ARMACME

ARM Airborne Carbon Measurements (ARM-ACME III)

1 October 2012 - 30 September 2013

Lead Scientist: Sebastien Biraud

Observatory: AAF, SGP

We continud our long-term airborne study of atmospheric composition and carbon cycling in the Southern Great Plains (SGP), with scientific objectives that are central to carbon-cycle and radiative-forcing goals of the US Climate Change Science Program. The goals of this measurement program are to improve understanding of: (a) land-atmosphere carbon exchanges of the ARM region; (b) how CO2 and associated water and energy fluxes influence radiative forcing, convective processes, and CO2 concentrations; and (c) how greenhouse gases are transported on continental scales. To meet these goals, we are conducting airborne measurements to support the following scientific objectives:

• Quantify trends and variability in atmospheric concentrations of CO2 and other greenhouse gases in North America, e.g., for NACP continental synthesis
• Contribute to the Earth System Model test-bed
• Apply carbonyl sulfide as a tracer of Gross Primary Productivity
• Improve understanding and modeling of PBL and FT exchange dynamics
• Contribute to characterization of cloud dynamics and precipitation processes
• Characterize fossil fuel emissions in the ARM Climate Research Facility
• Reduce uncertainties in GCM parameterization of radiative transfer

We maintained and enhanced the ongoing airborne carbon cycle measurements using ARM aircraft (Cessna 206) in the ARM-SGP. In September 2011, we were awarded by the ARM Aerial Facility (AAF) a total of 525 flight hours over the period January 1, 2012 through September 30, 2013. The following missions are being conducted: (1) vertical profiles from the surface to mid-troposphere (0-5 km); and (2) horizontal transects for spatial patterns in clear sky and cloudy day campaigns. During flights, we were measuring CO2 and meteorological data continuously and collected flasks for a rich suite of additional gases: CO, CH4, N2O, 13CO2, 14CO2, carbonyl sulfide (COS), and many trace hydrocarbon species. The core instruments were already integrated on the C206. These flights were the only regular, continuous CO2 vertical profiles collected in the U.S. We have already developed data processing, QC/QA, and archiving protocols under ARM support. In addition to ARM Aerial Facility (AAF) support, the proposed study received in-kind contributions from NOAA, LLNL, University of Colorado, Boulder, and the Carnegie Institution of Washington for sample analysis. Separate funding was obtained for publication and other downstream research activities. Our archived data from past flights have been requested and used by dozens of researchers. Support for research associated with the campaign is provided by DOE's Terrestrial Ecosystem Science program.