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Differentiating between Local and Remote Pollution over Taiwan

Category: Air Pollution Modeling

Accepted Manuscripts
DOI: 10.4209/aaqr.2017.10.0378
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Pavel Kishcha 1, Sheng-Hsiang Wang2, Neng-Huei Lin2, Arlindo da Silva3, Tang-Huang Lin2, Po-Hsiung Lin4, Gin-Rong Liu2, Boris Starobinets1, Pinhas Alpert1

  • 1 School of Geosciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
  • 2 Department of Atmospheric Sciences, National Central University, Taoyuan 32001, Taiwan
  • 3 Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, MD 20771, USA
  • 4 Department of Atmospheric Sciences, National Taiwan University, Taipei 10617, Taiwan


A new approach for differentiating between local and remote pollution in Taiwan.
It is based on both AERONET measurements and NASA MERRA aerosol reanalysis.
Differentiation between local and remote sulfate aerosols using MERRA sulfate AOD.


In this study, an approach has been developed for differentiating between local and remote pollution over Taiwan, based on homogeneity perspective (variations of the standard deviation) of both AERONET measurements and NASA MERRA aerosol reanalysis (version 2, MERRA-2) over a 15-year period (2002–2017). The analysis of seasonal variations of the standard deviation of aerosol optical depth (AOD) measurements at six AERONET sites and MERRA AOD data in Taiwan showed that, in spring when remote aerosols dominate, the standard deviation is almost three times lower than that in autumn, when aerosols from local sources dominate. This finding was supported by MERRA AOD over the open ocean area: total AOD data were used to differentiate between local and remote pollution over both Taiwan and the open ocean area in the vicinity of Taiwan. Over Taiwan, MERRA total AOD showed a primary maximum in spring and a secondary one in autumn. Over the open ocean area, where there are no local sources of anthropogenic aerosols, MERRA total AOD showed only one maximum in spring and no maximum in autumn. This suggests that, in Taiwan, the maximum in autumn is attributed to local air pollution, while the pronounced maximum in spring is mainly caused by air pollution from continental Asia. The analyses of spatial distribution of 15-year monthly mean MERRA winds confirmed the above-mentioned results. Furthermore, similar to total AOD, MERRA sulfate AOD peaked in autumn over Taiwan, but not over the oceanic area: this indicates the contribution of local emissions of anthropogenic aerosols from the industrial sector. The standard deviation of MERRA sulfate AOD in spring is two-three times lower than the standard deviation in autumn: this is additional evidence that, in spring, sulfate aerosols from remote sources are predominant; while in autumn sulfate aerosols from local sources dominate.


Local pollution Remote pollution AERONET MERRA aerosol reanalysis Taiwan

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DOI: 10.4209/aaqr.2017.10.0361