Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere
Abstract A severe cold spell with surface temperatures reaching 10 K below its climatology hit Eurasia during late February/early March 2018. This cold spell was associated with a Scandinavian blocking pattern followed by an extreme negative North Atlantic Oscillation (NAO) phase. Here we explore th...
Published in: | Quarterly Journal of the Royal Meteorological Society |
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Online Access: | http://dx.doi.org/10.1002/qj.3724 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.3724 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3724 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3724 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3724 |
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crwiley:10.1002/qj.3724 2024-09-15T18:24:17+00:00 Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere Kautz, Lisa‐Ann Polichtchouk, Inna Birner, Thomas Garny, Hella Pinto, Joaquim G. AXA Research Fund Helmholtz Association 2020 http://dx.doi.org/10.1002/qj.3724 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.3724 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3724 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3724 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3724 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Quarterly Journal of the Royal Meteorological Society volume 146, issue 727, page 1040-1055 ISSN 0035-9009 1477-870X journal-article 2020 crwiley https://doi.org/10.1002/qj.3724 2024-08-01T04:23:44Z Abstract A severe cold spell with surface temperatures reaching 10 K below its climatology hit Eurasia during late February/early March 2018. This cold spell was associated with a Scandinavian blocking pattern followed by an extreme negative North Atlantic Oscillation (NAO) phase. Here we explore the predictability of this cold spell/NAO event using ensemble forecasts from the Subseasonal‐to‐Seasonal (S2S) archive of the European Centre for Medium‐Range Weather Forecasts. We find that this event was predicted with the observed strength roughly 10 days in advance. However, the probability of the cold spell occurring doubled up to 25 days in advance, when a sudden stratospheric warming (SSW) occurred. Our results indicate that the amplitude of the cold spell was increased by a regime shift to the negative NAO phase at the end of February, which was likely favoured by the SSW. We quantify the contribution of the SSW to the enhanced extended‐range forecast skill for this particular event by running forecast ensembles in which the evolution of the stratosphere is nudged to (a) the observed evolution, and (b) a time‐invariant state. In the experiment with nudging to the observed stratospheric evolution, the probability of a strong cold spell occurring is enhanced to 45%, while it is at its climatological value of 5% when the stratosphere is nudged to a time‐invariant state. These results showing enhanced predictability of surface extremes following SSWs extend previous observational evidence, which is mostly based on composite analyses, to a single event. Our results suggest that it is the subsequent evolution throughout the lower stratosphere following the SSW, rather than the occurrence of the SSW itself, that is crucial in coupling to large‐scale tropospheric flow patterns. However, we caution that probabilistic gain in predictability alone is insufficient to conclude a causal link between the SSW and the cold spell event. Article in Journal/Newspaper North Atlantic North Atlantic oscillation Wiley Online Library Quarterly Journal of the Royal Meteorological Society 146 727 1040 1055 |
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Wiley Online Library |
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crwiley |
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English |
description |
Abstract A severe cold spell with surface temperatures reaching 10 K below its climatology hit Eurasia during late February/early March 2018. This cold spell was associated with a Scandinavian blocking pattern followed by an extreme negative North Atlantic Oscillation (NAO) phase. Here we explore the predictability of this cold spell/NAO event using ensemble forecasts from the Subseasonal‐to‐Seasonal (S2S) archive of the European Centre for Medium‐Range Weather Forecasts. We find that this event was predicted with the observed strength roughly 10 days in advance. However, the probability of the cold spell occurring doubled up to 25 days in advance, when a sudden stratospheric warming (SSW) occurred. Our results indicate that the amplitude of the cold spell was increased by a regime shift to the negative NAO phase at the end of February, which was likely favoured by the SSW. We quantify the contribution of the SSW to the enhanced extended‐range forecast skill for this particular event by running forecast ensembles in which the evolution of the stratosphere is nudged to (a) the observed evolution, and (b) a time‐invariant state. In the experiment with nudging to the observed stratospheric evolution, the probability of a strong cold spell occurring is enhanced to 45%, while it is at its climatological value of 5% when the stratosphere is nudged to a time‐invariant state. These results showing enhanced predictability of surface extremes following SSWs extend previous observational evidence, which is mostly based on composite analyses, to a single event. Our results suggest that it is the subsequent evolution throughout the lower stratosphere following the SSW, rather than the occurrence of the SSW itself, that is crucial in coupling to large‐scale tropospheric flow patterns. However, we caution that probabilistic gain in predictability alone is insufficient to conclude a causal link between the SSW and the cold spell event. |
author2 |
AXA Research Fund Helmholtz Association |
format |
Article in Journal/Newspaper |
author |
Kautz, Lisa‐Ann Polichtchouk, Inna Birner, Thomas Garny, Hella Pinto, Joaquim G. |
spellingShingle |
Kautz, Lisa‐Ann Polichtchouk, Inna Birner, Thomas Garny, Hella Pinto, Joaquim G. Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere |
author_facet |
Kautz, Lisa‐Ann Polichtchouk, Inna Birner, Thomas Garny, Hella Pinto, Joaquim G. |
author_sort |
Kautz, Lisa‐Ann |
title |
Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere |
title_short |
Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere |
title_full |
Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere |
title_fullStr |
Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere |
title_full_unstemmed |
Enhanced extended‐range predictability of the 2018 late‐winter Eurasian cold spell due to the stratosphere |
title_sort |
enhanced extended‐range predictability of the 2018 late‐winter eurasian cold spell due to the stratosphere |
publisher |
Wiley |
publishDate |
2020 |
url |
http://dx.doi.org/10.1002/qj.3724 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.3724 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3724 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3724 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3724 |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 146, issue 727, page 1040-1055 ISSN 0035-9009 1477-870X |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/qj.3724 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
146 |
container_issue |
727 |
container_start_page |
1040 |
op_container_end_page |
1055 |
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1810464608764297216 |