noaa-recon-18935 North Atlantic Oscillation 1000 Year Model-Tested Reconstruction Ortega, P.; Lehner, F.; Swingedouw, D.; Masson-Delmotte, V.; Raible, C.C.; Casado, M.; Yiou, P. North Atlantic Oscillation 1000 Year Model-Tested Reconstruction 2015-07-02 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/18935 Investigator P. Ortega Investigator F. Lehner Investigator D. Swingedouw Investigator V. Masson-Delmotte Investigator C.C. Raible Investigator M. Casado Investigator P. Yiou earth science paleoclimate climate reconstructions North Atlantic Oscillation Index,multiple proxies,two standard error upper bound,standard deviation unit,Dec-Feb,climate reconstructions,null,null,N,regression uncertainty as departure from the ensemble mean of 2 standard errors earth science paleoclimate climate reconstructions North Atlantic Oscillation Index,multiple proxies,two standard error lower bound,standard deviation unit,Dec-Feb,climate reconstructions,null,null,N,regression uncertainty as departure from the ensemble mean of -2 standard errors earth science paleoclimate climate reconstructions North Atlantic Oscillation Index,multiple proxies,null,standard deviation unit,Dec-Feb,climate reconstructions,null,null,N,ensemble of 100 model-constrained NAO reconstructions earth science paleoclimate climate reconstructions age,null,null,year Common Era,null,climate reconstructions,null,null,N,null earth science paleoclimate climate reconstructions North Atlantic Oscillation Index,multiple proxies,range lower bound,standard deviation unit,Dec-Feb,climate reconstructions,null,null,N,ensemble spread earth science paleoclimate climate reconstructions North Atlantic Oscillation Index,multiple proxies,range upper bound,standard deviation unit,Dec-Feb,climate reconstructions,null,null,N,ensemble spread earth science paleoclimate reconstructions atmospheric circulation geoscientificInformation Atmospheric and Oceanic Circulation Patterns Reconstruction North Atlantic Oscillation 1049 AD 1969 AD 901 cal yr BP -19 cal yr BP Complete 0 90 -180 180 Geographic Region Northern Hemisphere Northern Hemisphere>LATITUDE >LONGITUDE None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Pablo Ortega, Flavio Lehner, Didier Swingedouw, Valerie Masson-Delmotte, Christoph C. Raible, Mathieu Casado, and Pascal Yiou 2015 Nature 523 7558 71-74 10.1038/nature14518 http://www.nature.com/nature/journal/v523/n7558/full/nature14518.html

The North Atlantic Oscillation (NAO) is the major source of variability in winter atmospheric circulation in the Northern Hemisphere, with large impacts on temperature, precipitation and storm tracks, and therefore also on strategic sectors such as insurance, renewable energy production, crop yields and water management. Recent developments in dynamical methods offer promise to improve seasonal NAO predictions, but assessing potential predictability on multi-annual timescales requires documentation of past low-frequency variability in the NAO. A recent bi-proxy NAO reconstruction spanning the past millennium suggested that long-lasting positive NAO conditions were established during medieval times, explaining the particularly warm conditions in Europe during this period; however, these conclusions are debated. Here, we present a yearly NAO reconstruction for the past millennium, based on an initial selection of 48 annually resolved proxy records distributed around the Atlantic Ocean and built through an ensemble of multivariate regressions. We validate the approach in six past-millennium climate simulations, and show that our reconstruction outperforms the bi-proxy index. The final reconstruction shows no persistent positive NAO during the medieval period, but suggests that positive phases were dominant during the thirteenth and fourteenth centuries. The reconstruction also reveals that a positive NAO emerges two years after strong volcanic eruptions, consistent with results obtained from models and satellite observations for the Mt Pinatubo eruption in the Philippines. STUDY NOTES: This is a new reconstruction of North Atlantic Oscillation evolution during the last millennium. It has been produced by generating an ensemble of 100 different multi-proxy reconstructions, each one calibrated over a different time period. In each case, the final selection of proxies is constrained through the use of reanalyses and last millennium model simulations. For additional information about the data and the methodology please refer to Ortega et al. 2015. Provided Keywords: Last millennium, North Atlantic Oscillation, Perfect Model Analysis

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ortega2015/ortega2015nao.txt Data File; North Atlantic Oscillation 1000 Year Model-Tested Reconstruction USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11