Quantifying surface currents uncertaintiesin French coastal area

Ocean surface currents are controlled by upper ocean dynamics, atmospheric conditions, as well as air-sea momentum exchanges. In the context of oil spill drift forecasting, this diversity of driving mechanisms imprints various sources of uncertainty, each of which is characterized by specific spatio-temporal patterns. Focusing on French coastal area (i.e. Bay of Biscay and English Channel), we aim at quantifying these uncertainties through ensemble and stochastic modeling approaches. We will present recent model developments within MANGA (MANche-GAscogne) Shom’s operational forecasting system, and discuss preliminary results in this direction. We will pay a particular attention to air-sea momentum exchanges, discussing strategies to model it with a stochastic approach. Such a source of uncertainty includes both large-scale components associated with atmospheric conditions and small-scale components associated with upper ocean dynamics, which a stochastic model should account for.