The potential vorticity flux through the Yucatan Channel and the Loop Current in the Gulf of Mexico

Abstract. The anticyclonic Loop Current Eddy (LCE) shedding events are strongly associated with the evolution of Loop Current Frontal Eddies (LCFEs) over the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ measurements and satellite data, was used to investigate the Loop Current (LC) evolution and the surrounding LCFE formation, structure, growth and migration during the Eddy Ekman and Eddy Franklin shedding events in the summers of 2009 and 2010, respectively. During both events, northern GoM LCFEs appeared vertically coherent to at least 1500 m in temperature observations. They propagated towards the base of the LC, where, together with the migration of Campeche Bank (southwest GoM shelf) eddies from south of the LC, contributed to its "necking-down". Growth of Campeche Bank LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank waters following upwelling events. Slope processes associated with such upwelling included offshore exports of high positive potential vorticity that may trigger cyclone formation and growth. The advection and growth of LCFEs, originating from the northern and southern GoM, and their interaction with the LC over the LCE detachment area favor shedding conditions and may contribute to the final separation of the LCE.

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Transports through the Straits of Florida

Journal of Physical Oceanography ◽

10.1175/jpo-2688.1 ◽

2005 ◽

Vol 35 (3) ◽

pp. 308-322 ◽

Cited By ~ 43

Author(s):

Peter Hamilton ◽

Jimmy C. Larsen ◽

Kevin D. Leaman ◽

Thomas N. Lee ◽

Evans Waddell

Keyword(s):

Gulf Of Mexico ◽

North Atlantic Ocean ◽

Florida Current ◽

Loop Current ◽

Straits Of Florida ◽

Key West ◽

The North ◽

Side Channels ◽

Yucatan Channel ◽

Accurate Indicator

Abstract Transports were calculated for four sections of the Florida Current from Key West to Jupiter, Florida, using a moored current-meter array and voltages from cross-channel telephone cables at the western and northern ends of the Straits of Florida. In addition, moored arrays were used to estimate transport through the Northwest Providence, Santaren, and Old Bahama Channels that connect the Florida Current to the southwestern part of the North Atlantic Ocean. Transport measurements were obtained for an 11-month period from December 1990 to November 1991. Mean transports of ∼25 Sv (1 Sv ≡ 106 m3 s−1) for the flow across the western ends of the straits, which agree quite well with recent estimates of 23.8 ± 1 Sv entering the Gulf of Mexico through the Yucatan Channel, were obtained from both the Key West to Havana cable and the moored array. This estimate is about 5 Sv less than the generally accepted transport through the northern end of the straits at 27°N. This difference was partially accounted for by inflows through the side channels with more transport from the Old Bahama than the Northwest Providence Channel. The variability in the southern part of the straits was larger than at 27°N and included large diversions of the Florida Current south of the Cay Sal Bank and into the Santaren Channel that were caused by large meanders of the flow. The variability of transport in the side channels contributed to the variability of the Florida Current and reduces the correlations of the transports at the ends of the straits. Therefore, the well-measured transport at 27°N is not an accurate indicator of the transport of the Loop Current out of the Gulf of Mexico.

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Deep Cyclonic Circulation in the Gulf of Mexico

Journal of Physical Oceanography ◽

10.1175/jpo2790.1 ◽

2005 ◽

Vol 35 (10) ◽

pp. 1801-1812 ◽

Cited By ~ 40

Author(s):

Christopher J. DeHaan ◽

Wilton Sturges

Keyword(s):

Gulf Of Mexico ◽

Accurate Result ◽

Sea Water ◽

Cyclonic Circulation ◽

Loop Current ◽

Mean Flow ◽

Eastern Gulf Of Mexico ◽

Geostrophic Shear ◽

Layer Flow ◽

Yucatan Channel

Abstract The anticyclonic Loop Current dominates the upper-layer flow in the eastern Gulf of Mexico, with a weaker mean anticyclonic pattern in the western gulf. There are reasons, however, to suspect that the deep mean flow should actually be cyclonic. Topographic wave rectification and vortex stretching contribute to this cyclonic tendency, as will the supply of cold incoming deep water at the edges of the basin. The authors find that the deep mean flow is cyclonic both in the eastern and western gulf, with speeds on the order of 1–2 cm s−1 at 2000 m. Historical current-meter mooring data, as well as profiling autonomous Lagrangian circulation explorer (PALACE) floats (at 900 m), suggest that vertical geostrophic shear relative to 1000 m gives a surprisingly accurate result in the interior of the basin. The temperature around the edges of the basin at 2000 m is coldest near the Yucatan Channel, where Caribbean Sea water is colder by ∼0.1°C. The temperature increases steadily with distance in the counterclockwise direction from the Yucatan, consistent with a deep mean cyclonic boundary flow.

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Mean Flow in the Gulf of Mexico

Journal of Physical Oceanography ◽

10.1175/2007jpo3802.1 ◽

2008 ◽

Vol 38 (7) ◽

pp. 1501-1514 ◽

Cited By ~ 16

Author(s):

Wilton Sturges ◽

Kern E. Kenyon

Keyword(s):

Gulf Of Mexico ◽

Data Sources ◽

Loop Current ◽

Independent Data ◽

Ekman Pumping ◽

Mean Flow ◽

The West ◽

Net Flux ◽

Yucatan Channel ◽

Current Potential

Abstract Several independent data sources suggest that there is a net upper-layer mass flux O(3 Sv) (Sv ≡ 106 m3 s−1) to the west in the central Gulf of Mexico, even though the western gulf is a closed basin. A plausible explanation is that this net flux is pumped downward by the convergent wind-driven Ekman pumping, as is typical of all midlatitude anticlyclonic gyres. The downward flux can follow isopycnals to depths O(500–600 m) and deeper by eddy mixing; a mechanism for forcing deep water to the south through the Yucatan Channel is provided by the intrusion and ring-shedding cycle of the Loop Current. Potential vorticity maps show that a deep flow from the western gulf back to the Yucatan Channel is likely.

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Is the Loop Current a Chaotic Oscillator?

Journal of Physical Oceanography ◽

10.1175/jpo3066.1 ◽

2007 ◽

Vol 37 (6) ◽

pp. 1455-1469 ◽

Cited By ~ 28

Author(s):

Alexis Lugo-Fernández

Keyword(s):

Dynamical Systems ◽

Gulf Of Mexico ◽

North Atlantic ◽

Chaotic Oscillator ◽

Loop Current ◽

The North ◽

Short Memory ◽

The North Atlantic ◽

Yucatan Channel ◽

The North Atlantic Oscillation

Abstract Dynamical systems theory is employed to study the irregular Loop Current in the Gulf of Mexico using a short database of shedding periods and north–south positions of the current. Two independent tests based on these data suggest that the Loop Current is not chaotic but behaves as a nonlinear driven and dampened oscillator with a very short memory. It is suggested that this current varies around a limit-cycle elliptical attractor. It was found that the amplitude and period of the oscillation vary at time scales of 3–5 yr, a time scale that agrees with those of the North Atlantic Oscillation (NAO) and/or ENSO; however, it is proposed that NAO provides the link between these systems. The proposed mechanism is the ITCZ changes caused by NAO, which affects the wind strength and the transport across the Yucatan Channel. A forecasting scheme that allows for prediction of the next eddy-shedding period from knowledge of the last shedding event, a condition caused by the short memory of the system, is provided.

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Hydrography of the Gulf of Mexico Using Autonomous Floats

Journal of Physical Oceanography ◽

10.1175/jpo-d-17-0205.1 ◽

2018 ◽

Vol 48 (4) ◽

pp. 773-794 ◽

Cited By ~ 9

Author(s):

Peter Hamilton ◽

Robert Leben ◽

Amy Bower ◽

Heather Furey ◽

Paula Pérez-Brunius

Keyword(s):

Gulf Of Mexico ◽

Water Masses ◽

Intermediate Water ◽

Loop Current ◽

Western Basin ◽

Homogeneous Potential ◽

Comprehensive Survey ◽

Yucatan Channel ◽

Subtropical Underwater ◽

June July

ABSTRACTFourteen autonomous profiling floats, equipped with CTDs, were deployed in the deep eastern and western basins of the Gulf of Mexico over a four-year interval (July 2011–August 2015), producing a total of 706 casts. This is the first time since the early 1970s that there has been a comprehensive survey of water masses in the deep basins of the Gulf, with better vertical resolution than available from older ship-based surveys. Seven floats had 14-day cycles with parking depths of 1500 m, and the other half from the U.S. Argo program had varying cycle times. Maps of characteristic water masses, including Subtropical Underwater, Antarctic Intermediate Water (AAIW), and North Atlantic Deep Water, showed gradients from east to west, consistent with their sources being within the Loop Current (LC) and the Yucatan Channel waters. Altimeter SSH was used to characterize profiles being in LC or LC eddy water or in cold eddies. The two-layer nature of the deep Gulf shows isotherms being deeper in the warm anticyclonic LC and LC eddies and shallower in the cold cyclones. Mixed layer depths have an average seasonal signal that shows maximum depths (~60 m) in January and a minimum in June–July (~20 m). Basin-mean steric heights from 0–50-m dynamic heights and altimeter SSH show a seasonal range of ~12 cm, with significant interannual variability. The translation of LC eddies across the western basin produces a region of low homogeneous potential vorticity centered over the deepest part of the western basin.

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Loop Current Cycle: Coupled Response of the Loop Current with Deep Flows

Journal of Physical Oceanography ◽

10.1175/2010jpo4479.1 ◽

2011 ◽

Vol 41 (3) ◽

pp. 458-471 ◽

Cited By ~ 25

Author(s):

Y.-L. Chang ◽

L.-Y. Oey

Keyword(s):

Numerical Model ◽

Gulf Of Mexico ◽

Mass Flux ◽

Low Frequency ◽

Loop Current ◽

Current Cycle ◽

The Mean ◽

Yucatan Channel ◽

Upward Flux ◽

Current Stage

Abstract Although the upper-layer dynamics of the Loop Current and eddies in the Gulf of Mexico are well studied, the understanding of how they are coupled to the deep flows is limited. In this work, results from a numerical model are analyzed to classify the expansion, shedding, retraction, and deep-coupling cycle (the Loop Current cycle) according to the vertical mass flux across the base of the Loop. Stage A is the “Loop reforming” period, with downward flux and deep divergence under the Loop Current. Stage B is the “incipient shedding,” with strong upward flux and deep convergence. Stage C is the “eddy migration,” with waning upward flux and deep throughflow from the western Gulf into the Yucatan Channel. Because of the strong deep coupling between the eastern and western Gulf, the Loop’s expansion is poorly correlated with deep flows through the Yucatan Channel. Stage A is longest and the mean vertical flux under the Loop Current is downward. Therefore, because the net circulation around the abyssal basin is zero, the abyssal gyre in the western Gulf is cyclonic. The gyre’s strength is strongest when the Loop Current is reforming and weakest after an eddy is shed. The result suggests that the Loop Current cycle can force a low-frequency [time scales ∼ shedding periods; O(months)] abyssal oscillation in the Gulf of Mexico.

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The Flow through the Gulf of Mexico

Journal of Physical Oceanography ◽

10.1175/jpo-d-18-0189.1 ◽

2019 ◽

Vol 49 (6) ◽

pp. 1381-1401 ◽

Cited By ~ 3

Author(s):

J. Candela ◽

J. Ochoa ◽

J. Sheinbaum ◽

M. López ◽

P. Pérez-Brunius ◽

...

Keyword(s):

Gulf Of Mexico ◽

Straits Of Florida ◽

The North ◽

Astronomical Tide ◽

Flow Through ◽

Sverdrup Transport ◽

The Mean ◽

Yucatan Channel ◽

Range Variation

AbstractFour years (September 2012 to August 2016) of simultaneous current observations across the Yucatan Channel (~21.5°N) and the Straits of Florida (~81°W) have permitted us to investigate the characteristics of the flow through the Gulf of Mexico. The average transport in both channels is 27.6 Sv (1 Sv = 106 m3 s−1), in accordance with previous estimates. At the Straits of Florida section, the transport related to the astronomical tide explains 55% of the observed variance with a mixed semidiurnal/diurnal character, while in the Yucatan Channel tides contribute 82% of the total variance and present a dominant diurnal character. At periods longer than a week the transports in the Yucatan and Florida sections have a correlation of 0.83 without any appreciable lag. The yearly running means of the transport time series in both channels are well correlated (0.98) and present a 3-Sv range variation in the 4 years analyzed. This long-term variability is well related to the convergence of the Sverdrup transport in the North Atlantic between 14.25° and 18.75°N. Using 2 years (July 2014–July 2016) of simultaneous currents observations in the Florida section, the Florida Cable section (~26.7°N), and a section across the Old Bahama Channel (~78.4°W), a mean northward transport of 28.4, 31.1, and 1.6 Sv, respectively, is obtained, implying that only 1.1 Sv is contributed by the Northwest Providence Channel to the mean transport observed at the Cable section during this 2-yr period.

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The influence of Gulf of Mexico Loop Current intrusion on the transport of the Florida Current

Ocean Dynamics ◽

10.1007/s10236-010-0308-0 ◽

2010 ◽

Vol 60 (5) ◽

pp. 1075-1084 ◽

Cited By ~ 10

Author(s):

Yuehua Lin ◽

Richard J. Greatbatch ◽

Jinyu Sheng

Keyword(s):

Gulf Of Mexico ◽

Florida Current ◽

Loop Current

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