Multi-model Ensemble of Air Quality Forecasts for the Megacity Air Pollution Studies-Seoul (MAPS-Seoul): Model Inter-comparison and Evaluation

Abstract:

In this study, we present the results of model inter-comparison and evaluation of the multi-model air quality forecast system for the Megacity Air Pollution Studies-Seoul (MAPS-Seoul), which is a preparatory campaign for KORUS-AQ. The four global and regional modeling groups have participated in the campaign and have produced 7-day forecasts of hourly PM₁₀, PM_2.5, and O₃ concentrations over East Asia for May 18 - June 12, 2015. All models have used the same CREATE anthropogenic emissions over East Asia, but used their own natural emissions from soil and vegetation. Three regional models were driven by meteorological fields from the WRF model with the same initial and boundary meteorological conditions from the NCEP Global Forecast System (GFS). The global model is a fully coupled on-line chemistry-weather model and used the same initial meteorological condition from the GFS. The 26-day observational data are compared with the four participating model results and the multi-model ensemble of the model results. Each model forecast shows relatively a wide range of temporal and spatial variation compared to the observations such that the correlation coefficients between the simulated and observed daily PM₁₀ concentrations in surface air vary from 0.24 to 0.83. In general, we find that the multi-model ensemble forecast shows a relatively better performance than individual models. Detailed examination of the model performance and a possible cause for the discrepancy will be presented.