{"NOAAStudyId":"18935","contactInfo":{"address":"325 Broadway, E/NE31","city":"Boulder","constraints":"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.","country":"USA","dataCenterUrl":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data","email":"paleo@noaa.gov","fax":"303-497-6513","longName":"National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce ","phone":"303-497-6280","postalCode":"80305-3328","shortName":"DOC/NOAA/NESDIS/NCEI","state":"CO","type":"CONTACT INFORMATION"},"contributionDate":"2015-07-02","dataPublisher":"NOAA","dataType":"CLIMATE RECONSTRUCTIONS","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/climate-reconstruction","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-recon-18935.xml","doi":null,"earliestYearBP":901,"earliestYearCE":1049,"entryId":"noaa-recon-18935","funding":[{"fundingAgency":"Swedish Research Council ","fundingGrant":"C0629701"},{"fundingAgency":"Swiss National Science Foundation","fundingGrant":"200020 147174"},{"fundingAgency":"ANR France","fundingGrant":"ANR-10-CEPL-0008"}],"investigators":"Ortega, P.; Lehner, F.; Swingedouw, D.; Masson-Delmotte, V.; Raible, C.C.; Casado, M.; Yiou, P.","mostRecentYearBP":-19,"mostRecentYearCE":1969,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/18935","originalSource":null,"publication":[{"abstract":"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.","author":{"name":"Pablo Ortega, Flavio Lehner, Didier Swingedouw, Valerie Masson-Delmotte, Christoph C. Raible, Mathieu Casado, and Pascal Yiou\r\n"},"citation":"Pablo Ortega, Flavio Lehner, Didier Swingedouw, Valerie Masson-Delmotte, Christoph C. Raible, Mathieu Casado, and Pascal Yiou\r\n. 2015. A model-tested North Atlantic Oscillation reconstruction for the past millennium. Nature, 523(7558), 71-74. doi: 10.1038/nature14518","edition":null,"identifier":{"id":"10.1038/nature14518","type":"doi","url":"http://dx.doi.org/10.1038/nature14518"},"issue":"7558","journal":"Nature","pages":"71-74","pubRank":"1","pubYear":2015,"reportNumber":null,"title":"A model-tested North Atlantic Oscillation reconstruction for the past millennium","type":"publication","volume":"523"}],"reconstruction":"Y","scienceKeywords":["Atmospheric and Oceanic Circulation Patterns Reconstruction","North Atlantic Oscillation"],"site":[{"NOAASiteId":"34252","geo":{"geoType":"Feature","geometry":{"coordinates":["0","90","-180","180"],"type":"POLYGON"},"properties":{"easternmostLongitude":"180","maxElevationMeters":null,"minElevationMeters":null,"northernmostLatitude":"90","southernmostLatitude":"0","westernmostLongitude":"-180"}},"locationName":"Geographic Region>Northern Hemisphere","mappable":"N","paleoData":[{"NOAADataTableId":"29361","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>reconstructions>atmospheric circulation"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ortega2015/ortega2015nao.txt","linkText":"North Atlantic Oscillation 1000 Year Model-Tested Reconstruction","urlDescription":"Data File","variables":[{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"year Common Era","cvWhat":"age variable>age"},{"cvAdditionalInfo":"ensemble of 100 model-constrained NAO reconstructions","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":"3-month period>Dec-Feb","cvShortName":null,"cvUnit":"standard deviation unit","cvWhat":"earth system variable>mode-of-variability variable>North Atlantic Oscillation Index"},{"cvAdditionalInfo":"ensemble spread","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":null,"cvError":"range lower bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":"3-month period>Dec-Feb","cvShortName":null,"cvUnit":"standard deviation unit","cvWhat":"earth system variable>mode-of-variability variable>North Atlantic Oscillation Index"},{"cvAdditionalInfo":"ensemble spread","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":null,"cvError":"range upper bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":"3-month period>Dec-Feb","cvShortName":null,"cvUnit":"standard deviation unit","cvWhat":"earth system variable>mode-of-variability variable>North Atlantic Oscillation Index"},{"cvAdditionalInfo":"regression uncertainty as departure from the ensemble mean of -2 standard errors","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":null,"cvError":"two standard error lower bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":"3-month period>Dec-Feb","cvShortName":null,"cvUnit":"standard deviation unit","cvWhat":"earth system variable>mode-of-variability variable>North Atlantic Oscillation Index"},{"cvAdditionalInfo":"regression uncertainty as departure from the ensemble mean of 2 standard errors","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":null,"cvError":"two standard error upper bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":"3-month period>Dec-Feb","cvShortName":null,"cvUnit":"standard deviation unit","cvWhat":"earth system variable>mode-of-variability variable>North Atlantic Oscillation Index"}]}],"dataTableName":"Ortega2015NAO","dataTableNotes":null,"earliestYear":1049,"earliestYearBP":901,"earliestYearCE":1049,"mostRecentYear":1969,"mostRecentYearBP":-19,"mostRecentYearCE":1969,"species":[],"timeUnit":"AD"}],"siteName":"Northern Hemisphere"}],"studyCode":null,"studyName":"North Atlantic Oscillation 1000 Year Model-Tested Reconstruction","studyNotes":"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. \nProvided Keywords: Last millennium, North Atlantic Oscillation, Perfect Model Analysis","version":"1.0","xmlId":"16606"}