Change of Arctic cloud related to reduced sea ice in historical and future simulations with MIROC6

Abstract:

The reduction of Arctic sea ice is able to impact clouds in the Arctic Ocean (e.g., Serreze and Barry, 2011). Also, one issue is that the feedback related to the cloud change due to reduced sea ice has the potential to play an important role in the Arctic warming amplification process. Thus, to understand changes of cloud and cloud radiative forcing due to reduced sea ice is important for understanding and predicting the impact of global warming on the Arctic Ocean.

In this study, we investigated the temporal trend of cloud cover over the Arctic Ocean and its relationship with reduced sea ice in the historical and future simulations by the climate model, MIROC6 (Tatebe et al. 2019). The simulations were conducted along with the CMIP6 protocol. There are 50 ensemble members of the historical and future simulation with the different initial conditions.

In the historical simulations, the September sea ice area began to decrease in 1970’s and also decreased more remarkably after about 1980. In average for 50 members of the historical simulation, particularly October for 1991-2014, cloud cover in the Arctic Ocean tended to increase. Also, during October, sea ice concentrations had negative trends in the region from the East Siberian Sea to the Beaufort Sea. In the region, the trends in cloud cover were negatively correlated with the trend in sea ice cover between 50 members of the historical simulation. This means reduced sea ice makes cloud increase. In the presentation, we will show the results from future simulations and then discuss the impact of the cloud change by reduced sea ice on surface radiation.