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Multi-model Comparison of Lateral Boundary Contributions to Ozone Concentrations over the United States (CM
Citation:
Liu, P., C. Hogrefe, J. Bieser, U. Im, R. Mathur, U. Nopcmongcol, S. Roselle, AND T. Spero. Multi-model Comparison of Lateral Boundary Contributions to Ozone Concentrations over the United States (CM. 15th Annual CMAS conf, Chael Hill, NC, October 24 - 26, 2016.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.
Description:
As the National Ambient Air Quality Standards (NAAQS) for ozone become more stringent, there has been growing attention on characterizing the contributions and the uncertainties in ozone from outside the US to the ozone concentrations within the US. The third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) provides an opportunity to investigate this issue through the combined efforts of multiple research groups in the US and Europe. The model results cover a range of representations of chemical and physical processes, vertical and horizontal resolutions, and meteorological fields to drive the regional chemical transport models (CTMs), all of which are important components of model uncertainty (Solazzo and Galmarini, 2016). In AQMEII3, all groups were asked to track the contribution of ozone from lateral boundary through the use of chemically inert tracers. Though the inert tracer method tends to overestimate the impact of ozone boundary conditions compared with other methods such as chemically reactive tracers and source apportionment (Baker et al., 2015), the method takes the least effort to implement in different models, and is thus useful in highlighting and understanding the process-level differences amongst the models.In this study, results from four models were included, which are named as US3 (CMAQ driven by WRF, US EPA), US1 (CAMx driven by WRF, Ramboll Environ, US), DE1 (CMAQ driven by CCLM), and DK1 (DEHM). First, the model performance for surface ozone predictions was compared with observations. Then, at each site, the distribution of daily maximum 8-hour ozone, and the corresponding concentrations of the inert tracers was calculated and compared across different models. Furthermore, as required by AQMEII3, the impacts of lateral boundary ozone from lower troposphere, free troposphere and stratosphere were tracked separately by
