Wave‐induced mixing in the upper ocean: Distribution and application to a global ocean circulation model

TLDR

Wave‑induced vertical viscosity (Bv) is defined from Reynolds stress and serves as a parameter to quantify mixing strength in the upper ocean. A mixing‑penetration depth parameter D5 is introduced, and Bv averaged over the upper 20 m is mapped globally, with latitudinal transects examined for boreal summer and winter. The study finds strong summer mixing south of 30° S and winter mixing north of 30° N and south of 40° S, and shows that including Bv in a global circulation model yields an upper‑100 m temperature profile closer to observations.

Abstract

From the Reynolds stress expression, the wave‐induced vertical viscosity (or diffusivity) Bv is defined, which can be used as a parameter to estimate the strength of wave‐induced mixing. In addition, a parameter D 5 is introduced to represent a wave‐induced mixing penetration depth. The global distribution of Bv averaged over the upper 20 m is calculated and its latitudinal transects in boreal summer and winter is discussed. The results show that in summer the wave‐induced mixing is strong in the southern oceans south of 30°S, and in winter it is strong in the north Pacific and the north Atlantic north of 30°N, as well as in the southern oceans south of 40°S. Adding Bv to the vertical diffusivity in a global ocean circulation model yields a temperature structure in the upper 100 m that is closer to the observed climatology than a model without the wave‐induced mixing.