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Quantifying the influence of boundary conditions and anthropogenic emissions to ozone concentrations towards estimating the modeled controllable portion of the ozone burden in continental United States
Citation:
Astitha, M., H. Luo, C. Hogrefe, R. Mathur, AND S. Rao. Quantifying the influence of boundary conditions and anthropogenic emissions to ozone concentrations towards estimating the modeled controllable portion of the ozone burden in continental United States. 2018 CMAS Conference, Chapel Hill, NC, October 22 - 24, 2018.
Impact/Purpose:
By analyzing annual CMAQ simulations for cases with varying emissions and boundary conditions, the work in this study attempts to estimate the controllable portion of ambient ozone concentrations. The focus of this study is on quantifying the impact of these factors on the long-term component of the modeled ozone time series since previous work had shown that variations of this component have a strong influence on ozone exceedances. Results of this analysis can potentially help to inform approaches for utilizing model sensitivity simulations in designing effective and efficient measures aimed at meeting and maintaining ambient air quality standards.
Description:
This study investigates contributions from boundary conditions and anthropogenic emissions to ozone exceedances and infers the modeled controllable portion of the tropospheric ozone burden across the continental United States. We use a set of simulations performed with the WRF-CMAQ model with a horizontal grid spacing of 12 km as part of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) (Hogrefe et al.,2018). The simulations cover the year 2010 as the base simulation and are augmented by three simulations with the same meteorology: one with lateral boundary conditions for all species set to zero; the second with all anthropogenic emissions as well as wildfire emissions within the domain set to zero and a third one with a 20% reduction of anthropogenic emissions both in the global model simulations that provide lateral boundary conditions and within the WRF-CMAQ modeling domain. With the help of these simulations, we examine the drivers behind the baseline ozone concentration, defined as the long-term component of the spectral decomposition of ozone maximum daily 8hr concentration time series that exhibits significant influence on ozone exceedances. We determine the impacts on the ozone design value and assess the modeled controllable portion of ozone for various regions across CONUS.
