Measurements of Aerosols, Radiation, and Clouds over the Southern Ocean (MARCUS) Field Campaign Report

• Main Authors: McFarquhar, Greg, Maarchand, Roger, Bretherton, Chris, Alexander, Simon, Protat, Alain, Siems, Steven, Wood, Robert, DeMott, Paul
• Language: unknown
• Published: 2019
• Subjects: Antarctic; Southern Ocean; Antarc*; Antarctica; aurora australis; Macquarie Island
• Online Access: http://www.osti.gov/servlets/purl/1524775; https://www.osti.gov/biblio/1524775

The Southern Ocean (SO) is the stormiest place on earth, buffeted by winds and waves that circle the ice of Antarctica, sheathed in clouds that mantle a dynamic ocean with rich ecosystems. The remote and usually pristine environment, typically removed from anthropogenic and natural continental aerosol sources, makes the SO unique for examining cloud-aerosol interactions for liquid and ice clouds, and the role of primary and secondary marine biogenic aerosols and sea salt. There is strong seasonality in aerosol sources and sinks over the SO that are poorly understood. Weather and climate models are challenged by uncertainties and biases in the simulation of SO clouds, aerosols, precipitation, and radiative transfer that trace to poor physical understanding of these processes, and by cloud feedbacks (e.g., phase changes) in response to warming. Models almost universally underestimate sunlight reflected by near-surface cloud, particularly in the cold sector of cyclonic storm systems, and this may be due to difficulties in representing pervasive supercooled and mixed-phase boundary-layer (BL) clouds. The Southern Ocean Clouds Radiation Transport Aerosol Transport Experimental Study (SOCRATES) white paper (Marchand et al. 2014) describes the motivation, scientific themes, and testable hypotheses that led to a multi-agency and international measurement campaign to study clouds, aerosols, and the air-sea interface over the SO. As a separate project within this international umbrella, the Measurement of Aerosols, Radiation, and Clouds over the Southern Ocean (MARCUS) field program was conducted between 29 October 2017 and 25 March 2018. During MARCUS, instruments from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility’s second Mobile Facility (AMF2) were installed on the Australian icebreaker Aurora Australis as it made resupply missions from Hobart, Tasmania to the Australian Antarctic stations of Casey, Mawson, and Davis, as well as Macquarie Island. Figure 1 shows the voyages ...