The role of the QBO in the inter-hemispheric coupling of summer mesospheric temperatures
1Norwegian University of Science and Technology, Trondheim, Norway
2Chalmers University of Technology, Göteborg, Sweden
3Stockholm University, Stockholm, Sweden
4University of Cantabria, Santander, Spain
Abstract. Inter-hemispheric coupling between the polar summer mesosphere and planetary-wave activity in the extra-tropical winter stratosphere has recently been inferred using Polar Mesospheric Cloud (PMC) properties as a proxy for mesospheric temperature (Karlsson et al., 2007). Here we confirm these results using a ten-year time series of July mesospheric temperatures near 60° N derived from the hydroxyl (OH) nightglow. In addition, we show that the time-lagged correlation between these summer mesospheric temperatures and the ECMWF winter stratospheric temperatures displays a strong Quasi-Biennial Oscillation (QBO). The sign and phase of the correlation is consistent with the QBO modulation of the extra-tropical stratospheric dynamics in the Southern Hemisphere via the Holton-Tan mechanism (Holton and Tan, 1980). This lends strength to the identification of synoptic and planetary waves as the driver of the inter-hemispheric coupling, and results in a strong QBO modulation of the polar summer mesospheric temperatures.