Improved prediction of oil drift pattern using ensemble of ocean currents

Abstract

ABSTRACT Indian Coast Guard and oil spill responders utilise the operational oil spill advisory services of the Indian National Centre for Ocean Information Services (INCOIS) during the event of oil spills for setting up spill response operations. Oil drifts in marine zones are dominated by ocean currents. Ocean currents generated by numerical models have errors and uncertainties due to model approximations, inaccurate initial and boundary conditions in the model setup. An attempt was made to generate an oil spill advisory using a weighted ensemble of ocean currents. In this study, the oil spill trajectory model, General National Oceanic and Atmospheric Administration (NOAA) Operational Modeling Environment (GNOME) was forced using a weighted ensemble of ocean currents for the Heavy Furnace Oil (HFO) spill reported off Ennore port during 0400 hours (IST) of 28 January 2017. The inverse-variance weighting method was used to estimate weights by comparing zonal and meridional components of individual model ocean currents, with that of High Frequency (HF) Radar currents. The zone of HFO spread obtained while using an ensemble of ocean currents was compared with oil slick signatures obtained from Synthetic Aperture Radar (SAR) data on 0600 hours (IST) of 29 January 2017. It was noted that the trajectory patterns obtained from the weighted ensemble of ocean currents were well within the observed zone of oil slicks, compared to that of individual model ocean currents.