ModE-Sim - A new medium-size AGCM ensemble to analyze climate variability in the modern era

We introduce a 36 to 40-member ensemble of simulations with the atmospheric general circulation model ECHAM6 that is designed to form the basis for a 3-dimensional climate reconstruction dataset in the PALAEO-RA project. It covers the years 1420 to 2009, the period for which combining natural proxies such as tree rings and archives of society such as documentary data allows to perform global climate reconstructions. However, the information provided by these historical sources is usually sparse in temporal and spatial resolution. Our simulations provide the necessary background for data assimilation and thus complement the historical information by adding physical constraints implemented in the model formulation. Our experimental setup is designed to determine the range of internal climate variability under prescribed forcings. It is oriented on the PMIP4 setup with slight modifications, using realistic ocean boundary conditions (SST and sea ice cover) and radiative forcings while also accounting for uncertainties in these.

Our presentation will give an overview of our experimental setup and show the results of the first applications. We present an evaluation of the ensemble, including measures on how well the ensemble can sample the internal variability of some variables of interest. Beyond this, we hope to stimulate a discussion on possible further applications.