Public Lab Research note

Article: MODIS Detects Oil Spills in Lake Maracaibo, Venezuela

by warren | January 30, 2011 20:43 30 Jan 20:43 | #67 | #67


"The article highlights the unprecedented capability of MODIS 250-m bands for coastal monitoring, using oil spill events (news) as an example. Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used to study the oil spill event from late 2002 to early 2003 in Lake Maracaibo, Venezuela. It is found that 1) visual examination of raw radiance data in the 250-m bands (645 nm and 859 nm) is the simplest yet feasible method for spill detection; 2) available MODIS high-level data products (e.g., water-leaving radiance) cannot be used for such detection due to erroneous atmospheric correction over the spill surface and due to the coarse (1-km) spatial resolution; and 3) a customized, simple method to remove the atmospheric effects over the spill patch as well as over the surrounding background water yields the best contrast, ranging between C0.1 and C0.5 (negative means the spill patch is darker than the background) at 555 and 645 nm. This agrees conceptually with optical model results from the literature. Of the sixty-eight daily image sets, over half contain cloud cover <50%, and about a dozen images showed patterns within Maracaibo Lake that we suspected could be extensive spill patches. Such patterns were visible even when significant Sun glint contamination was present. Between 16 and 20 January 2003, the spill area has been estimated as about 130 C 140 km2. These findings suggest that the MODIS medium- resolution bands provide great potential in coastal monitoring, and traditional thoughts that satellite optical remote sensing has little potential for oil spill detection need to be reviewed. However, more effort is needed to establish an automatic monitoring system with little human interference."

Also see Evaluation of high resolution MODIS-Aqua data for oil spill monitoring from which the above graphic is taken.


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