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Fact Sheet on NCAR Simulations

June 3, 2010 - 12:00am

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The simulations released today show the potential for oil to reach the Atlantic at some point in the future, but don't project when, where or whether any of it would make landfall or at what concentrations.  Because of the effect of dispersants, mixing, and a range of other biological and physical factors, any oil that reaches the Atlantic would be at a much lower concentration.  Nevertheless, NOAA and our federal scientific teams are closely monitoring the path of the oil so that we can respond aggressively whereever it goes.

  • The National Oceanic and Atmospheric Administration is tracking the actual flow path of the oil and making projections about the future, based not only on computer modeling but actual data collected from a combination of highly sophisticated ships, aircraft and satellite imagery.
  • As the NCAR announcement notes: "Peacock and her colleagues stress that the simulations are not a forecast because it is impossible to accurately predict the precise location of the oil weeks or months from now.  Instead, the simulations provide an envelope of possible scenarios for the oil dispersal. The timing and course of the oil slick will be affected by regional weather conditions and the ever-changing state of the Gulf's Loop Current-neither of which can be predicted more than a few days in advance. The dilution of the oil relative to the source will also be impacted by details such as bacterial degradation, which are not included in the simulations." NOAA agrees that projections of specific impacts more than three days in advance tend to be unreliable because of the many uncertainties involved.
  • The scenarios released today are based on computer models that are an outstanding resource to understand ocean circulation and mixing, but are not designed to project impacts on a regional scale of less than about 50 miles.
  • The simulations cannot determine whether, when or where oil would make landfall, since the model is not operative in depths of less than 100 meters.
  • Again, as NCAR notes, this is not a forecast model.  It represents a "big picture" look at how the oil will enter the Gulf Stream.
  • The simulations model the path of tracer dye rather than actual oil.  The use of passive tracers in ocean circulation models is quite common in scientific literature as a means of diagnosing flow pathways and time scales.  But as the researchers note, "The dye tracer used in the model has no actual physical resemblance to true oil. Unlike oil, the dye has the same density as the surrounding water, does not coagulate or form slicks, and is not subject to chemical breakdown by bacteria or other forces."  In fact, as oil weathers, it changes characteristics and no longer behaves like a fluid, making it harder to do long term forcasts.
  • The simulations show that when the oil reaches the loop current, some of the oil will likely reach the Atlantic - though it is difficult to project when that will happen.  Because of the effects of dispersants, evaporation, mixing and a variety of other physical and biological factors, the oil that reaches the Atlantic will be at a much lower concentration.  NOAA and other federal agencies will continue to closely track the progress of the oil so that we are prepared to respond aggressively whereever the oil ends up.

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