Pattern decomposition of the transient climate response

Abstract

A two-pattern decomposition of the mean surface air temperature response to an increase of CO2 is assessed. This decomposition is based on a two-layer global energy-balance model and the hypothesis of separability in space and time. It is shown that this decomposition allows the regional transient warming of a given atmosphere - ocean general circulation model to be well represented. The pattern decomposition is applied to 16 CMIP5 climate models and each of the two retrieved patterns - the equilibrium pattern and the pattern associated with the deep-ocean heat uptake - is described and discussed.