Page History

...

In this section an overview of the dataset is provided (Table 2-1).

...

HighResMIP is a set of model experiments carried out as part of the Climate Model Intercomparison Phase 6 (CMIP6). The experiments cover the period 1950-2050 for a set of climate models with a resolution higher than 50 km. The historical periods (1950-2014) is constrained by observations, while the future period (2015-2050) is based on a high-emission scenario (i.e. SSP5-8.5). In general, the difference between emission scenarios are rather small until the mid-century. The members that are included are largely based on the availability at the time the GTSM simulations were carried out. An ensemble of 5 climate models is used. This ensemble consist of a mix of are both coupled and atmosphere-only (i.e. SST-forced) simulations (Table 2-5). The experimental design of HighResMIP is explained in more detail in Haarsma et al., (2018).

...

GTSMv3.0 uses the unstructured Delft3D Flexible Mesh software (Kernkamp et al., 2011). The spatially-varying resolution leads to high accuracy at relatively low computational costs. It has an unprecedented high coastal resolution globally (2.5 km, 1.25km in Europe, Figure 2-1). The resolution decreases from the coast to the deep ocean to a maximum of 25km. Grid resolution is refined in areas in the deep ocean with steep topography areas to enable the dissipation of barotropic energy through generation of internal tides. See User Guide (Yan et al., 2019) for more detailed regarding GTSM.

...

GTSM is the backbone of the global water level change time series and indicator products, and the validation of the model is thus key to the product validation. The GTSM model has been thoroughly calibrated and validated based on tide gauge observations, satellite products, and comparison with other hydrodynamic models. Table 2-6 provides a summary of the key references and description of the results. A summary is provided below.

...

The validation of tides is not published, and it is described in more detail here. We validated GTSM against observed tides from the University of Hawaii Sea Level Center (UHSLC) dataset, which contains 251 tide gauge stations. In addition, we validated GTSM against modelled tides derived with the FES2012 model, which is an assimilative global tide model. GTSM shows, in general, a good agreement with the observed and models tides (Table 2-7). In general, GTSM seems to overpredict tidal amplitudes (Table 2-7). Errors near the coast are larger than in the open ocean. However, with an average M2 vector difference error of 10.5cm at the coast, the model has a comparable accuracy to state-of-the-art assimilative global tide models. Moreover, when compared to non-assimilated global tide models, the GTSMv3.0 performs significantly better. For the semi-enclosed seas, a good agreement with observations proves more difficult. The semi-enclosed sea of the Baltic is sensitive to the narrow connection with the adjacent North Sea and the geometry of such connection, which seems to negatively affect the model performance. In some areas we cannot properly assess the model performance because of the lack of a full spatial coverage and long records of time-series.

...