Abstract. Long-term exposure to particulate matter (PM) with aerodynamic
diameters < 10 (PM10) and 2.5 µm (PM2.5) has
negative effects on human health. Although station-based PM monitoring has
been conducted around the world, it is still challenging to provide spatially
continuous PM information for vast areas at high spatial resolution.
Satellite-derived aerosol information such as aerosol optical depth (AOD) has
been frequently used to investigate ground-level PM concentrations. In this
study, we combined multiple satellite-derived products including AOD with
model-based meteorological parameters (i.e., dew-point temperature, wind
speed, surface pressure, planetary boundary layer height, and relative
humidity) and emission parameters (i.e., NO, NH3, SO2,
primary organic aerosol (POA), and HCHO) to estimate surface PM concentrations over South Korea. Random
forest (RF) machine learning was used to estimate both PM10 and
PM2.5 concentrations with a total of 32 parameters for 2015–2016. The
results show that the RF-based models produced good performance resulting in
R2 values of 0.78 and 0.73 and root mean square errors (RMSEs) of 17.08 and
8.25 µg m−3 for PM10 and
PM2.5, respectively. In particular, the proposed models successfully
estimated high PM concentrations. AOD was identified as the most significant
for estimating ground-level PM concentrations, followed by wind speed, solar
radiation, and dew-point temperature. The use of aerosol information derived
from a geostationary satellite sensor (i.e., Geostationary Ocean Color Imager, GOCI) resulted in slightly
higher accuracy for estimating PM concentrations than that from a
polar-orbiting sensor system (i.e., the Moderate Resolution
Imaging Spectroradiometer, MODIS). The proposed RF models yielded
better performance than the process-based approaches, particularly in
improving on the underestimation of the process-based models (i.e., GEOS-Chem
and the Community Multiscale Air Quality Modeling System, CMAQ).