Strategies for simulating the drift of marine debris

Jonathan V Durgadoo,Arne Biastoch,Adrian L New,Siren Rühs,Aylmer J.G Nurser,Yann Drillet,Jean-Raymond Bidlot

doi:10.1080/1755876x.2019.1602102

Abstract

ABSTRACT Modelling the drift of marine debris in quasi-real time can be of societal relevance. One pertinent example is Malaysia Airlines flight MH370. The aircraft is assumed to have crashed in the Indian Ocean, leaving floating wreckage to drift on the surface. Some of these items were recovered around the western Indian Ocean. We use ocean currents simulated by an operational ocean model in conjunction with surface Stokes drift to determine the possible paths taken by the debris. We consider: (1) How important is the influence of surface waves on the drift? (2) What are the relative benefits of forward- and backward-tracking in time? (3) Does including information from more items refine the most probable crash-site region? Our results highlight a critical contribution of Stokes drift and emphasise the need to know precisely the buoyancy characteristics of the items. The differences between the tracking approaches provide a measure of uncertainty which can be minimised by simulating a sufficiently large number of virtual debris. Given the uncertainties associated with the timings of the debris sightings, we show that at least 5 items are required to achieve an optimal most probable crash-site region. The results have implications for other drift simulation applications.

Highlights

Drift observations of objects near the surface of the ocean have led to fundamental advances in the understanding of ocean dynamics
South of the Agulhas Return Current, which lies near 42°S, the Indian Ocean sector of the Southern Ocean is strongly influenced by persistent westerly winds (Durgadoo et al 2008)
We undertook a detailed study of trajectory calculations in the Indian Ocean in connection with the disappearance of flight MH370 in 2014

Summary

Introduction

Drift observations of objects near the surface of the ocean have led to fundamental advances in the understanding of ocean dynamics. Nansen’s observations of ice drift in the Arctic led to the formulation of Ekman theory, which plays a central role in understanding the dynamics of ocean gyres, fronts, and upwelling, among others. Since the latter part of the twentieth century, satellite-tracked drifting buoys continuously provide a wealth of information on ocean circulation and in-situ properties (Lumpkin et al 2017)

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