noaa-icecore-12256 eng; USA utf8 dataset Bauer, Bruce DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce +1 303-497-6280 +1 303-497-6513 325 Broadway, E/CC23 Boulder CO 80305-3328 USA paleo@noaa.gov pointOfContact 2018-12-11 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) NOAA/WDS Paleoclimatology - Summit, Greenland Firn Cosmogenic 14CH4 Data 2011-10-16 publication noaa-icecore-12256 NCEI DSI 1200_01 Petrenko, V.V. originator Petrenko, V.V. author Severinghaus, J. originator Severinghaus, J. author NOAA National Centers for Environmental Information publisher tableDigital This archived Paleoclimatology Study is available from the NOAA National Centers for Environmental Information (NCEI), under the World Data Service (WDS) for Paleoclimatology. The associated NCEI study type is Ice Core. The data include parameters of ice cores with a geographic location of Greenland. The time period coverage is from 0 to -55 in calendar years before present (BP). See metadata information for parameter and study location details. Please cite this study when using the data. Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice caps around the world. Parameter keywords describe what was measured in this dataset. Additional summary information can be found in the abstracts of papers listed in the dataset citations. completed Bauer, Bruce DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce +1 303-497-6280 +1 303-497-6513 325 Broadway, E/CC23 Boulder CO 80305-3328 USA paleo@noaa.gov pointOfContact https://www.ncdc.noaa.gov/c/images/pc-default-icecore.png Paleoclimatology - Ice Core PNG Earth Science > Climate Indicators > Paleoclimate Indicators > Ice Core Records Earth Science > Paleoclimate > Ice Core Records theme Global Change Master Directory (GCMD) Science Keywords 2018 revision Version 8.6 Global Change Data Center, Science and Exploration Directorate, Goddard Space Flight Center (GSFC) National Aeronautics and Space Administration (NASA) https://earthdata.nasa.gov/about/gcmd/global-change-master-directory-gcmd-keywords HTTPS Web Browser Global Change Master Directory (GCMD) Keywords The information provided on this page seeks to define how the GCMD Keywords are structured, used and accessed. It also provides information on how users can participate in the further development of the keywords. information publisher earth science > paleoclimate > ice cores earth science > paleoclimate > ice cores earth science > paleoclimate > ice cores earth science > paleoclimate > ice cores earth science > paleoclimate > ice cores earth science > paleoclimate > ice core > radiogenic isotopes theme Global Change Master Directory (GCMD) Science Keywords 2018 revision Version 8.6 Global Change Data Center, Science and Exploration Directorate, Goddard Space Flight Center (GSFC) National Aeronautics and Space Administration (NASA) https://earthdata.nasa.gov/about/gcmd/global-change-master-directory-gcmd-keywords HTTPS Web Browser Global Change Master Directory (GCMD) Keywords The information provided on this page seeks to define how the GCMD Keywords are structured, used and accessed. It also provides information on how users can participate in the further development of the keywords. information publisher Continent > North America > Greenland> Summit Firn > LATITUDE 72.57963 > LONGITUDE -38.49253 place otherRestrictions Cite as: Petrenko, V.V.; Severinghaus, J. (2011-10-16): NOAA/WDS Paleoclimatology - Summit, Greenland Firn Cosmogenic 14CH4 Data . [indicate subset used]. NOAA National Centers for Environmental Information. https://www.ncdc.noaa.gov/paleo/study/12256. Accessed [date]. otherRestrictions Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives. otherRestrictions Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose. otherRestrictions None otherRestrictions 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. eng; USA geoscientificInformation Date Range: 1950 AD to 2005 AD; Date Range: 0 cal yr BP to -55 cal yr BP; -38.49253 -38.49253 72.57963 72.57963 Study Coordinates 72.57963 -38.49253 1950 2005 STUDY NOTES: This project successfully examined the question of whether or not cosmic ray-produced 14C forms radiomethane (14CH4) in polar firn. Firn samples from ~4.5 m depth were taken at Summit, Greenland. Around 1000 kg of firn per sample was melted in the presence of a 14C-free carrier gas to extract gases from the firn matrix. The findings indicate a small but clearly present cosmogenic 14CH4 component. A larger cosmogenic 14C – carbon monoxide (14CO) component was also found. The results further indicated that almost all cosmogenic 14C is being lost rapidly from the firn matrix at this depth level. These results confirm a surprising earlier finding (Petrenko et al., 2009) that cosmogenic 14CH4 may be present in glacial ice. Work using paleoatmospheric 14CH4 to study the fossil source contribution to the methane budget therefore needs to take the cosmogenic component into account. The results are currently in preparation for publication. The firn samples were collected between Jul 29 and Aug 18, 2009. INSTRUMENT AND METHOD DESCRIPTION The field and analytical system for determinations of in-situ cosmogenic 14CO and 14CH4 in glacial ice and firn have been described in (Petrenko et al., 2008a; Petrenko et al., 2008b; Petrenko et al., 2009). This system involves the melt-extraction of occluded air from very large volumes of glacial ice or at the sampling / ice coring site. Briefly, the present field system consists of a large chemically polished aluminum vacuum melting tank (~670 L internal volume) and a series vacuum and transfer pumps. The ice is loaded into the tank, and the headspace is evacuated and flushed 3x with either ultra-high purity (UHP) air, nitrogen or argon. The ice is then melted, releasing the ancient air into the headspace. This air is then recirculated through the tank via a bubbler manifold at the bottom, equilibrating all the gases between the water and the headspace. The air is then extracted from the tank by clean diaphragm transfer pumps and stored in electropolished stainless steel canisters for further laboratory handling and analyses. In the laboratory, the air is first processed through a system that converts either CH4 or CO to CO2, and captures this CO2 for further handling. In the case of CH4 processing, H2O, CO2, N2O and other condensibles are first removed by a series of traps at liquid nitrogen temperature. CO is then quantitatively oxidized to CO2 by the Sofonocat reagent and subsequently removed by further cryotraps. CH4 is then combusted to CO2 by passing the air through a 800°C furnace containing platinized quartz wool. The CH4-derived CO2 is then captured. This CO2 is then converted to graphite over ultra-high-purity iron powder and subsequently measured for 14C by AMS. The combined procedural 14CH4 blank for all steps of sampling handling was determined to be 0.75 ± 0.38 pMC, on the basis of 72 processed blank and standard samples (Petrenko et al., 2008b). For CO analyses, the sample handling is very similar except that the air bypasses Sofnocat, and the furnace temperature is reduced from 800 to 150 °C. This allows for complete combustion of CO while CH4 passes through unaffected. DATA COLLECTION AND PROCESSING The 14CH4 data are corrected for ambient air added to the samples from air bubbles in the firn as well as for the procedural blank. For 14CO, the ambient air correction is insignificant, but the samples are corrected for the procedural blank. ABSTRACT SUPPLIED BY ORIGINATOR: The cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (~11,600 years ago) has been the subject of much debate. The carbon-14 (14C) content of methane (14CH4) should distinguish between wetland and clathrate contributions to this increase. We present measurements of 14CH4 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured 14CH4 values were higher than predicted under any scenario. Sample 14CH4 appears to be elevated by direct cosmogenic 14C production in ice. 14C of CO was measured to better understand this process and correct the sample 14CH4. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas–Preboreal CH4 rise. 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Native Format(s) https://data.nodc.noaa.gov/cgi-bin/iso?id=noaa-icecore-12256 HTTPS Landing Page NCEI landing page for this dataset Dataset landing page with general information and links to access the data. information https://www.ncdc.noaa.gov/paleo/study/12256 HTTPS Web Browser NCEI Study Page Study page with dataset access information. search https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/ice-core HTTPS Information NCEI Ice Core Page General information for this data type. information https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/summitfirn14ch4.xls HTTP Download NCEI Direct Download Direct download links for dataset files. download https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/summitfirn14ch4.txt HTTP Download NCEI Direct Download Direct download links for dataset files. download asNeeded This metadata record was translated from DIF using dif-9x-to-iso-19115-2.xsl Version: 2018-10-25