A snapshot of the UK net greenhouse gas flux using a mass balance approach with aircraft measurements

Abstract:

We present airborne observations of high-precision in-situ and remotely sensed CO₂, CH₄ and other trace gases made from the NERC Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft during Spring and Summer months in 2014 and 2015. Measurements were recorded during the GAUGE (Greenhouse gAs Uk and Global Emissions) aircraft field campaign, based out of Cranfield, UK, with sampling around and over the UK Mainland and Ireland.

We derive Lagrangian mass-balanced net surface fluxes of CO₂, CH₄, CO, and N₂O from a large surface footprint of England based on data collected during a flight in May 2015 by combining in-situ and remote-sensed concentration measurements and measured boundary layer thermodynamic profiles. By employing an advective box model for the volume enclosed by the flight-tracks and combining aircraft-measured winds and along-track Lagrangian back-trajectory modelling, we examine the sensitivity of total flux uncertainty to atmospheric transport and measurement errors using error propagation implicit in the mass balancing method.

Finally, we compare the measured snapshot net fluxes to those reported in the current UK emissions inventory (weighted for surface footprint) and to previous UK-regional greenhouse gas top-down assessments.