Relating geostationary satellite measurements of aerosol optical depth (AOD) over East Asia to fine particulate matter (PM<sub>2.5</sub>): insights from the KORUS-AQ aircraft campaign and GEOS-Chem model simulations
<p>Geostationary satellite measurements of aerosol optical depth (AOD) over East Asia from the Geostationary Ocean Color Imager (GOCI) and Advanced Himawari Imager (AHI) instruments can augment surface monitoring of fine particulate matter (PM<span class="inline-formula"><su...
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| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/830494bd69aa4746bf55ffa09ea9dd7c |
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| Sumario: | <p>Geostationary satellite measurements of aerosol optical depth
(AOD) over East Asia from the Geostationary Ocean Color
Imager (GOCI) and Advanced Himawari Imager (AHI) instruments can augment surface
monitoring of fine particulate matter (PM<span class="inline-formula"><sub>2.5</sub></span>) air quality, but this
requires better understanding of the AOD–PM<span class="inline-formula"><sub>2.5</sub></span> relationship. Here we
use the GEOS-Chem chemical transport model to analyze the critical variables
determining the AOD–PM<span class="inline-formula"><sub>2.5</sub></span> relationship over East Asia by simulation of
observations from satellite, aircraft, and ground-based datasets. This
includes the detailed vertical aerosol profiling over South Korea from the
KORUS-AQ aircraft campaign (May–June 2016) with concurrent ground-based
PM<span class="inline-formula"><sub>2.5</sub></span> composition, PM<span class="inline-formula"><sub>10</sub></span>, and AERONET AOD measurements. The
KORUS-AQ data show that 550 nm AOD is mainly contributed by
sulfate–nitrate–ammonium (SNA) and organic aerosols in the planetary
boundary layer (PBL), despite large dust concentrations in the free
troposphere, reflecting the optically effective size and high hygroscopicity
of the PBL aerosols. We updated SNA and organic aerosol size distributions
in GEOS-Chem to represent aerosol optical properties over East Asia by using
in situ measurements of particle size distributions from KORUS-AQ. We find
that SNA and organic aerosols over East Asia have larger size (number median
radius of 0.11 <span class="inline-formula">µ</span>m with geometric standard deviation of 1.4) and
20 % larger mass extinction efficiency as compared to aerosols over North
America (default setting in GEOS-Chem). Although GEOS-Chem is successful in
reproducing the KORUS-AQ vertical profiles of aerosol mass, its ability to
link AOD to PM<span class="inline-formula"><sub>2.5</sub></span> is limited by under-accounting of coarse PM and by
a large overestimate of nighttime PM<span class="inline-formula"><sub>2.5</sub></span> nitrate. The GOCI–AHI AOD data
over East Asia in different seasons show agreement with AERONET AODs and a
spatial distribution consistent with surface PM<span class="inline-formula"><sub>2.5</sub></span> network data. The
AOD observations over North China show a summer maximum and winter minimum,
opposite in phase to surface PM<span class="inline-formula"><sub>2.5</sub></span>. This is due to low PBL depths
compounded by high residential coal emissions in winter and high relative
humidity (RH) in summer. Seasonality of AOD and PM<span class="inline-formula"><sub>2.5</sub></span> over South Korea
is much weaker, reflecting weaker variation in PBL depth and lack of
residential coal emissions.</p> |
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