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gulf stream

gulf stream

Oil Spill Creates "Dead Zones" in the Gulf

1y ago


The National Oceanic and Atmospheric Administration (NOAA) has used computer models to estimate the potential threats to U.S. coastlines that might result if oil spilling from the Deepwater Horizon site continues until a relief well successfully stops the flow. Although it is impossible to predict precisely where surface oil will go in the coming months, it is possible to analyze where surface oil is most likely to go by (a) using historical wind and ocean current records; and (b) accounting for both natural processes of "weathering" and human intervention to recover and remove the oil. This Web page will be updated as more information becomes available. Major Findings and Implications The details of the study are outlined below, but the major findings are represented in the figures that follow, and include: The coastlines with the highest probability (81%--100%) for impact—from the Mississippi River Delta to the panhandle of Florida—are already receiving oil. Along U.S. Gulf of Mexico shorelines, the oil is more likely to move east than west, with the south coast of Texas showing a relatively low probability (less than 1%) for impact. Much of the west coast of Florida has a low probability (1%--20%) for impact, but the Florida Keys, Miami, and Fort Lauderdale areas have a greater probability (61%--80%) due to the potential influence of the Loop Current [leaves OR&R site]. A projected threat to the shoreline does not necessarily mean that oil will come ashore. It means that oil or streamers or tar balls are likely to be in the general vicinity (within 20 miles of the coast). Winds and currents will have to move the oil or tar balls onto the shore. Booms and other countermeasures would be used to mitigate the potential coastal contact once oil is in the area. The longer it takes oil to travel, the more it will degrade, disperse, lose toxicity, and break into streamers and tar balls. For example, any oil that enters the Loop Current will take at least 8-12 days to reach the Florida Straits, but could take much longer. Over that time, the oil will degrade and disperse, and any shoreline impacts to Keys, southeast Florida or beyond would be in the form of scattered tar balls, not a large surface slick of oil. As the Gulf Stream moves northeast and angles away from the continental US, there is an increasingly lower probability of shoreline impacts from eastern central Florida up the eastern seaboard. If oil does reach these areas, it will be in the form of tar balls or highly weathered streamers after traveling a thousand miles or more through the ocean. Implications. The findings cover potential impacts based on a scenario that assumes a significant continuing spill. Some of these impacts may be weeks or months away or may not materialize. In light of these uncertainties and extended timeframes, NOAA will continue to work with the U.S. Coast Guard and other members of the response team to track the movement of oil, including monitoring the Loop Current, producing 72-hour projections of oil movement and updating these longer-term models, to inform states, communities, businesses, consumers, and others. More information about the oil impacts in Florida are available in the following document: What to Expect in South Florida (Document format: PDF, size: 392K) The two graphics below depict the composite results of 500 individual scenarios or runs of the model. The model assumes that oil is released at an average rate of 33,000 barrels per day for 90 days. The model predicts the location of oil after 120 days from the start. Figure 1 shows the probability of shoreline threats that resulted in enough oil to cause a dull sheen within 20 miles of shore. However, a projected threat to the shoreline does not necessarily mean that oil will come ashore. Figure 2 shows the percentage of spill model scenarios that resulted in enough oil to cause a dull sheen in a given 20-by-20 mile grid.