SOCRATES: Southern Ocean Clouds Radiation Aerosol Transport Experimental Study

Summary

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. Weather and climate models are challenged by uncertainties and biases in the simulation of SO clouds, aerosols, precipitation, and radiation which 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 in the Austral summer, particularly in the cold sector of cyclonic storm systems, possibly due to difficulties in representing pervasive supercooled and mixed-phase boundary layer (BL) clouds.

Motivated by these issues, a large international multi-agency effort called the Southern Ocean Clouds PI - Project - Facility Update 15 November 2015 Page 16 Radiation Transport Aerosol Transport Experimental Study (SOCRATES) has been proposed to improve our understanding of clouds, aerosols, air-sea exchanges and their interactions over the SO. As a component of SOCRATES, we are requesting the use of the NSF/NCAR G-V aircraft for 6 weeks between Jan. and March 2018 to sample a North-South curtain from Tasmania to ~62˚S. Concurrent measurements will be made by the Australian Research Vessel (R/V) Investigator equipped with the NCAR Integrated Sounding System (ISS). Hypotheses that can be addressed with the G-V and R/V Investigator data and related modeling and satellite analyses are described in the PI proposals.