OCTOPUS (Ocean Circulation and Transport for Oil Propagation from Underwater Spills)

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Although oil blowouts from the deep water drilling happen very rarely, their impact can be devastating, causing catastrophic damage to the wildlife and environment in both coastal and deep sea systems. When oil is released into the ocean, it undergoes chemical, physical and biological transformations affected by various seawater properties. However, it is ocean currents (and, for surface spills, wind) that determines the movement of oil towards either landfall or biologically sensitive areas in deep or shallow water. Consequently, as part of preparations for accidental spills, it is of critical importance that oil companies engaged in deep drilling assess the structure and variability of the ocean currents in the vicinity of their drilling locations, as well as provide scenarios of possible oil drift over a spill lifetime period of several months. By way of example, BP has a number of extant deep drilling locations in the Faeroe-Scotland channel. In their environmental statement for one of the wells (North Uist), BP uses ocean circulation data provided by the Norwegian Meteorological Institute to predict oil beaching. This reports that oil will most likely drift towards the northern coast of Norway, and that it will only beach there or on the Shetland Islands. At the National Oceanography Centre, Southampton, we have developed an advanced ocean circulation model that allows the detailed description of ocean currents at all depths anywhere in the World Ocean. Using this model we have performed oil release experiments similar to those of the BP environmental statement. However, our preliminary results show that, although the major threat is indeed for the northern Norwegian mainland, there is also a significant probability of the spill reaching environmentally sensitive areas of the Svalbard, Iceland and Denmark. Furthermore, oil remaining at depth will drift west into the northern North Atlantic potentially threatening the abundant deep sea life there.These results illustrate the risk of relying on a single model when forecasting the far-reaching and potentially catastrophic consequences of oil spills. Using limited complexity models may result in the development of spill response strategies that overlook what ultimately may become serious impacts. Our project aims to engage with stakeholders such as BP and DECC to demonstrate advances in ocean modelling achieved by the National Oceanography Centre, and to collaboratively design model experiments to better forecast the impacts of potential blowouts in the Faeroe-Shetland area. These experiments will track the transport of oil both on the surface and in the deep water and determine how variability in the northern North Atlantic may affect the extent and severity of oil spill impacts. One of the advantages of our approach is the use of a global ocean model, such that similar studies can be easily repeated for other deep water drilling locations anywhere in the world. As part of this work, we will produce visualisations of the drifting oil and the ocean currents affecting it within an interactive display that demonstrates the worldwide reach of this system.