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GES DISC User Services assists Brazilian reporter on oil spill story

Leak from offshore oil well observed by MODIS instrument on November 12

GES DISC User Services assists Brazilian reporter on oil spill story

MODIS image acquired on November 12, modified by O GLOBO, showing the oil slick from the offshore oil well leak.

GES DISC User Services assists Brazilian reporter on oil spill story

An oil well owned by Chevron off the Brazilian coast, near the famed city of Rio de Janeiro, began leaking oil on November 8. The oil leak concerned state officials and environmentalists, especially because it occurred during the spring, when whales are migrating and phytoplankton blooms are in full swing in the currents off Brazil and Argentina ("Blooming Waters off Argentina," NASA Earth Observatory).

The oil leak was big news in Brazil, and concerns were raised about drilling procedures and the potential threat to the vital Brazilian coastal environment. ("Oil spill off Brazil has Chevron in hot water," MSNBC). As the leak progressed, the Goddard Earth Sciences Data and Information Services Center (GES DISC) was contacted by a reporter from O GLOBO (, Carlos Alberto Teixeira, to find out if the GES DISC could supply any images of the spill that had been acquired by NASA satellites. Mary Greene, who handles numerous inquiries to the GES DISC User Services Help Desk, responded to the request from Teixeira.

Oil spills are actually very difficult to observe in data acquired from space. The best views of oil spills from space have been acquired when the waters affected by the spill are in the "sun glint" pattern that occurs when sunlight reflects off the water surface directly back to the instrument. While sun glint makes it impossible for NASA instruments to accurately quantify the optical properties and related quantities (such as chlorophyll concentration) of the ocean, the effect of oil on the surface waves makes an oil slick visible. [Because of the uncertainties introduced by sun glint, data from regions of the sea surface that are influenced by sun glint are not processed.]

A quick search of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) available in the MODIS Rapid Response archive (part of LANCE, Land Atmosphere Near-real-time Capability for EOS project) discovered a view of the ocean off Brazil acquired on November 12. The luck of the observation was remarkable; on nearly every other pass of either MODIS instrument on the Terra and Aqua satellites, the oil spill region was covered by clouds. However, the clouds moved out of the way on November 12, revealing the slick of oil in the sun glint pattern of the satellite. Ms. Greene was assisted by GES DISC staff members Zhong Liu and James Acker in this image search.

The images were sent back to the O GLOBO reporter, who had met with frustration in finding any other images acquired from space of the area affected by the oil leak. Teixeira immediately sent back a photograph of his earnest appreciation to the GES DISC, and a modified version of the MODIS image (shown at top right) was published in O GLOBO the next day. (O GLOBO front page, November 18, 2011).

Thanks from Carlos Alberto Teixeira


[Update, November 28:  According to the Skytruth blog, which also published a version of the November 12 MODIS image of the slick, the oil spill is abating.  Some residual oil may still be leaking from the sea floor, as reported by O GLOBO, which also reported that the well has been capped and cementing operations were underway.]


While it remains difficult to directly observe oil spills in satellite data, many data products available from the GES DISC can provide information important for monitoring the environmental effects and potential spread of the oil. Ocean color radiometry data can be used to observe if phytoplankton blooms, which attract sea life higher in the food chain, are interacting with oil-tainted waters. Sea surface temperature data can also show the current patterns in the region. Wind data can be used to determine if winds will keep the oil offshore, or potentially push it toward the vulnerable coast. Also, precipitation data can show the tracks of weather systems which could help disperse the oil, or concentrate it into patches which could drift toward the shore.

All of the data products in the NASA GES DISC archives and the NASA Giovanni data visualization and analysis system are available for investigations of environmental impacts of oil spills, as well as weather and climate phenomena around the world.


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Last updated: Nov 28, 2011 11:54 AM ET