The Effect of Wave-Induced Mixing on the Climates During the Last Glacial Maximum and Pre-Industrial Based on CESM1.2.2 Simulations

Vertical mixing in the upper ocean plays an important role in the model, the lack of vertical mixing makes the simulated ocean temperature and mixing depth significantly deviate from the observation. A modification scheme is discussed a real physical process which the vertical mixing generated by waves. Previous researchers parameterized the turbulent mixing generated by waves under the action of surface wind, and named wave-induced vertical mixing (Bv). The preliminary model results show that Bv can significantly improve the accuracy of simulation and forecasting. Based on two different climatic conditions, the Last Glacial Maximum (LGM) and Pre-industrial (PI), for the first time in the world, this paper explores the effects of Bv in the Community Earth System Model version 1.2.2 (CESM1.2.2). Because the LGM wind is weaker than that of PI, the Bv during LDM is weaker than that of PI. By including Bv to the coupled model, the simulation results show that sea surface cooling and subsurface surface warming occur in both background climate periods in mid-latitude regions, while the intensity of surface cooling during the LGM is weaker than that of PI. For seasonal variations, simulations show that surface cooling is coldest in summer in each hemisphere. The annual mean mixed layer depth in the two background periods is deepened in the middle latitude regions, and the deepening during LGM is weaker than that of PI. The simulation results show that the mixing layer deepening reaches the maximum in winter of each hemisphere. On the other hand, at high latitudes for LGM, sea surface temperature increased significantly, which is caused by the decrease of sea ice caused by the wave-induced mixing. Finally, by comparing the LGM simulations and the proxy data, it is found that the wave-induced mixing can improve the model simulation for data at 72% locations.