QUANTIFICATION AND CHARACTERISATION OF MULTI-SCALE GREENHOUSE GAS EMISSIONS USING IN SITU OBSERVATIONS

• Main Author: Barker, Patrick
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2023
• Subjects: Greenhouse Gases; Methane; Nitrous Oxide; In Situ Observations; Arctic; Fennoscandian
• Online Access: https://research.manchester.ac.uk/en/studentTheses/979b8bc9-8867-45a0-bd03-d97f196e3065; https://pure.manchester.ac.uk/ws/files/261214187/FULL_TEXT.PDF

Methane (CH4) and nitrous oxide (N2O) are the second and third most important greenhouse gases in terms of contribution to anthropogenic climate forcing, with the atmospheric abundances of these gases increasing to this day. The uncertainties in the individual sources and sinks of these gases remain poorly constrained, partly due to the lack of precise and accurate top-down greenhouse gas flux quantification and the discrepancy between top-down and bottom-up emission estimates. This thesis examines the use of in situ greenhouse gas measurements to quantify or otherwise characterise emissions from sources from a wide range of spatial scales, helping to constrain top-down estimates for CH4 and N2O emission sources. Two aircraft-based measurement studies are presented within this thesis, both using the Facility for Airborne Atmospheric Measurements (FAAM) research aircraft. The first of these case studies was focused on biomass burning emissions of greenhouse gases from biomass burning in northern sub-Saharan Africa. Fire plumes were sampled in Senegal in March 2017 and Uganda in January/February 2019 as part of the Methane Observations and Yearly Assessments (MOYA) project. Emission factors (in g emitted per kg of dry fuel burnt) were calculated for carbon dioxide (CO2), CH4, and carbon monoxide (CO) for both locations, as well as for N2O in Uganda. Strong positive linear correlation was found between CH4 emission factor and combustion efficiency of the fires for both locations. However, the slope of this linear relationship was significantly different between the two regions, which is likely a result of differences in biomass fuel composition. The second aircraft-based study focused on CH4 flux quantification from European arctic peatlands. A single research flight was carried out in July 2019, where a wide area of Fennoscandian mixed peatland and forest was surveyed. Area-normalised CH4 fluxes were positively correlated with peatland area within three subsections of the survey area. The observed fluxes were ...