{"NOAAStudyId":"2447","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":"2001-01-30","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-2447.xml","doi":null,"earliestYearBP":19050,"earliestYearCE":-17100,"entryId":"noaa-icecore-2447","funding":[],"investigators":"Thompson, L.G.; Mosley-Thompson, E.; Davis, M.D.; Lin, P-N.; Henderson, K.A.; Cole-Dai, J.; Bolzan, J.F.; Liu, K-B.","mostRecentYearBP":-43,"mostRecentYearCE":1993,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/2447","originalSource":null,"publication":[{"abstract":"Two ice cores from the col of Huascarán in the north-central Andes of Peru contain a paleoclimatic history extending well into the Wisconsinan (Würm) Glacial Stage and include evidence of the Younger Dryas cool phase. Glacial stage conditions at high elevations in the tropics appear to have been as much as 8° to 12°C cooler than today, the atmosphere contained about 200 times as much dust, and the Amazon Basin forest cover may have been much less extensive. Differences in both the oxygen isotope ratio d18O (8 per mil) and the deuterium excess (4.5 per mil) from the Late Glacial Stage to the Holocene are comparable with polar ice core records. These data imply that the tropical Atlantic was possibly 5° to 6°C cooler during the Late Glacial Stage, that the climate was warmest from 8400 to 5200 years before present, and that it cooled gradually, culminating with the Little Ice Age (200 to 500 years before present). A strong warming has dominated the last two centuries. ","author":null,"citation":"Thompson, L.G., E. Mosley-Thompson, M.E. Davis, \r\nP-N. Lin, K.A. Henderson, J. Cole-Dai, J.F. Bolzan and K-b. Liu. 1995. Late Glacial Stage and Holocene tropical ice core records from Huascarán, Peru. Science, Vol. 269, pp.46-50. DOI:10.1126/science.269.5220.46","edition":null,"identifier":{"id":"10.1126/science.269.5220.46","type":"doi","url":"http://dx.doi.org/10.1126/science.269.5220.46"},"issue":null,"journal":"Science","pages":null,"pubRank":"1","pubYear":1995,"reportNumber":null,"title":"Late Glacial Stage and Holocene tropical ice core records from Huascarán, Peru","type":"publication","volume":null}],"reconstruction":"N","scienceKeywords":["PAGES 2k Network","PAGES LOTRED SA2k"],"site":[{"NOAASiteId":"19996","geo":{"geoType":"Feature","geometry":{"coordinates":["-9","-77.5"],"type":"POINT"},"properties":{"easternmostLongitude":"-77.5","maxElevationMeters":"6050","minElevationMeters":"6050","northernmostLatitude":"-9","southernmostLatitude":"-9","westernmostLongitude":"-77.5"}},"locationName":"Continent>South America>Peru","mappable":"Y","paleoData":[{"NOAADataTableId":"2615","coreLengthMeters":160,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>ice core>oxygen 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Layer Thickness, and Particle Data","studyNotes":"General Information about the Huascarán Ice Cores\n\nSite Description and Analysis\n\tIn July-August 1993, two ice cores to bedrock were recovered from the col \nbetween the north and south peaks of Nevado Huascarán, Peru (9øS, 77ø30'W, col \nelevation 6050 m) and were subsequently transported back to the cold room facility at the \nByrd Polar Research Center (BPRC).  Core 1 (HSC1, 160.40 m) was sectioned in the \nfield into 2677 samples decreasing in thickness from 13 cm at the top to 3 cm at the base, \nwhich were then melted and poured into 2 or 4 oz. plastic (HDPE) bottles, and sealed \nwith wax.  Core 2 (HSC2, 166.08 m), drilled approximately 100 m from the HSC1 site, \nwas returned frozen in 1 m sections.  Ice motion vectors determined from stake \nmovements from 1991-93 indicate that the drill sites are proximal to the divide between \nice flow towards the east and west outlets of the col.  Visible observations and borehole \ntemperatures indicate that the glacier is 'polar' type, i.e., it remains frozen to the bed \n(Thompson et al., Science, v.269, 1995, p. 46-50).\n\tEach ice sample from HSC2 was prepared in a Class 100 clean room \nenvironment, and analyzed for major anion concentrations (Cl-, NO3-, and SO42-) on a \nDionex 2010i ion chromatograph, d18O on a Finnigan Mat mass spectrometer (Craig, \n1957), and for particulate concentration and size distribution using a Coulter TA-II \nparticle counter (Thompson, OSU IPS Report 46, 1973).  A complete d18O profile was \nalso produced from the bottled samples from HSC1.  Contamination during field \npreparation and transport of these samples precluded the development of a second \ncomplete record of particles and anion concentrations.\n\tFor display purposes, variable averaging on the core depth scale was utilized to \nshow the major large-scale events in the record without the confusion of the large annual \nvariations superimposed upon the upper portion.  Hence, for HSC2, 5-m integrated \naverages were calculated for between the surface and 140 meters depth and then 50-cm \naverages were generated between 140 and 160 meters.  Between 160 and 166 meters, \nevery sample value was plotted.  A similar scheme was used for HSC1 (all values plotted \nfor 155-160.4 m).  These data are included in hs12-5m.txt in this data archive, and the \ngraph can be seen in Thompson et al., 1995 (Fig. 3).\n\nDevelopment of the time/depth relationship\n\tTropical South American climate is marked by annual dry seasons (July-October) \nwhich were identifiable in the ice core record as elevated values in all relevant \nmeasurements.  The nitrate (NO3-) record from the Huascarán ice core provided the most \ndefinitive seasonal marker, but the final time scale was constructed from a comparison of \nfour major parameters (NO3-, d18O, dust and SO42-).  Each annual maximum corresponds \nto the middle of the dry season, assumed to occur on the 1st of August.  The rapid layer-\nthinning below 120 m limited annual resolution to the most recent 270 years.  However, \nthe high accumulation and strong preservation of seasonal cycles also made possible the \nsubannual resolution of d18O variations for a period of at least 100 years (1894-1993).\n\tThe accuracy of the time scale is of paramount importance in the development of \nrelationships between ice core proxy data and tropical climate conditions.  Several \nhorizons in recent times were useful for confirming the layer counting as a reliable \nmethod, and indicate almost certain ages for the uppermost 50 years.  In 1980, during the \noriginal reconnaissance expedition to Huascarán, a 10 m firn core was extracted and \nanalyzed for d18O at BPRC (Thompson et al., JGR, v. 89d3, 1984, p. 4638-4646). Aside \nfrom minor accumulation variation and slight signal attenuation, the 1993 cores \nduplicated the earlier stable isotope profile over the common portion, and confirmed the \nlayer counting to 1980 as absolute.  Additionally, a magnitude 7.7 earthquake struck \ncoastal Peru in May 1970, generating large mud flows following the collapse of a large \nportion of the Huascarán glacier from the north peak. The event was recognized in the ice \ncore by a sharp two-year rise in particulates from the newly-created sediment source.  A \nthird time horizon was provided by the HSC2 36Cl profile (Synal et al., Glaciers From the \nAlps, Paul Scherrer Inst., 1997, p. 99-102), a substance produced by neutron activation \nduring the explosion of atomic devices in the presence of a 35Cl source, such as sea water.  \nAn abrupt >100-fold rise in 36Cl concentration occurred at ~54 m depth, which dates (by \nlayer counting) to 1951-53.  This was in direct response to the October 31, 1952 U.S. \n'Ivy' surface test of an experimental nuclear device on the Eniwetok Atoll in the Pacific \nOcean (11øN, 162øE) (Carter and Moghissi, Health Physics, v. 33, 1977, p. 55-71).  \nFinally, in both HSC1 and HSC2, the 1883 eruption of Krakatau, Indonesia (6øS, \n105ø30'E) was identified by an anomalous sulfate concentration of ~400 ppb at 110 m \ndepth, more than twice the level of any other local (within 10 m) event.  A date of mid-\nyear 1884 was thus considered to be an absolute time marker for both cores within the \nerror of the time lag (less than one year).","version":"1.0","xmlId":"2229"}