A review of research on mesoscale ocean currents

Mesoscale ocean currents, for the purposes of this review, are defined as currents in the middle and high latitudes, in the mid‐ocean, of low frequency (i.e., with time scales* greater than or comparable to 10 5 s, which is long compared to the inverse of the Coriolis frequency), and of intermediate spatial scale* (i.e., horizontal scales from tens to hundreds of km). They are geostrophic currents of type 1 in the nomenclature of Phillips (1963). Excluded, therefore, from this review are the following topics: equatorial currents, coastal currents, surface, bottom, and lateral turbulent boundary layers, ageostrophic flow, gyre‐scale transience, seasonal cycles, and the general circulation of the ocean. This review is intended primarily as a record of published contributions on this subject since the last such review written in 1974 (Robinson, 1975), with a broad topical catagorization.