Abstract
AbstractThe radar volume reflectivity and turbulent kinetic energy dissipation rate in the Antarctic mesosphere were estimated from the polar mesosphere winter echoes (PMWE) recorded using a vertical beam of the PANSY radar, a Mesosphere‐Stratosphere‐Troposphere radar at Syowa Station (69°S, 40°E), over a period of 4 years. The observed radar volume reflectivity exhibits a lognormal distribution in the range of 2 × 10−18 to 5 × 10−15 m−1 for a height region of 55–82 km. The turbulent energy dissipation rate estimated from the spectral widths of the PMWE ranges from 10−4 to 100 m2 s−3. From monthly histograms of the turbulent energy dissipation rate for a fixed solar zenith angle (SZA) and height, it was found that the summer‐to‐winter transition of the turbulent energy dissipation rate occurs in March, while the winter‐to‐summer transition occurs in September. This seasonal variation agrees well with that of gravity wave activity, suggesting that the turbulence in the mesosphere is likely caused by gravity wave breaking.
Highlights
Polar mesosphere winter echoes (PMWEs) are VHF radar echoes observed in the 55–80 km height region in both hemispheres (Czechowsky et al, 1989; Ecklund & Balsley, 1981; Morris et al, 2011)
The present study examines the seasonal variation of mesospheric radar volume reflectivity and turbulence parameters estimated from polar mesosphere winter echoes (PMWE) observations recorded over a 4‐year period by the Program of the Antarctic Syowa Mesosphere‐Stratosphere‐Troposphere/Incoherent Scatter (PANSY) radar, a VHF
The minimum volume reflectivity detectable by the PANSY radar is an order of 10−18 m−1, which roughly corresponds to the cutoff in the left tail of the distribution
Summary
The turbulent kinetic energy dissipation rates in the Antarctic mesosphere from PMWE spectral widths are estimated.
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