Atmos. Chem. Phys. Discuss., 12, 26173-26205, 2012
© Author(s) 2012. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
High resolution VHF radar measurements of tropopause structure and variability at Davis, Antarctica (69° S, 78° E)
S. P. Alexander, D. J. Murphy, and A. R. Klekociuk
Australian Antarctic Division, Kingston, Tasmania, Australia

Abstract. Two years of VHF radar echo power observations are used to examine the structure and variability of the tropopause at Davis, Antarctica. Co-located radiosonde and ozonesonde launches provide data with which to calculate the thermal (lapse-rate) and chemical tropopauses at Davis. The dynamically-controlled radar tropopause can be used as a definition of the Antarctic tropopause throughout the year under all meteorological conditions. During the extended summer period of December–April (DJFMA) inclusive, radar tropopauses are (0.2 ± 0.4) km lower than co-located radiosonde thermal tropopauses and during the extended winter period of June–October (JJASO) inclusive, the radar tropopauses are (0.8 ± 1.0) km lower. The radar and ozone tropopauses both show a decrease in altitude under increasingly strong cyclonic conditions. During strong JJASO cyclonic conditions, there are large (several km) differences between radiosonde lapse-rate tropopause altitudes and radar tropopause altitudes. However, the radar tropopause altitude closely corresponds to the altitude of the 2 PVU surface (where 1 PVU = 106 m2 s−1 K kg−1) for both cyclonic and anticyclonic conditions. The monthly mean occurrence frequency of tropopause folds is investigated using the radar tropopause and is about 1 per month during DJFMA and about 3 per month during JJASO. The power spectrum of the Davis radar tropopause altitude indicates its influence by the passage of inertio-gravity waves. The higher power spectral density during JJASO also indicates an increase in gravity wave activity during this time.

Citation: Alexander, S. P., Murphy, D. J., and Klekociuk, A. R.: High resolution VHF radar measurements of tropopause structure and variability at Davis, Antarctica (69° S, 78° E), Atmos. Chem. Phys. Discuss., 12, 26173-26205, doi:10.5194/acpd-12-26173-2012, 2012.
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