Bulk parameterization of giant CCN

Results from previous work by our group based on large eddy simulation (LES) with size-resolved microphysics demonstrated that giant cloud condensation nuclei (GCCN) can profoundly influence cloud parameters and boundary layer thermodynamics. A bulk parameterization for GCCN has been developed that uses precise representations of the condensational growth of aerosol particles in the subcloud layer and is based on directly observable parameters of GCCN, such as concentration and the shape of the aerosol spectra. The behavior of the GCCN parameterization in an LES framework is consistent with previous simulations using explicit spectral microphysical methods. Removal of GCCN by cloud processing in a few eddy turnover timescales implies the importance of accurately specifying the flux of GCCN from the ocean surface.