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Carbon Dioxide Distribution, Origins, and Transport Along a Frontal Boundary During Summer in Mid‐Latitudes
Author(s) -
Samaddar Arkayan,
Feng Sha,
Lauvaux Thomas,
Barkley Zachary R.,
Pal Sandip,
Davis Kenneth J.
Publication year - 2021
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd033118
Subject(s) - troposphere , cold front , advection , front (military) , atmospheric sciences , latitude , environmental science , warm front , boundary layer , climatology , carbon dioxide , geology , chemistry , oceanography , mechanics , physics , thermodynamics , geodesy , organic chemistry
Synoptic weather systems are a major driver of spatial gradients in atmospheric CO 2 mole fractions. During frontal passages, air masses from different regions meet at the frontal boundary creating significant gradients in CO 2 mole fractions. We quantitatively describe the atmospheric transport of CO 2 mole fractions during a mid‐latitude cold front passage and explore the impact of various sources of CO 2 . We focus here on a cold front passage over Lincoln, Nebraska on August 4th, 2016 observed by aircraft during the Atmospheric Carbon and Transport‐America campaign. A band of air with elevated CO 2 was located along the frontal boundary. Observed and simulated differences in CO 2 across the front were as high as 25 ppm. Numerical simulations using Weather Research and Forecasting Model with Chemistry at cloud resolving resolutions (3 km), coupled with CO 2 surface fluxes and boundary conditions from CarbonTracker (CT‐NRTv2017x), were performed to explore atmospheric transport at the front. Model results demonstrate that the frontal CO 2 difference in the upper troposphere can be explained largely by inflow from outside of North America. This difference is modified in the atmospheric boundary layer and lower troposphere by continental surface fluxes, dominated in this case by biogenic and fossil fuel fluxes. Horizontal and vertical advection are found to be responsible for the transport of CO 2 mole fractions along the frontal boundary. We show that cold front passages lead to large CO 2 transport events including a significant contribution from vertical advection, and that midcontinent frontal boundaries are formed from a complex mixture of CO 2 sources.