Mesoscale eddies in the southern Gulf of California during summer: Characteristics and interaction with the wind stress

Abstract

[1] The hydrodynamic characteristics of mesoscale eddies of the southern Gulf of California are described from observations made in August 2004. Vertical profiles tõ 1000 m were made with a conductivity-temperature-depth (CTD) probe with dissolved oxygen and fluorescence sensors, and a lowered acoustic Doppler profiler. The four sampled eddies were aligned along the Gulf axis and had alternating sense of rotation. The Okubo-Weiss parameter was used to calculate the eddy core radii, and it also revealed that the current field of almost all the sampled area was eddy dominated. The mean radii of the eddy cores varied between 32 and 36 km. Maximum surface velocities were 0.4-0.5 m/s. The anticyclonic eddies were 500-700 m deep, while the cyclones were 450-500 m deep. The depression of the isolines associated with the anticyclonic eddies was~100 m at depths between 200 and 400 m; however, the thermocline/pycnocline, which spanned from~20 to 75 m, was domed by~10 m. The cyclonic eddies lifted the isolines by~70 m at depths above 500 m, but the isolines were flat above~60 m. This suggests that different dynamics operate in the layer above the strong and shallow pycnocline. In particular, the wind stress curl can affect circulation and pycnocline topography and, therefore, the patterns that appear in chlorophyll satellite images. In our case, the eddies were detectable in those images because of the chlorophyll-enhanced streamers along their edges and, for anticyclones, probably because the chlorophyll maximum found at 40-50 m depth was domed following the pycnocline.Citation: Lavı´n, M. F., R. Castro, E. Beier, and V. M. Godı´nez (2013), Mesoscale eddies in the southern Gulf of California during summer: Characteristics and interaction with the wind stress,

Effect of coastal‐trapped waves and wind on currents and transport in the Gulf of California

“…Similarly, coherences were not significant in the intraseasonal band. This suggests that the process of the CTW energy crossing the mouth of the gulf may be more complex and could involve the generation of eddies as CTWs pass capes and other coastline features, as suggested by numerical simulations [Zamudio et al, 2007[Zamudio et al, , 2008 and observations [Lav ın et al, 2013].…”

Surface dispersion in the Gulf of California

“…We consider that diffusivity in the GC is influenced by the presence of mesoscale vortices that occupy the width of the basin during part of the year. Some of these features are generated during the Summer at the southern and central regions, and persist during several months (Figueroa et al, 2003;Lavín et al, 2013Lavín et al, , 2014. At the northern part there is a semi-permanent seasonal gyre (Lavín et al, 1997).…”

“…The duration of the records ranges between 10 and 90 days, with a mean of 45 days and a standard deviation of 28 days. The deployment of the drifters was not designed to measure dispersion properties but to study mesoscale circulation features, specially at the southern and central regions (Lavín et al, 2013). Even though, it shall be shown that one and two-particle statistics can be estimated with the available buoy trajectories.…”

“…According to historical hydrographic data, however, there are no definite patterns in the position of the gyres, nor in the season at which they appear nor in their sense of rotation (Figueroa et al, 2003). Recently, Lavín et al (2013Lavín et al ( , 2014 described with great detail the hydrodynamic characteristics of a train of alternating mesoscale eddies in the southern GC during the Summer. According to numerical simulations (Zamudio et al, 2008), the geostrophic eddies are presumably formed as an intense jet flowing northwestward along the eastern boundary becomes unstable when interacting with coastal irregularities.…”

Aragonite saturation and pH variation in a fringing reef are strongly influenced by oceanic conditions

“…The first and second points are described by studies on the entrance of GC, which showed that water circulation follows a seasonal pattern where water from the Pacific Ocean enters the gulf near the mainland coast during summer and flows out near the peninsular coast during winter. The outward flow of the GCW is promoted by the wind coming from the north, whereas the TSW comes from the Pacific (Castro et al ; Lavin et al ). Seasonal circulation patterns explain much of the local variability (Fig.…”