www.ccsenet.org/mas Modern Applied Science Vol. 4, No. 10; October 2010 Published by Canadian Center of Science and Education 111 Aerosol Optical Depth of MODIS Imagery over Bright Coastal Water: A Regression Technique Abd Rahman Mat Amin Faculty of Applied Science Universiti Teknologi Mara, Kampus Kuala Terengganu 21080 Kuala Terengganu, Terengganu, Malaysia Tel: 60-96175-255 E-mail:abdra401@tganu.uitm.edu.my Khiruddin Abdullah School of Physics, Universiti Sains Malaysia, Minden, 11080 Pulau Pinang, Malaysia Tel: 60-46-532-477 E-mail: khirudd@usm.my Mohd Rivaie Faculty of Science Computer and Mathematic Universiti Teknologi Mara, Kampus Kuala Terengganu 21080 Kuala Terengganu, Terengganu, Malaysia Tel: 60-96-175-255 Abstract The contribution of sediment and bottom reflectance in the MODIS imagery over bright coastal water contaminate visible and near infrared channels. This contribution leads to the saturation in the ocean color channels and error in the MODIS derived product over that areas. The saturation in the ocean color channels lead to no aerosol optical depth (AOD) retrieved by MODIS algorithm over very turbid areas. The sediment contributions will increase the reflectance in the visible and near infrared channel that is used in the MODIS aerosol algorithm. This area is then masked using sediment masking algorithm. In this paper, a simple method to estimate the AOD over bright coastal water with high sediment and bottom reflectance contributions is proposed. The first seven MODIS solar channels centered at 0.47, 0.55, 0.66, 0.86, 1.24, 1.64 and 2.13 µm, originally designed for remote sensing over land and cloud properties have been utilized in this study. The algorithm is based on the excess reflectance at 0.55, 0.66 and 0.87 µm wavelength using the power law model that can be associated to the presence of sediment. The excess value of the reflectance is discarded, to obtain the atmospheric contribution in the data. Aerosol contribution over bright coastal water areas is then compared with AOD of 0.869 µm using regression technique. This study shows that the AOD and aerosol retrieved are in high correlation with R is greater than 0.90. The AOD map from the applications of the algorithm were constructed and extrapolated for the saturated channels areas. The sample result of AOD map from several MODIS datasets acquired over the Gulf of Martaban is presented. Keywords: MODIS, Remote sensing, Aerosol optical depth, Sediment, Turbid water 1. Introduction At present satellite remote sensing of ocean colour is the only way to measure synoptically wide area of ocean properties such as chlorophyll patterns, sea surface temperature, phytoplankton abundance, distribution of suspended particulate matter and absorption by coloured dissolved organic matter. Imaging spectrometry has important applications in a variety of fields, including mineral explorations, vegetation studies, and coastal monitoring. Since mid 1980’s, the concepts of imaging spectrometry and hyperspectral imaging have become increasingly popular. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) have provided a view of chlorophyll patterns and ocean biospheres on global scales by using the advanced atmospheric correction algorithm for data processing. High quality ocean color products for the global open oceans have been produced by both SeaWiFS and MODIS (McClain et al., 2004; Bailey & Werdell, 2006; Wang & Shi, 2005). Researchers and scientists around the world have used this data to study and understand ocean physical, optical, and biological changes and their effects on climatic processes. The current SeaWiFS/MODIS algorithm had implemented a method to account for the NIR ocean contributions,