The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
Samantha Howe ◽  
Carlos Miranda ◽  
Christopher T. Hayes ◽  
Robert T. Letscher ◽  
Angela N. Knapp
Keyword(s):  
Gulf Of Mexico ◽  
Isotopic Composition ◽  
Florida Straits

scholarly journals A Lagrangian approach to the Loop Current eddy separation

2013 ◽  
Vol 20 (1) ◽  
pp. 85-96 ◽  
Author(s):  
F. Andrade-Canto ◽  
J. Sheinbaum ◽  
L. Zavala Sansón
Keyword(s):  
Numerical Model ◽  
Gulf Of Mexico ◽  
Caribbean Sea ◽  
Separation Process ◽  
Sea Surface ◽  
Loop Current ◽  
Hyperbolic Point ◽  
Finite Time Lyapunov Exponents ◽  
Florida Straits ◽  
Strain Direction

Abstract. Determining when and how a Loop Current eddy (LCE) in the Gulf of Mexico will finally separate is a difficult task, since several detachment re-attachment processes can occur during one of these events. Separation is usually defined based on snapshots of Eulerian fields such as sea surface height (SSH) but here we suggest that a Lagrangian view of the LCE separation process is more appropriate and objective. The basic idea is very simple: separation should be defined whenever water particles from the cyclonic side of the Loop Current move swiftly from the Yucatan Peninsula to the Florida Straits instead of penetrating into the NE Gulf of Mexico. The properties of backward-time finite time Lyapunov exponents (FTLE) computed from a numerical model of the Gulf of Mexico and Caribbean Sea are used to estimate the "skeleton" of flow and the structures involved in LCE detachment events. An Eulerian metric is defined, based on the slope of the strain direction of the instantaneous hyperbolic point of the Loop Current anticyclone that provides useful information to forecast final LCE detachments. We highlight cases in which an LCE separation metric based on SSH contours (Leben, 2005) suggests there is a separated LCE that later reattaches, whereas the slope method and FTLE structure indicate the eddy remains dynamically connected to the Loop Current during the process.

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.

scholarly journals Mississippi River and Campeche Bank (Gulf of Mexico) Episodes of Cross-Shelf Export of Coastal Waters Observed with Satellites

2019 ◽  
Vol 11 (6) ◽  
pp. 723 ◽  
Author(s):  
Daniel Otis ◽  
Matthieu Le Hénaff ◽  
Vassiliki Kourafalou ◽  
Lucas McEachron ◽  
Frank Muller-Karger
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
Coastal Waters ◽  
Satellite Images ◽  
Seasonal Pattern ◽  
Ocean Color ◽  
Loop Current ◽  
Visual Examination ◽  
Mississippi River Water ◽  
Florida Straits

The cross-shelf advection of coastal waters into the deep Gulf of Mexico is important for the transport of nutrients or potential pollutants. Twenty years of ocean color satellite imagery document such cross-shelf transport events via three export pathways in the Gulf of Mexico: from the Campeche Bank toward the central Gulf, from the Campeche Bank toward the Florida Straits, and from the Mississippi Delta to the Florida Straits. A catalog of these events was created based on the visual examination of 7280 daily satellite images. Water transport from the Campeche Bank to the central Gulf occurred frequently and with no seasonal pattern. Transport from Campeche Bank to the Florida Straits occurred episodically, when the Loop Current was retracted. Four such episodes were identified, between about December and June, in 2002, 2009, 2016, and 2017, each lasting ~3 months. Movement of Mississippi River water to the Florida Straits was more frequent and showed near seasonal occurrence, when the Loop Current was extended, while the Mississippi River discharge seems to play only a secondary role. Eight such episodes were identified—in 1999, 2000, 2003, 2004, 2006, 2011, 2014, and 2015—each lasting ~3 months during summer. The 2015 episode lasted 5 months.

Source identification of n-alkanes and isoprenoids using diagnostic ratios and carbon isotopic composition on crude oils and surface waters from the Gulf of Mexico

2021 ◽  
Vol 193 (10) ◽  
Author(s):  
Félix Augusto Hernández-Guzmán ◽  
José Vinicio Macías-Zamora ◽  
Nancy Ramírez-Álvarez ◽  
Cristina Quezada-Hernández ◽  
Roxana Ortiz-López
Keyword(s):  
Gulf Of Mexico ◽  
Isotopic Composition ◽  
Surface Waters ◽  
Source Identification ◽  
Carbon Isotopic Composition ◽  
Crude Oils ◽  
Diagnostic Ratios ◽  
Carbon Isotopic

Stable and radiocarbon isotopic composition of dissolved organic matter in the Gulf of Mexico

2017 ◽  
Vol 44 (16) ◽  
pp. 8424-8434 ◽  
Author(s):  
B. D. Walker ◽  
E. R. M. Druffel ◽  
J. Kolasinski ◽  
B. J. Roberts ◽  
X. Xu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Gulf Of Mexico ◽  
Dissolved Organic Matter ◽  
Isotopic Composition

scholarly journals Mg ∕ Ca and <i xmlns="">δ</i><sup>18</sup>O in living planktic foraminifers from the Caribbean, Gulf of Mexico and Florida Straits

2018 ◽  
Vol 15 (23) ◽  
pp. 7077-7095 ◽  
Author(s):  
Anna Jentzen ◽  
Dirk Nürnberg ◽  
Ed C. Hathorne ◽  
Joachim Schönfeld
Keyword(s):  
Gulf Of Mexico ◽  
Mixed Layer ◽  
Environmental Influence ◽  
Seawater Temperature ◽  
Environmental Parameters ◽  
Ambient Seawater ◽  
Vital Effects ◽  
The Caribbean ◽  
Florida Straits

Abstract. Past ocean temperatures and salinities can be approximated from combined stable oxygen isotopes (δ18O) and Mg ∕ Ca measurements in fossil foraminiferal tests with varying success. To further refine this approach, we collected living planktic foraminifers by net sampling and pumping of sea surface water from the Caribbean Sea, the eastern Gulf of Mexico and the Florida Straits. Analyses of δ18O and Mg ∕ Ca in eight living planktic species (Globigerinoides sacculifer, Orbulina universa, Neogloboquadrina dutertrei, Pulleniatina obliquiloculata, Globorotalia menardii, Globorotalia ungulata, Globorotalia truncatulinoides and Globorotalia tumida) were compared to measured in situ properties of the ambient seawater (temperature, salinity and δ18Oseawater) and fossil tests of underlying surface sediments. “Vital effects” such as symbiont activity and test growth cause δ18O disequilibria with respect to the ambient seawater and a large scatter in foraminiferal Mg ∕ Ca. Overall, ocean temperature is the most prominent environmental influence on δ18Ocalcite and Mg ∕ Ca. Enrichment of the heavier 18O isotope in living specimens below the mixed layer and in fossil tests is clearly related to lowered in situ temperatures and gametogenic calcification. Mg ∕ Ca-based temperature estimates of G. sacculifer indicate seasonal maximum accumulation rates on the seafloor in early spring (March) at Caribbean stations and later in the year (May) in the Florida Straits, related to the respective mixed layer temperatures of ∼26 ∘C. Notably, G. sacculifer reveals a weak positive linear relationship between foraminiferal derived δ18Oseawater estimates and both measured in situ δ18Oseawater and salinity. Our results affirm the applicability of existing δ18O and Mg ∕ Ca calibrations for the reconstruction of past ocean temperatures and δ18Oseawater reflecting salinity due to the convincing accordance of proxy data in both living and fossil foraminifers, and in situ environmental parameters. Large vital effects and seasonally varying proxy signals, however, need to be taken into account.

scholarly journals A Trigger Mechanism for Loop Current Ring Separations

2010 ◽  
Vol 40 (5) ◽  
pp. 900-913 ◽  
Author(s):  
Wilton Sturges ◽  
Nicholas G. Hoffmann ◽  
Robert R. Leben
Keyword(s):  
Gulf Of Mexico ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Loop Current ◽  
Trigger Mechanism ◽  
Sea Levels ◽  
Delay Times ◽  
The Caribbean ◽  
Florida Straits ◽  
Current Ring

Abstract The Loop Current in the Gulf of Mexico sheds large anticyclonic rings on an irregular basis. The authors attempt to show what actually triggers the ring separations. Pulses of increased transport through the Florida Straits, as observed by the cable data, are observed prior to each ring separation. This finding is consistent over all separation events observed in the satellite altimetry record. The pulses of transport occur approximately two to four weeks before the rings separate. The increase in transport is usually accompanied by a corresponding increase in offshore sea level, suggesting forcing from the open ocean. The delay times between the pulses of increased transport and ring separations can be shown to be significantly correlated with the length of the Loop Current. Mean sea levels over the Caribbean and Gulf also peak before the separations, on average.

Mercury concentrations, speciation, and isotopic composition in sediment from a cold seep in the northern Gulf of Mexico

2013 ◽  
Vol 77 (1-2) ◽  
pp. 308-314 ◽  
Author(s):  
Garry Brown ◽  
Kenneth Sleeper ◽  
Marcus W. Johnson ◽  
Joel D. Blum ◽  
James V. Cizdziel
Keyword(s):  
Gulf Of Mexico ◽  
Isotopic Composition ◽  
Cold Seep ◽  
Northern Gulf Of Mexico
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