The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere
The life cycle of Northern Hemisphere downward wave coupling between the stratosphere and troposphere via wave reflection is analyzed. Downward wave coupling events are defined by extreme negative values of a wave coupling index based on the leading principal component of the daily wave-1 heat flux...
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ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D8W95M2F 2023-05-15T17:31:36+02:00 The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere Shaw, Tiffany Ann Perlwitz, Judith 2013 https://doi.org/10.7916/D8W95M2F English eng https://doi.org/10.7916/D8W95M2F Climatic changes Atmosphere Articles 2013 ftcolumbiauniv https://doi.org/10.7916/D8W95M2F 2019-04-04T08:09:13Z The life cycle of Northern Hemisphere downward wave coupling between the stratosphere and troposphere via wave reflection is analyzed. Downward wave coupling events are defined by extreme negative values of a wave coupling index based on the leading principal component of the daily wave-1 heat flux at 30 hPa. The life cycle occurs over a 28-day period. In the stratosphere there is a transition from positive to negative total wave-1 heat flux and westward to eastward phase tilt with height of the wave-1 geopotential height field. In addition, the zonal-mean zonal wind in the upper stratosphere weakens leading to negative vertical shear. Following the evolution in the stratosphere there is a shift toward the positive phase of the North Atlantic Oscillation (NAO) in the troposphere. The pattern develops from a large westward-propagating wave-1 anomaly in the high-latitude North Atlantic sector. The subsequent equatorward propagation leads to a positive anomaly in midlatitudes. The near-surface temperature and circulation anomalies are consistent with a positive NAO phase. The results suggest that wave reflection events can directly influence tropospheric weather. Finally, winter seasons dominated by extreme wave coupling and stratospheric vortex events are compared. The largest impacts in the troposphere occur during the extreme negative seasons for both indices, namely seasons with multiple wave reflection events leading to a positive NAO phase or seasons with major sudden stratospheric warmings (weak vortex) leading to a negative NAO phase. The results reveal that the dynamical coupling between the stratosphere and NAO involves distinct dynamical mechanisms that can only be characterized by separate wave coupling and vortex indices. Article in Journal/Newspaper North Atlantic North Atlantic oscillation Columbia University: Academic Commons |
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Open Polar |
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Columbia University: Academic Commons |
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ftcolumbiauniv |
language |
English |
topic |
Climatic changes Atmosphere |
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Climatic changes Atmosphere Shaw, Tiffany Ann Perlwitz, Judith The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere |
topic_facet |
Climatic changes Atmosphere |
description |
The life cycle of Northern Hemisphere downward wave coupling between the stratosphere and troposphere via wave reflection is analyzed. Downward wave coupling events are defined by extreme negative values of a wave coupling index based on the leading principal component of the daily wave-1 heat flux at 30 hPa. The life cycle occurs over a 28-day period. In the stratosphere there is a transition from positive to negative total wave-1 heat flux and westward to eastward phase tilt with height of the wave-1 geopotential height field. In addition, the zonal-mean zonal wind in the upper stratosphere weakens leading to negative vertical shear. Following the evolution in the stratosphere there is a shift toward the positive phase of the North Atlantic Oscillation (NAO) in the troposphere. The pattern develops from a large westward-propagating wave-1 anomaly in the high-latitude North Atlantic sector. The subsequent equatorward propagation leads to a positive anomaly in midlatitudes. The near-surface temperature and circulation anomalies are consistent with a positive NAO phase. The results suggest that wave reflection events can directly influence tropospheric weather. Finally, winter seasons dominated by extreme wave coupling and stratospheric vortex events are compared. The largest impacts in the troposphere occur during the extreme negative seasons for both indices, namely seasons with multiple wave reflection events leading to a positive NAO phase or seasons with major sudden stratospheric warmings (weak vortex) leading to a negative NAO phase. The results reveal that the dynamical coupling between the stratosphere and NAO involves distinct dynamical mechanisms that can only be characterized by separate wave coupling and vortex indices. |
format |
Article in Journal/Newspaper |
author |
Shaw, Tiffany Ann Perlwitz, Judith |
author_facet |
Shaw, Tiffany Ann Perlwitz, Judith |
author_sort |
Shaw, Tiffany Ann |
title |
The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere |
title_short |
The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere |
title_full |
The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere |
title_fullStr |
The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere |
title_full_unstemmed |
The Life Cycle of Northern Hemisphere Downward Wave Coupling between the Stratosphere and Troposphere |
title_sort |
life cycle of northern hemisphere downward wave coupling between the stratosphere and troposphere |
publishDate |
2013 |
url |
https://doi.org/10.7916/D8W95M2F |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_relation |
https://doi.org/10.7916/D8W95M2F |
op_doi |
https://doi.org/10.7916/D8W95M2F |
_version_ |
1766129266621153280 |