Factors influencing subseasonal predictability of northern Eurasian cold spells
Abstract Cold‐air outbreaks have significant impacts on human health, energy consumption, agriculture, and overall well‐being. This study aims to evaluate the effectiveness of Subseasonal‐to‐Seasonal (S2S) models in predicting cold conditions over northern Eurasia, defined here as the lower tercile...
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Online Access: | http://dx.doi.org/10.1002/qj.4744 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4744 |
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crwiley:10.1002/qj.4744 2024-09-15T18:24:15+00:00 Factors influencing subseasonal predictability of northern Eurasian cold spells Statnaia, Irina Karpechko, Alexey Magnus Ehrnroothin Säätiö Academy of Finland 2024 http://dx.doi.org/10.1002/qj.4744 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4744 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Quarterly Journal of the Royal Meteorological Society volume 150, issue 762, page 2955-2975 ISSN 0035-9009 1477-870X journal-article 2024 crwiley https://doi.org/10.1002/qj.4744 2024-08-09T04:23:32Z Abstract Cold‐air outbreaks have significant impacts on human health, energy consumption, agriculture, and overall well‐being. This study aims to evaluate the effectiveness of Subseasonal‐to‐Seasonal (S2S) models in predicting cold conditions over northern Eurasia, defined here as the lower tercile of weekly mean 2‐metre temperature anomalies. To assess the predictability of these events we use ensemble hindcasts from five prediction systems from the S2S database. Our analysis focuses on identifying the conditions under which the models confidently predict cold temperatures with a high (>0.5) probability 3–4 weeks ahead, which potentially can represent windows of forecast opportunity. We compare the group of forecasts that correctly predicted the events to the group that forecasted events that did not occur in practice (false alarms). Most of the confident forecasts of cold spells, both correct and false alarms, have cold anomalies already in the initial conditions, often in conjunction with either a negative phase of the North Atlantic Oscillation, or Scandinavian Blocking. We find that S2S models tend to overpredict cold temperatures, with false alarms occurring more likely when the forecasts are initialized during a weak polar vortex. Furthermore, most of the confident false alarms receive the signal from the stratosphere rather than following internal tropospheric dynamics. False alarms initialized during the weak polar vortex conditions are more common when the vortex is in a recovery stage and, subsequently, the downward ‐propagating signal is short‐lived in the troposphere. The analysis of forecasts during different Madden–Julian Oscillation (MJO) phases shows that nearly half of all confident correct cold‐temperature forecasts are initialized during an active MJO in phases 6–8. On the other hand, most false alarms occur during phase 3, which we suggest is due to the presence of the Scandinavian Blocking regime in the initial conditions for this phase. Article in Journal/Newspaper North Atlantic North Atlantic oscillation Wiley Online Library Quarterly Journal of the Royal Meteorological Society 150 762 2955 2975 |
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Open Polar |
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Wiley Online Library |
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crwiley |
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English |
description |
Abstract Cold‐air outbreaks have significant impacts on human health, energy consumption, agriculture, and overall well‐being. This study aims to evaluate the effectiveness of Subseasonal‐to‐Seasonal (S2S) models in predicting cold conditions over northern Eurasia, defined here as the lower tercile of weekly mean 2‐metre temperature anomalies. To assess the predictability of these events we use ensemble hindcasts from five prediction systems from the S2S database. Our analysis focuses on identifying the conditions under which the models confidently predict cold temperatures with a high (>0.5) probability 3–4 weeks ahead, which potentially can represent windows of forecast opportunity. We compare the group of forecasts that correctly predicted the events to the group that forecasted events that did not occur in practice (false alarms). Most of the confident forecasts of cold spells, both correct and false alarms, have cold anomalies already in the initial conditions, often in conjunction with either a negative phase of the North Atlantic Oscillation, or Scandinavian Blocking. We find that S2S models tend to overpredict cold temperatures, with false alarms occurring more likely when the forecasts are initialized during a weak polar vortex. Furthermore, most of the confident false alarms receive the signal from the stratosphere rather than following internal tropospheric dynamics. False alarms initialized during the weak polar vortex conditions are more common when the vortex is in a recovery stage and, subsequently, the downward ‐propagating signal is short‐lived in the troposphere. The analysis of forecasts during different Madden–Julian Oscillation (MJO) phases shows that nearly half of all confident correct cold‐temperature forecasts are initialized during an active MJO in phases 6–8. On the other hand, most false alarms occur during phase 3, which we suggest is due to the presence of the Scandinavian Blocking regime in the initial conditions for this phase. |
author2 |
Magnus Ehrnroothin Säätiö Academy of Finland |
format |
Article in Journal/Newspaper |
author |
Statnaia, Irina Karpechko, Alexey |
spellingShingle |
Statnaia, Irina Karpechko, Alexey Factors influencing subseasonal predictability of northern Eurasian cold spells |
author_facet |
Statnaia, Irina Karpechko, Alexey |
author_sort |
Statnaia, Irina |
title |
Factors influencing subseasonal predictability of northern Eurasian cold spells |
title_short |
Factors influencing subseasonal predictability of northern Eurasian cold spells |
title_full |
Factors influencing subseasonal predictability of northern Eurasian cold spells |
title_fullStr |
Factors influencing subseasonal predictability of northern Eurasian cold spells |
title_full_unstemmed |
Factors influencing subseasonal predictability of northern Eurasian cold spells |
title_sort |
factors influencing subseasonal predictability of northern eurasian cold spells |
publisher |
Wiley |
publishDate |
2024 |
url |
http://dx.doi.org/10.1002/qj.4744 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4744 |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 150, issue 762, page 2955-2975 ISSN 0035-9009 1477-870X |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/qj.4744 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
150 |
container_issue |
762 |
container_start_page |
2955 |
op_container_end_page |
2975 |
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1810464573750247424 |