SURROGATE CLIMATE-CHANGE SCENARIOS FOR REGIONAL CLIMATE MODELS

A methodology is presented for generating surrogate climate-change sce narios with a regional climate model. The procedure is simple to imple ment and dynamically consistent. It entails (i) adopting a realized or simulated atmospheric flow evolution and (ii) prescribing specific th ermodynamic modifications of this realization to a regional model's in itial fields and externally-specified time-dependent lateral boundarie s fields. The resulting scenarios can be used for process and paramete rization studies, to calibrate the regional response to a putative glo bal 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 atmosp heric water vapor content. Analysis reveals that there is a spatially- differentiated preciptation increase consonant with the domain-average d increase of about 16% in the water vapor content.