Abstract. Using 14 years (2007–2020) of data from passive (MODIS/Aqua)
and active (CALIOP/CALIPSO) satellite measurements over China, we
investigate (1) the temporal and spatial variation of aerosol properties
over the Beijing–Tianjin–Hebei (BTH) region, the Yangtze River Delta (YRD),
and the Pearl River Delta (PRD) and (2) the vertical distribution of aerosol
types and extinction coefficients for different aerosol optical depth (AOD)
and meteorological conditions. The results show the different spatial
patterns and seasonal variations of the AOD over the three regions. Annual
time series reveal the occurrence of AOD maxima in 2011 over the YRD and in
2012 over the BTH and PRD; thereafter the AOD decreases steadily. Using the
CALIOP vertical feature mask, the relative frequency of occurrence (rFO) of
each aerosol type in the atmospheric column is analyzed: rFOs of dust and
polluted dust decrease from north to south; rFOs of clean ocean, polluted
continental, clean continental and elevated smoke aerosol increase from
north to south. In the vertical, the peak frequency of occurrence (FO) for
each aerosol type depends on region and season and varies with AOD and
meteorological conditions. In general, three distinct altitude ranges are
observed with the peak FO at the surface (clean continental and clean marine
aerosol), at ∼1 km (polluted dust and polluted continental
aerosol) and at ∼3 km (elevated smoke aerosol), whereas dust
aerosol may occur over the whole altitude range considered in this study
(from the surface up to 8 km). The designation of the aerosol type in
different height ranges may to some extent reflect the CALIOP aerosol type
classification approach. Air mass trajectories indicate the different source
regions for the three study areas and for the three different altitude
ranges over each area. In this study nighttime CALIOP profiles are used. The
comparison with daytime profiles shows substantial differences in the FO
profiles with altitude, which suggest effects of boundary layer dynamics and
aerosol transport on the vertical distribution of aerosol types, although
differences due to day–night CALIOP performance cannot be ruled out.
Multi-dimensional satellite observations of aerosol
properties and aerosol types over three major urban
clusters in eastern China
