Measurements and Modeling of Radiocarbon (14CO2) from the Lower Troposphere to the Middle Stratosphere and Implications for Use as a Tracer of Large-scale Atmospheric Transport and Stratospheric Residence Times

Wednesday, 16 December 2015
Poster Hall (Moscone South)
Lauren Garofalo1, Amadu M Kanu1, Thomas P Guilderson2, Elliot L Atlas3, Donald Ray Blake4, Daniel J Bergmann2, Philip J Cameron-Smith2 and Kristie A Boering5, (1)University of California Berkeley, Berkeley, CA, United States, (2)Lawrence Livermore National Laboratory, Livermore, CA, United States, (3)University of Miami, Miami, FL, United States, (4)University of California Irvine, Irvine, CA, United States, (5)University of California Berkeley, Chemistry and Earth & Planetary Science, Berkeley, CA, United States
We report new measurements of the radiocarbon content of CO2 from whole air samples collected from the NASA ER-2 aircraft between 1997 and 2013 and the NASA DC-8 aircraft in 2012. While still somewhat sparse, the stratospheric measurements, and their comparison with the Lawrence Livermore National Laboratory 3D chemical transport model IMPACT, indicate that 14CO2 is a sensitive tracer of stratospheric transport and residence times. It is unique from, and complementary to, the stratospheric mean ages derived from mixing ratios of the troposphere-sourced gases such as CO2 and SF6. In addition, the vertical profiles of 14CO2 from ~2 km to the lower stratosphere in 2012 and 2013 provide much needed constraints on the vertical distribution of 14CO2 necessary for modeling studies that seek to (1) quantify the partitioning of carbon between the atmosphere, biosphere, and oceans, and (2) infer regional fossil fuel emissions from the large number of 14CO2 measurements made at Earth’s surface.