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). HSCore 2 Ave. Ave. Ave. Top Age Delta >0.63um NO3- Yrs. BP O-18 particles ppb 0 -17.38 14023 92.1 100 -17.24 11356 99.5 200 -18.30 10439 94.7 300 -19.10 9066 85.8 400 -19.34 9167 82.0 500 -19.20 10368 79.1 600 -18.72 11007 87.6 700 -18.45 11266 98.4 800 -18.16 12885 113.2 900 -18.40 13686 114.0 1000 -18.31 14240 113.4 1100 -18.50 16947 109.6 1200 -18.71 15840 104.6 1300 -18.70 14918 107.0 1400 -18.45 14343 108.8 1500 -18.09 15285 111.1 1600 -18.20 13408 111.9 1700 -18.50 13581 112.5 1800 -18.44 14121 107.9 1900 -18.51 16481 106.7 2000 -18.05 18179 107.5 2100 -18.13 16763 104.5 2200 -18.30 15085 105.5 2300 -18.32 13914 109.6 2400 -17.96 15452 116.0 2500 -17.99 16205 120.9 2600 -18.17 15095 121.7 2700 -18.35 15680 115.5 2800 -18.36 16709 115.7 2900 -18.57 14483 112.8 3000 -18.53 19126 106.0 3100 -18.50 18454 108.6 3200 -18.52 16077 109.9 3300 -18.31 13912 113.7 3400 -18.29 23265 110.2 3500 -18.18 29275 115.3 3600 -18.22 32989 120.5 3700 -18.41 18326 116.8 3800 -18.36 23236 118.2 3900 -18.37 21342 119.0 4000 -18.26 21674 127.1 4100 -18.13 22130 130.2 4200 -18.21 33369 127.0 4300 -18.54 41787 119.2 4400 -18.35 325785 116.4 4500 -18.06 59971 120.9 4600 -18.25 18290 117.5 4700 -17.92 17009 125.2 4800 -18.02 16728 129.0 4900 -17.90 13733 131.1 5000 -18.01 14237 128.6 5100 -18.00 12157 128.3 5200 -18.06 11437 124.6 5300 -17.81 12917 127.8 5400 -17.70 12434 125.9 5500 -17.87 14697 122.0 5600 -18.09 16127 120.6 5700 -17.87 14783 122.0 5800 -17.47 14943 125.0 5900 -17.26 18993 127.7 6000 -17.60 15697 128.1 6100 -17.56 15368 126.8 6200 -17.73 13600 125.7 6300 -17.71 15072 132.1 6400 -17.53 24036 131.9 6500 -17.52 18832 134.2 6600 -17.30 17564 133.8 6700 -17.21 16640 134.5 6800 -16.94 14845 134.7 6900 -16.99 17884 136.8 7000 -17.18 17100 135.9 7100 -17.03 15476 137.7 7200 -16.85 14625 140.4 7300 -17.02 17015 136.2 7400 -17.08 22156 138.6 7500 -17.07 17584 133.0 7600 -16.96 22795 137.8 7700 -16.67 22185 139.4 7800 -16.61 30810 137.3 7900 -16.61 32430 135.1 8000 -16.68 17755 130.1 8100 -16.68 19520 127.0 8200 -16.77 24047 126.8 8300 -16.79 26200 132.2 8400 -16.84 32067 132.6 8500 -16.82 21745 132.9 8600 -16.80 14353 134.6 8700 -16.48 16780 138.7 8800 -16.13 18160 134.5 8900 -16.18 15093 131.7 9000 -16.18 16167 132.7 9100 -16.01 14155 127.8 9200 -16.04 28320 125.1 9300 -15.90 28067 123.4 9400 -16.12 31507 120.6 9500 -15.93 17113 121.9 9600 -15.97 12827 120.8 9700 -16.20 18547 116.7 9800 -16.15 14793 115.1 9900 -16.20 25480 114.7 10000 -16.20 25410 114.0 10100 -16.21 26193 114.2 10200 -16.33 15640 113.5 10300 -16.24 12480 114.6 10400 -16.35 11507 115.2 10500 -16.49 11060 113.8 10600 -16.83 13107 109.9 10700 -17.09 15080 108.4 10800 -17.25 34593 107.5 10900 -17.79 12387 102.5 11000 -18.50 12780 96.4 11100 -18.76 10393 95.8 11200 -18.80 9080 94.4 11300 -18.82 11020 93.0 11400 -19.00 9540 91.4 11500 -19.13 9200 91.9 11600 -19.34 8900 93.2 11700 -19.64 8230 95.0 11800 -20.01 8600 88.3 11900 -20.35 13340 92.4 12000 -20.61 10080 93.5 12100 -20.79 8800 89.6 12200 -20.94 9120 90.7 12300 -21.01 7600 87.8 12400 -21.08 6820 87.6 12500 -21.07 6960 88.8 12600 -21.19 6960 86.4 12700 -21.19 8800 84.9 12800 -21.29 10720 84.1 12900 -21.44 8630 78.8 13000 -21.55 6880 78.1 13100 -21.39 10400 78.8 13200 -21.12 8900 79.1 13300 -20.99 8320 76.6 13400 -20.88 9280 73.0 13500 -20.75 8550 68.2 13600 -20.55 9280 66.9 13700 -20.52 9980 66.8 13800 -20.49 9400 67.3 13900 -20.27 11220 66.4 14000 -20.18 8820 67.2 14100 -20.15 9860 63.7 14200 -20.20 9620 63.1 14300 -20.27 10020 63.4 14400 -20.32 17600 64.4 14500 -20.33 9800 62.2 14600 -20.63 9020 61.6 14700 -20.83 7960 62.1 14800 -21.56 8190 60.1 14900 -21.98 6460 57.5 15000 -22.15 7780 58.6 15100 -22.04 8600 58.7 15200 -22.11 8420 59.2 15300 -22.21 6060 58.3 15400 -22.45 6870 56.2 15500 -22.43 8040 56.9 15600 -22.29 7780 56.9 15700 -22.16 7740 57.8 15800 -22.12 8760 57.4 15900 -22.14 8160 57.0 16000 -22.45 9020 57.5 16100 -22.78 7780 56.9 16200 -23.22 8440 54.5 16300 -23.35 11200 51.7 16400 -23.34 9140 52.2 16500 -23.33 8280 51.6 16600 -23.42 8040 49.1 16700 -23.49 8540 47.3 16800 -23.43 7840 46.1 16900 -23.30 8220 40.8 17000 -23.27 8270 38.3 17100 -23.40 12880 37.8 17200 -23.96 79460 38.7 17300 -24.61 132210 42.0 17400 -24.94 84290 41.4 17500 -25.01 112720 39.0 17600 -24.88 334260 42.3 17700 -24.50 235570 41.7 17800 -24.25 223630 39.4 17900 -23.67 379830 45.2 18000 -23.00 562940 59.3 18100 -22.28 479300 63.1 18200 -22.08 736910 63.1 18300 -22.19 718533 61.6 18400 -22.31 632400 58.4 18500 -22.36 543440 58.3 18600 -22.43 557420 56.1 18700 -22.35 764130 54.9 18800 -22.07 6082207 65.1 18900 -21.65 13613280 49.5 19000 -21.74 13097760 43.6 19100 -21.70 8758080 41.2 19200