 180° of longitude, allowing the different zonal wavenumbers to be distinguished. A westward-propagating planetary wave-1, likely generated in-situ, is observed to emerge at the time of the elevated stratopause events, in a composite of 13 stratospheric sudden warmings events (SSW) between 1995 and 2013. A robust enhancement of the migrating semidiurnal tide is also observed about two weeks after the SSW onset. The annual climatological cycle in both migrating and non-migrating components of the semi-diurnal tide is derived from the meridional wind (~95 km), over a 20-year period. The Trondheim meteor radar is also used to study tides and gravity waves following the SSW events. We also compare these radar observations with simulations performed with the WACCM model and with satellite observations by the SABER satellite instrument.