Detection Of Several Marine Oil Spill Cases By MODIS Data

Marine oil pollution not only polluted the oceanic and coastal environment, but also affected industrial production and daily life in coastal areas seriously. Now the main subject of the study in the detection of marine oil spill by remote sensing is the identification where oil spill occurred, the estimation of oil spill amount, and the analysis of oil types. Remote sensing has become the most important method for detecting marine oil spill due to convenience in data obtaining and processing, its high time resolution, with large coverage and etc.By using EOS/MODIS data, we analyzed four oil spill cases which happened in the Yangtze estuary (China), Lake Maracaibo (Venezuela), Mediterranean oil spill and Lebanon oil spill. Based on the image processing of the MODIS data, the spectral features of different bands were analyzed. It seems that the IR band (1000nm~2000nm) is the better choice for the oil spill detection. The ratio of visible band and the 7th infrared band can enhance the contrast between oil spill and surrounding water which can be used to detect oil spills with visible/IR sensors. The main results are summarized as follows:1 Due to the scanning and imaging effects, original MODIS image cannot be used directly. We use IDL and ENVI to reprocess image to remove stripes, sun-glint and bowtie shown in the MODIS image in the thesis.2 The oil-water contrast was calculated to evaluate the feature of oil at different spectral band. The result indicates that the value of C owns the maximum value at reflective IR band (1000nm~2000nm), and the smaller value in NIR band, visible band, and IR band respectively.3 In the visible band of MODIS data, the band ratio was calculated to increase the contrast of the oil spills feature. When the oil information is extracted from the image, the appropriate choice need to be considered that the band ratio is used at 400nm ~ 800nm and the original radiance image is used at 800nm ~2130nm.This result is also proved by several oil accidents found in the MODIS data.