{"NOAAStudyId":"5451","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":"2006-03-01","dataPublisher":"NOAA","dataType":"PALEOLIMNOLOGY","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/lake","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-lake-5451.xml","doi":null,"earliestYearBP":9494,"earliestYearCE":-7544,"entryId":"noaa-lake-5451","funding":[],"investigators":"Morrill, C.; Overpeck, J.T.; Cole, J.E.; Liu, K.-B.; Shen, C.; Tang, L.","mostRecentYearBP":3887,"mostRecentYearCE":-1937,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/5451","originalSource":null,"publication":[{"abstract":"We present a record of monsoon variations for the early and middle Holocene  that is inferred from the geochemistry of sediment cores from Ahung Co,  a lake in central Tibet.  The resolution of this record is better than 50 years  and the age model is derived from radiocarbon ages of terrestrial charcoal,  which eliminates errors associated with the lake hard-water effect.  We made  down-core geochemical measurements of: % carbonate, % organic carbon, C/N and  d13C of bulk organic matter, d13C and d18O of carbonate, and % dolomite.   Proxy calibration and modern water-balance reconstruction show that these are  proxies for lake depth and the amount of monsoon precipitation.  We find that  lake level and monsoon precipitation have been decreasing at Ahung Co since  the early Holocene (~7500 cal yr BP).  Superimposed on this trend are rapid  declines in monsoon rainfall at 7000-7500 and 4700 cal yr BP and seven  century-scale wet-dry oscillations.  The cores do not contain sediment from  the last ~4000 years.  Surface sediments from the lake accumulated during the  20th century, however.  From this, we argue that lake levels have risen again  recently following a late Holocene dry period.","author":null,"citation":"Morrill, C., J.T. Overpeck, J.E. Cole, K.-B. Liu, C. Shen, L. Tang. 2006. Holocene variations in the Asian monsoon inferred from the geochemistry of lake sediments in central Tibet. Quaternary Research Vol. 65, pp. 232-243","edition":null,"identifier":null,"issue":null,"journal":"Quaternary Research","pages":null,"pubRank":"1","pubYear":2006,"reportNumber":null,"title":"Holocene variations in the Asian monsoon inferred from the geochemistry of lake sediments in central Tibet","type":"publication","volume":null}],"reconstruction":"N","scienceKeywords":null,"site":[{"NOAASiteId":"8888","geo":{"geoType":"Feature","geometry":{"coordinates":["31.62","92.06"],"type":"POINT"},"properties":{"easternmostLongitude":"92.06","maxElevationMeters":"4575","minElevationMeters":"4575","northernmostLatitude":"31.62","southernmostLatitude":"31.62","westernmostLongitude":"92.06"}},"locationName":"Continent>Asia>Eastern Asia>China","mappable":"Y","paleoData":[{"NOAADataTableId":"7206","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth 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proxies","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"dimensionless","cvWhat":"statistical variable>multivariate eigenvector-based variable>principal component"},{"cvAdditionalInfo":"PC#2 of multiple geochemical proxies","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"dimensionless","cvWhat":"statistical variable>multivariate eigenvector-based variable>principal component"},{"cvAdditionalInfo":"PC#3 of multiple geochemical proxies","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"dimensionless","cvWhat":"statistical variable>multivariate eigenvector-based variable>principal component"}]},{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>geochemistry"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.xls","linkText":"ahungco2006.xls","urlDescription":"Data","variables":[]}],"dataTableName":"Ahung Co Core AHUNGCO","dataTableNotes":null,"earliestYear":9494,"earliestYearBP":9494,"earliestYearCE":-7544,"mostRecentYear":3887,"mostRecentYearBP":3887,"mostRecentYearCE":-1937,"species":[],"timeUnit":"cal yr BP"}],"siteName":"Ahung Co"}],"studyCode":null,"studyName":"Ahung Co, Tibet Holocene Sediment Geochemistry","studyNotes":"Geochemical data from cores 2A, 3A and 4A from Ahung Co, Tibet","version":"1.0","xmlId":"627"}