Kwon Ho Lee1, Man Sing Wong 2, Janet Nichol2, Pak Wai Chan3

  • 1 Department of Atmospheric & Environmental Sciences, Gangneung-Wonju National University (GWNU), (null), Korea
  • 2 Department of Land Surveying and Geo-Informatics, the Hong Kong Polytechnic University, (null), Hong Kong
  • 3 Hong Kong Observatory, (null, Hong Kong

Received: January 26, 2015
Revised: April 27, 2015
Accepted: June 14, 2015
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Cite this article:
Lee, K.H., Wong, M.S., Nichol, J. and Chan, P.W. (2015). Retrieval of Aerosol Size Distribution from Microtops II Sunphotometer in Hong Kong. Aerosol Air Qual. Res. 15: 1712-1719.


  • Spectral Extinction Fitting Technique (SEFT) for retrieval of aerosol size distribution (ASD).
  • Look up table based algorithms for retrieving ASD from spectral aerosol optical thickness.
  • ASD retrieval from Microtops II sunphotometer.
  • Evaluation and comparison with AERONET inversion products.



A new method has been developed for retrieving Aerosol Size Distribution (ASD) from spectral aerosol optical thickness (AOT) measured by Microtops II sunphotometer. The rationale of this method is based on a Spectral Extinction Fitting Technique (SEFT) between measured and model-simulated aerosol extinctions. Numerical simulation of aerosol extinctions includes seven aerosol microphysical properties and the resulting total of 64,324,260 datasets were used to compare with Microtops II sunphotometer AOT measurements at five wavelengths (340, 500, 675, 870, and 1020 nm). This SEFT method works directly on AOT measurements and does not require any specific inputs of aerosol properties. The accuracy was examined using AERONET inversion products, and the results show a difference between SEFT and AERONET inversion products of bimodal lognormal volume size concentrations, of ± 10%. The SEFT algorithm was applied for two specific conditions (hazy and clear atmospheres) in Hong Kong, and the corresponding ASD retrievals show reasonable agreements with AERONET inversion products.

Keywords: Aerosol optical thickness; Aerosol size distribution; Microtops II; Spectral extinction fitting technique

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