06.07.2017 Kolloquium: Dr. Moritz Mathis
Moritz Mathis, MPI Hamburg, Abteilung Ozean im Erdsystem, Arbeitsgruppe Physik des Ozeans
Climate change impact studies for the Northwest European Shelf (NWES) make use of various dynamical downscaling strategies in the experimental setup of regional circulation models. Projected change signals from coupled and uncoupled downscalings with different domain sizes and forcing global and regional models show substantial uncertainty. In my talk I will discuss influences of common downscaling strategies on projected changes in the physical conditions of the NWES and northern European atmosphere. By comparing various experiments with a consistent regionally coupled climate system model I can show that uncertainties due to different downscaling strategies are similar to uncertainties due to the choice of the parent global model and the downscaling regional model. Moreover, downscaled change signals reveal to depend stronger on the downscaling strategy than on the model skills in simulating present-day conditions. Nevertheless, my results affirm common practice in experiment design that the choice of the most appropriate downscaling strategy has to be rested on the variable of greatest interest. For SST or near-surface air temperature, regional models do not supply independent results unless ocean-atmosphere interactions are coupled interactively. For other variables, such as salinity or precipitation, uncoupled downscalings can yield reasonable approximations of coupled downscalings too.
25. April 2017