Observations of Southeast Asian Biomass Burning and Urban Trace Gas
Enhancement Ratios: Insights into Regional Air Quality and Aerosol
Composition
Abstract
Southeast Asian biomass burning is a major pollutant source that
contributes to poor air quality throughout the region. Thus,
understanding these emissions is critical for predicting and mitigating
their health impacts. While many studies have reported ground-based and
satellite measurements, airborne measurements at a regional scale
capable of tying the two together have not been common. The 2019 Cloud,
Aerosol and Monsoon Processes Philippines Experiment
(CAMP2Ex) field project examined Southeast Asian
regional sources and their effects on aerosol/cloud interactions using a
combination of airborne, shipboard, and ground-based measurements. These
flights sampled a variety of airmass sources over the Philippine, South
China, and Sulu seas during both the southwest monsoon and monsoon
transition periods. Measurements during CAMP2Ex provide a unique
opportunity to investigate how these transported and local emissions
affected air quality trends and airmass chemical composition. We present
correlated airborne in situ enhancement ratios of CH4 to
CO, using them to identify source regimes of either high urban or
biomass burning influence as well as urban regimes with different
emission factors. Combined with backtrajectory analysis using HYSPLIT,
source regimes were examined for differences in ozone, reactive
nitrogen, and aerosol chemical composition. While observed
O3/CO enhancement ratios remain constant for differing
urban source regimes, NOy/CO ratios varied across these
regimes. For biomass burning sources, O3/CO enhancement
ratios are observed to be lower than previously reported by measurements
in the region.