Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit https://espo.nasa.gov for information about our current projects.


Spatial heterogeneity in CO2, CH4, and energy fluxes: insights from airborne...

Hannun, R. A., G. M. Wolfe, S. R. Kawa, T. F. Hanisco, P. Newman, J. Alfieri, J. Barrick, K. Clark, J. P. DiGangi, G. S. Diskin, J. S. King, W. P. Kustas, B. Mitra, A. Noormets, J. B. Nowak, L. Thornhill, and R. Vargas (2020), Spatial heterogeneity in CO2, CH4, and energy fluxes: insights from airborne eddy covariance measurements over the Mid-Atlantic region, Environmental Research Letters., 15, 035008, doi:10.1088/1748-9326/ab7391.

The exchange of carbon between the Earth's atmosphere and biosphere influences the atmospheric abundances of carbon dioxide (CO2) and methane (CH4). Airborne eddy covariance (EC) can quantify surface-atmosphere exchange from landscape-to-regional scales, offering a unique perspective on carbon cycle dynamics. We use extensive airborne measurements to quantify fluxes of sensible heat, latent heat, CO2, and CH4 across multiple ecosystems in the Mid-Atlantic region during September 2016 and May 2017. In conjunction with footprint analysis and land cover information, we use the airborne dataset to explore the effects of landscape heterogeneity on measured fluxes. Our results demonstrate large variability in CO2 uptake over mixed agricultural and forested sites, with fluxes ranging from −3.4 ± 0.7 to −11.5 ± 1.6 μmol m−2 s−1 for croplands and −9.1 ± 1.5 to −22.7 ± 3.2 μmol m−2 s−1 for forests. We also report substantial CH4 emissions of 32.3 ± 17.0 to 76.1 ± 29.4 nmol m−2 s−1 from a brackish herbaceous wetland and 58.4 ± 12.0 to 181.2 ± 36.8 nmol m−2 s−1 from a freshwater forested wetland. Comparison of ecosystem-specific aircraft observations with measurements from EC flux towers along the flight path demonstrate that towers capture ~30%–75% of the regional variability in ecosystem fluxes. Diel patterns measured at the tower sites suggest that peak, midday flux measurements from aircraft accurately predict net daily CO2 exchange. We discuss next steps in applying airborne observations to evaluate bottom-up flux models and improve understanding of the biophysical processes that drive carbon exchange from landscape-to-regional scales.

PDF of Publication: 
Download from publisher's website.
Research Program: 
Tropospheric Composition Program (TCP)