Abstract
Air quality in the Middle East is changing due to extensive land conversion, intense industrialization and rapid urbanization. In this study, we analyze data from an ozonesonde station operated in Doha, Qatar, by the Qatar Environment and Energy Research Institute (QEERI). Ozonesondes were launched weekly at 13:00 LT (10:00 UTC) during a summer month (August 2015) representative of extremely hot and humid atmospheric conditions and during a winter period (January–February 2016) representative of cool conditions in the area. Unlike similar studies in the region, this work focuses on the lower troposphere and combines high frequency vertical measurement data with the use of the Weather Research Forecasting model coupled with Chemistry (WRF-Chem). A sensitivity study was conducted to identify the most representative planetary boundary layer (PBL) parameterization. Although all three parameterizations that were examined produced similar results, the Yonsei University (YSU) PBL scheme was found to be statistically superior. Comparisons of model predictions against observations show high correlation coefficients and encouragingly low biases in all meteorological variables. During wintertime, ozone is well predicted overall (fractional bias = –0.1). Results from the summertime comparison are more challenging and point towards possible biases in the anthropogenic emission inventory of the Middle East, especially for rapidly-changing urban environments.
Highlights
Surface ozone—one of the main criteria pollutants set forth by the US EPA (Environmental Protection Agency)— is formed photochemically through oxidation of VOCs in the presence of nitrogen oxides (NOx) (Jacob, 1999)
In this work—unlike previous studies in the region—we focus on the boundary layer and lower troposphere (0–6 km) and combine in situ data analysis of ozonesondes with a 3-D regional online-coupled meteorology-chemistry model
We explore two meteorologically different periods, a summer (August 2015) and a winter (January/February 2016) time period, and investigate the sensitivity of the model predictions to different planetary boundary layer (PBL) parameterizations in simulating meteorological and air quality parameters in the coastal urban environment of Doha, Qatar, using high spatial resolution over the state of Qatar
Summary
Surface ozone—one of the main criteria pollutants set forth by the US EPA (Environmental Protection Agency)— is formed photochemically through oxidation of VOCs (volatile organic compounds) in the presence of nitrogen oxides (NOx) (Jacob, 1999). The grid resolution is relatively low, or the meteorological and chemical processes are offline connected. Such approaches have the disadvantage of not accounting accurately enough for the sub-grid scale phenomena or the interactions and feedback between meteorology and chemistry which could be a significant loss of information especially in polluted urban environments with complex meteorological regimes. In this work—unlike previous studies in the region—we focus on the boundary layer and lower troposphere (0–6 km) and combine in situ data analysis of ozonesondes with a 3-D regional online-coupled meteorology-chemistry model. We explore two meteorologically different periods, a summer (August 2015) and a winter (January/February 2016) time period, and investigate the sensitivity of the model predictions to different PBL parameterizations in simulating meteorological and air quality parameters in the coastal urban environment of Doha, Qatar, using high spatial resolution over the state of Qatar
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