Comparing the effect of shortwave penetration and mixing induced by non-breaking surface waves in an ocean climate model

Numerical models have been widely utilized to simulate the ocean and climate system. Parameterizations of some important processes, however, including the vertical mixing induced by surface waves, are still missing in many ocean models. In this work we incorporate the vertical mixing induced by non-breaking surface waves derived from a wave model into the multi-resolution Finite Element Sea ice-Ocean Model (FESOM), and compare its effect with that of shortwave penetration, another key process to vertically redistribute the heat in the upper ocean. Numerical experiments reveal that both processes ameliorate the simulation of upper-ocean temperature in mid and low latitudes mainly on the summer hemisphere. The regions where nonbreaking wave generates stronger improvement are where large temperature bias exists. The non-breaking surface waves plays a more significant role in decreasing the mean cold biases at 50 m (by 1.0 °C, in comparison to 0.5 °C achieved by applying shortwave penetration). We conclude that the incorporation of mixing induced by non-breaking surface waves into FESOM is practically very helpful, and suggest that it needs to be considered in other ocean climate models as well.