{"NOAAStudyId":"12355","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":"2011-12-21","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-12355.xml","doi":null,"earliestYearBP":950,"earliestYearCE":1000,"entryId":"noaa-recon-12355","funding":[{"fundingAgency":"Danish Meteorological Institute","fundingGrant":"Danish Climate Centre"}],"investigators":"Christiansen, B.; Ljungqvist, F.C.","mostRecentYearBP":-50,"mostRecentYearCE":2000,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/12355","originalSource":null,"publication":[{"abstract":"A new multiproxy reconstruction of the Northern Hemisphere \r\nextratropical mean temperature over the last millennium \r\nis presented. The reconstruction is performed with a novel \r\nmethod designed to avoid the underestimation of low-frequency \r\nvariability that has been a general problem for regression-based \r\nreconstruction methods. The disadvantage of this method is an \r\nexaggerated high-frequency variability. The reconstruction \r\nis based on a set of 40 proxies of annual to decadal resolution \r\nthat have been shown to relate to the local temperature. \r\nThe new reconstruction shows a very cold Little Ice Age \r\ncentered around the 17th century with a cold extremum \r\n(for 50-yr smoothing) of about 1.1 K below the temperature \r\nof the calibration period, AD 1880-1960. This cooling is about \r\ntwice as large as corresponding numbers reported by most other\r\nreconstructions. In the beginning of the millennium the new \r\nreconstruction shows small anomalies in agreement with previous \r\nstudies. However, the new temperature reconstruction decreases \r\nfaster than previous reconstructions in the first 600 years \r\nof the millennium and has a stronger variability. The salient \r\nfeatures of the new reconstruction are shown to be robust \r\nto changes in the calibration period, the source of the local \r\ntemperatures, the spatial averaging procedure, and the screening \r\nprocess applied to the proxies. An ensemble pseudoproxy approach \r\nis applied to estimate the confidence intervals of the 50-yr \r\nsmoothed reconstruction showing that the period AD 1500-1850 \r\nis significantly colder than the calibration period.\r\n\r\n\r\n","author":null,"citation":"Christiansen, B. and F.C. Ljungqvist. 2011. \r\nReconstruction of the Extratropical NH Mean Temperature over the Last \r\nMillennium with a Method that Preserves Low-Frequency Variability. \r\nJournal of Climate, Vol. 24, Issue 23, pp. 6013-6034, December 2011. \r\ndoi: http://dx.doi.org/10.1175/2011JCLI4145.1 \r\n","edition":null,"identifier":{"id":"10.1175/2011JCLI4145.1","type":"doi","url":"http://dx.doi.org/10.1175/2011JCLI4145.1"},"issue":null,"journal":"Journal of Climate","pages":null,"pubRank":"1","pubYear":2011,"reportNumber":null,"title":"Reconstruction of the Extratropical NH Mean Temperature over the Last  Millennium with a Method that Preserves Low-Frequency Variability","type":"publication","volume":null}],"reconstruction":"Y","scienceKeywords":["Air Temperature Reconstruction","temperature"],"site":[{"NOAASiteId":"52563","geo":{"geoType":"Feature","geometry":{"coordinates":["30","90","-180","180"],"type":"POLYGON"},"properties":{"easternmostLongitude":"180","maxElevationMeters":null,"minElevationMeters":null,"northernmostLatitude":"90","southernmostLatitude":"30","westernmostLongitude":"-180"}},"locationName":"Geographic Region>Northern Hemisphere","mappable":"N","paleoData":[{"NOAADataTableId":"20717","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>reconstructions>air temperature"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/christiansen2011/christiansen2011.txt","linkText":"christiansen2011.txt","urlDescription":"Original Data and Full Metadata","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":"simple linear regression","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"anomalized","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":"regression analysis","cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"Thin blue curves in Figs. 9 and 14 (upper panel)","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"anomalized","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"Thick blue curves in Figs. 9 and 14 (upper panel); 50 year smooth","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"smoothed","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"Thick blue curves in Figs. 9 and 14 (upper panel); 50 year smooth","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"anomalized","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"Thick red curve in Fig. 14 (upper panel) 50 year smoothed plus bias","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"smoothed","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"Thick red curve in Fig. 14 (upper panel) 50 year smoothed plus bias","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"anomalized","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"97.5th percentile; Dashed red curve in Fig. 14 (upper panel); 50 year smoothed","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"smoothed","cvError":"percentile","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"97.5th percentile; Dashed red curve in Fig. 14 (upper panel); 50 year smoothed","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"anomalized","cvError":"percentile","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"2.5th percentile; Dashed red curve in Fig. 14 (upper panel) 50 year smoothed","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"smoothed","cvError":"percentile","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"2.5th percentile; Dashed red curve in Fig. 14 (upper panel) 50 year smoothed","cvDataType":"CLIMATE RECONSTRUCTIONS","cvDetail":"anomalized","cvError":"percentile","cvFormat":"Numeric","cvMaterial":"reconstruction material>multiple proxies","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"}]},{"NOAAKeywords":["earth science>paleoclimate>reconstructions>air temperature"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/christiansen2011/christiansen2011.xls","linkText":"christiansen2011.xls","urlDescription":"Original Data and Full Metadata","variables":[]}],"dataTableName":"ExtratropicsChristiansen2011","dataTableNotes":null,"earliestYear":1000,"earliestYearBP":950,"earliestYearCE":1000,"mostRecentYear":2000,"mostRecentYearBP":-50,"mostRecentYearCE":2000,"species":[],"timeUnit":"AD"}],"siteName":"Northern Hemisphere Extratropics"}],"studyCode":null,"studyName":"Northern Hemisphere Extratropical 1000 Year Temperature Reconstruction","studyNotes":"1000 year temperature reconstruction for the Northern Hemisphere \nextratropical region (30°N-90°N) by the LOC method.  The new LOC \nmethod reconstructs the local temperatures at the locations \nof the proxies. The reconstruction is based on one-dimensional \nlinear regression with the local temperature as the independent \nvariable and the proxy as the dependent variable. The local \nreconstructed temperatures are then averaged to get the NH mean \ntemperature. While this method preserves low-frequency variability, \nthe drawback is an exaggerated high-frequency variability. \nThis adverse effect can be dampened by temporal averaging \nand decreases with the number of (independent) proxies.\n","version":"1.0","xmlId":"10417"}