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We report,the first high spatial resolution measurements of the annual variation of temperatures in the stratosphere and lower mesosphere obtained using lidar from a site near the Antarctic Circle. The observations were made using a zenith-oriented Rayleigh backscatter lidar on 77 days between February 2001 and March 2002 at Davis, Antarctica (68.6°S, 78.0°E). Daily average temperature profiles with 1km vertical resolution were retrieved using the standard Rayleigh inversion method. The lidar temperatures were validated through comparison with a variety of observational and model data which included radiosonde measurements, satellite profiles, and meterorological analyses at various altitudes between approximately 30km (the top of the stratospheric aerosol layer) and 60km. Comparison of the lidar temperatures with the MSISE-90 model revealed some significant differences. Between the stratopause and the upper limit of the measurements (65km), monthly average temperatures from March to June and during September were warmer than MSISE-90 by up to 20K. Comparison with previous lidar measurements at South Pole (Pan et al., 2002) and McMurdo (Di Donfrancesco et al., 1996) suggests that stratopause region temperatures near midwinter over Antarctica may be more uniform than predicted by the MSIS model. Between 30km altitude and the stratopause, average temperatures from December to March and during July were cooler than the model (by an average of 5K). The October and November averages were warmer than the model (by up to 15K) below approximately 40km, and cooler than the model (by up to 10K) towards the stratopause. Temperature fluctuations associated with planetary wave activity were observed during late autumn (10K amplitude) and spring (up to 25K amplitude). The spring anomaly coincided with the development of a dominant zonal wavenumber 1 disturbance in the mid-stratosphere temperature field that was quasi-stationary in longitude near Davis. This feature appeared to have a vertical wavelength on the order of 50–60km. [Copyright &y& Elsevier]

Abstract: Polar Mesosphere Summer Echoes (PMSE) were detected above the high-latitude station Davis, Antarctica (68.6°S) using a 55MHz atmospheric radar during the 2003–2004 austral summer. In this paper, we examine the characteristics of southern hemisphere PMSE events observed during the interval 19 November to 16 February 2004. Coincident satellite-SABER temperature measurements and ground-VHF radar backscatter observations revealed that PMSE existed for mesosphere temperatures in the range ∼124.4–134.7K. An examination of the horizontal wind field using collocated VHF and MF radar measurements showed that PMSE also occurred during conditions of westward zonal winds and equatorward meridional winds. A remarkable correlation was evident between the onset (end) of the austral summer PMSE season and equatorward (poleward) flowing meridional mesospheric winds observed for the 19 November 2003 (16 February 2004), respectively. We present evidence of a semidiurnal influence of the meridional and zonal tides on the occurrence, intensity, and altitude of PMSE events. The effects of tidal, gravity and planetary waves on PMSE events are also considered. [Copyright &y& Elsevier]