Articles | Volume 18, issue 9
Atmos. Chem. Phys., 18, 6721–6732, 2018
https://doi.org/10.5194/acp-18-6721-2018

Special issue: Sources, propagation, dissipation and impact of gravity waves...

Atmos. Chem. Phys., 18, 6721–6732, 2018
https://doi.org/10.5194/acp-18-6721-2018

Research article 14 May 2018

Research article | 14 May 2018

Observation of Kelvin–Helmholtz instabilities and gravity waves in the summer mesopause above Andenes in Northern Norway

Gunter Stober1, Svenja Sommer1,a, Carsten Schult1, Ralph Latteck1, and Jorge L. Chau1 Gunter Stober et al.
  • 1Leibniz Institute of Atmospheric Physics at the University Rostock, Schlossstr. 6, 18225 Kühlungsborn, Germany
  • anow at: Fraunhofer Institute for High Frequency Physics and Radar Techniques, Fraunhoferstr. 20, 53343 Wachtberg, Germany

Abstract. We present observations obtained with the Middle Atmosphere Alomar Radar System (MAARSY) to investigate short-period wave-like features using polar mesospheric summer echoes (PMSEs) as a tracer for the neutral dynamics. We conducted a multibeam experiment including 67 different beam directions during a 9-day campaign in June 2013. We identified two Kelvin–Helmholtz instability (KHI) events from the signal morphology of PMSE. The MAARSY observations are complemented by collocated meteor radar wind data to determine the mesoscale gravity wave activity and the vertical structure of the wind field above the PMSE. The KHIs occurred in a strong shear flow with Richardson numbers Ri < 0.25. In addition, we observed 15 wave-like events in our MAARSY multibeam observations applying a sophisticated decomposition of the radial velocity measurements using volume velocity processing. We retrieved the horizontal wavelength, intrinsic frequency, propagation direction, and phase speed from the horizontally resolved wind variability for 15 events. These events showed horizontal wavelengths between 20 and 40 km, vertical wavelengths between 5 and 10 km, and rather high intrinsic phase speeds between 45 and 85 m s−1 with intrinsic periods of 5–10 min.

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