AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Impacts of New Particle Formation on Short-term Midwestern Meteorology and Air Quality as Determined by the NPF-explicit WRF-Chem
CAN DONG, Hitoshi Matsui, Scott N. Spak, Charles Stanier, University of Iowa
Abstract Number: 520 Working Group: Regional and Global Air Quality and Climate Modeling
Abstract Nucleation is a frequently observed gas to particle conversion process. Results from the new particle formation (NPF) explicit WRF-Chem model show that PBL nucleation can induce the changes of both meteorology and air pollutants in the Midwestern US. Simulations are conducted for the period during a field campaign in Iowa in June-July 2008. The model has a horizontal resolution of 36 km and uses CBMZ and MOSAIC for gas-phase chemistry and aerosol modules, respectively. In general, simulations with NPF have more shortwave radiation, higher surface temperatures and a deeper boundary layer. NPF changes the timing and location of precipitation. Nucleation enhances the concentration of condensation nuclei. Meanwhile, cloud condensation nuclei (CCN) concentrations are enhanced and suppressed at high and low supersaturations, respectively. For air pollutants, the most pronounced influence of PBL nucleation is PM2.5 reduction, which is mainly caused by SO4 decrease. Sensitivity tests demonstrate that reductions in secondary sulfate (SO42-) via cloud processing of sulfur dioxide (SO2) are primarily responsible for SO4 reduction with the PBL nucleation parameterization. The interactions among nucleation, CCN, cloud droplets, aqueous chemistry and OH radicals are investigated. The missing features of NPF and NPF-cloud feedback present in all models that do not treat NPF, and in models with limitations in feedbacks of meteorology and nuclei particles, may have implications beyond CN and cloud brightness such as PM mass and composition.