A128-01
Exploring XCO2 spatial variability across frontal boundaries using airborne lidar observations: Findings from ACT-America Field Campaigns

Friday, 11 December 2020: 10:30
Virtual
Samantha Walley1, Sandip Pal2, Joel F Campbell3, Emily Bell4, Brad Weir5, Sha Feng6, Jeremy Todd Dobler7, Wayne H. Erxleben8, Tai-Fang (Alice) Fan9, Bing Lin3, Michael D Obland3, Chris O'Dell10, Kenneth J Davis11 and Doug McGregor12, (1)Texas Tech University, Lubbock, TX, United States, (2)Texas Tech University, Geosciences, Lubbock, United States, (3)NASA Langley Research Center, Hampton, VA, United States, (4)Colorado State University, Fort Colins, CO, United States, (5)NASA Goddard Space Flight Center, Global Modeling and Assimilation Office, Greenbelt, MD, United States, (6)The Pennsylvania State University, Department of Meteorology and Atmospheric Science, University Park, PA, United States, (7)Spectral Sensor Solutions LLC, Environmental Sensing, Fort Wayne, IN, United States, (8)Organization Not Listed, Washington, DC, United States, (9)Science Systems and Applications, Inc. Hampton, Hampton, VA, United States, (10)Cooperative Institute for Research in the Atmosphere, Fort Collins, CO, United States, (11)The Pennsylvania State University, University Park, PA, United States, (12)Spectral Sensor Solutions LLC, Fort Wayne, IN, United States
Abstract:

Understanding greenhouse gas (e.g. Carbon Dioxide) transport processes in the Earth’s atmosphere is crucial during this current regime of dramatically changing climate. Previous research identified the impact of mid-latitude cyclones on the CO2 spatial variability in the boundary layer and free troposphere. However, some key issues remain unclear: (1) how the partial CO2 columnar content (i.e. XCO2) changes in both warm and cold sectors and at the vicinity of frontal boundaries to better interpret what satellites are missing (typically due to clouds, and coarse spatial resolutions),(2) how well numerical models such as WRF-Chem simulate these XCO2 frontal structures, and understand the biases toward reproducing the frontal patterns without direct observational constraint, and (3) what processes govern these changes. The data used were collected with the Multi Functional Fiber Laser Lidar (MFLL) onboard a C-130 aircraft during the NASA Atmospheric Carbon and Transport-America (ACT-America) field campaigns. The MFLL provided a columnar average of CO2 between MFLL and surface which we used to identify XCO2 structure modulated by frontal passages in the lower troposphere during four seasons. The results suggest relatively higher XCO2 in the warm sector than in the cold sector in Summer 2016. However, Winter 2017, Fall 2017, and Spring 2018 do not show the clear warm vs. cold sector XCO2 differences that are seen in Summer. The observed XCO2 was compared with an XCO2 field obtained from WRF-Chem simulations. Intercomparison efforts (MFLL- XCO2 versus WRF-Chem- XCO2) provide unique quantification of XCO2 model-data-mismatch errors. Preliminary results suggest that the model tends to underestimate XCO2 in the warm sector of the frontal passage and overestimate XCO2 in the cold sector for the majority of cases, with the exception of the spring, where the model tends to underestimate in both warm and cold sectors. The model preforms well with the frontal contrast in Summer and Spring but tends to have a larger difference from the MFLL in Fall and Winter. Future work will include the use of two-dimensional transects, aka “curtains”, of assimilated in-situ CO2 to help identify XCO2 enhancements that frequently occur at the frontal boundary, along with further quantification of the seasonal variations in the frontal contrast.

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