A Climatological Study of Short‐Period Gravity Waves and Ripples at Davis Station, Antarctica (68°S, 78°E), During the (Austral Winter February–October) Period 1999–2013. Issue 21 (3rd November 2017)

• Record Type: Journal Article
• Authors: Rourke, S.; Mulligan, F. J.; French, W. J. R.; Murphy, D. J.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 21(2017)
• Page Start: 11, 388
• Page End: 11, 404
• Publication Date: 2017-11-03
• Subjects: gravity waves -- mesopause -- Antarctica; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2017JD026998
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: A scanning radiometer deployed at Davis Station, Antarctica (68°S, 78°E), has been recording infrared (1.10–1.65 μm) images of a small region (24 km × 24 km) of the zenith night sky once per minute each austral winter night since February 1999. These images have been processed to extract information on the passage of gravity waves (GWs) (horizontal wavelength, λ h > 15 km) and ripples ( λ h ≤ 15 km) over the observing station. Phase speeds, periods, horizontal wavelengths, and predominant propagation directions have been deduced. Observed speeds were found to be highly correlated with horizontal wavelengths as has been reported in previous studies. Reverse ray tracing of the detected GWs only enabled us to identify four distinct groups. On average, only 15% of waves detected can be traced back to the troposphere, and a large proportion (~45%) were not successfully reverse traced substantially below the airglow layer. Two smaller groups were found to reach a termination condition for reverse ray tracing at altitudes near 50 km and 75 km. Of those that reached the termination altitude in the troposphere (10 km), most of the end points fell within a radius of 300 km of the station, with a very pronounced concentration of wave initiation to the northwest of the observing point. The predominant direction of propagation was southward, and they were observed throughout the year. Recent reports suggest the interaction of planetary waves with the background wind field as a potential source for these waves. Key Points: Gravity waves and ripples have been observed in winter mesopause OH* emissions at Davis Station, Antarctica, from 1999 to 2013 Intrinsic wave propagation directions exhibited meridional anisotropy as well as seasonal and altitude‐dependent zonal anisotropy Reverse ray tracing was used to identify the altitudinal and geographical origin of the observed waves