Connectivity of deep waters in the Gulf of Mexico

Maslo, Aljaz; Souza, João Marcos Azevedo Correia de; Andrade-Canto, F.; Outerelo, Javier Rodríguez

doi:10.1016/j.jmarsys.2019.103267

Cited by 12 publications

(14 citation statements)

References 36 publications

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“…Gough et al 27 showed the efficacy of some of the cLCS as transport barriers by using synthetic drifters advected by the instantaneous model velocities and by using 3207 satellite-tracked drifter trajectories spanning over two decades . Maslo et al 28 showed that cLCS were efficient in identifying predominant transport patterns in the deep ( ≈ 1500 m) Gulf of Mexico, as determined by RAFOS floats and synthetic drifter trajectories.…”

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confidence: 99%

“…To compute cLCS, Gough et al 27 and Maslo et al 28 used a free-run simulation performed with NEMO (Nucleus for European Modelling of the Ocean) and ROMS (Regional Ocean Modeling System), respectively, while Duran et al 26 used an operational HyCOM (Hybrid Coordinate Ocean Model) simulation. Thus, in combination, these three papers show that cLCS are robust in bypassing the variability inherent to geophysical flows, while accurately identifying predominant transport patterns.…”

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confidence: 99%

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Persistent meanders and eddies lead to quasi-steady Lagrangian transport patterns in a weak western boundary current

Gouveia

Duran

Lorenzzetti

et al. 2021

Sci Rep

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The Brazil Current (BC) is a weak western boundary current flowing along the Southwestern Atlantic Ocean. It is frequently described as a flow with intense mesoscale activity and relatively low volume transport between 5.0 and 10.0 Sv. We use a 13-year eddy-resolving primitive-equation simulation to show that the presence of persistent meanders and eddies leads to characteristic quasi-steady Lagrangian transport patterns, aptly extracted through climatological Lagrangian Coherent Structures (cLCS). The cLCS position the surface expression of the BC core along the 2000-m isobath, in excellent visual agreement with high resolution satellite sea-surface temperature and the model Eulerian mean velocity. The cLCS deformation pattern also responds to zonally persistent cross-shelf SSH transition from positive (high) values near coastline to low (negative) values between 200- and 2000-m and back to positive (high) offshore from the 2000-m isobath. Zonally-paired cyclonic and anticyclonic structures are embedded in this transition, also causing the cLCS to deform into chevrons. An efficient transport barrier is identified close to the 200-m isobath confirmed by limited inshore movement of drogued drifters and accurately indicated by an along slope maxima of climatological strength of attraction. We also show that the persistent cyclonic and anticyclonic structures may induce localized cross-shelf transport. Regions of low climatological strength of attraction coincide with large shelves and with stagnant synthetic trajectories. We also show that cLCS accurately depict trajectories initiated at the location of Chevron’s spill (November 2011) as compared to synthetic and satellite-tracked trajectories, and the outline of the oil from that accident. There is also an agreement between the large-scale oil slicks reaching the Brazilian beaches (from August 2019 to February 2020) and the strength of climatological attraction at the coast. Our work also clarifies the influence of persistent mesoscale structures on the regional circulation. The identification and quantitative description of climatological Lagrangian coherent structures is expected to improve the effectiveness of future emergency response to oil spills, contingency planning, rescue operations, larval and fish connectivity assessment, drifter launch strategies, waste pollutant and marine debris dispersion and destination.

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confidence: 99%

mentioning

confidence: 99%

Persistent meanders and eddies lead to quasi-steady Lagrangian transport patterns in a weak western boundary current

Gouveia

Duran

Lorenzzetti

et al. 2021

Sci Rep

View full text Add to dashboard Cite

show abstract

“…When cLCS deform as chevrons, they do not represent transport barriers, but instead, they identify a jet-like structure, as is the case in this study where cLCS identifies a coastal jet-like current. However, depending on the local circulation, cLCS may also indicate persistent and efficient transport barriers (Duran et al, 2018;Gough et al, 2019) or recurrent attractive pathways (Duran et al, 2018;Aljaz et al, 2020). The different interpretations for cLCS follow the fact that cLCS can be thought of as a superposition of 7-day LCS from the climatological velocity, with the integration initiating at different times (see, e.g., Appendix C of Duran et al, 2018).…”

Section: Climatological Lagrangian Coherent Structuresmentioning

confidence: 99%

On the Advection of Upwelled Water on the Western Yucatan Shelf

et al. 2021

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Upwelling events over the Yucatan Shelf are an important physical phenomenon to the region. They typically happen during spring and summer and had been studied for some time with a primary focus on the development on the eastern side of the shelf and later transport to the central part of the Peninsula. There has been very little effort looking at the impact of upwelling on the western shelf, on the Campeche side. Using a combination of observations and modeling from 2018, we show evidence for the first time, of the presence of upwelled water on the western side. Particle tracking, integrated back-in-time, was used to identify the origin of the upwelled water. Our results show that Caribbean Subtropical Underwater was brought from the northeast shelf, over 500 km away from the study area, by advection. This water took over a month (40 days) to arrive at the study region, traveling along-shelf with an average velocity of 14.5 cm/s. In the nearshore waters off the Campeche Coast, Caribbean Tropical Water was underlain by upwelling Caribbean Subtropical Underwater. Monthly averaged sea surface temperature (SST) anomalies from a 39-year time series suggest that upwelled water off Campeche is a regular phenomenon during summer, while the recurrence of westward advection is supported by climatological Lagrangian Coherent Structures. More studies are needed to explore the frequency of occurrence and impact of these events on the western shelf.

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“…For example, a common choice in the LCS literature appears to be a variable-time-step integrator of order 4 and 5 (see, e.g. Ali and Shah, 2007;Shadden et al, 2010;Beron-Vera et al, 2010;Maslo et al, 2020). Theoretically, seventh-order spline interpolation, yielding five continuous derivatives, is required for the error estimates in the step size control routine to hold.…”

Section: Discontinuous Derivativesmentioning

confidence: 99%

“…Some alternatives seek to cut computational time by using fewer evaluations, like the fourth-order Milne predictor, Hamming corrector integration scheme (see, e.g. Narváez et al, 2012), or the fourth-order Adams-Bashforth method (see, e.g. Yang et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Numerical integrators for Lagrangian oceanography

Nordam¹,

Duran²

2020

Geosci. Model Dev.

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Abstract. A common task in Lagrangian oceanography is to calculate a large number of drifter trajectories from a velocity field precalculated with an ocean model. Mathematically, this is simply numerical integration of an ordinary differential equation (ODE), for which a wide range of different methods exist. However, the discrete nature of the modelled ocean currents requires interpolation of the velocity field in both space and time, and the choice of interpolation scheme has implications for the accuracy and efficiency of the different numerical ODE methods. We investigate trajectory calculation in modelled ocean currents with 800 m, 4 km, and 20 km horizontal resolution, in combination with linear, cubic and quintic spline interpolation. We use fixed-step Runge–Kutta integrators of orders 1–4, as well as three variable-step Runge–Kutta methods (Bogacki–Shampine 3(2), Dormand–Prince 5(4) and 8(7)). Additionally, we design and test modified special-purpose variants of the three variable-step integrators, which are better able to handle discontinuous derivatives in an interpolated velocity field. Our results show that the optimal choice of ODE integrator depends on the resolution of the ocean model, the degree of interpolation, and the desired accuracy. For cubic interpolation, the commonly used Dormand–Prince 5(4) is rarely the most efficient choice. We find that in many cases, our special-purpose integrators can improve accuracy by many orders of magnitude over their standard counterparts, with no increase in computational effort. Equivalently, the special-purpose integrators can provide the same accuracy as standard methods at a reduced computational cost. The best results are seen for coarser resolutions (4 and 20 km), thus the special-purpose integrators are particularly advantageous for research using regional to global ocean models to compute large numbers of trajectories. Our results are also applicable to trajectory computations on data from atmospheric models.

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Connectivity of deep waters in the Gulf of Mexico

Cited by 12 publications

References 36 publications

Persistent meanders and eddies lead to quasi-steady Lagrangian transport patterns in a weak western boundary current

Persistent meanders and eddies lead to quasi-steady Lagrangian transport patterns in a weak western boundary current

On the Advection of Upwelled Water on the Western Yucatan Shelf

Numerical integrators for Lagrangian oceanography

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