System of quasi‐zonal jets off California revealed from satellite altimetry

Abstract

A discrete wavelet transform was applied to satellite altimetry data for the period 1992–2007 off California to decompose the SSH signal into inter‐annual, annual, semi‐annual and shorter period components. For the lowest frequency (inter‐annual) component, a system of alternating quasi‐zonal jets was detected. The jet system was delineated by a north‐south series of quasi‐zonal bands of co‐rotating eddies; that is, the eddies were embedded in a shearing zonal flow. The direction of eddy rotation alternated between adjacent bands. The temporal behavior of the jet system showed the existence of quasi‐stationary states and transitions between them. Observed non‐linear effects of the evolution of the jets included southward drift at about 0.2 cm sec−1, deviations of the jets from the zonal direction, and re‐forming of the jet system through decay and merging of eddy chains.

Global observations of quasi‐zonal bands in microwave sea surface temperature

“…Figures 6, 9, 11, and 12c, in conjunction with Figure 8). This differs from earlier studies [Maximenko et al, 2005[Maximenko et al, , 2008Ivanov et al, 2009Ivanov et al, , 2010van Sebille et al, 2011;Cravatte et al, 2012;Buckingham and Cornillon, 2013] in which alternating jet-like structures are observed. To understand this perceived discrepancy, we revisit the nature of the detection algorithm [Cayula and Cornillon, 1992] (cf.…”

“…Referred to as quasi-zonal in reference to their departure from a strictly zonal orientation and latent owing to their O(1 cm s 21 ) magnitude relative to the more dominant O(10 cm s 21 ) eddy field, these jet-like structures have been observed globally [Maximenko et al, 2005[Maximenko et al, , 2008 and regionally in studies involving each or a combination of the aforementioned data sets (altimeter SSH, MDT, and Argo). Regional studies include those in the subtropics Centurioni et al, 2008;Scott et al, 2008;Ivanov et al, 2009Ivanov et al, , 2010van Sebille et al, 2011;Buckingham and Cornillon, 2013], Southern Ocean [Sokolov and Rintoul, 2007] and near-equatorial waters [Cravatte et al, 2012;Qiu et al, 2013]. Some suggestion of their existence is also found within the trajectories of Lagrangian isopycnal floats in the Deep Brazil Basin [Hogg and mesoscale eddies identified and tracked by Chelton et al [2011a] but that two characteristics were inconsistent with their model of random eddies: the (i) variance of u did not decay as expected and (ii) number of eddies, as well as the size and amplitude of these eddies, correlated with the observed jet-like structures was large and broad in spectrum.…”

Stability of large-scale oceanic flows and the importance of non-local effects

“…It is intriguing that stationary quasi-zonal jet-like features (called also striations) have been observed in the eastern parts of the oceans (Maximenko et al, 2005;Cen-turioni et al, 2008;Ivanov et al, 2009). Similar quasi-zonal jet-like features can be found also in numerical simulations with high-resolution models, e.g.…”

Zonal jets in equilibrating baroclinic instability on the polar beta‐plane: Experiments with altimetry

“…One of them uses a concept of bplumes. Observational evidence indicates that the jets often originate at the eastern boundary of oceans [Centurioni et al, 2008;Ivanov et al, 2009]. b-plumes are formed via the radiation of Rossby waves by perturbations at the boundary.…”