Parameterizing ice nuclei concentration dependence on aerosol concentration, temperature, and composition

Description

It has been suggested that ice nuclei concentrations active in mixed-phase cloud conditions can be parameterized in an average sense for global models as a function of aerosol concentrations > 0.5 micron and temperature alone (DeMott et al. 2010). Comparison of this parameterization with independent ice nuclei and aerosol data collected in the Indirect and Semi-Direct Aerosol Campaign (ISDAC) suggests that such a representation may be quite suitable for use in modeling ice nuclei influences on Arctic mixed-phase clouds. Nevertheless, additional dependencies on aerosol composition can be expected at different times and places: for example, where stronger local and regional sources exist. In any case, quantifying compositional dependencies would be expected to provide more robust prediction of ice nuclei concentrations for use in modeling studies. Here we report on measurements of ice nuclei specific to strong potential sources such as desert dust plumes, smoke plumes, ocean wave spray, and terrestrial biological particles. We utilize data from both laboratory and field studies to show that consideration of ice nuclei sources can potentially provide more robust parameterizations for models that are capable of specifying different compositional categories for ice nuclei.

Reference: DeMott, PJ, AJ Prenni, X Liu, MD Petters, CH Twohy, MS Richardson, T Eidhammer, SM Kreidenweis, and DC Rogers. 2010. “Predicting global atmospheric ice nuclei distributions and their impacts on climate.” Proceedings of the National Acadamy of Sciences 107 (25): 11217–11222.