P18 City-scale top-down verifications of NOx emissions in South Korea using satellite observations

Lee, Jae-Hyeong, Sang-Hyun Lee, Kongju National University, South Korea

A quantitative evaluation of anthropogenic emissions is a prerequisite for accurate modeling of air quality using a chemical transport model. South Korea is suffering from poor air quality due to the influence of strong local emissions and trans-boundary emissions of China. In the study, a top-down verification method is applied to assess NOX emissions over local urbanized areas in South Korea using OMI/KNMI (Ozone Monitoring Instrument/Royal Netherlands Meteorological Institute) NO2 columns. The WRF-Chem (Weather Research and Forecasting-Chemistry) is configured over the East Asia domain (DX = 32.4 km) and nested down to South Korea domain (DX = 3.6 km) using a one-way nesting technique. The model simulation was conducted for 6 months (from April to September) 2010 with the MICS-ASIA 2010 (Model Inter-Comparison Study for ASIA 2010) emissions which includes both the local and trans-boundary emissions in the model domain. Ten sector areas with high emission intensities in South Korea were defined and the NOX emission of each sector was assessed. The satellite-observed NO2 columns range from 3.9×1015 molec. cm-2-13.5×1015 molec. cm-2 with a highest value in Seoul. The model simulated NO2 columns of a range of 6.2×1015 molec. cm-2-15.7×1015 molec. cm-2 compare well within the estimated model-observation errors. Appling OMI averaging kernels to modeled NO2 column increased ~24% on average, and the magnitude changed seasonally by a combined influence of monthly variations in vertical distributions of the modeled NO2 mixing ratios and the OMI averaging kernels. Further details are discussed including the influence of a sector-size and a OMI NO2 column down-scaling.