Large ensemble climate model simulations: introduction, overview, and future prospects for utilising multiple types of large ensemble

Abstract. Single model initial-condition large ensembles (SMILEs) are valuable tools that can be used to investigate the climate system. SMILEs allow scientists quantify and separate internal variability of system its response external forcing, with different types appropriate answer scientific questions. In this editorial we first provide an introduction overview studies in special issue “Large Ensemble Climate Model Simulations: Exploring Natural Variability, Change Signals Impacts”. These analyse a range including global models (GCMs), regionally downscaled (RCMs), hydrological input from RCM SMILE, SMILE prescribed sea surface temperature (SST) built for event attribution, assimilates observed data, initialised regional model. novel methods, SMILEs. The methods published include snapshot empirical orthogonal function analysis El Niño–Southern Oscillation teleconnections; partitioning future uncertainty into differences, variability, scenario choices; weighting scheme multi-model incorporate SMILEs; method identify required ensemble size any given problem. Studies also focus on SMILEs, projections North Atlantic impacts assessed over Europe, intercomparison. Finally subset projected warming, increased water flows hydrometeorological events southern Ontario; precipitation central Europe investigated found inconsistent across Alps, continuation past tendencies Mid-Europe; equatorial Asia is have increase probability fire drought under higher levels warming. demonstrate utility second part perspective how three could combined exploit advantages each. To do so use GCM all forcings, as well naturally forced (nat-GCM) European domain. We utilise one key precisely separating within individual variety simple Broadly show broad-scale patterns directly compared nat-GCM attribute changes either anthropogenic emissions or volcanoes. provides high-resolution spatial information both change around at warming levels. By combining gain would not available using single type alone, providing research undertaken these tools.