Surrogate climate‐change scenarios for regional climate models

Abstract

A methodology is presented for generating surrogate climate‐change scenarios with a regional climate model. The procedure is simple to implement and dynamically consistent. It entails (i) adopting a realized or simulated atmospheric flow evolution and (ii) prescribing specific thermodynamic modifications of this realization to a regional model's initial fields and externally‐specified time‐dependent lateral boundaries fields. The resulting scenarios can be used for process and parameterization studies, to calibrate the regional response to a putative global climate change, and to intercompare different models. The approach is illustrated with two month‐long regional climate model simulations. The experiment is designed to explore the response within Europe to a pseudo‐global warming of 2 K with an accompanying increase in atmospheric water vapor content. Analysis reveals that there is a spatially‐differentiated preciptation increase consonant with the domain‐averaged increase of about 16% in the water vapor content.