REAL-TIME OIL-SPILL FORECASTING DURING AN EXPERIMENTAL OIL-SPILL IN THE ARCTIC ICE

The oil spill trajectory and weathering model OILMAP was used to forec ast spill trajectories for an experimental oil spill in the Barents Se a marginal ice zone. The model includes capabilities to enter graphica lly and display environmental data governing oil behavior: ice fields, tidal and background current fields, and wind time series, as well as geographical map information. Forecasts can also be updated from obse rvations such as airplane overflights. The model performed well when w ind was 'off-ice' and speeds were relatively low (3-7 m s(-1)), with i ce cover between 60 and 90%. Errors in forecasting the trajectory coul d be directly attributed to errors in the wind forecasts. Appropriate drift parameters for oil and ice were about 2.5% of the wind speed, wi th an Ekman veering angle of 35 degrees to the right. Ice sheets were typically 1 m thick. When the wind became 'on-ice', wind speeds increa sed to about 10 m s(-1) and trajectory simulations began to diverge fr om the observations, with observed drift parameters being 1.5% of the wind speed, with a 60 degrees veering angle. Although simple assumptio ns for the large scale movement of oil in dense ice fields appear appr opriate, the importance of good wind forecasts as a basis for reliable trajectory prognoses cannot be overstated.