Comparison of NOAA's current greenhouse gas observing network to a hypothetical network hosted on commercial aircraft for constraining fluxes at regional to continental scales

Abstract:

The NOAA Global Greenhouse Gas Reference Network (GGGRN) is composed surface and tower sites with continuous and flask measurements and aircraft sites where vertical profiles of flask air samples are collected 1-2 times per month and are analyzed for CO₂, CH₄, and more than 50 other trace gases and isotopes. Compared to surface measurements, atmospheric vertical profile measurements are advantageous due to their sensitivity to surface fluxes over large scales, high information content for evaluating atmospheric transport models, and because they also provide information about boundary conditions. Since the GGGRN aircraft network began over 20 years ago, the data have been used in a huge variety of analyses, but, by themselves, are too sparse to provide information on inter-annual variability in fluxes and on fluxes at sub-continental scales, which are crucial for diagnosis and attribution of the carbon-cycle and which were an original purpose of the program.

Given this critical and long-standing limitation, we envision greatly increasing the density and coverage of greenhouse gas vertical profile measurements through the deployment of continuous measurement systems on commercial aircraft. We investigate the potential increase in data coverage from such a program with 1, 3, or 10 instrumented aircraft using historical flight tracks from the AMDAR (Aircraft Meteorological Data Reports) program. We report results from an observing system simulation experiment (OSSE) with NOAA’s CarbonTracker CO₂ modeling system and posterior fluxes from the European Copernicus Atmosphere Monitoring Service (CAMS) as the truth condition to investigate potential improvements in our ability to constrain CO₂ fluxes for the continental U.S. and North American Arctic in comparison to and in addition to the current observing network.