Impacts of air–sea interactions on regional air quality predictions using WRF/Chem v3.6.1 coupled with ROMS v3.7: southeastern US example
J. He, R. He, and Y. Zhang
Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA
Received: 17 Sep 2015 – Accepted for review: 20 Oct 2015 – Discussion started: 13 Nov 2015
Abstract. Air–sea interactions have significant impacts on coastal convection and surface fluxes exchange, which are important for the spatial and vertical distributions of air pollutants that affect public health, particularly in densely populated coastal areas. To understand the impacts of air–sea interactions on coastal air quality predictions, sensitivity simulations with different cumulus parameterization schemes and atmosphere–ocean coupling are conducted in this work over southeastern US in July 2010 using the Weather Research and Forecasting Model with Chemistry (WRF/Chem). The results show that different cumulus parameterization schemes can result in an 85 m difference in the domain averaged planetary boundary layer height (PBLH), and 4.8 mm difference in the domain averaged daily precipitation. Comparing to WRF/Chem without air–sea interactions, WRF/Chem with a 1-D ocean mixed layer model (WRF/Chem-OML) and WRF/Chem coupled with a 3-D Regional Ocean Modeling System (WRF/Chem-ROMS) predict the domain averaged changes in the sea surface temperature of 0.1 and 1.0 °C, respectively. The simulated differences in the surface concentrations of ozone (O3) and PM2.5 between WRF/Chem-ROMS and WRF/Chem can be as large as 17.3 ppb and 7.9 μg m−3, respectively. The largest changes simulated from WRF/Chem-ROMS in surface concentrations of O3 and particulate matter with diameter less than and equal to 2.5 μm (PM2.5) occur not only along coast and remote ocean, but also over some inland areas. Extensive validations against observations, show that WRF/Chem-ROMS improves the predictions of most cloud and radiative variables, and surface concentrations of some chemical species such as sulfur dioxide, nitric acid, maximum 1 h and 8 h O3, sulfate, ammonium, nitrate, and particulate matter with diameter less than and equal to 10 μm (PM10). This illustrates the benefits and needs of using coupled atmospheric–ocean model with advanced model representations of air–sea interactions for regional air quality modeling.
He, J., He, R., and Zhang, Y.: Impacts of air–sea interactions on regional air quality predictions using WRF/Chem v3.6.1 coupled with ROMS v3.7: southeastern US example, Geosci. Model Dev. Discuss., 8, 9965-10009, doi:10.5194/gmdd-8-9965-2015, 2015.