AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
The Contribution of Sub-Grid, Plume-Scale Nucleation to Global and Regional Aerosol and CCN Concentrations
ROBIN STEVENS, Jeffrey Pierce, Dalhousie University
Abstract Number: 188 Working Group: Aerosols, Clouds, and Climate
Abstract New-particle formation in the plumes of coal-fired power plants and other anthropogenic sulphur sources may be an important source of particles in the atmosphere. It has been unclear, however, how best to reproduce this formation in global and regional aerosol models with grid-box lengths that are 10s of kilometres and larger. The predictive power of these models is thus limited by the resultant uncertainties in aerosol size distributions.
Based on the results of the System for Atmospheric Modelling (SAM), a Large-Eddy Simulation/Cloud-Resolving Model (LES/CRM) with online TwO Moment Aerosol Sectional (TOMAS) microphysics, we develop the Predicting Particles Produced in Power-Plant Plumes (P6) parameterization: a computationally-efficient, but physically-based, parameterization that predicts the characteristics of aerosol formed within sulphur-rich plumes based on parameters commonly available in global- and regional-scale models. Given large-scale mean meteorological parameters, emissions from the source, the desired distance from the source, and the mean background SO$_2, NO$_x, and condensation sink, the parameterization will predict the fraction of the emitted SO$_2 that is oxidized to H$_2SO$_4, the fraction of that H$_2SO$_4 that forms new particles instead of condensing onto preexisting particles, the median diameter of the newly-formed particles, and the number of newly-formed particles per kilogram SO$_2 emitted.
We implement the P6 parameterization in the GEOS-Chem global chemical-transport model in order to evaluate the contributions of coal-fired power plants globally to particle number and CCN concentrations.