{"id":928,"date":"2023-07-02T23:15:05","date_gmt":"2023-07-02T22:15:05","guid":{"rendered":"https:\/\/research.reading.ac.uk\/s2s-summit2023\/?page_id=928"},"modified":"2023-07-02T23:15:05","modified_gmt":"2023-07-02T22:15:05","slug":"abstract120","status":"publish","type":"page","link":"https:\/\/research.reading.ac.uk\/s2s-summit2023\/programme\/abstract120\/","title":{"rendered":"Abstract 120"},"content":{"rendered":"

[vc_row][vc_column][vc_column_text]Abstract ID:<\/strong> 120<\/p>\n

Underestimation of Arctic warming trends in sub-seasonal forecasts<\/h2>\n

Lead Author:<\/strong> Steffen Tietsche
\nEuropean Centre for Medium-Range Weather Forecasts, United Kingdom
\n<\/span><\/p>\n

Keywords:<\/strong> Arctic, sea ice, trends, reforecasts, climate change<\/p>\n

Abstract: <\/strong>The Arctic has warmed substantially over the last decades and will continue to do so owing to global warming in conjunction with polar amplification. The changing mean state poses many challenges to the construction, evaluation and calibration of subseasonal-to-seasonal forecasting systems, because it puts into question the representativeness of the system’s retrospective forecasts (reforecasts). Furthermore, any inconsistencies with observed trends degrade the forecast skill and point to deficiencies in either the physical modelling or the initialization methods. Here, we assess the consistency of boreal winter trends of surface air temperature (SAT) in the Eurasian Arctic between the ERA5 reanalysis and ECMWF sub-seasonal reforecasts initialised from ERA5, for the 35-year period 1986-2021. We present methods to quantify robustness and importance of the observed trends, and to quantify the consistency of reforecast trends with these observed trends. We find that, in large parts of the marine Arctic, the reforecasts clearly underestimate the reanalsyis warming trend of about 1 K per decade at lead times beyond two weeks. For longer lead times, the reforecast trend is less than half of the reanalysis trend, with very high statistical significance. We present a series of numerical experiments to investigate potential reasons for the trend underestimation. These concern the sea-ice thermodynamic coupling to the atmosphere, impact of sea surface temperatures, and possible remote atmospheric influences from the North Atlantic and the Tropics. The outcome of these experiments provides guidance for future improvements in the physical forecast model and data assimilation methods needed to faithfully represent and predict Arctic climate variability and change.<\/p>\n

Co-authors:
\n<\/strong>Frederic Vitart (ECMWF)
\nMichael Mayer (ECMWF, University of Vienna)
\nAntje Weisheimer (ECMWF, University of Oxford)
\nMagdalena Balmaseda (ECMWF)[\/vc_column_text][vc_separator][\/vc_column][\/vc_row][vc_row][vc_column width=”1\/6″][vc_single_image image=”344″ img_size=”full” onclick=”custom_link” link=”http:\/\/s2sprediction.net\/”][\/vc_column][vc_column width=”1\/6″][vc_single_image image=”345″ img_size=”full” onclick=”custom_link” link=”https:\/\/public.wmo.int\/en”][\/vc_column][vc_column width=”1\/6″][vc_single_image image=”346″ img_size=”full” onclick=”custom_link” link=”https:\/\/community.wmo.int\/activity-areas\/wwrp”][\/vc_column][vc_column width=”1\/6″][vc_single_image image=”347″ img_size=”full” onclick=”custom_link” link=”https:\/\/www.wcrp-climate.org\/”][\/vc_column][vc_column width=”1\/6″][vc_single_image image=”348″ img_size=”full”][\/vc_column][vc_column width=”1\/6″][vc_single_image image=”349″ img_size=”full” onclick=”custom_link” link=”https:\/\/www.reading.ac.uk\/”][\/vc_column][\/vc_row]<\/p>\n","protected":false},"excerpt":{"rendered":"

[vc_row][vc_column][vc_column_text]Abstract ID: 120 Underestimation of Arctic warming trends in sub-seasonal forecasts Lead Author: Steffen Tietsche European Centre for Medium-Range Weather Forecasts, United Kingdom Keywords: Arctic, sea ice, trends, reforecasts, climate…Read More ><\/a><\/p>\n","protected":false},"author":145,"featured_media":0,"parent":528,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"__cvm_playback_settings":[],"__cvm_video_id":"","footnotes":""},"coauthors":[13],"class_list":["post-928","page","type-page","status-publish","hentry"],"acf":[],"yoast_head":"\nAbstract 120 - WWRP\/WCRP S2S Summit 2023<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/research.reading.ac.uk\/s2s-summit2023\/programme\/abstract120\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Abstract 120 - 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WWRP\/WCRP S2S Summit 2023","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/research.reading.ac.uk\/s2s-summit2023\/programme\/abstract120\/","og_locale":"en_GB","og_type":"article","og_title":"Abstract 120 - WWRP\/WCRP S2S Summit 2023","og_description":"[vc_row][vc_column][vc_column_text]Abstract ID: 120 Underestimation of Arctic warming trends in sub-seasonal forecasts Lead Author: Steffen Tietsche European Centre for Medium-Range Weather Forecasts, United Kingdom Keywords: Arctic, sea ice, trends, reforecasts, climate...Read More >","og_url":"https:\/\/research.reading.ac.uk\/s2s-summit2023\/programme\/abstract120\/","og_site_name":"WWRP\/WCRP S2S Summit 2023","twitter_card":"summary_large_image","twitter_misc":{"Estimated reading time":"2 minutes","Written by":"Robert Lee"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/research.reading.ac.uk\/s2s-summit2023\/programme\/abstract120\/","url":"https:\/\/research.reading.ac.uk\/s2s-summit2023\/programme\/abstract120\/","name":"Abstract 120 - 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