An Investigation of Sea Salt Effects as Cloud Condensation Nuclei (CCN) through Implementing Sea Salt Emission and Microphysics in a Bulk Microphysical Scheme

This study implements sea salt emission and sea salt microphysics into a bulk microphysical scheme (aerosol-aware Thompson) in WRF to investigate the effects of sea salt as a new CCN species on weather processes related to sea salt behaviors.

As previous study indicated, sea salt source function is parameterized as a function of 10-m wind in model simulation. Emission of sea salt is a sea salt size (radius) integration of this source function. In this study, drop activation, collection and aqueous aerosol freezing about sea salt are newly added in the microphysical scheme. Drop activation by sea salt is calculated using the results of a parcel model as a function temperature, updraft and its concentration with different background water-friendly aerosol conditions.

Introducing sea salt as a new CCN species in model simulation specifies the activation of cloud droplets. The approach in this study generally leads to a decrease in cloud droplet number concentration and thus an increase in mean diameter. This change will affect rain formation, latent heat release and therefore system development. These impacts will be present through different cases such as maritime and coastal convection and Typhoon. However, mass of sea salt is not prognosed for now and wet growth and sedimentation of sea salt are ignored in current microphysical scheme, which will be developed in the near future.