Abstract

The estimation of ocean dynamics is a key challenge for applications ranging from climate modeling to ship routing. State-of-the-art methods relying on satellite-derived altimetry data can hardly resolve spatial scales below ∼100 km. In this work we investigate the relevance of AIS data streams as a new mean for the estimation of the surface current velocities. Using a physics-informed observation model, we propose to solve the associated the ill-posed inverse problem using a trainable variational formulation. The latter exploits variational auto-encoders coupled with neural ODE to represent sea surface dynamics. We report numerical experiments on a real AIS dataset off South Africa in a highly dynamical ocean region. They support the relevance of the proposed learning-based AIS-driven approach to significantly improve the reconstruction of sea surface currents compared with state-of-the-art methods, including altimetry-based ones.

Highlights

  • Currents from AutomaticIdentification System (AIS) Maritime TrafficOver the last decades, in a context of globalization, we have observed an exponential growth of maritime traffic

  • Drawing inspiration from a 4D-Var data assimilation formulation [7], we cast the estimation of sea surface current from AIS data streams as a minimization problem that involves a physics-informed observation term coupled with a trainable ordinary differential equation (ODE) prior

  • We investigate the use of AIS maritime data and deep learning methods for the reconstruction of sea surface current

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Summary

Introduction

In a context of globalization, we have observed an exponential growth of maritime traffic. Drawing inspiration from a 4D-Var data assimilation formulation [7], we cast the estimation of sea surface current from AIS data streams as a minimization problem that involves a physics-informed observation term coupled with a trainable ordinary differential equation (ODE) prior. This formulation relates to variational auto-encoders (VAEs) and exploits external data to regularize the considered ill-posed inverse problem. The proposed learning scheme applies directly to AIS data streams with no requirement for a groundtruthed dataset for sea surface currents As such, it is regarded as a non-supervised approach.

Related Work
Observational Model
Problem Statement
Proposed Approach
Observation Term J
Space–Time Dynamical Prior
Trainable Regulatization Terms
Training and Evaluation Phase
Experimental Setting
Neural Network Architecture
Method
Ageostrophy
Generalization Capacity
Sensitivity Analysis
Discussion
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