Determination of Aerosol Optical Thickness from Spectral Sky Transmittance
H. S. Lim 1 M. Z. MatJafri 2 , K. Abdullah 2 , N. M. Saleh 3 and Sultan AlSultan 4
1 Student, 2 Assoc. Prof. Dr., 3 Mr., School of Physics,
University of Science Malaysia,
11800 Penang, Malaysia
Email: mjafri@usm.my,
khirudd@usm.my
Tel: +604-6533888, Fax: +604-6579150
4 Dr., Al Sultan Environmental Research Center. Al Madina Rd., P.O.Box.
242 Riaydh Al Khabra, Al Qassim, Saudi Arabia.
Tel: +966504890977, Fax: +96663340366
Email: allssultan7@hotmail.com
ABSTRACT
The objective of this study is to test the feasibility of the proposed technique for retrieving spectral
aerosol optical thickness (AOT) from the spectral transmittance measurements. The measurements
have been acquired around Penang Island, Malaysia. Ground-based measurements were made with
a handheld spectroradiometer. The measured spectral transmittance data were then converted to
AOT values 6 spectral bands between 400 and 900 nm. Spectral AOT maps were generated using
Kriging interpolation method for the 6 spectral bands. Air quality map was produced using this
technique.
1.0 INTRODUCTION
Knowledge of the parameters that are related to the optical properties of atmospheric aerosols is
essential for the determination of their climatic effects, development of techniques for remote
sensing of aerosol from space or the necessary correction of atmospheric effects in satellite imagery
(Sanchez, et al., 1998). Particulate matter (PM), or aerosol, is the general term used for a mixture of
the solid particles and the liquid droplets were found in the atmosphere (Wang and Christopher,
2003). AOT, t, is a measure of aerosol loading in the atmosphere (Christopher, et al., 2002).
Generally, a higher AOT value indicates higher column of aerosol loading and therefore low
visibility (Wang and Christopher, 2003). The Penang atmosphere is often affected by large plumes
of dust especially from the industrial areas.
many researchers have conducted satellite monitoring of the AOT [Husar, et al., (1997),
Sanchez Oliveros, et al., (1998) and Liu, et al., (2002)]. In this study, we present results from
ground-based measurements. Our purpose is to generated spectral AOT map over Penang. The well
knows Beer-Lambert law was used in this study to retrieve AOT values from the measured
transmittance value. Finally, AOT maps were generated using Kriging interpolation technique. Ung
et al., (2001) and Patil et al., (2003) also applied interpolation technique in their studies (air quality
mapping).
