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

Candela, Julio; Sheinbaum, Julio; Ochoa, José; Badan, A.; Leben, R. R.

doi:10.1029/2002gl015587

Cited by 90 publications

(106 citation statements)

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“…With maximum surface temperatures exceeding 288C and the 208C isotherm varying from 100 to 240 m depth across the current, the mean temperature structure of the Loop Current in the Gulf of Mexico (Fig. 8a) compares well with the mean temperature distribution across the Yucatan Channel in Candela et al (2002). This suggests that the cross-stream structure of the current does not change significantly within the Gulf of Mexico.…”

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confidence: 56%

Potential Vorticity Structure in the North Atlantic Western Boundary Current from Underwater Glider Observations

Todd

Owens

Rudnick

2016

Journal of Physical Oceanography

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Potential vorticity structure in two segments of the North Atlantic's western boundary current is examined using concurrent, high-resolution measurements of hydrography and velocity from gliders. Spray gliders occupied 40 transects across the Loop Current in the Gulf of Mexico and 11 transects across the Gulf Stream downstream of Cape Hatteras. Cross-stream distributions of the Ertel potential vorticity and its components are calculated for each transect under the assumptions that all flow is in the direction of measured vertically averaged currents and that the flow is geostrophic. Mean cross-stream distributions of hydrographic properties, potential vorticity, and alongstream velocity are calculated for both the Loop Current and the detached Gulf Stream in both depth and density coordinates. Differences between these mean transects highlight the downstream changes in western boundary current structure. As the current increases its transport downstream, upper-layer potential vorticity is generally reduced because of the combined effects of increased anticyclonic relative vorticity, reduced stratification, and increased cross-stream density gradients. The only exception is within the 20-km-wide cyclonic flank of the Gulf Stream, where intense cyclonic relative vorticity results in more positive potential vorticity than in the Loop Current. Cross-stream gradients of mean potential vorticity satisfy necessary conditions for both barotropic and baroclinic instability within the western boundary current. Instances of very low or negative potential vorticity, which predispose the flow to various overturning instabilities, are observed in individual transects across both the Loop Current and the Gulf Stream.

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confidence: 56%

Potential Vorticity Structure in the North Atlantic Western Boundary Current from Underwater Glider Observations

Todd

Owens

Rudnick

2016

Journal of Physical Oceanography

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“…To analyze the main dynamical features of the flow, we determine to what extent the normal velocity v is in geostrophic balance. Density was obtained from temperature through an empirical relation developed by Candela et al [2002], where details are discussed. We also calculated the mean Rossby number across the section, defined here as the ratio between the [19] The rms time difference between the objectively interpolated along-channel velocity and the geostrophic normal flow, calculated from the thermal-wind relation and the objectively analyzed temperature (density) field was estimated (not shown).…”

Section: Mean Flow Structure and Variabilitymentioning

confidence: 99%

Analysis of flow variability in the Yucatan Channel

et al. 2003

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[1] The structure and variability of the velocity and temperature fields in Yucatan Channel are analyzed using data from an eight-mooring array deployed from August 1999 to June 2000. The area-averaged kinetic energy and transport fluctuations spectra show that the extrema of these quantities do not coincide, and that flow variability is dominated by highly energetic processes with weak transport contributions. Transport fluctuations peak in the 20-40 and 5-10 day period bands, but show no clear correlation with the local wind-stress forcing. Empirical orthogonal function (EOF) analysis of the along-channel velocity component shows that approximately 55% of the total velocity variance is retained in the first two EOFs, which depict tripolar (the center of the channel is out of phase with the sides) and dipolar structures. A multivariate complex EOF analysis of low-passed temperature and velocity components suggests the tripole-dipole structures are the components of irregular oscillations of the flow, related to the northwestward propagation of anticyclones and cyclones through the channel. The weak transport signal in these modes is consistent with the eddies being advected by the mean flow. In contrast to other western boundary current regions, the passage of eddies provides the predominant explanation for the variability in the Yucatan Channel. However, the processes controlling transport variability remain unclear.

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“…Although the Loop Current is influenced by vorticity input and transport in the Yucatan Straits [Candela et al, 2002;Oey et al, 2003], the mechanisms governing its variability remain poorly understood. We speculate that mesoscale variability in the Caribbean may have progressively inhibited the development of the Loop Current in recent millennia, leading to an SST warming trend near the Dry Tortugas and Carolina Slope that differs from reconstructed Florida Straits transport.…”

Section: Tortugas Eddies Form Preferentially When a Well-developed Lomentioning

confidence: 99%

Low-latitude western north atlantic climate variability during the past millennium : insights from proxies and models

Saenger¹

2009

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Estimates of natural climate variability during the past millennium provide a frame of reference in which to assess the significance of recent changes. This thesis investigates new methods of reconstructing low-latitude sea surface temperature (SST) and hydrography, and combines these methods with traditional techniques to improve the present understanding of western North Atlantic climate variability. A new strontium/calcium (Sr/Ca) -SST calibration is derived for Atlantic Montastrea corals. This calibration shows that Montastrea Sr/Ca is a promising SST proxy if the effect of coral growth is considered. Further analyses of coral growth using Computed Axial Tomography (CAT) imaging indicate growth in Siderastrea corals varies inversely with SST on interannual timescales. A 440-year reconstruction of low-latitude western North Atlantic SST based on this relationship suggests the largest cooling of the last few centuries occurred from -1650-1730 A.D., and was -I°C cooler than today. Sporadic multidecadal variability in this record is inconsistent with evidence for a persistent 65-80 year North Atlantic SST oscillation. Volcanic and anthropogenic radiative forcing are identified as important sources of externally-forced SST variability, with the latter accounting for most of the 2 0 th century warming trend. An 1800-year reconstruction of SST and hydrography near the Gulf Stream also suggests SSTs remained within about I°C of modern values. This cooling is small relative to other regional proxy records and may reflect the influence of internal oceanic and atmospheric circulation. Simulations with an atmospheric general circulation model (AGCM) indicate that the magnitude of cooling estimated by proxy records is consistent with tropical hydrologic proxy records. AcknowledgementsI thank my advisors Anne Cohen and Delia Oppo for their time and support. Listening to their ideas has been inspirational, and their willingness to listen to mine has been appreciated. They will be role models to me throughout my scientific career. The generous and selfless contributions of my thesis committee, including Bill Curry, Ping Chang, Ed Boyle and Jeff Donnelly are also greatly appreciated. My only regret is not taking greater advantage of their collective knowledge.I also express my appreciation to the members of WHOI's Paleoceanography group, within which the analytical efforts of Rindy Ostermann, Scot Birdwhistell, Simon Thorrold, Darlene Ketten, Julie Arruda, Kathyrn Rose and Luping Zou deserve special recognition. The support of the Academic Programs Office is unparalleled and is greatly appreciated. I also thank the Geology and Geophysics administrative staff, the MIT Education Office and WHOI's Facilities staff for their efforts to make daily operations run smoothly.I am grateful to know my fellow Joint Program students and I thank them for their encouragement, shop talk and countless dinner parties. Thanks also to the larger Woods Hole community. I will miss sharing a smile and a wave as I ride past. Finally, to Em....

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

Cited by 90 publications

References 9 publications

Potential Vorticity Structure in the North Atlantic Western Boundary Current from Underwater Glider Observations

Potential Vorticity Structure in the North Atlantic Western Boundary Current from Underwater Glider Observations

Analysis of flow variability in the Yucatan Channel

Low-latitude western north atlantic climate variability during the past millennium : insights from proxies and models

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