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Ocean, Climate, Arctic: A one-hour "workshop" at COP26, in the Nordic Pavilion in Glasgow & virtual About this event This workshop will explore the importance of the ocean in the global and north west European climate, the need to ensure we are measuring the strength of ocean currents and the ocean's properties, and how this information can be incorporated into climate models, climate services and decision-making at national and international levels. Speakers: Bee Berx (Scottish Government) Mark Payne (Danish Meteorological Institute) Jacob Høyer (Danish Meteorological Institute, GHRSST Group for High Resolution Sea Surface Temperature) Noel Keenlyside (Bjerknes Centre for Climate Research, University of Bergen) Marit Reigstad (UiT the Arctic University of Norway) Siân Henley (University of Edinburgh) Finlo Cottier (Scottish Association for Marine Science) Streaming page: https://youtu.be/fJ31QC4uIcw Organizer: Scottish Government, with the support of Blue-Action (H2020) and GHRSST (Copernicus) Venue: Nordic Pavilion in Glasgow & virtual. SEC Centre, Hall 4, Exhibition Way, Glasgow, G3 8YW, United Kingdom

One of the main aims of the Blue‐Action project is to establish a strong clustering activity with the European and international scientific communities focusing on climate services, Arctic impacts and Blue Growth. Our work wackage WP6 supports the exchange and interaction between the products and services that Blue‐Action delivers and the communities focusing on those themes. The goals of this work packages are to identify open research questions/development needs, to create synergies between these projects, to share knowledge and support knowledge transfer. Within this framework, two workshops have been organised in the first half of 2019: ● A workshop on the "Representativeness of ocean observations and Flux calculations", in collaboration with ASOF (Arctic and Subarctic Ocean Fluxes), held at the Danish Meteorological Institute (DMI) in Copenhagen (DK) on 24 ‐26 April 2019. ● A workshop on "Climate Prediction in the Atlantic‐Arctic sector", in collaboration with the EU Climate Modelling Cluster and the Bjerknes Climate Prediction Unit (BCPU), held in Bergen (NO) on 5‐7 June 2019. The main results of these workshops can be found in this deliverable, with links to resources an materials of the workshops. ; The Blue‐Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852.

The Arctic is warming twice as fast as anywhere else on the planet and rapid changes are occurring, from sea ice melt to warming air temperatures. However, these impacts are not restricted to the far north, as the Arctic is connected to the rest of the world via the atmospheric and ocean circulations. Understanding the drivers of these changes, and the connections between the Arctic and the Northern Hemisphere, allows us to make predictions about the impact beyond the Arctic. Developing robust predictions is a vital step to allow businesses, communities and government to be able to adapt to the future. Blue-Action is building blocks of ocean observations and computer models to co-design tools that enable stakeholders to act on climate change. ; The Blue-Action project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 727852.

The Arctic is warming twice as fast as anywhere else on the planet and rapid changes are occurring, from sea ice melt to warming air temperatures. However, these impacts are not restricted to the far north, as the Arctic is connected to the rest of the world via the atmospheric and ocean circulations. Understanding the drivers of these changes, and the connections between the Arctic and the Northern Hemisphere, allows us to make predictions about the impact beyond the Arctic. Developing robust predictions is a vital step to allow businesses, communities and government to be able to adapt to the future. Blue-Action is building blocks of ocean observations and computer models to co-design tools that enable stakeholders to act on climate change. ; The Blue-Action project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 727852.

The second Stakeholder Engagement Knowledge Exchange event entitled "Ocean observations and predictions in response to the climate emergency" was held in Edinburgh (UK) on 16 October 2019. The event was hosted and moderated by Blue-Action, with five speakers representing partners across the consortium. The goal of this event was to share cutting-edge research by Blue-Action on ocean observations and model projections, and how this work can lead to robust predictions of the physical characteristics and productivity of Scottish seas up to a decade in advance. The audience was comprised of invited stakeholders across academia, industry, NGOs and policymaking. The structure and outcomes of this event are described in this deliverable, with references to the outputs and documentation. The key take-home messages from this event form the basis of a new publicly available document published by Blue-Action to highlight the importance of ocean observations and predictions and translation to climate services to relevant sectors. With this action, Blue-Action has increased its profile in Scotland, and built a reputation as a valuable and reputable source of climate information. ; The Blue-Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852.

The eastern boundary region off Angola encompasses a highly productive ecosystem important for the food security of the coastal population. The fish-stock distribution, however, undergoes large variability on intraseasonal, interannual, and longer time scales. These fluctuations are partly associated with large-scale warm anomalies that are often forced remotely from the equatorial Atlantic and propagate southward, reaching the Benguela upwelling off Namibia. Such warm events, named Benguela Niños, occurred in 1995 and in 2011. Here we present results from an underexplored extensive in situ dataset that was analyzed in the framework of a capacity-strengthening effort. The dataset was acquired within the Nansen Programme executed by the Food and Agriculture Organization of the United Nations and funded by the Norwegian government. It consists of hydrographic and velocity data from the Angolan continental margin acquired biannually during the main downwelling and upwelling seasons over more than 20 years. The mean seasonal changes of the Angola Current from 6° to 17°S are presented. During austral summer the southward Angola Current is concentrated in the upper 150 m. It strengthens from north to south, reaching a velocity maximum just north of the Angola Benguela Front. During austral winter the Angola Current is weaker, but deeper reaching. While the southward strengthening of the Angola Current can be related to the wind forcing, its seasonal variability is most likely explained by coastally trapped waves. On interannual time scales, the hydrographic data reveal remarkable variability in subsurface upper-ocean heat content. In particular, the 2011 Benguela Niño was preceded by a strong subsurface warming of about 2 years' duration.

The eastern boundary region off Angola encompasses a highly productive ecosystem important for the food security of the coastal population. The fish-stock distribution, however, undergoes large variability on intraseasonal, interannual, and longer time scales. These fluctuations are partly associated with large-scale warm anomalies that are often forced remotely from the equatorial Atlantic and propagate southward, reaching the Benguela upwelling off Namibia. Such warm events, named Benguela Niños, occurred in 1995 and in 2011. Here we present results from an underexplored extensive in situ dataset that was analyzed in the framework of a capacity-strengthening effort. The dataset was acquired within the Nansen Programme executed by the Food and Agriculture Organization of the United Nations and funded by the Norwegian government. It consists of hydrographic and velocity data from the Angolan continental margin acquired biannually during the main downwelling and upwelling seasons over more than 20 years. The mean seasonal changes of the Angola Current from 6° to 17°S are presented. During austral summer the southward Angola Current is concentrated in the upper 150 m. It strengthens from north to south, reaching a velocity maximum just north of the Angola Benguela Front. During austral winter the Angola Current is weaker, but deeper reaching. While the southward strengthening of the Angola Current can be related to the wind forcing, its seasonal variability is most likely explained by coastally trapped waves. On interannual time scales, the hydrographic data reveal remarkable variability in subsurface upper-ocean heat content. In particular, the 2011 Benguela Niño was preceded by a strong subsurface warming of about 2 years' duration. ; publishedVersion

This briefing document was produced for the Science-Policy Discussion on 'Forecasting fish distribution and abundance in the Atlantic Ocean: The Challenge of balancing exploitation and sustainability" organised by three Horizon 2020 projects, Blue-Action, TRIATLAS and MISSION ATLANTIC, with the support of the European Parliament Intergroup on Climate Change, Biodiversity & Sustainable Development on 3 December 2020 as an online event. Corresponding Authors: Mark R. Payne (mpay@aqua.dtu.dk) and Noel Keenlyside (noel.keenlyside@gfi.uib.no) ; The Blue-Action, TRITLAS and MISSION ATLANTIC projects have received funding from the European Union's Horizon 2020 research and innovation pogramme under grant agreement no. 727852, 817578 and 862428 respectively.

The western Pacific subtropical high (WPSH) is closely related to Asian climate. Previous examination of changes in the WPSH found a westward extension since the late 1970s, which has contributed to the inter-decadal transition of East Asian climate. The reason for the westward extension is unknown, however. The present study suggests that this significant change of WPSH is partly due to the atmosphere's response to the observed Indian Ocean-western Pacific (IWP) warming. Coordinated by a European Union's Sixth Framework Programme, Understanding the Dynamics of the Coupled Climate System (DYNAMITE), five AGCMs were forced by identical idealized sea surface temperature patterns representative of the IWP warming and cooling. The results of these numerical experiments suggest that the negative heating in the central and eastern tropical Pacific and increased convective heating in the equatorial Indian Ocean/ Maritime Continent associated with IWP warming are in favor of the westward extension of WPSH. The SST changes in IWP influences the Walker circulation, with a subsequent reduction of convections in the tropical central and eastern Pacific, which then forces an ENSO/Gill-type response that modulates the WPSH. The monsoon diabatic heating mechanism proposed by Rodwell and Hoskins plays a secondary reinforcing role in the westward extension of WPSH. The low-level equatorial flank of WPSH is interpreted as a Kelvin response to monsoon condensational heating, while the intensified poleward flow along the western flank of WPSH is in accord with Sverdrup vorticity balance. The IWP warming has led to an expansion of the South Asian high in the upper troposphere, as seen in the reanalysis.

This poster presents shortly how Blue-Action contributes to the BluePrint for Ocean Observing in the Atlantic. The poster was presented at OceanObs'2019 by Steffen Olsen (DMI). Blue-Action contributes to defining the future Atlantic monitoring system by: optimizing the monitoring systems at the gateways to the Arctic, assessing and enhancing the usefulness of the North Atlantic ocean observations in decadal prediction systems, demonstrating the value of initialized decadal predictions in climate services ; Blue-Action received funding from the European Union's Horizon 2020 research and innovation programme Grant agreement no. 727852

Quantifying signals and uncertainties in climate models is essential for the detection, attribution, prediction and projection of climate change1,2,3. Although inter-model agreement is high for large-scale temperature signals, dynamical changes in atmospheric circulation are very uncertain4. This leads to low confidence in regional projections, especially for precipitation, over the coming decades5,6. The chaotic nature of the climate system7,8,9 may also mean that signal uncertainties are largely irreducible. However, climate projections are difficult to verify until further observations become available. Here we assess retrospective climate model predictions of the past six decades and show that decadal variations in North Atlantic winter climate are highly predictable, despite a lack of agreement between individual model simulations and the poor predictive ability of raw model outputs. Crucially, current models underestimate the predictable signal (the predictable fraction of the total variability) of the North Atlantic Oscillation (the leading mode of variability in North Atlantic atmospheric circulation) by an order of magnitude. Consequently, compared to perfect models, 100 times as many ensemble members are needed in current models to extract this signal, and its effects on the climate are underestimated relative to other factors. To address these limitations, we implement a two-stage post-processing technique. We first adjust the variance of the ensemble-mean North Atlantic Oscillation forecast to match the observed variance of the predictable signal. We then select and use only the ensemble members with a North Atlantic Oscillation sufficiently close to the variance-adjusted ensemble-mean forecast North Atlantic Oscillation. This approach greatly improves decadal predictions of winter climate for Europe and eastern North America. Predictions of Atlantic multidecadal variability are also improved, suggesting that the North Atlantic Oscillation is not driven solely by Atlantic multidecadal variability. Our results highlight the need to understand why the signal-to-noise ratio is too small in current climate models10, and the extent to which correcting this model error would reduce uncertainties in regional climate change projections on timescales beyond a decade. ; DMS, AAS, NJD, LH and RE were supported by the Met Office Hadley Centre Climate Programme funded by BEIS and Defra and by the European Commission Horizon 2020 EUCP project (GA 776613). FJDR, LPC, SW and RB also acknowledge the support from the EUCP project (GA 776613) and from the Ministerio de Econom´ıa y Competitividad (MINECO) as part of the CLINSA project (Grant No. CGL2017-85791-R). SW received funding from the innovation programme under the Marie Sk´lodowska-Curie grant agreement H2020-MSCA-COFUND-2016-754433 and PO from the Ramon y Cajal senior tenure programme of MINECO. The EC-Earth simulations were performed on Marenostrum 4 (hosted by the Barcelona Supercomputing Center, Spain) using Auto-Submit through computing hours provided by PRACE.WAM, HP, KMand KP were supported by the German FederalMinistry for Education and Research (BMBF) project MiKlip (grant 01LP1519A). NK, IB, FC and YW were supported by the Norwegian Research Council projects SFE (grant 270733) the Nordic Center of excellent ARCPATH (grant 76654) and the Trond Mohn Foundation, under the project number : BFS2018TMT01 and received grants for computer time from the Norwegian Program for supercomputing (NOTUR2, NN9039K) and storage grants (NORSTORE, NS9039K). JM, LFB and DS are supported by Blue-Action (European Union Horizon 2020 research and innovation program, Grant Number: 727852) and EUCP (European Union Horizon 2020 research and innovation programme under grant agreement no 776613) projects. The National Center for Atmospheric Research (NCAR) is a major facility sponsored by the US National Science Foundation (NSF) under Cooperative Agreement No. 1852977. NCAR contribution was partially supported by the National Oceanic and Atmospheric Administration (NOAA) Climate Program Office under Climate Variability and Predictability Program Grant NA13OAR4310138 and by the US NSF Collaborative Research EaSM2 Grant OCE-1243015. ; Peer Reviewed ; Postprint (author's final draft)

Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. http://www.sciencemag.org/about/science-licenses-journal-article-reuse This is an article distributed under the terms of the Science Journals Default License. ; The El Niño–Southern Oscillation (ENSO), which originates in the Pacific, is the strongestand most well-known mode of tropical climate variability. Its reach is global, and it canforce climate variations of the tropical Atlantic and Indian Oceans by perturbing the globalatmospheric circulation. Less appreciated is how the tropical Atlantic and Indian Oceansaffect the Pacific. Especially noteworthy is the multidecadal Atlantic warming that began inthe late 1990s, because recent research suggests that it has influenced Indo-Pacificclimate, the character of the ENSO cycle, and the hiatus in global surface warming.Discovery of these pantropical interactions provides a pathway forward for improvingpredictions of climate variability in the current climate and for refining projections offuture climate under different anthropogenic forcing scenarios. ; W.C. is supportedby National Key R&D Program of China (2018YFA0605700).L.W., Xia.L., and B.G. are supported by the National NaturalScience Foundation of China (NSFC) projects (41490643,41490640, U1606402, and 41521091). W.C., G.W., B.N., and A.S.are supported by CSHOR and the Earth System and ClimateChange Hub of the Australian Government'sNationalEnvironment Science Program. CSHOR is a joint research Centrefor Southern Hemisphere Oceans Research between QNLM andCSIRO. M.L. is supported by the GOTHAM Belmont project(ANR-15-JCLI-0004-01) and the ARiSE ANR project. T.L. issupported by NSFC 41630423 and NSF AGS-1565653 grants.S.M. is supported by the Australian Research Council (ARC)through grant number FT160100162. J.-S.K. was supported bya National Research Foundation of Korea (NRF) grant fundedby the Korea government (MSIT) (NRF-2018R1A5A1024958).J.-Y.Y. is supported by NSF AGS-1505145 and AGS-1833075grants. M.F.S is supported by the Institute for Basic Science(project code IBS-R028-D1). Y.-G.H. is funded by the KoreaMeteorological AdministrationResearchandDevelopmentProgram under grant KMI2018-03214. M.J.M is supported byNOAA and PMEL contribution number 4838. Y.D. is supportedby the National Natural Science Foundation of China (41525019,41830538, and 41521005) and the State Oceanic Administrationof China (GASI-IPOVAI-02). D.D. is supported by ARC grantnumber CE170100023. M.M.-R. has been supported by theMORDICUS grant under contract ANR-13-762 SENV-0002-01and CGL2017-86415-R. Y.R.-R. is supported by an 800154-INADEC individual MSCA-IF-EF-ST grant. S.-P.X. is supportedby the NSF. J.B.K. was supported by the National EnvironmentResearch Council (NE/N005783/1).Author contributions:The manuscript was written as a group effort during two"Pantropical interbasin climate interactions"workshops heldat Xiamen University and Jeju Island. All authors contributedto the manuscript preparation, interpretations, and thediscussions that led to the final figure design. W.C. and L.W.designed the study and coordinated the writing. M.L., T.L., S.M.,J.-S.K., A.S., J.-Y.Y., Xic.L., M.F.S., Y.C., Y.-G.H., M.J.M., N.K.,Y.R.-R., and J.B.K. coordinated the discussion for varioussections.B.N.helpedtocollatecomments and prepare an initialversion.Competing interests:The authors declare nocompeting interests.Data and materials availability:Allobservation and model datasets used here are publiclyavailable or available on request. ; Peer Reviewed ; Postprint (author's final draft)