Loop Current excursions and ring detachments during 1993–2009

Abstract

Linkages between the variability of Loop Current (LC) surface dynamics, LC ring detachments, and the mean sea height anomaly in the Gulf of Mexico (GOM) are explored using a new methodology that locates the LC fronts and detects the shedding of LC rings. Based on satellite altimetry observations and dynamic height gradient, this methodology allows the determination of the dynamic structure in the region from 1993 to 2009. Northward penetration of the LC was found to be seasonal, with a tendency to increase during the spring and peaking in summer. Whereas northward oscillations exhibit ranges of 4 degrees of latitude, the range of westward oscillations is 6 degrees of longitude. Using the newly developed methodology, 28 LC rings are identified and described during 1993-2009. Starting in 2003, the LC is located more to the north on average, and the average number of LC rings formed per year increases. Since 2003, a significant increase in sea height residuals in the GOM has been observed, exhibiting a linear trend of 2.78 ± 0.26 cm/decade for the period 1993-2009. It is hypothesized here that the increase observed in sea height residuals is linked to the increase in mesoscale activity (LC northward intrusions and number of rings shed) obtained from satellite altimetry observations. Results shown here complement previous observational studies in the region, cover a longer time span, and define objectively the locations of the LC front and the shedding of the rings.

The influence of mesoscale eddies on a commercial fishery in the coastal waters of the Andaman and Nicobar Islands, India

“…LindoAtichati et al (2012) classified altimeter SSH fields and derived cyclonic and anticyclonic eddies into core and boundary regions, using the standard deviation of SSH and the standard deviation of the absolute value of the gradient of SSH in the Gulf of Mexico. This method was used again by Lindo-Atichati, Bringas, and Goni (2013) for studying the loop current in the Gulf of Mexico. A simplified version of the zoning approach of Lindo-Atichati et al (2012) using the mean value of SLA within the eddy bounding contour, instead of standard deviation and gradient of SSH of entire region, was followed in this study to delineate eddy zones.…”

Patterns of the loop current system and regions of sea surface height variability in the eastern Gulf of Mexico revealed by the self‐organizing maps

“…The complex LC pattern variations were a subject of many previous studies [e.g., Sturges and Leben , ; Leben , ; Lugo‐Fernández , ]. Particularly, the intrusion, eddy shedding, and retraction processes of the LC are of interest [e.g., Chang and Oey , ; Xu et al ., ; Lindo‐Atichati et al ., ; Dukhovskoy et al ., ]. Lugo‐Fernández and Leben [] found a linear correlation between LC retreat latitude following eddy separation and the subsequent eddy separation period.…”

Characterization of the uncertainty of loop current metrics using a multidecadal numerical simulation and altimeter observations

“…Recently, changes in the mean eddy separation period and eddy separation frequency were discussed in Vukovich (2012) and Lindo-Atichati et al (2013). Both studies reported an increase of eddy separation frequency and decrease in the LC's average separation period during the 2000s compared to estimates from an earlier time period of observations.…”

“…Past studies have used SSH contours for tracking of the LC front in SSH fields assuming that the LC front coincides with a single streamline. Other LC tracking methods have also been proposed (e.g., Andrade-Canto et al, 2013;Lindo-Atichati et al, 2013), and each yields somewhat different results. Thus, metrics for describing LC front positions vary depending on the method used to identify the front.…”