Activities of Small-Scale Gravity Waves in the Upper Mesosphere Observed From Meteor Radar at King Sejong Station, Antarctica (62.22°S, 58.78°W) and Their Potential Sources

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Song, B. G., Song, I. S., Chun, H. Y., Lee, C., Kam, H., Kim, Y. H., Kang, M. J., Hindley, N. P., Mitchell, N. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Antarctica; gravity waves; meteor radar; MLT; upper mesosphere; /dk/atira/pure/subjectarea/asjc/1900/1902; name=Atmospheric Science; /dk/atira/pure/subjectarea/asjc/1900/1908; name=Geophysics; /dk/atira/pure/subjectarea/asjc/1900/1901; name=Earth and Planetary Sciences (miscellaneous); /dk/atira/pure/subjectarea/asjc/1900/1912; name=Space and Planetary Science; King Sejong Station; Antarc*
• Online Access: https://researchportal.bath.ac.uk/en/publications/88022f7f-057e-4761-b748-9a553f4a1c7f; https://doi.org/10.1029/2021JD034528; https://purehost.bath.ac.uk/ws/files/287682891/JGR_Atmospheres_2021_Song_Activities_of_Small_Scale_Gravity_Waves_in_the_Upper_Mesosphere_Observed_From_Meteor_Radar.pdf; http://www.scopus.com/inward/record.url?scp=85106686564&partnerID=8YFLogxK

Gravity wave (GW) activities in the upper mesosphere (80–100 km) and their potential sources are investigated using meteor radar observations at King Sejong Station, Antarctica (KSS; 62.22°S, 58.78°W) during recent 14 years (2007–2020). GW activities are estimated by horizontal wind variances of small-scale GWs (periods <2 h, horizontal wavelength <400 km, or vertical wavelength <3–5 km). The wind variances show clear semiannual variations with maxima at solstices, and annual variations are also seen above z = 90 km. The deseasonalized wind variances at z = 96.8 km have a statistically significant periodicity of ∼11 years that can be associated with solar cycle variations. Three major potential GW sources in the lower atmosphere are examined. Orography is a potential source of GWs in winter and autumn, when the basic-state wind is westerly from the surface up to the mesosphere. The residual of the nonlinear balance equation (RNBE) at 5 hPa, a diagnostic of the GWs associated with jet stream, is the largest in winter and has a secondary maximum in spring. The correlation between the observed GWs and RNBE is significant in equinoxes, while correlation is low in winter. Deep convection in storm tracks is a potential source in autumn and winter. Secondary GWs generated in the mesosphere can also be observed in the upper mesosphere. Ray-tracing analysis for airglow images observed at KSS indicates that secondary GWs are mostly generated in winter mesosphere, which may be associated with the breaking of orographic GWs.