scholarly journals Hydrography of the Gulf of Mexico Using Autonomous Floats

2018 ◽  
Vol 48 (4) ◽  
pp. 773-794 ◽  
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.

scholarly journals Transports through the Straits of Florida

2005 ◽  
Vol 35 (3) ◽  
pp. 308-322 ◽  
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.

scholarly journals Deep Cyclonic Circulation in the Gulf of Mexico

2005 ◽  
Vol 35 (10) ◽  
pp. 1801-1812 ◽  
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.

scholarly journals Mean Flow in the Gulf of Mexico

2008 ◽  
Vol 38 (7) ◽  
pp. 1501-1514 ◽  
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.

scholarly journals Dominant Circulation Patterns of the Deep Gulf of Mexico

2018 ◽  
Vol 48 (3) ◽  
pp. 511-529 ◽  
Author(s):  
Paula Pérez-Brunius ◽  
Heather Furey ◽  
Amy Bower ◽  
Peter Hamilton ◽  
Julio Candela ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Large Scale ◽  
Bottom Layer ◽  
Loop Current ◽  
Cyclonic Gyre ◽  
Boundary Current ◽  
Mean Flow ◽  
Western Basin ◽  
Boundary Flow ◽  
Circulation Patterns

AbstractThe large-scale circulation of the bottom layer of the Gulf of Mexico is analyzed, with special attention to the historically least studied western basin. The analysis is based on 4 years of data collected by 158 subsurface floats parked at 1500 and 2500 m and is complemented with data collected by current meter moorings in the western basin during the same period. Three main circulation patterns stand out: a cyclonic boundary current, a cyclonic gyre in the abyssal plain, and the very high eddy kinetic energy observed in the eastern Gulf. The boundary current and the cyclonic gyre appear as distinct features, which interact in the western tip of the Yucatan shelf. The persistence and continuity of the boundary current is addressed. Although high variability is observed, the boundary flow serves as a pathway for water to travel around the western basin in approximately 2 years. An interesting discovery is the separation of the boundary current over the northwestern slope of the Yucatan shelf. The separation and retroflection of the along-slope current appears to be a persistent feature and is associated with anticyclonic eddies whose genesis mechanism remains to be understood. As the boundary flow separates, it feeds into the westward flow of the deep cyclonic gyre. The location of this gyre—named the Sigsbee Abyssal Gyre—coincides with closed geostrophic contours, so eddy–topography interaction via bottom form stresses may drive this mean flow. The contribution to the cyclonic vorticity of the gyre by modons traveling under Loop Current eddies is discussed.

scholarly journals Is the Loop Current a Chaotic Oscillator?

2007 ◽  
Vol 37 (6) ◽  
pp. 1455-1469 ◽  
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.

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

2002 ◽  
Vol 29 (22) ◽  
pp. 16-1-16-4 ◽  
Author(s):  
Julio Candela ◽  
Julio Sheinbaum ◽  
José Ochoa ◽  
Antoine Badan ◽  
Robert Leben
Keyword(s):  
Gulf Of Mexico ◽  
Potential Vorticity ◽  
Loop Current ◽  
Yucatan Channel ◽  
Vorticity Flux

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

2011 ◽  
Vol 41 (3) ◽  
pp. 458-471 ◽  
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.

scholarly journals The Ventilation of the Deep Gulf of Mexico

2005 ◽  
Vol 35 (10) ◽  
pp. 1763-1781 ◽  
Author(s):  
David Rivas ◽  
Antoine Badan ◽  
José Ochoa
Keyword(s):  
Gulf Of Mexico ◽  
Mass Transport ◽  
Cold Water ◽  
Intermediate Water ◽  
Deep Waters ◽  
The Mean ◽  
The Caribbean ◽  
Florida Straits ◽  
Yucatan Channel ◽  
Bottom Oxygen

Abstract Recent measurements over the sill in the Yucatan Channel indicate that the deepest flows between the Caribbean Sea and the Gulf of Mexico, those that take place below the sill level at the Florida Straits, have zero mean net mass transport but carry significant amounts of heat and oxygen. The heat flux associated with the mean exchange exports approximately 150 GW from the deep Gulf toward the Caribbean and may be related to the formation of the Yucatan Undercurrent. The eddy heat transfer is also significantly different from zero and exports on average an additional 60 GW. This eddy transfer is attributable mostly to events that last from a few days to about 1.5 months, during which colder water from deeper levels in the Caribbean (beneath 2000 m) flows over the sill within a bottom boundary layer close to 200 m thick. The colder water is also very rich in oxygen, and the deep exchange sustains the near-bottom oxygen maximum in the Gulf of Mexico, whence that cold water must slide down the northern slope of the Yucatan Sill. Estimates of oxygen transport by diffusion from the deep water into the overlying intermediate water (∼50 m3 s−1) and the oxygen consumption reported in the literature (∼100 m3 s−1) are balanced by the rates of mean and eddy transfers over the sill (∼150 m3 s−1). The near-bottom mass transport [∼0.32 Sv (1 Sv ≡ 106 m3 s−1)] measured across the deepest portion of the central Yucatan Channel suggests a residence time for the deep waters of the Gulf of about 250 yr.

scholarly journals The Flow through the Gulf of Mexico

2019 ◽  
Vol 49 (6) ◽  
pp. 1381-1401 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document