Details

Autor(en) / Beteiligte

• Volodin, E.

Titel

The Mechanisms of Cloudiness Evolution Responsible for Equilibrium Climate Sensitivity in Climate Model INM‐CM4‐8

Ist Teil von

• Geophysical research letters, 2021-12, Vol.48 (24), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• Current climate models demonstrate large discrepancy in equilibrium climate sensitivity (ECS). The effects of cloudiness parameterization changes on the ECS of the INM‐CM4‐8 climate model were investigated. This model shows the lowest ECS among CMIP6 models. Reasonable changes in the parameterization of the degree of cloudiness yielded ECS variability of 1.8–4.1 K in INM‐CM4‐8, which was more than half of the interval for the CMIP6 models. The three principal mechanisms responsible for the increased ECS were increased cloudiness dissipation in warmer climates due to the increased water vapor deficit in the non‐cloud fraction of a cell, decreased cloudiness generation in the atmospheric boundary layer in warm climates, and the instantaneous cloud response to CO2 increases due to stratification changes. Plain Language Summary One of the most important problems in present‐day climatology is the different equilibrium climate sensitivity (ECS) of current climate models. The range of uncertainty is 1.8–5.6 K. Climate model INM‐CM4‐8 has the lowest ECS of 1.8 K. This study shows that different assumptions about cloudiness formation lead to changes in the ECS in the interval of 1.8–4.1 K, which is more than half of the interval for all current climate models. Three mechanisms (cloud dissipation due to the mixing of clouds and an unsaturated environment, cloud generation in the atmospheric boundary layer, and instantaneous cloud adjustment) are primarily responsible for the different ECS values. Key Points In a climate model equilibrium climate sensitivity (ECS) can be changed from 1.8 to 4.1 K by changing cloud parametrization only Variation of mechanisms responsible for low level clouds, convective clouds, and cloud mixing with the environment can change ECS from 2.5 to 4.1 K Variation of instantaneous cloud adjustment leads to variation in ECS from 1.8 to 2.5 K