News | Nonlinear Dynamics | University of Miami

We used transition path theory (TPT) to infer reactive pathways of floating marine debris trajectories. The TPT analysis was applied on a pollution-aware time-homogeneous Markov-chain model constructed from trajectories produced by satellite-tracked undrogued buoys from the National Oceanic and Atmospheric Administration’s Global Drifter Program.

Directly connecting pollution sources along coastlines with garbage patches of varied strengths, the unveiled reactive pollution routes represent alternative targets for ocean cleanup efforts. Among our specific findings we highlight: constraining a highly probable pollution source for the Great Pacific garbage patch; characterizing the weakness of the Indian Ocean gyre as a trap for plastic waste; and unveiling a tendency of the subtropical gyres to export garbage toward the coastlines rather than to other gyres in the event of anomalously intense winds.

Inferred reactive probability currents of marine debris into garbage patches (red boxes). Black boxes indicate coastal boxes where the debris are released. The color of the arrows represents the probability of the transition route.

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EurekaAlert!, AcademicTimes, DailyMail

Link to scientific publication:
Transition paths of marine debris and the stability of the garbage patches
P. Miron, F.J. Beron-Vera, L. Helfmann, and P. Koltai
Phys. Fluids 32, 026601 (2020)

In 2019, under the supervision of Prof. M.J. Olascoaga from University of Miami, and R. Lumpkin and G. Goni from NOAA Atlantic Oceanographic and Meteorological Laboratory, a project was designed to better understand the mechanism by which ocean currents and winds control floating debris.

Four types of special drifters were constructed for the experiment. Three of them consisted of a main body made of Styrofoam. These special drifters represented a sphere of radius 12 cm, a cube of about 25 cm side, and a cuboid of approximate dimensions 30 cm × 30 cm × 10 cm. These were submerged below the sea level by roughly 10 cm, 6.5 cm, and 5 cm, respectively. The fourth special drifter, made of plastic, was designed to mimic a macroalgal mat, such as a Sargassum mat. The field experiment consisted in deploying simultaneously those objects of varied sizes, buoyancies, and shapes and was performed on 7 December 2017 at 79.88°W, 25.74°N, off the southeastern Florida Peninsula in the Florida Current, and subsequently tracking them via a satellite.

The objects were released in close vicinity of each other and were subjected to the same external conditions but their trajectories differ dramatically 3 days after deployment. Furthermore, each trajectory cannot be explained by adding a small constant fraction of wind to the ocean current, as it is usually performed in leeway models.

In a recent publication by our group, we developed a Maxey-Riley framework to describe the movement of a particle floating at an unperturbed air–sea interface with unsteady nonuniform winds and ocean currents. The object trajectory can be predicted as a function of ocean currents, winds, and its size, buoyancy and shape. The last figure presents the special drifters (from left to right: mat, cuboid, sphere, and cube) observed trajectories (solid lines) and predicted trajectories (dashed lines). The gray area spanned by Maxey–Riley trajectories represents the range for a ±10% change of the objects' buoyancy.

Link to news article:
EurekaAlert!, UPI

Link to scientific publications:
Building a Maxey–Riley framework for surface ocean inertial particle dynamics
F.J. Beron-Vera, M.J. Olascoaga and P. Miron
Phys. Fluids 31, 096602 (2019)

Observation and quantification of inertial effects on the drift of floating objects at the ocean surface
M.J. Olascoaga, F.J. Beron-Vera, P. Miron, J. Triñanes, N.F. Putman, R. Lumpkin and G.J. Goni
Phys. Fluids 32, 026601 (2020)

The oil spill started on August 30, 2019 and has affected over 2000 km of coastline in Northeast Brazil. The incident is already the biggest oil spill in Brazilian history and one of the worst environment disaster (source Folha de São Paulo) and as of today, the origin of the oil spill is still unknown.

Using drifters from the Global Drifters Program and tools described in Probabilistic method, Dr. P. Miron and, Dr. Marlos Goes and Dr. Rick Lumpkin from NOAA Atlantic Oceanographic and Meteorological Laboratory, backtraced the origin of the oil from the coast near Recife, Pernambuco. Presented on the figure below, the most probable source of the oil spill is dependent on the depth at which the oil is spreading. The dynamics on the surface of the ocean is approximated by undrogued drifter trajectories while the subsurface dynamics is approximated by the drogued drifters (15 m deep).

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Folha de S.Paulo, Diário do Centro do Mundo, Brasil 247, Tijolaço

Francisco J. Beron-Vera invited to join the Editorial Board for Scientific Reports on May 17th, 2019.

Scientific Reports, Scientific Reports Editors

Markov-chain models are constructed for the probabilistic description of the drift of marine debris from Malaysian Airlines flight MH370. En route from Kuala Lumpur to Beijing, MH370 mysteriously disappeared in the southeastern Indian Ocean on 8 March 2014, somewhere along the arc of the 7th ping ring around the Inmarsat-3F1 satellite position when the airplane lost contact.

The models are obtained by discretizing the motion of undrogued satellite-tracked surface drifting buoys from the global historical data bank. A spectral analysis, Bayesian estimation, and the computation of most probable paths between the Inmarsat arc and confirmed airplane debris beaching sites are shown to constrain the crash site, near 25^°S on the Inmarsat arc.

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A study from Research Prof. Beron-Vera and Prof. Olascoaga on how ocean currents and winds affect the transport floating debris gives new explanation on why plastic debris converge to the center of Ocean Gyres and accumulate in those infamous Garbage patches. Using surface drifters from the Global Drifter Program, they show that undrogued drifters, more affected by winds than drogued drifters which provide measurements of the 15-m depth ocean current, accumulate precisely where platic accumulate to form the great garbage patches.

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Phys.org, Science Daily, Miami Herald, Lohud

Red tide, a common name for Karenia brevis blooming, can lead to human respiratory distress, death of fish and marine mammals and affect the economy of the Florida coast. In a study by Dr. G. Maze, Prof. M. J. Olascoaga and Prof. L. E. Brand, the authors show the importance of the position of the Loop Current for the development of algae bloom on the West Florida Shelf. From historical analysis of environmental conditions during Florida Red Tide, the periods of large blooms are found to occur only when the LC is in its northern position. 

Link to video:
Univision Miami

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Science Daily, News UM, Terra Daily, AccuWeather, EurekAlert, Agris

A collaborative work between researchers from ETH Zurich and the University of Miami established a simple variational principle to extract coherent material vortices in a two-dimensional turbulent flow. Ocean eddies boundaries are sought as elliptic Lagrangian Coherent Structures. The dynamic of particles gravitating around the boundaries of such objects is similar to the dynamic of photons around black holes. Similarly to black boles, large ocean eddies trap water parcels while traveling across Ocean basins.

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PHYS.org, EurekAlert!, WAMC Radio, MNN, DailyMail, Science Daily, Express, News Scientist, Huffington Post, Discover Magazine