AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
In-cloud AqSOA and Sulfate Formation: A New Microphysical Parameterization for Regional and Global Models
BARBARA ERVENS, Renee McVay, NOAA/ESRL and CIRES/CU
Abstract Number: 108 Working Group: There Must be Something in the Water: Cloud, Fog and Aerosol Aqueous Chemistry for Aerosol Production
Abstract It has been known for several decades that substantial amounts of atmospheric sulfate, and more recently secondary organic aerosol (SOA), are formed in the aqueous phase of clouds and fogs. While the former can be described by a few well-defined chemical reactions, aqSOA formation processes are much more complex, leading to a greater variety of products and aerosol properties.
The representation of these formation processes in models is challenging since both chemical and cloud microphysical parameters have to be taken into account. In this presentation, we will discuss the weaknesses of various parameterizations of sulfate and aqSOA formation that are currently implemented in regional and global models.
Based on process model studies, we will show the importance of surface-limited and drop-size dependent mass formation rates throughout cloud droplet size distributions. Usually neither observational data sets nor regional or higher-scale models can provide such detail of cloud droplet size distributions.
We present a microphysical parameterization of aqSOA and sulfate formation in clouds that reproduces the mass formation rates in polydisperse cloud droplet populations by using only one representative droplet size. The underlying reasoning of this simplification will be discussed together with its uncertainties and applicability. Finally an outlook will be given on how to implement this new parameterization into regional models.