Microphysical and Macrophysical Properties of Mixed-Phase Clouds over the Southern Ocean and Antarctica and Comparisons with the NCAR CAM6 Model

Mixed-phase clouds (MPCs) have large spatial coverage over the Southern Ocean, while the understanding of the coexistence between ice particles and liquid droplets in MPCs are still limited. In this work, we will analyze the micro- and macrophysical properties of MPCs based on aircraft-based observations from two National Science Foundation (NSF) campaigns over the Southern Ocean – the NSF ORCAS (2016) and SOCRATES (2018) campaigns, and ground-based observations from the DOE/NSF AWARE campaign (2016-2017).

The observations will be compared with two types of simulations from the NCAR Community Atmosphere Model Version 6 (CAM6): the single-column model simulations and the nudged simulations towards the meteorological conditions from reanalysis data. Using these two types of simulations, we will compare the occurrences of ice supersaturation (ISS) and its relationship with ice particles and liquid droplets. In addition, relationships of ISS and phase partitioning with respect to vertical velocity and aerosol number concentrations (i.e., Na > 500 nm and total Na) will also be quantified. This work will help to provide more observation constraints to the parameterizations of cloud microphysics in the CAM6 model, especially for the representations of RH sub-grid variabilities and the assumptions of liquid saturation and ice saturation related to MPCs and ice clouds.