The Relationship Between Cloud Radiative Effect and Surface Temperature Variability at El Niño-Southern Oscillation Frequencies in CMIP5 Models

Abstract

The relationship between the tropical cloud radiative effect (CRE) and tropical surface temperature variability on El Niño–Southern Oscillation (ENSO) time scales is investigated in preindustrial control simulations from the fifth Climate Model Intercomparison Project (CMIP5) archive. The tropical CRE is binned according to midtropospheric vertical velocities and then regressed in frequency space versus tropical mean surface temperatures. Low clouds play a leading role in the relationship between clouds and surface temperature variability, amplifying ENSO-induced surface temperature anomalies through thermodynamically driven changes in the shortwave CRE. Changes in CRE driven by changes in the large-scale dynamics have a minor influence on surface temperature variability. It is shown that the regression coefficients at ENSO frequencies between the CRE in regions of moderate subsidence and of weak ascent, and tropical mean surface temperatures are well correlated with models' climate sensitivities, constituting a potential emergent constraint on climate sensitivity.