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Application, evaluation and sensitivity analysis of the coupled WRF-CMAQ system from regional to urban scales
Citation:
Appel, W., R. Gilliam, R. Mathur, S. Roselle, Jon Pleim, AND C. Hogrefe. Application, evaluation and sensitivity analysis of the coupled WRF-CMAQ system from regional to urban scales. 2017 AGU Fall Meeting, New Orleans, LA, December 11 - 15, 2017.
Impact/Purpose:
Research Motivation: Demonstrate ability to model air quality at fine-scales (e.g. 1-km); Better understanding of model configuration for application at these scales; Determine whether the model can resolve fine-scale features (e.g. bay-breeze, terrain effects, etc.) better at fine scales. Demonstrate usefulness of increased information at finer scales and examine the impact of tighter meteorological coupling vs. standard off-line practices. Finally, determine the impact on model performance with direct radiative feedback effects vs. no feedback effects. The agency needs include fine-scale AQ modeling for: NAAQS-related assessments; persistent non-attainment areas; hourly NO2/SO2 standards; and exposure and risk assessments.
Description:
The Community Multiscale Air Quality (CMAQ) model is a state-of-the-science chemical transport model (CTM) capable of simulating the emission, transport and fate of numerous air pollutants. Similarly, the Weather Research and Forecasting (WRF) model is a state-of-the-science meteorological model capable of simulating meteorology at many scales (e.g. global to urban). The coupled WRF-CMAQ system integrates these two models in a “two-way” configuration which allows feedback effects between the chemical (e.g. aerosols) and physical (e.g. solar radiation) states of the atmosphere. In addition, the coupled modeling system allows for more frequent communication between the CTM and meteorological model than is typically done in uncoupled WRF-CMAQ simulations. The goal of this modeling exercise is to assess the ability of the coupled WRF-CMAQ system at fine-scales (e.g. 4km to 1km) through comparison with high space and time resolution field measurements, and comparing those results to the traditional regional scale (e.g. 12km) simulation. This work will specifically examine several fine-scale simulations over the Eastern United States and the Baltimore, MD/Washington D.C. region for 2011, with special emphasis on the period of the DISCOVERAQ field campaign. In addition to evaluating the model performance at the various scales, the impact of the more frequent time coupling of the CTM and meteorology, aerosol feedback effects and lightning generated NO at the finer spatial resolutions will be assessed. The effect of simulating sub-grid clouds using several different options (i.e. explicit, parameterized or assimilated) will also be examined, since clouds are particularly important as they can have a large impact on both the meteorology (beyond the clouds themselves) and air quality, and are notoriously difficult to simulate accurately.
