| dc.description.abstract | Biomass burning (BB) emissions in peninsular Southeast Asia have a large impact on regional air quality, but are also elevated to higher altitudes and then transported long distances. This extended footprint of BB plumes significantly impacts downwind locations and the global climate. However, model evaluation of these BB emissions and transport are complicated by uncertainties stemming from long-term meteorological components like El Niño-Southern Oscillation (ENSO) and spatial and temporal variability of BB emissions in the peninsular Southeast Asia region. In this research, we used Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ) modeling system integrated with the plume rise module (PLMRIM) to capture the elevation of peninsular Southeast Asia BB plumes into the free troposphere, and subsequently the transport to Lulin Atmospheric Background Station (LABS) in central Taiwan.
To account for ENSO impacts, the rising plume height, transport route, and impact frequency on downwind areas were all evaluated in the model simulations. Our results reveal the key factors for elevating the BB emissions to the free troposphere are biomass burning intensity, convergence of the horizontal wind field and vertical wind shear, and vertical motion ahead of a frontal system. El Niño is associated with dry, warm and relatively low-pressure weather conditions over peninsular Southeast Asia, thus generating more favorable conditions for BB aerosols in our model to reach the altitudes needed for long-range transport. During El Niño, BB plumes enable long-range transport by mid-latitude trough-and-ridge system. Arrival of the plumes to LABS occurred 3-4 days after emission in our model. During La Niña, BB is less frequent and of lower intensity, limiting the vertical transport of pollutants. | en_US |