Uncertainties in numerical weather prediction and Earth system models over high latitudes are associated with predicted declines in Arctic ice cover that are slower than observed and large biases in simulated radiation budgets over the Southern Ocean. These deficiencies are associated with a lack of in situ and remote sensing observations to adequately constrain the treatment of aerosol-cloud-precipitation-radiation interactions. Several recent observational campaigns over the Arctic and Southern Ocean have been dedicated to improving fundamental understanding of microphysical processes occurring in liquid and ice-containing clouds, and determining roles of primary and secondary marine biogenic aerosols and sea-salt emissions. This session solicits contributions that describe recent ship, ground or airborne measurements of high latitude clouds, aerosols, precipitation, and radiation, and that use data from such campaigns, satellite remote sensing, and/or numerical simulations at any spatial/temporal scale to advance understanding of aerosol, cloud, precipitation and radiation properties and their interactions.