Possible linkage of sea surface height anomaly, surface wind stress and sea surface temperature with the falling ice radiative effects under a gradual warming scenario

Abstract

This study investigates the possible linkage of sea surface height anomaly (SSHA), sea surface temperature (SST) and surface wind stress (TAU) with the falling ice radiative effects (FIREs) over the Pacific Ocean under the CMIP5 scenario of 1% CO2 increase per year (1pctCO2) for 140 years. Two sensitivity experiments using the fully-coupled ocean-atmosphere CESM1-CAM5 model are compared: one with FIREs (SON) and the other without (NOS). The warming period of the last 20 year is compared to the control period of the first 20 years. The mean state of the first 20 years exhibits a stronger west-east SSHA gradient in SON than in NOS over the Pacific Ocean, attributed to the stronger prevailing easterly trade winds and the SST pattern of being warmer in the western Pacific but colder in the eastern Pacific. In the last 20 years, SON continues to display a stronger SSHA west-east gradient with higher sea level and SST over the western Pacific Ocean compared to NOS. In the southwest Pacific, stronger trade winds are linked with the wind-evaporation-SST feedback, leading to a more significant decline in SSHA there in SON than in NOS. The CMIP5 ensemble mean shows similar relationships of SSHA with TAU and SST to those of NOS when both are compared against SON, highlighting the importance of FIREs in the SSH projection over the Pacific Ocean and the impact of FIREs on the changing relationships between SSHA, SST and TAU under global warming.