A multi-year record of airborne continuous CO2 in the U.S. Southern Great Plains

Description

We report on two years of airborne measurements of continuous atmospheric CO2 concentrations over the Atmospheric Radiation Measurement (ARM) Climate Research Facility in the U.S. Southern Great Plains. Measurements are made weekly from a small aircraft (Cessna 206) on a series of horizontal legs ranging from 5000 to 300 m above sea level. Since November 2007, more than 100 continuous CO2 vertical profiles have been collected, along with NOAA/ESRL 12-flask (carbon cycle gases and isotopes) packages for cross-validation. Gradients between the mixed layer and free troposphere varied seasonally, reflecting variations in surface fluxes and large-scale vertical and horizontal transport. Horizontal variability in CO2 concentration near the top of the boundary layer indicates that convective mixing may be more important than diurnal entrainment processes in vertical PBL-FT exchange. We focus on resolving vertical transport, which is poorly constrained in many atmospheric models.