Application of the CMAQ Model to Assess the Vertical Distribution of PM2.5 Pollution in the Hanoi Area
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Abstract
The study applies the CMAQ model, and combine with the WRF model, to analyze the vertical distribution of PM2.5 pollution in Hanoi, Vietnam, highlighting the city’s severe air quality challenges. Simulations show a significant decline in PM2.5 concentrations with altitude, ranging from 50–84 µg/m³ at 30 meters to 34–40 µg/m³ at 320 meters, with urban hotspots exceeding Vietnam’s air quality standard of 50 µg/m³ and the WHO guideline of 25 µg/m³. Seasonal analysis reveals higher concentrations from autumn to winter due to temperature inversions and low mixing heights, which trap pollutants near the ground. Despite capturing these trends, the model exhibited substantial errors, including a Mean Absolute Percentage Error of 63%, a Mean Absolute Error of 18 µg/m³, and an RMSE of 377 µg/m³, indicating challenges in incorporating local meteorology, urban architecture, and vegetation effects. The findings underscore the importance of integrating localized data and improved modeling to enhance the accuracy of PM2.5 predictions and inform effective air quality management and urban planning strategies in Hanoi.