Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation
In Part I of this study, it was shown that the Eurasian cold anomalies related to Arctic warming depend strongly on the quasi stationarity and persistence of the Ural blocking (UB). The analysis here revealed that under weak mean westerly wind (MWW) and vertical shear (VS) (quasi barotropic) conditi...
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ftosti:oai:osti.gov:1537011 2023-07-30T04:01:36+02:00 Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation Luo, Dehai Yao, Yao Dai, Aiguo Simmonds, Ian Zhong, Linhao 2021-08-02 application/pdf http://www.osti.gov/servlets/purl/1537011 https://www.osti.gov/biblio/1537011 https://doi.org/10.1175/jcli-d-16-0262.1 unknown http://www.osti.gov/servlets/purl/1537011 https://www.osti.gov/biblio/1537011 https://doi.org/10.1175/jcli-d-16-0262.1 doi:10.1175/jcli-d-16-0262.1 54 ENVIRONMENTAL SCIENCES 2021 ftosti https://doi.org/10.1175/jcli-d-16-0262.1 2023-07-11T09:34:54Z In Part I of this study, it was shown that the Eurasian cold anomalies related to Arctic warming depend strongly on the quasi stationarity and persistence of the Ural blocking (UB). The analysis here revealed that under weak mean westerly wind (MWW) and vertical shear (VS) (quasi barotropic) conditions with weak synoptic-scale eddies and a large planetary wave anomaly, the growth of UB is slow and its amplitude is small. For this case, a quasi-stationary and persistent UB is seen. However, under strong MWW and VS (quasi baroclinic) conditions, synoptic-scale eddies are stronger and the growth of UB is rapid; the resulting UB is less persistent and has large amplitude. In this case, a marked retrogression of the UB is observed. The dynamical mechanism behind the dependence of the movement and persistence of UB upon the background conditions is further examined using a nonlinear multiscale model. The results show that when the blocking has large amplitude under quasi-baroclinic conditions, the blocking-induced westward displacement greatly exceeds the strong mean zonal-wind-induced eastward movement and hence generates a marked retrogression of the blocking. By contrast, under quasi-barotropic conditions because the UB amplitude is relatively small the blocking-induced westward movement is less distinct, giving rise to a quasi-stationary and persistent blocking. It is further shown that the strong mid–high-latitude North Atlantic mean zonal wind is the quasi-barotropic condition that suppresses UB’s retrogression and thus is conducive to the quasi stationarity and persistence of the UB. The model results show that the blocking duration is longer when the mean zonal wind in the blocking region or eddy strength is weaker. Other/Unknown Material Arctic North Atlantic SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Arctic Journal of Climate 30 10 3569 3587 |
institution |
Open Polar |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
op_collection_id |
ftosti |
language |
unknown |
topic |
54 ENVIRONMENTAL SCIENCES |
spellingShingle |
54 ENVIRONMENTAL SCIENCES Luo, Dehai Yao, Yao Dai, Aiguo Simmonds, Ian Zhong, Linhao Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation |
topic_facet |
54 ENVIRONMENTAL SCIENCES |
description |
In Part I of this study, it was shown that the Eurasian cold anomalies related to Arctic warming depend strongly on the quasi stationarity and persistence of the Ural blocking (UB). The analysis here revealed that under weak mean westerly wind (MWW) and vertical shear (VS) (quasi barotropic) conditions with weak synoptic-scale eddies and a large planetary wave anomaly, the growth of UB is slow and its amplitude is small. For this case, a quasi-stationary and persistent UB is seen. However, under strong MWW and VS (quasi baroclinic) conditions, synoptic-scale eddies are stronger and the growth of UB is rapid; the resulting UB is less persistent and has large amplitude. In this case, a marked retrogression of the UB is observed. The dynamical mechanism behind the dependence of the movement and persistence of UB upon the background conditions is further examined using a nonlinear multiscale model. The results show that when the blocking has large amplitude under quasi-baroclinic conditions, the blocking-induced westward displacement greatly exceeds the strong mean zonal-wind-induced eastward movement and hence generates a marked retrogression of the blocking. By contrast, under quasi-barotropic conditions because the UB amplitude is relatively small the blocking-induced westward movement is less distinct, giving rise to a quasi-stationary and persistent blocking. It is further shown that the strong mid–high-latitude North Atlantic mean zonal wind is the quasi-barotropic condition that suppresses UB’s retrogression and thus is conducive to the quasi stationarity and persistence of the UB. The model results show that the blocking duration is longer when the mean zonal wind in the blocking region or eddy strength is weaker. |
author |
Luo, Dehai Yao, Yao Dai, Aiguo Simmonds, Ian Zhong, Linhao |
author_facet |
Luo, Dehai Yao, Yao Dai, Aiguo Simmonds, Ian Zhong, Linhao |
author_sort |
Luo, Dehai |
title |
Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation |
title_short |
Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation |
title_full |
Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation |
title_fullStr |
Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation |
title_full_unstemmed |
Increased Quasi Stationarity and Persistence of Winter Ural Blocking and Eurasian Extreme Cold Events in Response to Arctic Warming. Part II: A Theoretical Explanation |
title_sort |
increased quasi stationarity and persistence of winter ural blocking and eurasian extreme cold events in response to arctic warming. part ii: a theoretical explanation |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1537011 https://www.osti.gov/biblio/1537011 https://doi.org/10.1175/jcli-d-16-0262.1 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic North Atlantic |
genre_facet |
Arctic North Atlantic |
op_relation |
http://www.osti.gov/servlets/purl/1537011 https://www.osti.gov/biblio/1537011 https://doi.org/10.1175/jcli-d-16-0262.1 doi:10.1175/jcli-d-16-0262.1 |
op_doi |
https://doi.org/10.1175/jcli-d-16-0262.1 |
container_title |
Journal of Climate |
container_volume |
30 |
container_issue |
10 |
container_start_page |
3569 |
op_container_end_page |
3587 |
_version_ |
1772812365436289024 |