The NASA Carbon Airborne Flux Experiment (Carafe): Instrumentation And Methodology

Abstract: The exchange of trace gases between the Earth’s surface and atmosphere strongly influences atmospheric composition. Airborne eddy covariance can quantify surface fluxes at local to regional scales (1–1000 km), potentially helping to bridge gaps between top-down and bottom up flux estimates and offering novel insights into biophysical and biogeochemical processes. The NASA Carbon Airborne Flux Experiment (CARAFE) utilizes the NASA C-23 Sherpa aircraft with a suite of commercial and custom instrumentation to acquire fluxes of carbon dioxide, methane, sensible heat, and latent heat at high spatial resolution. Key components of the CARAFE payload are described, including the meteorological, greenhouse gas, water vapor, and surface imaging systems. Continuous wavelet transforms deliver spatially resolved fluxes along aircraft flight tracks. Flux analysis methodology is discussed in depth, with special emphasis on quantification of uncertainties. Typical uncertainties in derived surface fluxes are 40–90 % for a nominal resolution of 2 km or 16–35 % when averaged over a full leg (typically 30–40 km). CARAFE has successfully flown two missions in the eastern US in 2016 and 2017, quantifying fluxes over forest, cropland, wetlands, and water. Preliminary
results from these campaigns are presented to highlight the performance of this system.

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Authors: Wolfe, Glenn M., S. Randy Kawa, Thomas F. Hanisco, Reem A. Hannun, Paul A. Newman, Andrew Swanson, Steve Bailey et al.

Associations: 1Atmospheric Chemistry and Dynamics Lab, NASA Goddard Space Flight Center, Greenbelt, MD, USA 2 Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD, USA 3Goddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD, USA 4NASA Langley Research Center, Hampton, VA, USA 5NASA Ames Research Center, Moffett Field, CA, USA 6Wallops Flight Facility, NASA Goddard Space Flight Center, Wallops Island, VA, USA 7AECOM, ATM Project, Wallops Flight Facility, NASA Goddard Space Flight Center, Wallops Island, VA, USA 8SSAI, ATM Project, Wallops Flight Facility, NASA Goddard Space Flight Center, Wallops Island, VA, USA