Current and hydrographic conditions at the East Flower Garden Bank in 2011

Teague, William J.; Wijesekera, H. W.; Jarosz, Ewa; Fribance, Diane B.; Lugo-Fernández, Alexis; Hallock, Zachariah R.

doi:10.1016/j.csr.2013.04.039

Cited by 16 publications

(28 citation statements)

References 33 publications

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“…These observations encompassed almost the entire time period of the field experiment and showed that there was a very shallow mixed layer during this time as also indicated by Teague et al . []. Salinity at S8 varied little vertically with a range between 35.20 and 36.66 psu, while temperature showed more variability ranging from 18.10°C near the bottom to 28.64°C at about 6 m below the sea surface.…”

Section: Atmospheric and Oceanographic Settingsmentioning

confidence: 98%

“…Ten Barny (trawl‐resistant pods) and six string moorings were in place around and on the EFGB during the field experiment (Figure ). Five Barny (M1–M5) and four string (S1–S4) moorings were already deployed for the COB project and remained in the water for approximately 1 year [ Teague et al ., ]. Another five Barny (M4a, M5a, M6, M7, and M8) and two string (S5 and S8) moorings were deployed just for 2 weeks specifically for the experiment as a part of the MORT project.…”

Section: East Flower Garden Bank Experimentsmentioning

confidence: 99%

“…Detailed information such as deployment times and depths, sampling rates, ADCP frequency, and bin depth resolutions for all moorings deployed for the COB program is in Teague et al . []. Similar details for the MORT moorings are given here in Table .…”

Section: East Flower Garden Bank Experimentsmentioning

confidence: 99%

“…Teague et al . [] estimated amplitudes of major tidal constituents M 2 , K 1 , and O 1 to be between 3 and 5 cm s −1 in the EFGB region. Near‐inertial oscillations have a period of 25.58 h (close to the O 1 period), and they are generally more energetic than barotropic tides in the northwestern Gulf of Mexico [ Chen et al ., ].…”

Section: Atmospheric and Oceanographic Settingsmentioning

confidence: 99%

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Observations on stratified flow over a bank at low Froude numbers

et al. 2014

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In June 2011, a 9 day oceanographic survey was conducted over the East Flower Garden Bank, a coral reef, located on the outer shelf in the northwestern Gulf of Mexico. Current, temperature, conductivity, and microstructure measurements were collected to characterize flow evolution, turbulence, and mixing over the bank. During the experiment, the flow was highly stratified, subcritical (Froude number below 0.4), hydrostatic, and nonlinear with rotational effects being important. Observations showed that flow structure, turbulence, and mixing were highly dependent on the direction and strength of the current; thus, they varied spatially and temporarily. Responses resulting from interactions between the free-stream flow and the obstacle were significantly different on the upstream and downstream sides of the bank. Blocking and diverging of the flow just below the bank height was observed on the upstream side. On the downstream side, a wake with imbedded vortices developed. Moreover, turbulence was amplified over the bank top and on its downstream side. Turbulent dissipation rates were as high as 10 26 W kg 21 and resulted in measured rates of energy dissipation and mixing by turbulence per unit width as high as 40 W m 21 . Mixing on the downstream side was elevated with eddy diffusivities reaching 10 23 m 2 s 21 , well above a typical value of 10 25 m 2 s 21 commonly found in the ocean thermocline and over shelves with flat topography. On the upstream side, estimated eddy diffusivities were close to that for the ocean thermocline, i.e., they were generally less than 0.5310 24 m 2 s 21 .

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Section: Atmospheric and Oceanographic Settingsmentioning

confidence: 98%

Section: East Flower Garden Bank Experimentsmentioning

confidence: 99%

Section: East Flower Garden Bank Experimentsmentioning

confidence: 99%

Section: Atmospheric and Oceanographic Settingsmentioning

confidence: 99%

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Observations on stratified flow over a bank at low Froude numbers

et al. 2014

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“…Both cyclonic and anti-cyclonic eddies are formed around the perimeter where there is strong horizontal current shear. If detachment occurs far to the north, the path of the spin-off eddy and its attendant eddies interact with the upper continental slope (Hamilton et al 1999, Ohlmann et al 2001, Teague et al 2013) with resultant exchange of water between the shelf and deep basin. The principal impact is felt along the outer continental shelf from about 90°W (Mississippi Delta) westward, although attendant eddy exchange with the shelf has been observed east of this longitude (Niiler 1976, Huh et al 1981.…”

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confidence: 99%

Loop Current Spin-off Eddies, Slope Currents and Dispersal of Reef Fish Larvae from The Flower Gardens National Marine Sanctuary and The Florida Middle Grounds

Johnson¹,

Perry²,

Sanchez-Rubio³

et al. 2017

GCR

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Large energetic spin-off eddies from Loop Current intrusions into the Gulf of Mexico play a major role in water exchange between the continental shelf and the deep basin in the northern Gulf. Reef fish larvae, spawned on the outer shelf and planktonic during their early life history, are broadly dispersed by this mechanism, but may be lost to the cohort by transport away from suitable settlement habitat. In this study, satellite altimeter data-assimilative ocean model currents (HYCOM) from 2003-2015 are used to calculate kinetic energy of the mixed layer over the upper continental slope (200 m -1000 m) due to eddy interactions with the shelf and to track the dispersal of larvae spawned during core summer (June-August) season. Over the 13 year model period, dispersal into the deep basin from the Flower Gardens National Marine Sanctuary averaged 63.5%, with a high of 90.8% and a low of 34.6%. Dispersal from the Florida Middle Grounds averaged 9.5%, with a high of 23.1% and a low of 0.6%. Temporal dispersal of larvae was associated with trends in turbulent kinetic energy and mean kinetic energy over the continental slope, and varied with the North Atlantic Oscillation Index. Between 2010 and 2011, mean kinetic energy replaced turbulent kinetic energy as the dominant dispersal mechanism.

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Mode-2 hydraulic control of flow over a small ridge on a continental shelf

Gregg

Klymak

2014

J. Geophys. Res. Oceans

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Some of the most intense turbulence in the ocean occurs in hydraulic jumps formed in the lee of sills where flows are hydraulically controlled, usually by the first internal mode. Observations on the outer Texas-Louisiana continental shelf reveal hydraulic control of internal mode-2 lasting more than 3 h over a 20 m high ridge on the 100 m deep continental shelf. When control began the base of the weakly stratified surface layer bulged upward and downward, a signature of mode-2. As the westward flow producing control was lost, large-amplitude disturbances, initially resembling a bore in the weakly stratified layer, began propagating eastward. Average dissipation rates inferred from density inversions over the ridge were 10 28 and 10 27 W kg 21 , one to two decades above local background. Corresponding diapycnal diffusivities, K q , were 10 24 to 10 23 m 2 s 21 . Short-term mixing averages did not evolve systematically with hydraulic control, possibly owing to our inability to observe small overturns in strongly stratified water directly over the ridge.To test the feasibility of our interpretation of the observations, hydrostatic runs with a three-dimensional MITgcm simulated mode-2 control and intense mixing over the ridge below the interface. Details differed from observations, principally because we lacked three-dimensional density fields to initialize the model which was forced with currents observed by a bottom-mounted ADCP several kilometers east of the ridge. Consequently, the model did not capture all flow features around the bank. The principal conclusion is that hydraulic responses to higher modes can dominate flows around even modest bathymetric irregularities. Background and IntroductionSome of the most intense mixing in the ocean occurs in hydraulic jumps downstream of sills lying across channels and straits. Internal modes are hydraulically controlled where their propagation speeds are slower than opposing currents. Control is lost downstream as the current slows and/or mode speeds increase with increases in channel width or depth. The transition from a high-energy to a low-energy state releases energy in the form of strong turbulence. Many cases prominent in the oceanographic literature are forced by M 2 barotropic tides and have controls lasting only a few hours of the tidal cycle [Farmer and Smith, 1980;Armi and Farmer, 1988;Wesson and Gregg, 1994;Ferron et al., 2003;Klymak and Gregg, 2004]. Hydraulic controls, however, also occur at subtidal frequencies. For instance, observations on the Oregon shelf found intense mixing when irregular flows produced mode-1 control atop 20 m high Stonewall Bank [Moum and Nash, 2000;Nash and Moum, 2001]. Controls have also been demonstrated in quasi-steady flows, such as the Bosphorus, where currents vary principally in response to changes in synoptic weather patterns [O guz et al., 1990;Gregg et al., 1999].The introduction to Pratt and Whitehead [2008] provide an extensive discussion of the range of hydraulic flows found in ocean and atmosphere. Much o...

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Current and hydrographic conditions at the East Flower Garden Bank in 2011

Cited by 16 publications

References 33 publications

Observations on stratified flow over a bank at low Froude numbers

Observations on stratified flow over a bank at low Froude numbers

Loop Current Spin-off Eddies, Slope Currents and Dispersal of Reef Fish Larvae from The Flower Gardens National Marine Sanctuary and The Florida Middle Grounds

Mode-2 hydraulic control of flow over a small ridge on a continental shelf

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