Low latitude 2-day planetary wave impact on austral polar mesopause temperatures: revealed by a January diminution in PMSE above Davis, Antarctica

A new characteristic of the austral summer polar mesopause as revealed by ground-based radar and satellite temperature measurements is reported, that is linked to inter-annual variability of the low-latitude easterly wind jet. Four consecutive seasons of polar mesosphere summer echoes (PMSE) and mesosphere temperature observations above Davis, Antarctica (68.6 degrees S) show a mid-January diminution in PMSE occurrence rate that coincides with a minor mesopause warming of several degrees. Spectral analyses of PMSE, Aura Microwave Limb Sounder (MLS) temperatures and radar meridional winds show the presence of similar to 4-5-day planetary waves (PWs) throughout the austral summer in the polar upper mesosphere together with enhanced similar to 2-day PW activity from mid-January to mid-February. Analysis of MLS temperatures show that the similar to 2-day PWs have zonal wavenumbers (S) with both westward (S = similar to 2, similar to 3) and eastward (S = +2, +3) components. Although displaying some inter-annual variation in the peak onset time, the mid-January mesopause warming coincides with a weakening of the equatorward meridional wind above Davis and enhancement of low-latitude 2-day PW activity. Citation: Morris, R. J., A. R. Klekociuk, and D. A. Holdsworth (2009), Low latitude 2-day planetary wave impact on austral polar mesopause temperatures: revealed by a January diminution in PMSE above Davis, Antarctica, Geophys. Res. Lett., 36, L11807, doi:10.1029/2009GL037817.