Cyclonic and anticyclonic motion in the upper ocean

Abstract

Upper ocean variability is highly energetic and contributes to key processes such as heat transport and water mass formation. Here, the distribution of ocean surface cyclonic and anticyclonic motion is computed from global drifter observations for scales from large eddies to submesoscale. Two zonal bands of small‐scale motion are recovered: a known anticyclonic band at 30°–40° latitude, mostly wind‐induced, and an unexpected cyclonic band at 10°–20° latitude. It is suggested that this is due to submesoscale processes related to salinity front instabilities. These results provide a first global view of the upper ocean including these motions.

Cyclonic activity in the eastern Gulf of Mexico: Characterization from along-track altimetry and in situ drifter trajectories

“…Non-zero values for the spin are associated with cyclonic (Ω>0 in Northern hemisphere) or anticyclonic (Ω<0) motions of the drifter. Large values of the spin are associated with drifter looping and spiraling; trajectories presenting such features are often referred to as loopers (Richardson, 1993, Griffa et al, 2008. When the drifter is in the core of a coherent eddy, the spin value provides a good estimate of the relative vorticity ζ (ζ ~ 2Ω, Veneziani et al, 2005).…”

“…To do so, we calculate for each drifter trajectory the spin Ω (Borgas et al, 1997), which represents the mean rotation per time interval along the trajectory (Veneziani et al, 2004, Griffa et al, 2008:…”

“…Griffa et al, 2008, Lumpkin andElipot, 2010). Drifter data are especially adapted for studying the ocean eddy field, in particular the rotation rate or spin (Veneziani et al, 2004).…”

Benchmarking the mesoscale variability in global ocean eddy-permitting numerical systems

“…Drifters and floats typically can extract these values regionally, from the number of loops or their vorticity sign (e.g., Trani et al 2011;Griffa et al 2008;Shoosmith et al 2005). However, it is difficult to quantify the horizontal and vertical extents of eddies with these sparse Lagrangian data.…”

Dynamics of Eddies in the Southeastern Tropical Indian Ocean

“…Iskandar et al, (2010) confirmed the direction of propagation of the eddy to the west, and further added that they are part of the Rossby waves. Other than cyclonic eddies, there are also anticyclonic eddies that spin in a counter-clockwise direction for southern hemisphere (Griffa et al, 2008). In 1959 and 1960, Wyrtki (1962) detected anticyclonic eddies near the SEC.…”