Improving prediction of trans-boundary biomass burning plume
dispersion: from northern peninsular Southeast Asia to downwind
western north Pacific Ocean
Abstract. The boreal spring biomass burning (BB) in the northern peninsular Southeast Asia (nPSEA) are lifted into the subtropical jet stream, get transported and deposited across nPSEA, South China, Taiwan, and even the western North Pacific Ocean. This paper as part of the 7-Southeast Asian Studies (7-SEAS) project effort attempts to improve the prediction capability of the chemical transport model (WRF-CMAQ) over a vast region including the mountainous near-source burning sites at nPSEA to its downwind region. Several sensitivity analyses of plume rise are compared in the paper and it discovers that the initial vertical allocation profile of BB plume and plume rise module (PLMRIM) are the main reasons causing the inaccuracies of the WRF-CMAQ simulations. The smoldering emission from the Western Regional Air Partnership (WRAP) empirical algorithm included has improve the accuracies of PM10, O3 and CO at the source. The best performance at the downwind sites is achieved with the inline PLMRIM that accounts for the atmospheric stratification at the mountainous source region with the high-resolution FINN burning emission dataset. The calibrated model greatly improves not only the BB emission prediction over near-source and receptor ground-based measurement sites but also the aerosol vertical distribution (MPLNET, CALIPSO) and column aerosol optical depth (MODIS AOD) of the BB aerosol along the transport route. Three distinct transport mechanisms from nPSEA to the western North Pacific are then identified while a particular mechanism which involves Asian cold surge is able to mix the BB smoke plumes into the boundary layer and affects the ground surface over the western Taiwan.