Speaker：Greg McFarquhar
Time：10:00-11:00, Friday, 2018.11.9
Dddress：Physics North 539
Host：Ji Nie
Summary：
Weather and climate models are challenged by biases in simulating Southern Ocean (SO) clouds, aerosols, and radiation due to poor understanding of processes and few observations. The SO Cloud Radiation Aerosol Transport Experimental Study (SOCRATES) and the Measurements of Aerosols, Radiation and Clouds over the SO (MARCUS) projects made unique measurements of clouds, aerosols and precipitation in a North-South Curtain between 2017 and 2018.
Observations include in-situ measurements of cloud condensation nuclei, ice nucleating particles, and cloud and aerosol size-resolved and bulk properties from the NSF/NCAR G-V, cloud and aerosol remotely sensed properties from sensors on the G-V and on the R/V Investigator and Aurora Australis, surface aerosols on the ships, and atmospheric profiles from radiosondes. Synergistically these data provide measurements of the boundary layer and free troposphere structure, together with vertical distributions of liquid and mixed-phase clouds and aerosols over cold waters where supercooled water is frequent, including comprehensive data south of the oceanic polar front, in the cold sector of cyclones, and seasonal variations.
New findings from these projects that will be discussed include measurements of pristine environments with numerous small and few large aerosols above cloud suggesting regions of new particle formation, ubiquitous supercooled water in thin, multi-layered clouds and small-scale generating cells near cloud top, dependence of ice and liquid cloud properties on aerosol amount, wind speed, coupling of the boundary layer, sea surface temperature and position relative to cyclone center, dependence of icing on environmental parameters, and observations of fine-scale transitions between phases. The use of SO data for evaluating and improving models is also discussed.
