Learning excursion sets of vector-valued Gaussian random fields for autonomous ocean sampling

TL;DR

This paper develops efficient statistical sampling methods for mapping oceanographic phenomena using autonomous vehicles, focusing on regions where multiple responses exceed thresholds, with demonstrated success in field deployments.

Contribution

It introduces a novel sampling criterion based on excursion sets of vector-valued Gaussian fields, optimizing autonomous ocean sampling strategies.

Findings

Effective sampling location prioritization based on uncertainty reduction.

Simulation studies showing improved exploration efficiency.

Successful field deployment demonstrating practical applicability.

Abstract

Improving and optimizing oceanographic sampling is a crucial task for marine science and maritime resource management. Faced with limited resources in understanding processes in the water-column, the combination of statistics and autonomous systems provide new opportunities for experimental design. In this work we develop efficient spatial sampling methods for characterizing regions defined by simultaneous exceedances above prescribed thresholds of several responses, with an application focus on mapping coastal ocean phenomena based on temperature and salinity measurements. Specifically, we define a design criterion based on uncertainty in the excursions of vector-valued Gaussian random fields, and derive tractable expressions for the expected integrated Bernoulli variance reduction in such a framework. We demonstrate how this criterion can be used to prioritize sampling efforts at locations that are ambiguous, making exploration more effective. We use simulations to study and compare properties of the considered approaches, followed by results from field deployments with an autonomous underwater vehicle as part of a study mapping the boundary of a river plume. The results demonstrate the potential of combining statistical methods and robotic platforms to effectively inform and execute data-driven environmental sampling.