{"NOAAStudyId":"6109","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":"2009-03-01","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-6109.xml","doi":null,"earliestYearBP":9190,"earliestYearCE":-7240,"entryId":"noaa-lake-6109","funding":[],"investigators":"Conroy, J.L.; Overpeck, J.T.; Cole, J.E.; Shanahan, T.; Steinitz-Kannan, M.","mostRecentYearBP":-50,"mostRecentYearCE":2000,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/6109","originalSource":null,"publication":[{"abstract":"Paleoclimate records from the tropical Pacific suggest the early to mid-Holocene was a period of reduced El Niño/Southern Oscillation (ENSO) variability, with a transition to modern, increased ENSO frequency occurring some time in the last few thousand years. However, the nature and timing of this shift remains uncertain due to the discontinuous nature and/or coarse resolution of many ENSO proxies, as well as a lack of agreement between previously published records. A new, continuous, climate record from El Junco Crater Lake in the Galápagos Islands reveals several abrupt changes in lake level and precipitation through the Holocene. Hydroclimatic model simulations suggest that El Junco lake level responds sensitively to increases in precipitation associated with El Niño events, rising during wet El Niño events and falling during the intervening dry periods. Grain size data from El Junco sediment cores indicate past lake level variability, likely associated with changing seasonal precipitation and ENSO frequency. The grain size data suggest increased precipitation intensity prior to 9000±120 cal years BP, and after 4200±130 cal years BP, as well as a two-step increase in precipitation at 3200±160 and 2000±100 cal years BP. Maximum Holocene precipitation and inferred ENSO variability occurred between 2000±100 and 1500±70 cal years BP, during the same period that six other independent proxy records suggest higher ENSO frequency and longer, stronger El Niño events. Decreasing sediment carbon/nitrogen (C/N) ratios in El Junco sediments indicate rising lake levels from the early Holocene to present, corroborating the grain size data. The inferred increase in precipitation at 4200±130 cal years BP and at 2000±100 cal years BP coincides with decreasing Southwest Asian and East Asian Monsoon intensity, suggesting tropical Pacific climate and the Asian monsoon were interconnected systems at centennial to millennial timescales during the Holocene. A weakening trend in the Asian monsoon and the trend toward wetter conditions at El Junco also coincide with a trend toward cooler and drier conditions inferred from Cariaco Basin sediment proxies from the mid-Holocene to present, suggesting the migration of the Intertropical Convergence Zone (ITCZ) likely influenced hydrological changes in both the eastern tropical Pacific and the Asian Monsoon region during the Holocene.","author":{"name":"Jessica L. Conroy, Jonathan T. Overpeck, Julia E. Cole, Timothy M. Shanahan, Miriam Steinitz-Kannan"},"citation":"Jessica L. Conroy, Jonathan T. Overpeck, Julia E. Cole, Timothy M. Shanahan, Miriam Steinitz-Kannan. 2008. Holocene changes in eastern tropical Pacific climate inferred from a Galápagos lake sediment record. Quaternary Science Reviews, 27(11-12), 1166-1180. doi: 10.1016/j.quascirev.2008.02.015","edition":null,"identifier":{"id":"10.1016/j.quascirev.2008.02.015","type":"doi","url":"http://dx.doi.org/10.1016/j.quascirev.2008.02.015"},"issue":"11-12","journal":"Quaternary Science Reviews","pages":"1166-1180","pubRank":"1","pubYear":2008,"reportNumber":null,"title":"Holocene changes in eastern tropical Pacific climate inferred from a Galápagos lake sediment record","type":"publication","volume":"27"}],"reconstruction":"N","scienceKeywords":["PAGES LOTRED SA2k","PAGES 2k Network"],"site":[{"NOAASiteId":"9286","geo":{"geoType":"Feature","geometry":{"coordinates":["-.87","-89.45"],"type":"POINT"},"properties":{"easternmostLongitude":"-89.45","maxElevationMeters":null,"minElevationMeters":null,"northernmostLatitude":"-0.87","southernmostLatitude":"-0.87","westernmostLongitude":"-89.45"}},"locationName":"Continent>South America>Ecuador","mappable":"Y","paleoData":[{"NOAADataTableId":"9412","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>mineralogy"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/ecuador/galapagos/eljunco2008.txt","linkText":"eljunco2008.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"centimeter","cvWhat":"depth variable>depth"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"year Common Era","cvWhat":"age variable>age"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"calendar year before present","cvWhat":"age variable>age"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological material>sediment","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"percent","cvWhat":"physical property>diameter>grain size>grain size class>clay"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological material>sediment","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"percent","cvWhat":"physical property>diameter>grain size>grain size class>sand"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological material>sediment","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"percent","cvWhat":"physical property>diameter>grain size>grain size class>silt"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological material>sediment","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"percent","cvWhat":"chemical composition>element or single-element molecule>carbon>organic carbon"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological material>sediment","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"percent","cvWhat":"chemical composition>element or single-element molecule>nitrogen"},{"cvAdditionalInfo":"organic carbon/organic nitrogen","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological material>sediment","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"dimensionless","cvWhat":"chemical composition>element or compound ratio>carbon/nitrogen"}]},{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>mineralogy"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/ecuador/galapagos/eljunco2008.xls","linkText":"eljunco2008.xls","urlDescription":"Data","variables":[]}],"dataTableName":"ELJUNCO grain size","dataTableNotes":null,"earliestYear":9190,"earliestYearBP":9190,"earliestYearCE":-7240,"mostRecentYear":-50,"mostRecentYearBP":-50,"mostRecentYearCE":2000,"species":[],"timeUnit":"cal yr BP"}],"siteName":"El Junco"}],"studyCode":null,"studyName":"El Junco Lake, Galápagos Holocene Grain Size Data","studyNotes":"The dataset contains clay, silt, sand, organic C, organic N, and C/N values with the corresponding sampling depths and ages (calibrated radiocarbon, 210Pb and 137Cs age model). Age model data is published in Conroy et al. 2008.","version":"1.0","xmlId":"678"}