Revised records of atmospheric trace gases CO 2 , CH 4 , N 2 O, and δ 13 C-CO 2 over the last 2000 years from Law Dome, Antarctica

• Published in: Earth System Science Data
• Main Authors: Rubino, M, Etheridge, DM, Thornton, DP, Howden, R, Allison, CE, Francey, RJ, Langenfelds, RL, Steele, LP, Trudinger, CM, Spencer, DA, Curran, MAJ, van Ommen, TD, Smith, AM
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2019
• Subjects: Earth Sciences; Physical geography and environmental geoscience; Palaeoclimatology; East Antarctica; Law Dome; Antarc*; Antarctica; ice core
• Online Access: https://doi.org/10.5194/essd-11-473-2019; http://ecite.utas.edu.au/151900

Ice core records of the major atmospheric greenhousegases ( CO 2 , CH 4 , N 2 O ) and their isotopologues covering recentcenturies provide evidence of biogeochemical variations during theLate Holocene and pre-industrial periods and over the transition to theindustrial period. These records come from a number of ice core and firn airsites and have been measured in several laboratories around the world andshow common features but also unresolved differences. Here we presentrevised records, including new measurements, performed at the CSIRO Ice CoreExtraction LABoratory(ICELAB) on air samples from ice obtained at the high-accumulation site of Law Dome (East Antarctica). We are motivated by theincreasing use of the records by the scientific community and by recentdata-handling developments at CSIRO ICELAB. A number of cores and firn airsamples have been collected at Law Dome to provide high-resolution recordsoverlapping recent, direct atmospheric observations. The records have beenupdated through a dynamic link to the calibration scales used in the GlobalAtmospheric Sampling LABoratory(GASLAB) at CSIRO, which are periodicallyrevised with information from the latest calibration experiments. Thegas-age scales have been revised based on new ice-age scales and theinformation derived from a new version of the CSIRO firn diffusion model.Additionally, the records have been revised with new, rule-based selectioncriteria and updated corrections for biases associated with the extractionprocedure and the effects of gravity and diffusion in the firn. Allmeasurements carried out in ICELABGASLAB over the last 25years are nowmanaged through a database (the ICElab dataBASE or ICEBASE), which providesconsistent data management, automatic corrections and selection ofmeasurements, and a web-based user interface for data extraction. We presentthe new records, discuss their strengths and limitations, and summarise theirmain features. The records reveal changes in the carbon cycle andatmospheric chemistry over the last 2 millennia, ...