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Extreme vertical drafts in the polar summer mesosphere: A mesospheric super bore?
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  • Jorge L. Chau,
  • Raffaele Marino,
  • Fabio Feraco,
  • Juan Miguel Urco Cordero,
  • Gerd Baumgarten,
  • Franz-Josef Luebken,
  • Wayne K. Hocking,
  • Carsten Schult,
  • Toralf Renkwitz,
  • Ralph Latteck
Jorge L. Chau
Leibniz-Institute of Atmospheric Physics at the University of Rostock

Corresponding Author:[email protected]

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Raffaele Marino
Laboratoire de Mecanique des Fluides et d'Acoustique
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Fabio Feraco
Laboratoire de Mecanique des Fluides et d'Acoustique
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Juan Miguel Urco Cordero
University of Illinois at Urbana Champaign
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Gerd Baumgarten
Leibniz-Institute of Atmospheric Physics at the Rostock University
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Franz-Josef Luebken
Leibniz-Institute of Atmospheric Physics (LG)
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Wayne K. Hocking
University of Western Ontario
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Carsten Schult
Leibniz Institute of Atmospheric Physics at the University of Rostock
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Toralf Renkwitz
Leibniz-Institute of Atmospheric Physics (LG)
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Ralph Latteck
Leibniz-Institute of Atmospheric Physics (LG)
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Abstract

The polar summer mesosphere is the Earth’s coldest region, allowing the formation of mesospheric ice clouds. These clouds produce strong polar mesospheric summer echoes (PMSE) that are used as tracers of mesospheric dynamics. Here we report the first observations of extreme vertical drafts (±50~m/s) in the mesosphere obtained from PMSE, characterized by velocities more than five standard deviations larger than the observed vertical wind variability. Using aperture synthesis radar imaging, the observed PMSE morphology resembles mesospheric bores, i.e., narrow along propagation (3–4~km) and elongated (>10~km) transverse to propagation direction. Additionally, our event presents a large vertical extent (± 3–4~km), resembling a “super bore”. Powerful vertical drafts, intermittent in space and time, emerge also in direct numerical simulations of stratified flows, predicting non-Gaussian statistics of vertical velocities. This evidence suggests that our event, and perhaps previous bores, might result from the interplay of gravity waves and turbulent motions.