The Southern Ocean currently absorbs a significant amount of the atmospheric burden of human produced CO2 emitted into the atmosphere, but the future trajectory of this sink is highly uncertain. Sparse observations and complex interacting physical and biological processes limit our understanding of biogeochemistry and climate feedbacks at high southern latitudes. The O2/N2 Ratio and CO2 Airborne Southern Ocean (ORCAS) Study will advance our understanding of the physical and biological controls on tropospheric air-sea exchange of O2 and CO2 over the Southern Ocean. This will be achieved through intensive airborne surveys of atmospheric O2, CO2, related gases, along with ocean surface properties over selected biogeochemical sites over the South Pacific and the Antarctic Peninsula.
ORCAS will utilize the NSF/NCAR Gulfstream V (GV) aircraft with a suite of high precision in situ and remote sensing instruments, and whole-air samplers on 14 flights over an interval of 6 weeks in austral mid-summer. The primary objectives are to observe the large scale tropospheric distributions of O2 and CO2, to characterize regional scale relationships between vertical O2 and CO2 gradients, and to estimate local scale O2 fluxes via Lagrangian boundary layer budgeting with coincident bio-optical remote sensing of the ocean surface.