To identify the long-term trend of particle size variation, we analyzed aerosol optical depth
(AOD, τ) separated as dust (τD) and coarse-(τPC) and fine-pollution particles (τPF) depending on
emission sources and size. Ångström exponent values are also identified separately as total and
fine-mode particles (αT and αPF). We checked these trends in various ways; (1) first-order linear
regression analysis of the annual average values, (2) percent variation using the slope of linear
regression method, and (3) a reliability analysis using the Mann–Kendall (MK) test. We selected
17 AERONET sun/sky radiometer sites classified into six regions, i.e., Europe, North Africa, the
Middle East, India, Southeast Asia, and Northeast Asia. Although there were regional differences, τ
decreased in Europe and Asian regions and increased in the Middle East, India, and North Africa.
Values of τPC and τPF, show that aerosol loading caused by non-dust aerosols decreased in Europe
and Asia and increased in India. In particular, τPF considerably decreased in Europe and Northeast
Asia (95% confidential levels in MK-test), and τPC decreased in Northeast Asia (Z-values for Seoul
and Osaka are −2.955 and −2.306, respectively, statistically significant if |z| ≥ 1.96). The decrease in
τPC seems to be because of the reduction of primary and anthropogenic emissions from regulation by
air quality policies. The meaningful result in this paper is that the particle size became smaller, as
seen by values of αT that decreased by −3.30 to −30.47% in Europe, North Africa, and the Middle
East because αT provides information on the particle size. Particle size on average became smaller
over India and Asian regions considered in our study due to the decrease in coarse particles. In
particular, an increase of αPF in most areas shows the probability that the average particle size of
fine-mode aerosols became smaller in recent years. We presumed the cause of the increase in αT is
because relatively large-sized fine-mode particles were eliminated due to air quality policies.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:90415 |
| Date | 11 March 2024 |
| Creators | Shin, Juseon, Sim, Juhyeon, Dehkhoda, Naghmeh, Joo, Sohee, Kim, Taegyeong, Kim, Gahyeong, Müller, Detlef, Tesche, Matthias, Shin, Sung-Kyun, Shin, Dongho, Noh, Youngmin |
| Publisher | MDPI |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 2072-4292, 10.3390/rs14184429 |
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