Quasi-10 d wave activity in the southern high-latitude mesosphere and lower thermosphere (MLT) region and its relation to large-scale instability and gravity wave drag

• DOI: 10.5194/acp-24-3559-2024
• Publication Date: 2024-03-21T08:54:33Z
• Authors: Wonseok Lee; In-Sun Song; Byeong-Gwon Song; Yong Ha Kim
• Keywords: Wavenumber; Solstice; Airglow; Microwave Limb Sounder

Abstract. Seasonal variation in westward-propagating quasi-10 d waves (Q10DWs) the mesosphere and lower thermosphere of Southern Hemisphere (SH) high-latitude regions is investigated using meteor radar (MR) observations for period 2012–2016 Specified Dynamics (SD) version Whole Atmosphere Community Climate Model (WACCM). The phase difference meridional winds measured by two MRs located Antarctica gives observational estimates amplitude Q10DW with zonal wavenumber 1 (W1). observed Q10DW-W1 large around equinoxes. In order to elucidate variations its possible amplification mechanism, we carry out SD-WACCM experiments nudged towards MERRA-2 reanalysis from surface up ∼ 60 km (EXP60) 75 (EXP75). Results EXP75 indicate that can be amplified barotropic and/or baroclinic instability middle 60–70° S. EXP60 experiment, it was also found instability, but too compared MR observations. large-scale SH summer stronger than Microwave Limb Sounder larger related vertical polar mesospheric association gravity wave parameterization (GWP). Given uncertainties inherent GWP, these results suggest models spuriously generate traveling planetary such as Q10DW, especially summer, due excessively strong mesosphere.