Aerosol Optical Thickness data retrieval over Penang Island, Malaysia

In this study, we propose a new cost effective approach to retrieve aerosol optical thickness (AOT) data in the visible spectrum by using sky transmittance measurements measured by a handheld spectroradiometer. The transmittance values were measured in spectral region from 350 nm to 1050 nm at the earth´s surface. The well known Beer-Lambert law was used in this study to retrieve AOT values from the measured transmittance value. The concentrations of particulate matter of less than 2.5 micron (PM2.5) were measured simultaneously with the measurements of the transmittance data. The station locations of the PM2.5 measurements were detemined using a handheld GPS. Three interpolation techniques, namely Kriging Interpolation, Inverse Distance Interpolation and Natural Neighbour Interpolation, were used for mapping the PM2.5 concentration in this study. The accuracies of the three interpolation techniques were determined in this study in order to select the most suitable technique for mapping the air pollution concentration over Penang Island, Malaysia. The results of the analysis indicated that the AOT values were linearly correlated with the PM2.5 readings. AOT and PM10 maps were generated using an interpolation technique (Kriging) based on the measured data. Basically, both PM2.5 and AOT maps agree reasonably well over Penang Island, Malaysia. The highest PM2.5 concentrations were found in densely populated and industrialized areas.