{"NOAAStudyId":"14172","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":"2013-03-28","dataPublisher":"NOAA","dataType":"ICE CORES","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/ice-core","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-icecore-14172.xml","doi":null,"earliestYearBP":2377,"earliestYearCE":-427,"entryId":"noaa-icecore-14172","funding":[{"fundingAgency":"US National Science Foundation","fundingGrant":"ANT-0538049, AGS-0704169"}],"investigators":"Sofen, E.D.; Alexander, B.; Steig, E.J.; Thiemens, M.H.; Kunasek, S.A.; Amos, H.M.; Schauer, A.J.; Hastings, M.G.; Bautista, J.; Jackson, T.L.; Vogel, L.E.; McConnell, J.R.; Pasteris, D.R.; Saltzman, E.S.","mostRecentYearBP":-58,"mostRecentYearCE":2008,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/14172","originalSource":null,"publication":[{"abstract":"The 17O excess (D17O = d17O-0.52 x d18O) of sulfate and nitrate reflects the relative importance of their different production pathways in the atmosphere. A new record of sulfate and nitrate D17O spanning the last 2400 years from the West Antarctic Ice Sheet Divide ice core project shows significant changes in both sulfate and nitrate D17O in the most recent 200 years, indicating changes in their formation pathways. The sulfate D17O record exhibits a 1.1 per mil increase in the early 19th century from (2.4 +/- 0.2) per mil to (3.5 +/- 0.2) per mil, which suggests that an additional 12-18% of sulfate formation occurs via aqueous-phase production by O3, relative to that in the gas phase. Nitrate D17O gradually decreases over the whole record, with a more rapid decrease between the mid-19th century and the present day of 5.6 per mil, indicating an increasing importance of RO2 in NOx cycling between the mid-19th century and the present day in the mid- to high-latitude Southern Hemisphere. The former has implications for the climate impacts of sulfate aerosol, while the latter has implications for the tropospheric O3 production rate in remote low-NOx environments. Using other ice core observations, we rule out drivers for these changes other than variability in extratropical oxidant (OH, O3, RO2, H2O2, and reactive halogens) concentrations. However, assuming OH, H2O2, and O3 are the main oxidants contributing to sulfate formation, Monte Carlo box model simulations require a large (>= 260%) increase in the O3 /OH mole fraction ratio over the Southern Ocean in the early 19th century to match the sulfate D17O record. This unlikely scenario points to a~deficiency in our understanding of sulfur chemistry and suggests other oxidants may play an important role in sulfate formation in the mid- to high-latitude marine boundary layer. The observed decrease in nitrate D17O since the mid-19th century is most likely due to an increased importance of RO2 over O3 in NOx cycling and can be explained by a 60-90% decrease in the O3 / RO2 mole fraction ratio in the extratropical Southern Hemisphere NOx-source regions.","author":{"name":"Sofen, E.D., B. Alexander, E.J. Steig, M.H. Thiemens, S.A. Kunasek, H.M. Amos, A.J. Schauer, M.G. Hastings, J. Bautista, T.L. Jackson, L.E. Vogel, J.R. McConnell, D.R. Pasteris, and E.S. Saltzman"},"citation":"Sofen, E.D., B. Alexander, E.J. Steig, M.H. Thiemens, S.A. Kunasek, H.M. Amos, A.J. Schauer, M.G. Hastings, J. Bautista, T.L. Jackson, L.E. Vogel, J.R. McConnell, D.R. Pasteris, and E.S. Saltzman. 2014. WAIS Divide ice core record suggests sustained changes in the chemical formation pathways of sulfate and nitrate aerosol since the 19th century. Atmospheric Chemistry and Physics, 14(11), 5749-5769. doi: 10.5194/acp-14-5749-2014","edition":null,"identifier":{"id":"10.5194/acp-14-5749-2014","type":"doi","url":"http://dx.doi.org/10.5194/acp-14-5749-2014"},"issue":"11","journal":"Atmospheric Chemistry and Physics","pages":"5749-5769","pubRank":"1","pubYear":2014,"reportNumber":null,"title":"WAIS Divide ice core record suggests sustained changes in the chemical formation pathways of sulfate and nitrate aerosol since the 19th 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