Annual application and evaluation of the online coupled WRF–CMAQ system over North America under AQMEII phase 2

A comparison between 2010 and 2006 air quality and meteorological conditions, and emissions and boundary conditions used in simulations of the AQMEII-2 North American domain

“…Several participants in the AQMEII-2 collaboration who are applying coupled models to the North American domain are comparing model results for two very different years: 2006 and 2010 (Campbell et al, 2015;Hogrefe et al, 2015;Wang et al, 2015). While the key differences of interest between these two years from a modeling perspective are the predicted air quality impacts of the large reductions in emissions of NO x (21%) and SO 2 (36%) which occurred mostly in the eastern U.S. and the lower emissions from wildfires in the western U.S., meteorological conditions and model boundary conditions (BCs) also differed significantly between these two years.…”

“…1). Seasonal mean PM 2.5 speciation data calculated from observations collected at CSN and IMPROVE network monitoring sites as provided by Hogrefe et al (2015) were examined to determine which PM species contributed to the different trends in winter mean PM 2.5 in the Northeast, where PM 2.5 mass was generally 2e6 mg/m 3 lower in 2010 in both summer and winter, as compared to the Midwest where PM 2.5 was higher in 2010 at most sites during the winter but lower during the summer. This analysis was restricted to 15 sites with valid data in both 2006 and 2010 in 5 Midwest states (IL, IN, IA, MN, OH) and 4 Northeastern states (MA, NH, RI, VT).…”

“…Air quality observations from all available monitoring sites in the U.S. for 2006 and 2010 were extracted from the U.S. Environmental Protection Agency (EPA) Air Quality System (AQS) and processed into seasonal means by Hogrefe et al (2015). Seasons were defined by month as follows: winter (DecembereFebruary), spring (MarcheMay), summer (JuneeAugust) and fall (SeptembereNovember).…”

“…Moreover, as discussed in the next section, year specific emission information for 2006 and 2010 was available only for the U.S., therefore the analysis of emissions and observed air quality is limited to the U.S. Comparisons of observed meteorological and air quality conditions with model predictions are not included in this paper but are the subject of several companion papers (Campbell et al, 2015;Hogrefe et al, 2015;Wang et al, 2015); the current study provides context for these studies.…”

Sensitivity of the Weather Research and Forecast/Community Multiscale Air Quality modeling system to MODIS LAI, FPAR, and albedo

“…Thus, both the LSMs have simple canopy treatments with a big-leaf empirical function stomatal conductance following the approach described by Noilhan and Planton [1989] as well as simple soil hydrology and snow processes. When applied retrospectively for long term simulations, such as for full years, accurate Noah WRF simulations rely on frequent (e.g., every 2-5 days) restart of simulations with reinitialized soil conditions [e.g., Hogrefe et al, 2014] while the PX LSM uses continuous data assimilation for dynamic nudging of soil moisture [Pleim and Xiu, 2003] and temperature [Pleim and Gilliam, 2009] to optimize surface fluxes. The PX LSM is mainly designed for air quality simulations using the WRF/CMAQ system where the WRF LSM parameters (e.g., stomatal and aerodynamic resistances) are consistently used in the AQ dry deposition model.…”