Inflow of Anthropogenic Aerosols in the Philippines during the Asian Summer Monsoon Season

Prevailing southwesterly winds in Southeast Asia (SEA) allow for the long-range transport of aerosol particles and other atmospheric constituents into the Philippines from the Maritime Continent during the Asian summer monsoon season. While there have been several observational studies that focused on selected areas in the Philippines, there is a need to investigate the transport patterns of inflowing aerosols for better spatial characterization in the different subregions of the country. This study is part of the Philippine science agenda for the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP 2 Ex), an airborne campaign which aims to investigate the role of aerosols in Philippine weather and climate during the Asian summer monsoon season. Specifically, this study aims to 1) characterize the spatial distribution of inflowing aerosol species, 2) identify key aerosol transport pathways into the country, and 3) determine the relative contribution of local versus inflowing aerosol mass in the Philippines.

The WRF-Chem and NOAA HYSPLIT models are used to simulate height-resolved aerosol transport into the country as well as conduct experiments isolating inflowing versus local pollution. Ground and satellite-based observations of aerosol optical depth (AOD) from AERONET and MODIS, respectively, are then compared to model output in order to explain the spatial distribution of inflowing aerosols as well as their contribution to aerosol concentrations in the Philippines.

Initial results show that most inflowing aerosols from SEA are transported downwind into the southern regions of the Philippines. Analysis of parcel trajectories suggests that biomass burning in Borneo is the largest source of aerosol transport into the Philippines, although other pollution sources are present.