Extreme sea levels in the Baltic Sea under climate change scenarios – Part 1: Model validation and sensitivity

摘要: Abstract. We analyze extreme sea levels (ESLs) and related uncertainty in an ensemble of regional climate change scenarios for the Baltic Sea. The ERA-40 reanalysis five Coupled Model Intercomparison Project phase 5 (CMIP5) global general circulation models (GCMs) have been dynamically downscaled with coupled atmosphere–ice–ocean model RCA4-NEMO (Rossby Centre atmospheric version 4 – Nucleus European Modelling Ocean). The 100-year return along Swedish coast hindcast are within 95 % confidence limits observational estimates, except those on west coast. The mean averaged over GCMs shows biases less than 10  cm . A series sensitivity studies explores how choice different parameterizations, open boundary conditions forcing affects estimates levels. A small (RCMs) forced highest ESLs southwestern Sea northeastern part Bothnian Bay. Some regions like Skagerrak, Gulf Finland Riga sensitive to RCM. second one RCM uncovers a lower against variance introduced by GCMs. ranges from 20 40  at stations includes based observations. It is similar size tide gauge records.