{"xmlId":"2908","NOAAStudyId":"9096","studyName":"Okhotsk Sea MD01-2412 Alkenone Data and SST Reconstruction","doi":"https://doi.org/10.25921/9sfa-b552","uuid":"a1df5d3f-15c6-4fd7-b29e-e13c89314234","dataPublisher":"NOAA","contactInfo":{"type":"CONTACT INFORMATION","shortName":"DOC/NOAA/NESDIS/NCEI","longName":"National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce ","address":"325 Broadway, E/NE31","city":"Boulder","state":"CO","postalCode":"80305-3328","country":"USA","dataCenterUrl":"https://www.ncei.noaa.gov/products/paleoclimatology","email":"paleo@noaa.gov","phone":"828-271-4800","fax":null,"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."},"dataType":"PALEOCEANOGRAPHY","investigators":"Harada, N.; Ahagon, N.; Sakamoto, T.; Uchida, M.; Ikehara, M.; Shibata, Y.","investigatorDetails":[{"firstName":"Naomi","lastName":"Harada","initials":"N.","orcId":"0000-0002-2725-7346"},{"firstName":"Naokazu","lastName":"Ahagon","initials":"N.","orcId":null},{"firstName":"Tatsuhiko","lastName":"Sakamoto","initials":"T.","orcId":null},{"firstName":"Masao","lastName":"Uchida","initials":"M.","orcId":null},{"firstName":"Minoru","lastName":"Ikehara","initials":"M.","orcId":"0000-0002-2695-4713"},{"firstName":"Yasuyuki","lastName":"Shibata","initials":"Y.","orcId":null}],"version":"1.0","funding":[{"fundingAgency":"Japan Agency for Marine-Earth Science and Technology","fundingGrant":null},{"fundingAgency":"Japan Ministry of Education, Culture, Sports, Science and Technology (MEXT)","fundingGrant":"KAKENHI No. 14540458"}],"studyNotes":"Sea surface temperature data derived from alkenones, phytoplankton-produced biomarkers used as a proxy for past sea surface conditions; the data reveal abrupt changes of SST in the south-western Okhotsk Sea over the past 120 kyr. Data from Okhotsk Sea IMAGES core MD01-2412: 44 deg. 31.65'N, 145 deg. 0.25'E, 1225m water depth. The alkenone unsaturation index, UK'37, which is the ratio of methyl alkenones with 37 carbon atoms and two double bonds to those with two or three double bonds [UK'37 = [C37:2)/[C37:2 + C37:3)], is a proxy for a water temperature. The calibration equation, UK'37 = 0.034T (DegreeC) + 0.039, was used. An age model was constructed by using multiple proxies: radiocarbon ages of planktonic foraminiferal tests (Neogloboquadrina pachyderma, test sizes > 125 um); oxygen isotopic stratigraphy of benthic foraminifera (Uvigerina akitaensis, test sizes > 180 um); variations of biogenic opal content; and tephrochronology. Eleven 14C ages, 1.85, 3.17, 8.2, 9.76, 23.66, 27.85, 28.91, 36.98, 37.2, 40.89, and 43.45 kyr BP, were determined at the AMS facility of the National Institute for Environmental Studies of Japan (Tandem Accelerator for Environmental Research and Radiocarbon Analysis).  The 14C reservoir age, 784 yr, which is the mean northwestern North Pacific reservoir age  (Kuzumin et al., 2001), was used. Radiocarbon ages <21 kyr BP were converted to calendar ages by using the CALIB4.4 program (Stuiver and Braziunas, 1993) and its data set (Stuiver et al., 1998a, 1998b), and ages >21 kyr BP were converted by the polynomial equation of Bard (1998). Plural alkenone temperatures at the same depth indicate the results of duplicate or triplicate analysis.","onlineResourceLink":"https://www.ncei.noaa.gov/access/paleo-search/study/9096","difMetadataLink":"https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-ocean-9096.xml","isoMetadataLink":"https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/iso/xml/noaa-ocean-9096.xml","originalSource":null,"dataTypeInformation":"https://www.ncei.noaa.gov/products/paleoclimatology/paleoceanography","studyCode":null,"scienceKeywords":["Sea Surface Temperature Reconstruction"],"reconstruction":"Y","contributionDate":"2006-12-01","entryId":"noaa-ocean-9096","earliestYearBP":115970,"mostRecentYearBP":0,"earliestYearCE":-114020,"mostRecentYearCE":1950,"publication":[{"author":{"name":"Harada, N., N. Ahagon, T. Sakamoto, M. Uchida, M. Ikehara, and Y. Shibata"},"pubYear":2006,"title":"Rapid fluctuation of alkenone temperature in the southwestern Okhotsk Sea during the past 120 ky","journal":"Global and Planetary Change","volume":"53","edition":null,"issue":"1-2","pages":"29-46","reportNumber":null,"citation":"Harada, N., N. Ahagon, T. Sakamoto, M. Uchida, M. Ikehara, and Y. Shibata. 2006. Rapid fluctuation of alkenone temperature in the southwestern Okhotsk Sea during the past 120 ky. Global and Planetary Change, 53(1-2), 29-46. doi: 10.1016/j.gloplacha.2006.01.010","type":"publication","identifier":{"type":"doi","id":"10.1016/j.gloplacha.2006.01.010","url":"http://dx.doi.org/10.1016/j.gloplacha.2006.01.010"},"abstract":"Sea-ice expansion in the Okhotsk Sea in winter is sensitively affected by global warming and cooling. Regionally, the southwestern Okhotsk Sea is closely linked to climate change in East Asia, including Japan, because the cold sea surface temperature (SST) in the southwestern Okhotsk Sea influences directly the development of the Okhotsk atmospheric high-pressure system, and the activated Okhotsk high causes cold climatic conditions in northern Japan. Therefore, environmental change in the Okhotsk Sea indicates two-way interactions as a sensitive mirror reflecting global climate change and as a driving force of regional climate change. To better understand how surface environmental changes in the Okhotsk Sea can influence climate change in East Asia, SSTs were estimated in the southwestern Okhotsk Sea for the past 120 ky with millennial to centennial time resolution using the long-chain unsaturated alkyl ketone (alkenone) thermometer. The alkenone temperature, which corresponds to the SST to 20 m depth in autumn, showed repeated abrupt changes at a centennial timescale, especially during the last glacial period, 20-60 ky before present (BP). The alkenone temperature changed concurrently with changes from interstadials (warm events) to stadials (cold events) in the d18O record of the ice cores from Greenland, although some interstadials could not be identified in the alkenone temperature record. A wavelet power spectrum analysis showed that a periodicity of about 8 ky was prominent during 10K90 ky BP, and a 4- to 5-ky cycle was characteristic during 30K40 ky BP in the alkenone temperature records. These periodicities were both similar and dissimilar to those in the Polar Circulation Index, which is based on the atmospheric circulation intensity at high latitudes, as recorded by major-ion concentrations in GISP2. Both the similarity and dissimilarity imply that the SST in the southwestern Okhotsk Sea is controlled mainly by the atmosphere-ocean circulation system in the Northern Hemisphere; however, the relationship between the SST in the Okhotsk Sea and the climate in the Greenland is not linear. Anomalously high alkenone temperatures occurred repeatedly in the glacial period. These warm alkenone temperature episodes would have had multiple causes. In particular, high alkenone temperatures during the last glacial maximum (LGM) have been reported previously for locations near this study site. More investigations are necessary to understand what happened in the Okhotsk Sea and in adjacent seas at the time of the LGM.","pubRank":"1"}],"site":[{"NOAASiteId":"30652","siteName":"MD01-2412","siteCode":null,"mappable":"Y","locationName":"Ocean>Pacific Ocean>North Pacific Ocean","geo":{"geoType":"Feature","geometry":{"type":"POINT","coordinates":["44.5275","145.0042"]},"properties":{"southernmostLatitude":"44.5275","northernmostLatitude":"44.5275","westernmostLongitude":"145.0042","easternmostLongitude":"145.0042","minElevationMeters":"-1225","maxElevationMeters":"-1225"}},"paleoData":[{"dataTableName":"MD01-2412","NOAADataTableId":"12407","earliestYear":115970,"mostRecentYear":0,"timeUnit":"cal yr BP","earliestYearBP":115970,"mostRecentYearBP":0,"earliestYearCE":-114020,"mostRecentYearCE":1950,"coreLengthMeters":null,"dataTableNotes":null,"species":[],"dataFile":[{"fileUrl":"https://www.ncei.noaa.gov/pub/data/paleo/paleocean/sediment_files/complete/md1-2412-tab.txt","urlDescription":"Alternate Format Data","linkText":"md1-2412-tab.txt","variables":[],"NOAAKeywords":["earth science>paleoclimate>paleocean>biomarkers","earth science>paleoclimate>paleocean>reconstruction"]},{"fileUrl":"https://www.ncei.noaa.gov/pub/data/paleo/paleocean/by_contributor/harada2006/harada2006.txt","urlDescription":"Text File","linkText":"Sea of Okhotsk Alkenone Data and SST Reconstruction","variables":[{"cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOCEANOGRAPHY","cvWhat":"earth system variable>temperature variable>temperature>sea water temperature>sea surface temperature","cvMaterial":"reconstruction material>organic compound index>alkenone unsaturation index","cvError":null,"cvUnit":"temperature unit>degree Celsius","cvSeasonality":null,"cvDetail":null,"cvMethod":null,"cvAdditionalInfo":null,"cvFormat":"Numeric","cvShortName":"SST"},{"cvDataType":"PALEOCEANOGRAPHY","cvWhat":"depth variable>depth","cvMaterial":null,"cvError":null,"cvUnit":"length unit>meter","cvSeasonality":null,"cvDetail":null,"cvMethod":null,"cvAdditionalInfo":null,"cvFormat":"Numeric","cvShortName":"depth_m"},{"cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOCEANOGRAPHY","cvWhat":"age variable>age","cvMaterial":null,"cvError":null,"cvUnit":"time unit>age unit>calendar kiloyear before present","cvSeasonality":null,"cvDetail":null,"cvMethod":null,"cvAdditionalInfo":null,"cvFormat":"Numeric","cvShortName":"age_calkaBP"},{"cvDataType":"PALEOCEANOGRAPHY","cvWhat":"chemical composition>compound>organic compound>organic compound index>alkenone unsaturation index>alkenone unsaturation index Uk37 prime","cvMaterial":null,"cvError":null,"cvUnit":"dimensionless","cvSeasonality":null,"cvDetail":null,"cvMethod":null,"cvAdditionalInfo":null,"cvFormat":"Numeric","cvShortName":"Uk37"}],"NOAAKeywords":["earth science>paleoclimate>paleocean>reconstruction","earth science>paleoclimate>paleocean>biomarkers"]}]}]}],"reference":{"pastThesaurusSkos":"https://www.ncei.noaa.gov/access/paleo-search/skos/past-thesaurus.rdf","pastThesaurusExplorer":"https://www.ncei.noaa.gov/access/paleo-search/cvterms","gcmdKeywordThesaurus":"https://earthdata.nasa.gov/earth-observation-data/find-data/idn/gcmd-keywords"},"dataLicenseDescription":null,"dataLicenseUrl":null}