The Southern Ocean plays a critical role in the global climate system by mediating atmosphere–ocean partitioning of heat and carbon dioxide. However, Earth system models are demonstrably deficient in the Southern Ocean, leading to large uncertainties in future air–sea CO2 flux projections under climate warming and incomplete interpretations of natural variability on interannual to geologic time scales. Here, we describe a recent aircraft observational campaign, the O2/N2 Ratio and CO2 Airborne Southern Ocean (ORCAS) study, which collected measurements over the Southern Ocean during January and February 2016. The primary research objective of the ORCAS campaign was to improve observational constraints on the seasonal exchange of atmospheric carbon dioxide and oxygen with the Southern Ocean. The campaign also included measurements of anthropogenic and marine biogenic reactive gases; high-resolution, hyperspectral ocean color imaging of the ocean surface; and microphysical data relevant for understanding and modeling cloud processes. In each of these components of the ORCAS project, the campaign has significantly expanded the amount of observational data available for this remote region. Ongoing research based on these observations will contribute to advancing our understanding of this climatically important system across a range of topics including carbon cycling, atmospheric chemistry and transport, and cloud physics. This article presents an overview of the scientific and methodological aspects of the ORCAS project and highlights early findings.
Britton Stephens, Matthew Long, Ralph Keeling, Eric Kort, Colm Sweeney, Eric Apel, Elliot Atlas, Stuart Beaton, Jonathan Bent, Nicola Blake, James Bresch, Joanna Casey, Bruce Daube, Minghui Diao, Ernesto Diaz, Heidi Dierssen, Valeria Donets, Bo-Cai Gao, Michelle Gierach, Robert Green, Justin Haag, Matthew Hayman, Alan Hills, Martín Hoecker-Martínez, Shawn Honomichl, Rebecca Hornbrook, Jorgen Jensen, Rong-Rong Li, Ian McCubbin, Kathryn McKain, Eric Morgan, Scott Nolte, Jordan Powers, Bryan Rainwater, Kaylan Randolph, Mike Reeves, Sue Schauffler, Katherine Smith, Mackenzie Smith, Jeff Stith, Gregory Stossmeister, Darin Toohey, and Andrew Watt. "The O2/N2 Ratio and CO2 Airborne Southern Ocean Study" Bulletin of the American Meteorological Society (2018): 381-402. doi:10.1175/BAMS-D-16-0206.1