Influence of stratification and Yucatan Current transport on the Loop Current Eddy shedding process

2020 ◽  
Author(s):  
Efraín Moreles ◽  
Jorge Zavala‐Hidalgo ◽  
Benjamín Martínez‐López ◽  
Ángel Ruiz‐Angulo
Keyword(s):  
Loop Current ◽  
Current Transport ◽  
Eddy Shedding

scholarly journals Changes in the Loop Current's Eddy Shedding in the Period 2001–2010

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Fred M. Vukovich
Keyword(s):  
Tilt Angle ◽  
Major Change ◽  
Loop Current ◽  
Average Period ◽  
Year 2000 ◽  
Eddy Shedding

A major change in the Loop Current's eddy shedding was found in the decade 2001–2010. Sixteen (16) rings separated from the Loop Current in that decade, whereas in two previous decades, 11 rings separated in each decade. More than half the rings (i.e., 56%) that separated from the Loop Current in the decade 2001–2010 had separation periods ≤8 months. In the period prior to 2001, only 26% of the rings had separation periods ≤8 months. Furthermore, the dataset average period for ring separation for the period prior to 2001, an average over a 29-year period, was about 11 months, and the dataset average Loop Current's westward tilt angle—a factor that indicates whether the Loop Current will soon shed an eddy or not—was about 16°. After the year 2000, the dataset average period for ring separation, an average over a 39-year period, decreased by about 1 month and was about 10 months. The average ring-separation period in the decade 2001–2010 was about 9 months. The dataset average of the Loop Current's westward tilt angle increased by about 5° in the period 1998–2008 and was about 20° in 2010. Potential causes for these changes are discussed.

scholarly journals Loop Current Growth and Eddy Shedding Using Models and Observations: Numerical Process Experiments and Satellite Altimetry Data

2013 ◽  
Vol 43 (3) ◽  
pp. 669-689 ◽  
Author(s):  
Yu-Lin Chang ◽  
L.-Y. Oey
Keyword(s):  
Trade Wind ◽  
Loop Current ◽  
Reduced Gravity ◽  
Trade Winds ◽  
Numerical Process ◽  
The Asymmetry ◽  
Yucatan Channel ◽  
Satellite Altimetry Data ◽  
Eddy Shedding

Abstract Recent studies on Loop Current’s variability in the Gulf of Mexico suggest that the system may behave with some regularity forced by the biannually varying trade winds. The process is analyzed here using a reduced-gravity model and satellite data. The model shows that a biannual signal is produced by vorticity and transport fluctuations in the Yucatan Channel because of the piling up and retreat of warm water in the northwestern Caribbean Sea forced by the biannually varying trade wind. The Loop grows and expands with increased northward velocity and cyclonic vorticity of the Yucatan Current, and eddies are shed when these are near minima. Satellite sea surface height (SSH) data from 1993 to 2010 are analyzed. These show, consistent with the reduced-gravity experiments and previous studies, a (statistically) significant asymmetric biannual variation of the growth and wane of Loop Current: strong from summer to fall and weaker from winter to spring; the asymmetry being due to the asymmetry that also exists in the long-term observed wind. The biannual signal is contained in the two leading EOF modes, which together explain 47% of the total variance, and which additionally describe the eddy shedding and westward propagation from summer to fall. The EOFs also show connectivity between Loop Current and Caribbean Sea’s variability by mass and vorticity fluxes through the Yucatan Channel.

scholarly journals Loop Current Growth and Eddy Shedding Using Models and Observations: Analyses of the July 2011 Eddy-Shedding Event*

2013 ◽  
Vol 43 (5) ◽  
pp. 1015-1027 ◽  
Author(s):  
F.-H. Xu ◽  
Y.-L. Chang ◽  
L.-Y. Oey ◽  
P. Hamilton
Keyword(s):  
Baroclinic Instability ◽  
Trade Wind ◽  
Loop Current ◽  
Reduced Gravity ◽  
Westward Expansion ◽  
Wave Dynamics ◽  
Orthogonal Function ◽  
Current Growth ◽  
The Caribbean ◽  
Eddy Shedding

Abstract Recent studies suggest that as the trade wind in the Caribbean Sea weakens from summer to fall, conditions become more favorable for the Loop Current in the Gulf of Mexico to shed an anticyclonic ring. This idea originated with observations showing a preference for more eddies from summer through fall, and it was confirmed using multidecadal model experiments. Here, the hypothesis is further tested by studying the dynamics of a specific eddy-shedding event in summer 2011 using a model experiment initialized with observation-assimilated reanalysis and forced by reanalysis wind from NCEP. Eddy shedding in July 2011 is shown to follow the weakening of the trade wind and Yucatan transport in late June. The shedding time is significantly earlier than can be explained based on reduced-gravity Rossby wave dynamics. Altimetry and model data are analyzed to show that empirical orthogonal function modes 1 + 2 dominate the reduced-gravity process, while higher modes contain the coupling of the Loop Current with deep layer underneath. The Loop’s westward expansion at incipient shedding induces a deep cyclonic gyre in the eastern Gulf, embedded within which are small cyclones caused by the baroclinic instability of the strongly sheared current north of the Campeche Bank. The associated deep upwelling and upper-layer divergence from these cyclonic circulations accelerate eddy shedding.

Predictability of the Loop Current Variation and Eddy Shedding Process in the Gulf of Mexico Using an Artificial Neural Network Approach

2015 ◽  
Vol 32 (5) ◽  
pp. 1098-1111 ◽  
Author(s):  
Xiangming Zeng ◽  
Yizhen Li ◽  
Ruoying He
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Gulf Of Mexico ◽  
Function Analysis ◽  
Optimal Number ◽  
Loop Current ◽  
Neural Network Approach ◽  
Current Variation ◽  
Artificial Neural ◽  
Eddy Shedding

AbstractA novel approach based on an artificial neural network was used to forecast sea surface height (SSH) in the Gulf of Mexico (GoM) in order to predict Loop Current variation and its eddy shedding process. The empirical orthogonal function analysis method was applied to decompose long-term satellite-observed SSH into spatial patterns (EOFs) and time-dependent principal components (PCs). The nonlinear autoregressive network was then developed to predict major PCs of the GoM SSH in the future. The prediction of SSH in the GoM was constructed by multiplying the EOFs and predicted PCs. Model sensitivity experiments were conducted to determine the optimal number of PCs. Validations against independent satellite observations indicate that the neural network–based model can reliably predict Loop Current variations and its eddy shedding process for a 4-week period. In some cases, an accurate forecast for 5–6 weeks is possible.

scholarly journals Adjoint sensitivity studies of loop current and eddy shedding in the Gulf of Mexico

2013 ◽  
Vol 118 (7) ◽  
pp. 3315-3335 ◽  
Author(s):  
Ganesh Gopalakrishnan ◽  
Bruce D. Cornuelle ◽  
Ibrahim Hoteit
Keyword(s):  
Gulf Of Mexico ◽  
Loop Current ◽  
Adjoint Sensitivity ◽  
Sensitivity Studies ◽  
Eddy Shedding

Instabilities and Multiscale Interactions Underlying the Loop Current Eddy Shedding in the Gulf of Mexico

2020 ◽  
Vol 50 (5) ◽  
pp. 1289-1317
Author(s):  
Yang Yang ◽  
Robert H. Weisberg ◽  
Yonggang Liu ◽  
X. San Liang
Keyword(s):  
Energy Transfer ◽  
Gulf Of Mexico ◽  
High Frequency ◽  
Baroclinic Instability ◽  
Mesoscale Eddy ◽  
Mesoscale Eddies ◽  
Loop Current ◽  
Background Flow ◽  
Pressure Work ◽  
Eddy Shedding

AbstractA recently developed tool, the multiscale window transform, along with the theory of canonical energy transfer is used to investigate the roles of multiscale interactions and instabilities in the Gulf of Mexico Loop Current (LC) eddy shedding. A three-scale energetics framework is employed, in which the LC system is reconstructed onto a background flow window, a mesoscale eddy window, and a high-frequency eddy window. The canonical energy transfer between the background flow and the mesoscale windows plays an important role in LC eddy shedding. Barotropic instability contributes to the generation/intensification of the mesoscale eddies over the eastern continental slope of the Campeche Bank. Baroclinic instability favors the growth of the mesoscale eddies that propagate downstream to the northeastern portion of the well-extended LC, eventually causing the shedding by cutting through the neck of the LC. These upper-layer mesoscale eddies lose their kinetic energy back to the background LC through inverse cascade processes in the neck region. The deep eddies obtain energy primarily from the upper layer through vertical pressure work and secondarily from baroclinic instability in the deep layer. In contrast, the canonical energy transfer between the mesoscale and the high-frequency frontal eddy windows accounts for only a small fraction in the mesoscale eddy energy balance, and this generally acts as a damping mechanism for the mesoscale eddies. A budget analysis reveals that the mesoscale eddy energy gained through the instabilities is balanced by horizontal advection, pressure work, and dissipation.

Loop current eddy shedding estimated using Geosat altimeter data

1990 ◽  
Vol 17 (13) ◽  
pp. 2385-2388 ◽  
Author(s):  
Gregg A. Jacobs ◽  
Robert R. Leben
Keyword(s):  
Altimeter Data ◽  
Loop Current ◽  
Eddy Shedding
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