An Improved Atmospheric Dynamic Representation and its Influence on Cloud Radiative Effect in the CMIP6 Models

Abstract:

In response to increased CO₂ warming, a persistent inter-model spread in large scale atmospheric circulation has been reported in the CMIP6 models. Recent analysis of CMIP6 models also showed generally higher climate sensitivities compared to CMIP5, and this increase has been primarily attributed to Shortwave Cloud Radiative Effect (SWCRE) anomalies over the Southern Oceans. In this work, we explore whether the CMIP6 models simulate a more realistic atmospheric circulation than their CMIP5 counterparts. Additionally, we assess the simulation of SWCRE over the Southern Oceans in CMIP6. We find an improved representation of Hadley Circulation and jet stream, both in terms of location and strength, in CMIP6 models. The results show how the representation of the atmospheric dynamics influences the circulation changes as well as the climate sensitivities in response to increased CO_2. We extend the study across different seasons. The results will contribute to quantify any emerging dynamical constraints as simulated by the CMIP6 models.