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 (9øS, 77ø30'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 (11øN, 162øE) (Carter and Moghissi, Health Physics, v. 33, 1977, p. 55-71). Finally, in both HSC1 and HSC2, the 1883 eruption of Krakatau, Indonesia (6øS, 105ø30'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). THERMAL YEAR (Aug.-Jul.) LAYER THICKNESSES Huascaran (1993) Core 1 Year Core Depth Layer Mean IED Bottom IED Layer Bottom (m) Thickness Density (m) Thickness 1993 0 1992 -93 3.37 3.37 0.388 1.600 1.600 1991 -92 5.51 2.14 0.486 2.785 1.185 1990 -91 8.29 2.78 0.533 4.473 1.687 1989 -90 10.27 1.98 0.584 5.764 1.291 1988 -89 12.89 2.62 0.616 7.573 1.810 1987 -88 14.45 1.56 0.655 8.704 1.130 1986 -87 16.27 1.82 0.678 10.071 1.367 1985 -86 17.67 1.40 0.704 11.158 1.087 1984 -85 19.27 1.60 0.724 12.437 1.280 1983 -84 21.17 1.90 0.747 14.008 1.571 1982 -83 22.73 1.56 0.774 15.339 1.331 1981 -82 24.05 1.32 0.795 16.493 1.154 1980 -81 25.25 1.20 0.813 17.563 1.070 1979 -80 26.19 0.94 0.828 18.415 0.852 1978 -79 27.70 1.51 0.840 19.808 1.393 1977 -78 28.72 1.02 0.857 20.765 0.957 1976 -77 29.51 0.79 0.868 21.514 0.749 1975 -76 30.74 1.23 0.876 22.692 1.179 1974 -75 31.81 1.07 0.887 23.729 1.037 1973 -74 33.12 1.31 0.896 25.011 1.282 1972 -73 34.19 1.07 0.905 26.067 1.056 1971 -72 35.59 1.40 0.910 27.457 1.390 1970 -71 37.07 1.48 0.916 28.933 1.477 1969 -70 38.42 1.35 0.920 30.283 1.350 1968 -69 39.84 1.42 0.920 31.703 1.420 1967 -68 41.17 1.33 0.920 33.033 1.330 1966 -67 42.98 1.81 0.920 34.843 1.810 1965 -66 44.13 1.15 0.920 35.993 1.150 1964 -65 45.21 1.08 0.920 37.073 1.080 1963 -64 46.19 0.98 0.920 38.053 0.980 1962 -63 47.01 0.82 0.920 38.873 0.820 1961 -62 48.16 1.15 0.920 40.023 1.150 1960 -61 49.53 1.37 0.920 41.393 1.370 1959 -60 50.83 1.30 0.920 42.693 1.300 1958 -59 51.90 1.07 0.920 43.763 1.070 1957 -58 52.88 0.98 0.920 44.743 0.980 1956 -57 53.71 0.83 0.920 45.573 0.830 1955 -56 54.47 0.76 0.920 46.333 0.760 1954 -55 55.69 1.22 0.920 47.553 1.220 1953 -54 56.75 1.06 0.920 48.613 1.060 1952 -53 57.61 0.86 0.920 49.473 0.860 1951 -52 58.46 0.85 0.920 50.323 0.850 1950 -51 59.39 0.93 0.920 51.253 0.930 1949 -50 60.04 0.65 0.920 51.903 0.650 1948 -49 60.79 0.75 0.920 52.653 0.750 1947 -48 61.54 0.75 0.920 53.403 0.750 1946 -47 62.42 0.88 0.920 54.283 0.880 1945 -46 63.28 0.86 0.920 55.143 0.860 1944 -45 64.29 1.01 0.920 56.153 1.010 1943 -44 65.24 0.95 0.920 57.103 0.950 1942 -43 66.38 1.14 0.920 58.243 1.140 1941 -42 68.50 2.12 0.920 60.363 2.120 1940 -41 69.43 0.93 0.920 61.293 0.930 1939 -40 70.40 0.97 0.920 62.263 0.970 1938 -39 71.70 1.30 0.920 63.563 1.300 1937 -38 72.55 0.85 0.920 64.413 0.850 1936 -37 73.52 0.97 0.920 65.383 0.970 1935 -36 74.42 0.90 0.920 66.283 0.900 1934 -35 75.07 0.65 0.920 66.933 0.650 1933 -34 75.94 0.87 0.920 67.803 0.870 1932 -33 76.67 0.73 0.920 68.533 0.730 1931 -32 77.10 0.43 0.920 68.963 0.430 1930 -31 77.66 0.56 0.920 69.523 0.560 1929 -30 78.38 0.72 0.920 70.243 0.720 1928 -29 79.09 0.71 0.920 70.953 0.710 1927 -28 79.65 0.56 0.920 71.513 0.560 1926 -27 80.89 1.24 0.920 72.753 1.240 1925 -26 82.80 1.91 0.920 74.663 1.910 1924 -25 84.40 1.60 0.920 76.263 1.600 1923 -24 85.15 0.75 0.920 77.013 0.750 1922 -23 86.03 0.88 0.920 77.893 0.880 1921 -22 87.20 1.17 0.920 79.063 1.170 1920 -21 87.95 0.75 0.920 79.813 0.750 1919 -20 88.72 0.77 0.920 80.583 0.770 1918 -19 89.34 0.62 0.920 81.203 0.620 1917 -18 90.68 1.34 0.920 82.543 1.340 1916 -17 91.49 0.81 0.920 83.353 0.810 1915 -16 92.86 1.37 0.920 84.723 1.370 1914 -15 93.61 0.75 0.920 85.473 0.750 1913 -14 94.38 0.77 0.920 86.243 0.770 1912 -13 95.07 0.69 0.920 86.933 0.690 1911 -12 95.84 0.77 0.920 87.703 0.770 1910 -11 97.03 1.19 0.920 88.893 1.190 1909 -10 98.07 1.04 0.920 89.933 1.040 1908 - 9 98.76 0.69 0.920 90.623 0.690 1907 - 8 99.83 1.07 0.920 91.693 1.070 1906 - 7 100.57 0.74 0.920 92.433 0.740 1905 - 6 101.11 0.54 0.920 92.973 0.540 1904 - 5 101.53 0.42 0.920 93.393 0.420 1903 - 4 102.09 0.56 0.920 93.953 0.560 1902 - 3 102.48 0.39 0.920 94.343 0.390 1901 - 2 102.94 0.46 0.920 94.803 0.460 1900 - 1 103.50 0.56 0.920 95.363 0.560 1899 - 0 104.14 0.64 0.920 96.003 0.640 1898 -99 104.98 0.84 0.920 96.843 0.840 1897 -98 105.47 0.49 0.920 97.333 0.490 1896 -97 106.09 0.62 0.920 97.953 0.620 1895 -96 106.64 0.55 0.920 98.503 0.550 1894 -95 107.07 0.43 0.920 98.933 0.430 1893 -94 107.63 0.56 0.920 99.493 0.560 1892 -93 107.98 0.35 0.920 99.843 0.350 1891 -92 108.32 0.34 0.920 100.183 0.340 1890 -91 108.71 0.39 0.920 100.573 0.390 1889 -90 109.00 0.29 0.920 100.863 0.290 1888 -89 109.23 0.23 0.920 101.093 0.230 1887 -88 109.47 0.24 0.920 101.333 0.240 1886 -87 109.80 0.33 0.920 101.663 0.330 1885 -86 110.15 0.35 0.920 102.013 0.350 1884 -85 110.49 0.34 0.920 102.353 0.340 1883 -84 110.89 0.40 0.920 102.753 0.400 1882 -83 111.21 0.32 0.920 103.073 0.320 1881 -82 111.50 0.29 0.920 103.363 0.290 1880 -81 111.68 0.18 0.920 103.543 0.180 1879 -80 111.93 0.25 0.920 103.793 0.250 1878 -79 112.12 0.19 0.920 103.983 0.190 1877 -78 112.30 0.18 0.920 104.163 0.180 1876 -77 112.45 0.15 0.920 104.313 0.150 1875 -76 112.64 0.19 0.920 104.503 0.190 1874 -75 112.90 0.26 0.920 104.763 0.260 1873 -74 113.12 0.22 0.920 104.983 0.220 1872 -73 113.41 0.29 0.920 105.273 0.290 1871 -72 113.60 0.19 0.920 105.463 0.190 1870 -71 113.76 0.16 0.920 105.623 0.160 1869 -70 113.90 0.14 0.920 105.763 0.140 1868 -69 114.03 0.13 0.920 105.893 0.130 1867 -68 114.17 0.14 0.920 106.033 0.140 1866 -67 114.28 0.11 0.920 106.143 0.110 1865 -66 114.41 0.13 0.920 106.273 0.130 1864 -65 114.52 0.11 0.920 106.383 0.110 1863 -64 114.67 0.15 0.920 106.533 0.150 1862 -63 114.82 0.15 0.920 106.683 0.150 1861 -62 115.01 0.19 0.920 106.873 0.190 1860 -61 115.145 0.135 0.920 107.008 0.135 1859 -60 115.240 0.095 0.920 107.103 0.095 1858 -59 115.335 0.095 0.920 107.198 0.095 1857 -58 115.415 0.080 0.920 107.278 0.080 1856 -57 115.490 0.075 0.920 107.353 0.075 1855 -56 115.555 0.065 0.920 107.418 0.065 1854 -55 115.670 0.115 0.920 107.533 0.115 1853 -54 115.785 0.115 0.920 107.648 0.115 1852 -53 115.885 0.100 0.920 107.748 0.100 1851 -52 115.960 0.075 0.920 107.823 0.075 1850 -51 116.025 0.065 0.920 107.888 0.065 1849 -50 116.095 0.070 0.920 107.958 0.070 1848 -49 116.150 0.055 0.920 108.013 0.055 1847 -48 116.215 0.065 0.920 108.078 0.065 1846 -47 116.310 0.095 0.920 108.173 0.095 1845 -46 116.395 0.085 0.920 108.258 0.085 1844 -45 116.490 0.095 0.920 108.353 0.095 1843 -44 116.605 0.115 0.920 108.468 0.115 1842 -43 116.695 0.090 0.920 108.558 0.090 1841 -42 116.780 0.085 0.920 108.643 0.085 1840 -41 116.880 0.100 0.920 108.743 0.100 1839 -40 116.965 0.085 0.920 108.828 0.085 1838 -39 117.055 0.090 0.920 108.918 0.090 1837 -38 117.135 0.080 0.920 108.998 0.080 1836 -37 117.205 0.070 0.920 109.068 0.070 1835 -36 117.300 0.095 0.920 109.163 0.095