การประเมินหมอกควันข้ามแดนจากการเผาชีวมวล ในภาคเหนือ ของประเทศไทย โดยใช้ข้อมูลดาวเทียมและผลลัพธ์จากแบบจำลอง WRF-Chem

Abstract

The objectives of this study were to investigate the impact of the number of hotspots on the transboundary haze problem, and the proportion of transboundary haze in northern Thailand by analyzing from the WRF-Chem simulated PM2.5 during January to May 2019. According to the analysis results, the PM2.5 concentrations from the model simulated using the biomass burning emission calculated from all hotspots within the model domain (called a normal case) were correlated with measurement data in medium to high-level criteria. This showed that the WRF-Chem model is not only reliable but also effective to simulate the PM2.5 haze situation in the study area. The relationship of PM2.5 concentrations from the transboundary haze simulation case (No burning in the 9 northern provinces) had a slightly lower correlation compared to the normal case and tend to be close to the observed one in the majority of the stations. This finding meant that the transboundary haze is from the surrounding areas and has influenced the amount of haze in the northern areas, thus contributing to a higher health hazard. The model results also show that transboundary haze began entering the northern region in January from the south, which gradually increased in February from the north. In March, the haze concentration in the northern areas was the highest and the transboundary haze ratio was the highest. In April, PM2.5 concentrations remained high and the proportion of haze crossed the border from all directions. In May, the concentration and proportion of transboundary haze decreased, with haze crossing in some parts of the northern region. It can be seen that the density of the surrounding hotspots contributes to the transboundary haze situation in the northern regions. According to the analysis of the number of days that transboundary haze affects air quality at unhealthy to sensitive groups to unhealthy levels, it was found that all stations received at least 50% of the transboundary haze. The stations with a high percentage of transboundary haze are located near the border of the northern region and affect air quality at very unhealthy to hazardous levels. Therefore, it can be noted that the transboundary haze from the surrounding region's origin contributes to the haze in the northern regions, thus worsening the air quality, especially in the areas adjacent to the border. To effectively resolve the haze, which is a health and environmental problem in the northern regions, it is necessary to treat the sources of haze both inside and outside the northern areas.