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Abstract We present an analysis of planetary‐scale oscillations during sudden stratospheric warming (SSW) events based on data obtained from a meteor radar located at Mohe (MH, 53.5°N, 122.3°E), the Aura satellite and Modern‐Era Retrospective analysis for Research and Applications, Version 2 data (MERRA2). The planetary‐scale oscillations in the mesosphere and lower thermosphere (MLT) region during eight SSW events from 2012 to 2019 have been statistically investigated. Our analysis reveals that the enhancement or the generation of westward propagating quasi 16‐day oscillation with wavenumber 1 (W1) is a common feature during SSWs over MH. A strong enhancement of the quasi 4‐day oscillation during the 2018/2019 SSW is captured by both radar and satellite observations. The amplified quasi 4‐day oscillation has a period of ~4.3 days in both meridional and zonal winds and with a wavenumber of W2 in the zonal component. Using the meteor radar and MERRA2 data, the vertical structure of the quasi 4‐day oscillation from the stratosphere to the lower thermosphere is derived. The upward propagating feature of the quasi 4‐day oscillation in the meridional component indicates that the oscillation is very likely generated in the lower mesosphere. The mesospheric zonal wind reversal after an elevated stratopause event is observed during the SSW, which results in a negative meridional gradient of the quasi‐geostrophic potential vorticity. Our results not only reveal that the amplified quasi 4‐day oscillation in the MLT region is associated with the 2018/2019 SSW but also suggest that the amplification is originally generated around 60 km due to barotropic/baroclinic instability and propagates upward to MLT region.
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First Observational Evidence for the Role of Polar Vortex Strength in Modulating the Activity of Planetary Waves in the MLT Region
Abstract Based on the meteor winds measured at Mohe (MH; 53.5°N, 122.3°E) and the reanalysis data, we investigate the variations of planetary waves in the mesosphere and lower thermosphere (MLT) region during the 2019/2020 Arctic winter. Four stratospheric polar warmings, including two sudden stratospheric warmings (SSWs), are observed from November 2019 to March 2020. Quasi‐10‐day waves (Q10DWs) are found to be enhanced following three of these warmings in the zonal winds in the MLT region over MH, but unusually weak after the SSW in February 2020. The trigger mechanisms of the enhanced Q10DWs are investigated and the reason for the unusually weak Q10DWs in February is revealed. Upward propagations and in situ generations of Q10DWs are both limited during the February SSW. Our analysis indicates that Q10DWs in the MLT region in February 2020 are largely inhibited by the extremely strong polar vortex and a lack of mesospheric instability.
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- Award ID(s):
- 1744033
- PAR ID:
- 10367529
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 49
- Issue:
- 3
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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