Abstract. The frequent occurrence of severe air pollution episodes
in China has been a great concern and thus the focus of intensive studies.
Planetary boundary layer height (PBLH) is a key factor in the vertical
mixing and dilution of near-surface pollutants. However, the relationship
between PBLH and surface pollutants, especially particulate matter (PM)
concentration across China, is not yet well understood. We investigate this
issue at ∼1600 surface stations using PBLH derived from
space-borne and ground-based lidar, and discuss the influence of topography
and meteorological variables on the PBLH–PM relationship. Albeit the PBLH–PM
correlations are roughly negative for most cases, their magnitude,
significance, and even sign vary considerably with location, season, and
meteorological conditions. Weak or even uncorrelated PBLH–PM relationships
are found over clean regions (e.g., Pearl River Delta), whereas nonlinearly
negative responses of PM to PBLH evolution are found over polluted regions
(e.g., North China Plain). Relatively strong PBLH–PM interactions are found
when the PBLH is shallow and PM concentration is high, which typically
corresponds to wintertime cases. Correlations are much weaker over the
highlands than the plains regions, which may be associated with lighter
pollution loading at higher elevations and contributions from mountain
breezes. The influence of horizontal transport on surface PM is considered
as well, manifested as a negative correlation between surface PM and wind
speed over the whole nation. Strong wind with clean upwind air plays a
dominant role in removing pollutants, and leads to obscure PBLH–PM
relationships. A ventilation rate is used to jointly consider horizontal and
vertical dispersion, which has the largest impact on surface pollutant
accumulation over the North China Plain. As such, this study contributes to
improved understanding of aerosol–planetary boundary layer (PBL) interactions and thus our ability
to forecast surface air pollution.