Stratospheric tropical warming event and its impact on the polar and tropical troposphere
Stratosphere–troposphere coupling is investigated in relation to middle atmospheric subtropical jet (MASTJ) variations in boreal winter. An exceptional strengthening of the MASTJ occurred in association with a sudden equatorward shift of the stratospheric polar night jet (PNJ) in early December 2011...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/615/2017/acp-17-615-2017.pdf |
| Summary: | Stratosphere–troposphere coupling is investigated in
relation to middle atmospheric subtropical jet (MASTJ) variations in boreal
winter. An exceptional strengthening of the MASTJ occurred in association
with a sudden equatorward shift of the stratospheric polar night jet (PNJ)
in early December 2011. This abrupt transformation of the MASTJ and PNJ had
no apparent relation to the upward propagation of planetary waves from the
troposphere. The impact of this stratospheric event penetrated into the
troposphere in two regions: in the northern polar region and the tropics. Due
to the strong MASTJ, planetary waves at higher latitudes were deflected and
trapped in the northern polar region. Trapping of the planetary waves resulted
in amplification of zonal wave number 1 component, which appeared in the
troposphere as the development of a trough over the Atlantic sector and a
ridge over the Eurasian sector. A strong MASTJ also suppressed the
equatorward propagation of planetary waves, which resulted in weaker
tropical stratospheric upwelling and produced anomalous warming in the
tropical stratosphere. In the tropical tropopause layer (TTL), however,
sublimation of ice clouds kept the temperature change minor. In the
troposphere, an abrupt termination of a Madden–Julian Oscillation (MJO)
event occurred following the static stability increase in the TTL. This
termination suggests that the stratospheric event affected the convective
episode in the troposphere. |
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| ISSN: | 1680-7316 1680-7324 |