Modeling the long-term transport and fate of oil spilled from the 2021 A Symphony tanker collision in the Yellow Sea, China: Reliability of the stochastic simulation

Abstract

Coupled with a 3D hydrodynamic model, a well-established 3D oil spill model is used to simulate the transport and fate of oil spilled from the A Symphony oil tanker collision in the Yellow Sea on April 27, 2021. The model is first validated by airborne mini-SAR and shipborne X-band radar observation in a 30-day simulation. Subsequently, the model prediction capabilities are investigated over a longer period when hydrodynamic data may not be available. In these cases, hydrodynamic data in earlier years are used for stochastic simulation, and the reliability of a multi-year stochastic simulation is tested. To evaluate the impact of hydrodynamics and meteorological conditions, indexes including oil sweeping area for surface oil, as well as oil centroid trajectory and oil fate for both the surface and subsurface oil, are statistically analyzed for a period up to 90 days after the spill. Over time, the deviation in the stochastic simulation relative to the deterministic simulation increased in the modeled oil transport, indicating an error accumulation. However, in the modeled oil fate, the deviation showed an interesting variation of first increasing and then gradually decreasing. This phenomenon can be attributed to three contributing factors: (1) limitations in empirical equations used in the model; (2) limited environmental impact of the spill; (3) differential role of small-scale ocean processes in short- and long-term simulations. The uncertainty in stochastic members may serve as an indicator of forecast accuracy.