C033-08
Recent changes in carbon monoxide mole fraction and stable isotope values observed in firn air from Summit, Greenland
Thursday, 10 December 2020: 10:51
Virtual
Philip Place Jr1, Vasilii V Petrenko1, Benjamin Hmiel1,2, Isaac Vimont3, Lee T Murray1, Kostas Tsigaridis4 and Christo Buizert5, (1)University of Rochester, Department of Earth and Environmental Sciences, Rochester, NY, United States, (2)Environmental Defense Fund, Austin, TX, United States, (3)NOAA, ESRL, GML, CCGG, Boulder, CO, United States, (4)Columbia University, New York, NY, United States, (5)Oregon State University, College of Earth, Ocean, and Atmospheric Sciences, Corvallis, OR, United States
Abstract:
Carbon Monoxide (CO) is an important atmospheric trace gas that affects the oxidative capacity of the atmosphere and contributes indirectly to anthropogenic radiative forcing. Stable isotopes of CO (δ
13CO and δC
18O) serve as tracers that provide constraints for partitioning the sources of CO. Therefore, a good understanding of the past variations in CO mole fractions (x
CO), δ
13CO, and δC
18O can help improve the skill of chemical transport models.
We present measurements of past atmospheric CO and CO stable isotopes from firn air at Summit, Greenland, which provides a record from approximately 1965 to 2011 CE. A firn gas transport model was used to simulate the transport of gases through the porous firn column, and an inverse model was used to reconstruct the firn air atmospheric histories of xCO, δ13CO and δC18O. Our results agree with previously published firn air records from Greenland: all three tracers show an increasing trend to a maximum in the late 1970s, followed by a negative trend through the end of the record. The negative trend in δ13CO and δC18O intensified in the last decade. We present an investigation into the cause of this continued decline using a mass balance approach and determine changes in CO source partitioning over time.
