During the threat of an oil spill, responders need to know where that spilled oil will go in order to protect shorelines with containment boom, stage cleanup equipment, or close areas for fishing and boating.
In order to answer these questions, NOAA oceanographers use specialized computer models to predict the movement of spilled oil on the water surface. They predict where the oil is most likely to go and how soon it may arrive there. During a major spill response, trajectory maps are created to show predictions for the path of spilled oil.
Trajectory maps are produced using a NOAA-developed computer model called GNOME (General NOAA Operational Modeling Environment), which helps to predict the movement of oil. GNOME can forecast the effects that currents, winds, and other physical processes have on the movement of oil in the ocean. During an oil spill, this model is updated daily based on field observations, aerial surveys, and new forecasts for ocean currents and winds.
In addition to showing oiled locations and potential beached oil on a trajectory map, oceanographers will also include an uncertainty boundary on the map to indicate other locations where oil potentially could be located. This uncertainty boundary is necessary to account for differences in models as well as changes in currents and winds.
During the threat of an oil spill, NOAA predicts where the oil might spread. To predict where oil might go, we model how weather, wind, tides and currents affect oil movement. But natural variability in wind, weather and water currents can change the trajectory of a spill in ways difficult to predict. To get the best forecast possible we use aircraft and field observations to monitor the actual course and extent of an oil spill. These observations are then fed back into our computer model to improve the next forecast. Predicting the trajectory of an oil spill is tricky. But having better data and technology helps us show where oil is and where it could spread. NOAA continues to refine both current and emerging techniques in oil spill science.