Uncertainty analysis of a decadal simulation with a regional ocean model for the North Sea and Baltic Sea

Abstract

A coupled ice/ocean model for the region of the North Sea and the Baltic Sea is pre- sented. It was developed to simulate the inter-annual and intra-annual variability of the dynamic and thermodynamic state of this region. The response of hydrographic conditions to transient forcing was calculated and the ability of the model to describe observed variability of sea surface elevation, tem- perature and salinity is investigated. Based on various observational data sets, the skill of the model is assessed. It was found that modelled and observed sea surface elevations were highly correlated. The lower frequency variability in sea surface elevation, i.e. periods >10 d, was described almost per- fectly by the model. The bias of the model for sea surface temperature (SST) was about 1°C for the summer and about 0.5°C for the winter. The inter-annual SST anomalies, including temporal as well as regional variability, are reproduced with greater accuracy. The model was able to realistically describe the development of the halocline in the Baltic Sea. The halocline was preserved over the full cycle of the 15 yr hindcast period. From the results of the present study, it can be concluded that the model is a valuable tool for investigating the regional influence of climate variability and climate change on North Sea and Baltic Sea hydro- and thermodynamics.