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First Direct Observational Evidence for Secondary Gravity Waves Generated by Mountain Waves Over the Andes
Author(s) -
Kogure Masaru,
Yue Jia,
Nakamura Takuji,
Hoffmann Lars,
Vadas Sharon L.,
Tomikawa Yoshihiro,
Ejiri Mitsumu K.,
Janches Diego
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl088845
Subject(s) - geology , gravity wave , wavelength , atmospheric infrared sounder , geophysics , gravitational wave , remote sensing , climatology , troposphere , physics , astronomy , optoelectronics
A mountain wave with a significant brightness temperature amplitude and ~500 km horizontal wavelength was observed over the Andes on 24–25 July 2017 in Atmospheric Infrared Sounder (AIRS)/Aqua satellite data. In the Modern‐Era Retrospective Analysis for Research and Applications, version 2 (MERRA‐2), reanalysis data, the intense eastward wind flowed over the Andes. Visible/Infrared Imaging Radiometer Suite (VIIRS)/Suomi‐NPP (National Polar‐orbiting Partnership) 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 above a region of mountain wave breaking. Therefore, the concentric ring‐like waves were likely secondary 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.