Abstract
Abstract. This study analyzes long-range transport of aerosol and aerosol chemical characteristics based on instances of high- and low-aerosol-loading events determined via ground-based size-resolved aerosol measurements collected at the Manila Observatory in Metro Manila, Philippines, from July to October 2018. Multiple data sources, including models, remote sensing, and in situ measurements, are used to analyze the impacts of long-range aerosol transport on Metro Manila and the conditions at the local and synoptic scales facilitating this transport. Through the use of case studies, evidence of long-range transport of biomass burning aerosol and continental emissions is identified in Metro Manila. Long-range transport of biomass burning aerosol from the Maritime Continent, bolstered by southwesterly flow and permitted by low rainfall, was identified through model results and the presence of biomass burning tracers (e.g., K, Rb) in the ground-based measurements. The impacts of emissions transported from continental East Asia on the aerosol characteristics in Metro Manila are also identified; for one of the events analyzed, this transport was facilitated by the nearby passage of a typhoon. Changes in the aerosol size distributions, water-soluble chemical composition, and contributions of various organic aerosol species to the total water-soluble organic aerosol were examined for the different cases. The events impacted by biomass burning transport had the overall highest concentration of water-soluble organic acids, while the events impacted by long-range transport from continental East Asia showed high percent contributions from shorter-chain dicarboxylic acids (i.e., oxalate) that are often representative of photochemical and aqueous processing in the atmosphere. The low-aerosol-loading event was subject to a larger precipitation accumulation than the high-aerosol events, indicative of wet scavenging as an aerosol sink in the study region. This low-aerosol event was characterized by a larger relative contribution from supermicrometer aerosols and had a higher percent contribution from longer-chain dicarboxylic acids (i.e., maleate) to the water-soluble organic aerosol fraction, indicating the importance of both primary aerosol emissions and local emissions.
Highlights
Better understanding of long-range transport of aerosol is critical for determining the fate of atmospheric emissions and improving models of atmospheric aerosol
The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) back trajectory for this sample set shows an air mass originating around the Maritime Continent (MC) to the southwest of Manila Observatory (MO) that is transported over the ocean towards the Philippines (Fig. 2a)
As evidenced by the name of the season (i.e., Southwest Monsoon), this trajectory is typical for this time of the year and was the dominating trajectory pattern for the remaining eight sample sets not chosen for in-depth analysis (Fig. S2)
Summary
Better understanding of long-range transport of aerosol is critical for determining the fate of atmospheric emissions and improving models of atmospheric aerosol. Nutrients (e.g., Duce et al, 1991; Artaxo et al, 1994), bacteria (e.g., Bovallius et al, 1978; Maki et al, 2019), and pollutants (e.g., Nordø, 1976; Lyons et al, 1978; Lindqvist et al, 1991) can be transported through the atmosphere over large distances across the globe. Braun et al.: Long-range aerosol transport iochemical changes through photochemical and aqueousprocessing mechanisms such that their characteristics at the emission source can be quite different from those farther downwind (e.g., Yokelson et al, 2009; Akagi et al, 2012). Large uncertainties remain in atmospheric aerosol models due to impacts of aqueous processing and wet scavenging on aerosol (Kristiansen et al, 2016; Xu et al, 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
