Motivated by these issues, the Southern Ocean Clouds Radiation and Aerosols Transport Experiment (SOCRATES) made airborne and ship-based measurements of cold sector clouds and their interaction with the underlying ocean between Tasmania and the Antarctic coast during Jan.-Feb. 2018. The 15 SOCRATES research flights of NCAR’s G-V research aircraft sampled diverse environmental conditions, including stable and unstable boundary layers, near-surface winds up to 25 m s-1, and persistent supercooled liquid clouds at temperatures as cold as -30◦ C and liquid cloud droplet concentrations ranging from 20-300 cc-1.
Here, we evaluate nudged hindcasts from the Community Atmosphere Model (CAM6) and the Geophysical Fluid Dynamics Laboratory Atmosphere Model (AM4) using time-space collocated SOCRATES airborne observations. Both global models are nudged toward global wind and temperature fields from MERRA reanalysis for the SOCRATES period. This forces a realistic evolution of storm systems and other atmospheric circulations in the GCM. Humidity, cloud fields, and aerosol fields are not nudged, so it is meaningful to compare these with the airborne observations. Those observations include vertical cloud and precipitation profiles from a cloud radar and lidar, size distributions of aerosol, liquid and frozen cloud and precipitation, CCN/IFN measurements, limited aerosol composition measurements, and meteorology. These observations will be used to evaluate the current simulation of SO boundary-layer clouds and aerosols. They will also inform future improvements of the microphysics, turbulence and cumulus parameterizations in the models.