Arctic winter longwave aerosol indirect effect with a new parameterization of frost flower salt particle emissions
Authors
Li Xu — University of California, San Diego
Lynn M Russell — Scripps Institution of Oceanography
Richard C. J. Somerville — Scripps Institution of Oceanography
Category
Aerosol-Cloud-Radiation Interactions
Description
Frost flowers are clusters of highly saline ice crystals growing on newly formed sea ice or frozen lakes. Based on observations of particles derived from frost flowers in the Arctic, we formulate an observation-based parameterization of a seawater-derived aerosol source function from frost flowers. The particle flux from frost flowers in winter is of the order of 10^6 m-2 s-1 at the wind speed of 10 m s-1, but the source flux is highly sensitive to the wind speed. We have implemented this parameterization in the regional model of WRF-Chem. The WRF-Chem was configured using two-way nested domains with grid spaces of 30 kilometers and 6 kilometers. The period of 31 January 2009 00:00 UTC through 3 February 2009 21:00 UTC was chosen for the simulation. This period maximized the amount of sodium and chloride measured in Barrow, Alaska. The preliminary results suggest that the addition of salt particle sources from frost flowers increases both sodium chloride and cloud droplet number concentration as well as cloud liquid water path, thereby resulting in the enhancement of cloud longwave forcing in Arctic winter.
