Turbulence Measurements in a Gulf of Mexico Warm-Core Ring

2007 ◽  
Author(s):  
Thomas M. Mitchell ◽  
Rolf G. Lueck ◽  
Michael J. Vogel ◽  
Robert E. Raye ◽  
George Z. Forristall
Keyword(s):  
Gulf Of Mexico ◽  
Gulf Stream ◽  
Noise Level ◽  
Acoustic Doppler Current Profiler ◽  
Florida Current ◽  
Depth Range ◽  
Loop Current ◽  
Environmental Signals ◽  
Warm Core ◽  
Warm Core Ring

Oceanographic measurements were made in a Loop Current Eddy in the Gulf of Mexico to characterize the turbulence associated with these eddies. Measurements were made within the eddy, and across the strong frontal boundary delineating the eddy from the surrounding waters. The survey was conducted August 23–30, 2003, from the R/V Pelican. The towed vehicle, the TOMI, was equipped with a special 300 kHz acoustic Doppler current profiler (Medusa ADCP) that had its four beams directed fore, port, starboard and down. The along-beam velocities resolved structures with wavelengths of 4 to 60 m. The vehicle also carried shear probes for measuring velocity fluctuations in the dissipation range (0.5 to 100 cycles per meter), and other environmental sensors for measuring temperature, salinity, depth and vehicle orientation. Ship equipment included a 75 and 300 kHz hull-mounted ADCP, CTD, and meteorological sensors. Tows were conducted at 25, 50, 100 and 150 m depths around the northern edge of the Loop Eddy in currents of up to 1.7 m s−1. Turbulence was detected with the shear probes, but mostly in the 130–150 m depth range around the local salinity maxima. The level of turbulence is weak and it is distributed intermittently in both space and time. The most energetic events of turbulence have eddy scales of at most 4 meters and velocity scales of only 1 cm s−1. The typical and average values are more than 10 times smaller. The concurrent measurements of velocity with the Medusa ADCP did not reveal any signals significantly larger than the noise level of this instrumentation, namely 2 cm s−1. Overlap averaging of the forward directed beam reduced the noise level to 0.5 cm s−1 but still failed to reveal real environmental signals. This “null-result” is consistent with the simultaneous measurements taken with the shear probe. These low levels of turbulence are also consistent with reports of measurements in the Gulf Stream, the Florida Current, and a Gulf Stream Warm-Core Ring. Funding was provided by the DeepStar oil industry research consortium. Complete details of the program are provided in Reference [6].

scholarly journals The Dynamical Structure of a Warm Core Ring as Inferred from Glider Observations and Along-Track Altimetry

2021 ◽  
Vol 13 (13) ◽  
pp. 2456
Author(s):  
Thomas Meunier ◽  
Enric Pallás Sanz ◽  
Charly de Marez ◽  
Juan Pérez ◽  
Miguel Tenreiro ◽  
...  
Keyword(s):  
Rotation Axis ◽  
Relative Vorticity ◽  
Dynamical Structure ◽  
Loop Current ◽  
Energy Partition ◽  
Warm Core ◽  
Warm Core Ring ◽  
Current Ring ◽  
Along Track ◽  
Pv Gradient

This study investigates the vertical structure of the dynamical properties of a warm-core ring in the Gulf of Mexico (Loop Current ring) using glider observations. We introduce a new method to correct the glider’s along-track coordinate, which is, in general, biased by the unsteady relative movements of the glider and the eddy, yielding large errors on horizontal derivatives. Here, we take advantage of the synopticity of satellite along-track altimetry to apply corrections on the glider’s position by matching in situ steric height with satellite-measured sea surface height. This relocation method allows recovering the eddy’s azimuthal symmetry, precisely estimating the rotation axis position, and computing reliable horizontal derivatives. It is shown to be particularly appropriate to compute the eddy’s cyclo-geostrophic velocity, relative vorticity, and shear strain, which are otherwise out of reach when using the glider’s raw traveled distance as a horizontal coordinate. The Ertel potential vorticity (PV) structure of the warm core ring is studied in details, and we show that the PV anomaly is entirely controlled by vortex stretching. Sign reversal of the PV gradient across the water column suggests that the ring might be baroclinically unstable. The PV gradient is also largely controlled by gradients of the vortex stretching term. We also show that the ring’s total energy partition is strongly skewed, with available potential energy being 3 times larger than kinetic energy. The possible impact of this energy partition on the Loop Current rings longevity is also discussed.

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

2010 ◽  
Vol 60 (5) ◽  
pp. 1075-1084 ◽  
Author(s):  
Yuehua Lin ◽  
Richard J. Greatbatch ◽  
Jinyu Sheng
Keyword(s):  
Gulf Of Mexico ◽  
Florida Current ◽  
Loop Current

Copper complexation in sargasso sea and gulf stream warm-core ring waters

1988 ◽  
Vol 23 (1-2) ◽  
pp. 181-203 ◽  
Author(s):  
Alfred K Hanson ◽  
Carole M Sakamoto-Arnold ◽  
Douglas L Huizenga ◽  
Dana R Kester
Keyword(s):  
Gulf Stream ◽  
Sargasso Sea ◽  
Warm Core ◽  
Warm Core Ring ◽  
Copper Complexation

A cyclonic eddy and shelf-slope water exchange associated with a Gulf Stream warm-core ring

1986 ◽  
Vol 91 (C8) ◽  
pp. 9615 ◽  
Author(s):  
James H. Churchill ◽  
Peter C. Cornillon ◽  
George W. Milkowski
Keyword(s):  
Gulf Stream ◽  
Water Exchange ◽  
Cyclonic Eddy ◽  
Warm Core ◽  
Warm Core Ring ◽  
Shelf Slope

scholarly journals Loop Current Variability as Trigger of Coherent Gulf Stream Transport Anomalies

2019 ◽  
Vol 49 (8) ◽  
pp. 2115-2132 ◽  
Author(s):  
Joël J.-M. Hirschi ◽  
Eleanor Frajka-Williams ◽  
Adam T. Blaker ◽  
Bablu Sinha ◽  
Andrew Coward ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Gulf Stream ◽  
Time Lag ◽  
Ocean Model ◽  
Surface Velocity ◽  
Loop Current ◽  
Intrinsic Variability ◽  
Cape Hatteras ◽  
Florida Straits ◽  
Stream Transport

AbstractSatellite observations and output from a high-resolution ocean model are used to investigate how the Loop Current in the Gulf of Mexico affects the Gulf Stream transport through the Florida Straits. We find that the expansion (contraction) of the Loop Current leads to lower (higher) transports through the Straits of Florida. The associated surface velocity anomalies are coherent from the southwestern tip of Florida to Cape Hatteras. A simple continuity-based argument can be used to explain the link between the Loop Current and the downstream Gulf Stream transport: as the Loop Current lengthens (shortens) its path in the Gulf of Mexico, the flow out of the Gulf decreases (increases). Anomalies in the surface velocity field are first seen to the southwest of Florida and within 4 weeks propagate through the Florida Straits up to Cape Hatteras and into the Gulf Stream Extension. In both the observations and the model this propagation can be seen as pulses in the surface velocities. We estimate that the Loop Current variability can be linked to a variability of several Sverdrups (1Sv = 106 m3 s−1) through the Florida Straits. The exact timing of the Loop Current variability is largely unpredictable beyond a few weeks and its variability is therefore likely a major contributor to the chaotic/intrinsic variability of the Gulf Stream. However, the time lag between the Loop Current and the flow downstream of the Gulf of Mexico means that if a lengthening/shortening of the Loop Current is observed this introduces some predictability in the downstream flow for a few weeks.

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