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First Direct Observational Evidence for Secondary Gravity Waves Generated by Mountain Waves over the Andes
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  • Masaru Kogure,
  • Jia Yue,
  • Takuji Nakamura,
  • Lars Hoffmann,
  • Sharon L. Vadas,
  • Yoshihiro Tomikawa,
  • Mitsumu K. Ejiri,
  • Diego Janches
Masaru Kogure
Kyushu University

Corresponding Author:[email protected]

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Jia Yue
Goddard Space Flight Center
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Takuji Nakamura
National Institute of Polar Research
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Lars Hoffmann
Forschungszentrum Jülich
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Sharon L. Vadas
NorthWest Research Associates, Inc.
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Yoshihiro Tomikawa
National Institute of Polar Research
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Mitsumu K. Ejiri
National Institute of Polar Research
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Diego Janches
National Aeronautics and Space Administration (NASA)
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A mountain wave with a significant brightness temperature amplitude and ~500 km horizontal wavelength was observedover the Southern Andes on 24–25 July 2017 in AIRS/Aqua satellite data. In the MERRA-2 reanalysis data, a mesoscale vortex-like pattern appeared to the west of the Andes at 2 km, and the wind flowed over the Andes. VIIRS/Suomi-NPP did not detect the mountain waves; however, it observed concentric ring-like waves in the nightglow emissions at ~87 km with ~100 km wavelengths on the same night over and leeward of the Southern Andes. A ray tracing analysis showed that the mountain waves propagated to the east of the Andes, where concentric ring-like waves appeared while mountain waves broke. Therefore, the concentric ring-like waves were likely secondary gravity waves generated by momentum deposition that accompanied mountain wave breaking. These results provide the first direct evidence for secondary gravity waves generated by momentum deposition.
16 Sep 2020Published in Geophysical Research Letters volume 47 issue 17. 10.1029/2020GL088845