Measuring gaseous species emissions from ships and wetlands using FAAM BAe-146 research aircraft

This work discusses novel airborne measurements of emissions from shipping and wetlands. Both parts focus on testing and developing methods for quantification of emissions using a large research aircraft, FAAM’s BAe-146.
Shipping is the major source of anthropogenic sulphur affecting both air quality and climate. In coastal areas, shipping causes serious pollution problem affecting human health and contributing to acidification of the local environment. However, it is also thought to be a negative climate forcer due to its effect on cloud properties. From 2020 International Maritime Organisation requires all ships in international waters to reduce their sulphur emissions from 3.5% to 0.5% of apparent fuel content.
This work is the first airborne study of ship plumes in open water aiming to verify compliance to the regulations and to establish the framework for future measurements. A decrease in sulphur fuel content was seen between measurements in 2020 (2.34% ± 1.09% 1σ), 2021 (0.27% ± 0.50% 1σ) and 2022 (0.12% ± 0.21% 1σ).
Methane is a more potent greenhouse gas than carbon dioxide, yet there are still large gaps in understanding the global methane budget. Wetlands are thought to be the biggest single source, but their emissions bear 50% uncertainty, largely because there is few studies of tropical wetlands worldwide and nearly none on the entire continent of Africa.
This work shows the first successful airborne eddy covariance (AEC) measurement on board of a large research aircraft and first large scale quantification of methane emissions from Zambian wetlands. It also presents other attempts of deploying the technique and provides a guide for future AEC experiments. For the two most successful wetlands - Kafue Flats and Lukanga Swamp the average methane flux estimated with AEC was 23.0 (± 1.57) mg CH4 m-2 h-1 and 27.9 (± 1.67) mg CH4 m-2 h-1, respectively.