GISP2 Ice Core 17KYr In-situ 14C Data Lal, D.; Jull, A.J.T.; Burr, G.S.; Donahue, D.J. Lal, D. Jull, A.J.T. Burr, G.S. Donahue, D.J. earth science/paleoclimate/ice cores (depth at sample start,null,null,meter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (accumulation rate,bulk ice,null,centimeter per year,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (14C,carbon dioxide,unspecified margin of error,count per gram,null,ice cores,null,accelerator mass spectrometry,N,atom per gram) earth science/paleoclimate/ice cores (14C,null,null,dimensionless,null,ice cores,null,null,N,Approximate fraction 14C from in-situ production during storage.) earth science/paleoclimate/ice cores (depth at sample end,null,null,meter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (14C,carbon dioxide,null,count per gram,null,ice cores,null,null,N,Total: Decay-corrected 14C; atom per gram) earth science/paleoclimate/ice cores (14C,carbon dioxide,unspecified margin of error,count per gram,null,ice cores,null,null,N,Total: Decay-corrected 14C; atom per gram) earth science/paleoclimate/ice cores (14C,carbon monoxide,null,count per gram,null,ice cores,null,accelerator mass spectrometry,N,atom per gram) earth science/paleoclimate/ice cores (14C,carbon dioxide,null,count per gram,null,ice cores,null,null,N,the amount of trapped 14CO2 is estimated from the amount of air in the ice (see Table 1) and assuming 250 ppm CO2 in air; constant thickness model; atom per gram) earth science/paleoclimate/ice cores (weight,bulk ice,null,kilogram,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (14C,carbon dioxide,null,count per gram,null,ice cores,null,accelerator mass spectrometry,N,atom per gram) earth science/paleoclimate/ice cores (depth,null,null,meter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (14C,carbon dioxide,null,count per gram,null,ice cores,null,null,N,In situ produced: Decay-corrected 14C; atom per gram) earth science/paleoclimate/ice cores (accumulation rate,bulk ice,unspecified margin of error,centimeter per year,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (air content,bulk ice,null,cubic centimeter per liter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (age,null,null,calendar year before present,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (14C,carbon monoxide,unspecified margin of error,count per gram,null,ice cores,null,accelerator mass spectrometry,N,atom per gram) earth science/paleoclimate/ice cores (14C,carbon dioxide,unspecified margin of error,count per gram,null,ice cores,null,null,N,In situ produced: Decay-corrected 14C; atom per gram) earth science/paleoclimate/ice core (GISP2>LATITUDE 72.6>LONGITUDE -38.5) We present results of measurements of 14C in CO and CO2 phases for selected Greenland Ice Sheet Project 2 firn and ice samples up to a depth of 1838 m (16.6 kyr B.P.). The results show that 14C in ice consists of both in situ-produced cosmogenic 14C, which can be either in the form of CO or CO2, and trapped atmospheric 14CO2. In agreement with our previous work on studies of 14C concentrations in Antarctic firn and ice samples and some GISP2 samples, we found that the cosmogenic in situ-produced 14C (from spallation of oxygen nuclei) is greater than the trapped atmospheric 14C component. Also, we can show the total 14C amounts in ice are consistent with an efficient retention of the in situ variety of 14C in older ice where we expect lower average temperatures at the time of formation. The firn samples appear to have lost much of the 14C, probably during storage. The ice accumulation rates are estimated after due corrections for the CO2 content of trapped air and "secondary" 14C production in ice during storage at altitude. These values are in good accord with the recent model estimates of Cutler et al. [1995], except for two samples, at depths 1518.5 m (9740 years B.P.) and 1698.5 m (12,360 years B.P.). In the first case, the in situ 14C concentration is significantly higher than that predicted by either of the models, by a factor of about 2. In the second case, the estimate of Cutler et al. [1995] is a ~50% lower accumulation rate, but the 14C result is consistent with adjacent samples. A possible reason for the first discrepancy may be the decreased atmospheric pressure at that time at the site, as suggested by D. Raynaud et al. (unpublished manuscript, 1995). STUDY NOTES: 14C concentrations in CO and CO2 for selected depths in the GISP2 ice core NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Lal, D. Investigator : Jull, A.J.T. Investigator : Burr, G.S. Investigator : Donahue, D.J. 1997-11-30 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/17801 https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14c.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14a.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14c.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14a.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14b.txt English https://www.ncdc.noaa.gov/paleo/study/17801 https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14c.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14a.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/cosmoiso/c14b.txt D. Lal, A. J. T. Jull, G. S. Burr, D. J. Donahue1997Measurements of in situ 14C concentrations in Greenland Ice Sheet Project 2 ice covering a 17-kyr time span: Implications to ice flow dynamicsJournal of Geophysical Research: Oceans102C1226505-2651010.1029/96JC02224http://onlinelibrary.wiley.com/enhanced/doi/10.1029/96JC02224/ START YEAR: 16200 cal yr BP * END YEAR: 50 cal yr BP -38.5 72.6 -38.5 72.6