A comparison study between model-predicted and OMI-retrieved tropospheric NO2 columns over the Korean peninsula

In this study, Community Multi-scale Air Quality (CMAQ) model simulations, using the INTEX-B (Intercontinental Chemical Transport Experiment-Phase B) emission inventory for North Korea and China, CAPSS (Clean Air Policy Support System) emission inventory for South Korea, and REAS (Regional Emission Inventory in Asia) emission inventory for Japan, were carried out over four seasonal episodes from 2006, with a fine grid resolution of 30 km x 30 km, in order to evaluate the accuracy of the NOx emissions over the Korean peninsula. The tropospheric NO2 columns from the CMAQ model simulations were then compared with those retrieved from a satellite sensor, Ozone Monitoring Instrument (OMI), over the Korean peninsula as well as briefly over East Asia. The results showed that the CMAQ modeling, using the NOx emissions from the CAPSS inventory over South Korea, produced tropospheric NO2 columns that were over-predicted by factors between 1.38 and 1.87 compared to the OMI-retrieved tropospheric NO2 columns. This appears to be in line with the findings from a previous study, i.e. when the ACE-ASIA emission inventory was used for the episodes from 2001 to 2003, the CMAQ modeling tended to produce NO2 columns that were similar to 1.46 times larger than the GOME-derived NO2 columns over South Korea. On the other hand, over North Korea, the NOx emissions of the INTEX-B emission inventory appear to be overestimated by factors between 1.55 and 7.46 (3.18 over the four seasonal episodes), based on the comparison study between the CMAQ-simulated and OMI-retrieved tropospheric NO2 columns. This may be caused by the large uncertainty in the NOx emission fluxes from North Korea due to insufficient information on the economic activity and energy consumption related to the political instability in North Korea. (C) 2010 Elsevier Ltd. All rights reserved.