Huascarán Ice Core Data: Readme file --------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program --------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Huascarán Ice Core Data LAST UPDATE: 8/2013 (addition of annions data file). Original receipt by WDC Paleo 1/2001 CONTRIBUTOR: Lonnie G. Thompson, Byrd Polar Research Center of The Ohio State University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2001-008 SUGGESTED DATA CITATION: Thompson, L.G., 2001, Huascarán Ice Core Data, IGBP PAGES/World Data Center A for Paleoclimatology Data Contribution Series #2001-008. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Thompson, L.G., E. Mosley-Thompson, M.E. Davis, P-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, 269, 46-50. GEOGRAPHIC REGION: South America, Peruvian Andes PERIOD OF RECORD: 19.5 KYrBP - present LIST OF FILES: Readme_Huascaran.txt (this file), ASCII text data files: age.txt Age-scale/averaging doc. all-mo.txt Linearized profiles 100yr. annualc.txt Cal. Annual avg for 100yr. annualt.txt Thermal Annual avg - 100yr. hs12-5m.txt 5m/.5m/every averages hs1layer.txt C1 layer depths/thickness hs2layer.txt C2 layer depths/thickness hs2-100a.txt Revised C2 100-yr averages. annions.txt decadal averages of major anions (Chloride, Nitrate, Sulfate) DESCRIPTION: General Information about the Huascarán Ice Cores Site Description and Analysis In July-August 1993, two ice cores to bedrock were recovered from the col between the north and south peaks of Nevado Huascarán, Peru (9řS, 77ř30'W, col elevation 6050 m) and were subsequently transported back to the cold room facility at the Byrd Polar Research Center (BPRC). Core 1 (HSC1, 160.40 m) was sectioned in the field into 2677 samples decreasing in thickness from 13 cm at the top to 3 cm at the base, which were then melted and poured into 2 or 4 oz. plastic (HDPE) bottles, and sealed with wax. Core 2 (HSC2, 166.08 m), drilled approximately 100 m from the HSC1 site, was returned frozen in 1 m sections. Ice motion vectors determined from stake movements from 1991-93 indicate that the drill sites are proximal to the divide between ice flow towards the east and west outlets of the col. Visible observations and borehole temperatures indicate that the glacier is 'polar' type, i.e., it remains frozen to the bed (Thompson et al., Science, v.269, 1995, p. 46-50). Each ice sample from HSC2 was prepared in a Class 100 clean room environment, and analyzed for major anion concentrations (Cl-, NO3-, and SO42-) on a Dionex 2010i ion chromatograph, d18O on a Finnigan Mat mass spectrometer (Craig, 1957), and for particulate concentration and size distribution using a Coulter TA-II particle counter (Thompson, OSU IPS Report 46, 1973). A complete d18O profile was also produced from the bottled samples from HSC1. Contamination during field preparation and transport of these samples precluded the development of a second complete record of particles and anion concentrations. For display purposes, variable averaging on the core depth scale was utilized to show the major large-scale events in the record without the confusion of the large annual variations superimposed upon the upper portion. Hence, for HSC2, 5-m integrated averages were calculated for between the surface and 140 meters depth and then 50-cm averages were generated between 140 and 160 meters. Between 160 and 166 meters, every sample value was plotted. A similar scheme was used for HSC1 (all values plotted for 155-160.4 m). These data are included in hs12-5m.txt in this data archive, and the graph can be seen in Thompson et al., 1995 (Fig. 3). Development of the time/depth relationship Tropical South American climate is marked by annual dry seasons (July-October) which were identifiable in the ice core record as elevated values in all relevant measurements. The nitrate (NO3-) record from the Huascarán ice core provided the most definitive seasonal marker, but the final time scale was constructed from a comparison of four major parameters (NO3-, d18O, dust and SO42-). Each annual maximum corresponds to the middle of the dry season, assumed to occur on the 1st of August. The rapid layer- thinning below 120 m limited annual resolution to the most recent 270 years. However, the high accumulation and strong preservation of seasonal cycles also made possible the subannual resolution of d18O variations for a period of at least 100 years (1894-1993). The accuracy of the time scale is of paramount importance in the development of relationships between ice core proxy data and tropical climate conditions. Several horizons in recent times were useful for confirming the layer counting as a reliable method, and indicate almost certain ages for the uppermost 50 years. In 1980, during the original reconnaissance expedition to Huascarán, a 10 m firn core was extracted and analyzed for d18O at BPRC (Thompson et al., JGR, v. 89d3, 1984, p. 4638-4646). Aside from minor accumulation variation and slight signal attenuation, the 1993 cores duplicated the earlier stable isotope profile over the common portion, and confirmed the layer counting to 1980 as absolute. Additionally, a magnitude 7.7 earthquake struck coastal Peru in May 1970, generating large mud flows following the collapse of a large portion of the Huascarán glacier from the north peak. The event was recognized in the ice core by a sharp two-year rise in particulates from the newly-created sediment source. A third time horizon was provided by the HSC2 36Cl profile (Synal et al., Glaciers From the Alps, Paul Scherrer Inst., 1997, p. 99-102), a substance produced by neutron activation during the explosion of atomic devices in the presence of a 35Cl source, such as sea water. An abrupt >100-fold rise in 36Cl concentration occurred at ~54 m depth, which dates (by layer counting) to 1951-53. This was in direct response to the October 31, 1952 U.S. 'Ivy' surface test of an experimental nuclear device on the Eniwetok Atoll in the Pacific Ocean (11řN, 162řE) (Carter and Moghissi, Health Physics, v. 33, 1977, p. 55-71). Finally, in both HSC1 and HSC2, the 1883 eruption of Krakatau, Indonesia (6řS, 105ř30'E) was identified by an anomalous sulfate concentration of ~400 ppb at 110 m depth, more than twice the level of any other local (within 10 m) event. A date of mid- year 1884 was thus considered to be an absolute time marker for both cores within the error of the time lag (less than one year). Huascaran (1993) Core 2 Huascaran (1993) Core 1 Calendar Ave. Ave. Ave. Ave. Ave. Jan-Dec. O-18 Part>2um Part>.63um NO3- O-18 1993 -21.58 951 12279 63.3 1992 -12.18 2726 24719 131.5 -13.06 1991 -16.77 2287 27140 127.8 -17.21 1990 -14.94 2432 33631 119.7 -15.45 1989 -17.58 2712 41187 82.1 -18.15 1988 -16.64 1654 18488 125.4 -16.49 1987 -16.25 1862 18686 110.0 -16.08 1986 -18.69 1690 20507 103.4 -18.80 1985 -14.85 2688 27108 115.7 -15.01 1984 -21.05 1382 13694 78.4 -21.47 1983 -14.89 3036 26996 131.4 -14.54 1982 -17.34 1624 18083 96.0 -17.62 1981 -17.06 2768 34325 134.5 -17.43 1980 -17.10 2377 21012 99.1 -17.00 1979 -18.23 2670 15304 131.7 -17.17 1978 -14.59 3566 16756 186.4 -15.56 1977 -18.71 2201 11017 106.3 -18.01 1976 -19.31 2276 11453 113.6 -19.40 1975 -19.85 1480 8849 80.2 -19.49 1974 -17.39 2508 15424 73.8 -18.75 1973 -19.52 1638 30102 73.2 -17.91 1972 -19.88 2366 29473 75.4 -20.58 1971 -18.72 3550 24821 92.0 -19.99 1970 -16.11 4241 27552 101.8 -16.23 1969 -15.58 2377 14564 105.5 -17.25 1968 -15.08 2663 16757 117.7 -14.94 1967 -17.53 1549 9921 79.0 -17.42 1966 -15.73 2547 17337 99.5 -15.95 1965 -15.18 2790 17124 97.3 -14.42 1964 -15.64 2466 13764 94.4 -15.65 1963 -14.59 1845 11327 77.3 -15.05 1962 -19.58 2884 17903 101.5 -19.83 1961 -17.14 2445 17751 99.9 -17.13 1960 -17.21 1691 11514 106.6 -17.53 1959 -16.56 2582 16921 99.8 -16.19 1958 -18.87 2105 15660 116.8 -18.72 1957 -14.78 3856 27111 112.7 -14.99 1956 -14.82 2206 11744 99.9 -15.38 1955 -18.04 1980 16018 92.6 -17.31 1954 -19.49 1481 11318 120.4 -19.62 1953 -17.29 1506 12130 90.0 -17.26 1952 -19.90 1545 12958 78.9 -20.08 1951 -17.44 1484 12105 66.1 -17.84 1950 -19.00 1355 11887 75.5 -19.05 1949 -19.78 1330 10446 93.3 -19.98 1948 -17.00 2545 17435 97.5 -17.45 1947 -15.99 1895 13355 91.4 -15.23 1946 -14.82 1900 17021 76.9 -14.51 1945 -17.20 1527 10931 104.1 -17.36 1944 -18.77 1718 12387 75.1 -19.08 1943 -16.03 2030 17246 84.8 -16.47 1942 -20.78 1485 9746 77.4 -18.36 1941 -15.74 2176 14095 96.0 -17.78 1940 -15.26 3142 20753 100.7 -16.33 1939 -16.19 1555 10049 67.4 -16.62 1938 -17.78 1513 10978 58.7 -17.80 1937 -15.88 2495 14967 110.5 -16.13 1936 -15.80 1633 10608 102.7 -17.37 1935 -13.54 3122 19879 108.6 -14.03 1934 -16.80 2292 12636 105.1 -17.58 1933 -18.95 1661 11779 75.9 -18.65 1932 -17.95 2378 13071 83.3 -18.78 1931 -18.27 965 8424 54.7 -17.01 1930 -16.92 2073 13634 82.3 -17.97 1929 -18.86 1408 10987 61.8 -18.55 1928 -15.73 3244 21426 102.7 -16.77 1927 -15.28 1913 11900 85.9 -18.85 1926 -17.48 1554 8698 74.2 -18.38 1925 -16.26 2211 14463 82.9 -17.50 1924 -17.13 1707 10138 81.9 -18.55 1923 -16.84 1909 11321 81.8 -16.13 1922 -19.64 1350 8895 66.2 -19.97 1921 -17.75 2504 12741 104.0 -17.92 1920 -17.99 1128 6949 64.5 -16.87 1919 -20.48 764 4809 51.5 -20.24 1918 -18.77 2119 9390 97.9 -21.00 1917 -17.87 2765 16590 85.3 -17.68 1916 -18.44 1688 8979 80.4 -18.77 1915 -18.18 1741 8488 76.3 -17.29 1914 -17.06 1548 8139 92.5 -17.92 1913 -17.16 2027 9700 102.7 -17.76 1912 -17.10 2015 9475 90.4 -16.81 1911 -18.96 2390 12734 73.4 -17.80 1910 -17.19 1851 10834 76.4 -17.85 1909 -16.86 2708 13762 90.2 -16.70 1908 -17.84 1974 11055 92.4 -18.89 1907 -19.94 1690 8692 93.1 -19.67 1906 -18.79 1190 7617 74.4 -19.44 1905 -18.72 1848 9698 82.3 -19.19 1904 -13.93 2119 15491 99.6 -14.52 1903 -16.58 2388 16689 81.7 -13.27 1902 -19.64 1381 7837 63.4 -18.57 1901 -16.30 2058 15925 99.2 -17.64 1900 -19.67 1662 11801 84.4 -18.98 1899 -15.96 2447 15435 101.3 -17.46 1898 -17.47 1428 9594 66.8 -15.19 1897 -22.29 1346 7861 59.0 -19.94 1896 -20.24 1025 6844 67.9 -18.36 1895 -17.99 2266 13166 79.9 -15.90 1894 -18.62 1071 6297 65.5 -17.77