Better parameterisation for upper ocean temperature leads to more precise simulations of coupled ocean-atmosphere systems

Temperature difference along 30° S (longitude vs. depth) in February for simulations with the new model development and World Ocean Atlas 2013 version 2 climatology.

Numerical forecasts for ocean, weather, and climate play an important role in our daily life as accurate predictions help us plan day‐to‐day activities. However, our prediction ability so far has been much lower than expected. For example, some ocean models simulate a warmer sea surface temperature and cooler subsurface (30–100 m deep) temperature in subtropical oceans, especially in summer, which can lead to errors in the weather and climate forecasting. This is usually alleviated by distributing solar radiation in the upper ocean rather than only heating up the ocean surface. Although shortwave penetration makes some improvement on ocean model performance, it is still far from solving the common simulated temperature bias in the upper ocean. 

In a joint collaboration between Chinese scientists from the College of Oceanic and Atmospheric Sciences in Qingdao and German partners at the Alfred Wegener Institute in Bremerhaven, the simulated temperature has considerably improved by incorporating the mixing induced by nonbreaking surface waves into the new generation ocean model FESOM. The multi-resolution Finite Element Sea ice‐Ocean Model (FESOM) has shown great capability in reconstructing the ocean and sea ice in both standalone and coupled simulations at a relatively low computational cost. Parameterisations of some important processes, including the vertical mixing induced by surface waves, however, were still missing, contributing to temperature biases in the upper ocean. This new model development will help climate scientists to better simulate the ocean surface and therefore also some important processes such as the South Asian summer monsoon system.

The open access paper explaining in details the new model development has been published in the AGU Journal Of Advances in Modelling Earth Systems: https://doi.org/10.1029/2018MS001494

You can watch animations produced with FESOM on YouTube: https://www.youtube.com/channel/UCmDgmx_Zwr4vA8_6NYoVOqA/featured