High RESolution Atmospheric Forcing Fields (HiResAFF) consist of key meteorological variables on daily scale which are typically used to drive ocean or ecosystem models. The fields are reconstructed through non-linear statistical upscaling using the analog-method (Schenk and Zorita, 2012). The method resamples atmospheric fields from a regional climate model (RCAO/RCA3) in time based on the best pattern similarity in the predictor space of homogenous historical station data since 1850. The dataset provides physically consistent homogeneous atmospheric fields suitable to derive long-term simulations and statistical analysis since 1850 over the North Sea and Baltic Sea region of Europe. The analog-method and reconstruction skill is described in Schenk and Zorita (2012) and the extended dataset to 1850 in Schenk (2015). The research leading to these results has received funding from the European Union Seventh Framework Programme (FP/2007-2013) under grant agreement no. 217246 made with the joint Baltic Sea research and development programme BONUS, and the German Federal Ministry of Education and Research (03F0492A).

The data are from multi-decadal hindcast simulation with the wave model WAM 4.5 covering the Southern North Sea (51-56.5 N and -3W-10.5E) using a grid size of about 5,5x5.5 km (0.05 degrees latitude x 0.10 degrees longitude). The hindcast covers the period 1948-2007. Integrated parameter derived from 2D spectra are available every hour; the wave spectra themselves are available with a 3-hour time step. Atmospheric forcing was obtained from an atmospheric hindcast with SN-REMO driven by the NCEP/NCAR Reanalysis 1 data set. Lateral boundary conditions were obtained from corresponding coarse grid hindcast covering most of the Northeast Atlantic driven by the same atmospheric forcing.

The data are from a multi-decadal tide-surge hindcast 1958-2004 for the North Sea using the TELEMAC2D model. Data (sea surface elevation, depth averaged currents) are available every hour on an unstructured grid with about 27,000 nodes and varying resolution ranging from about 5 km in the open North Sea to about 75m near the coast and within estuarys. The model was driven by hourly atmospheric data from a multi-decadal atmospheric hindcast ( http://cera-www.dkrz.de/WDCC/ui/Entry.jsp?acronym=coastDat-1_SN-REMO ) and, at the open boundries, by the most relevant tidal constituents. In addition, hourly sea level data from Aberdeen were assimilated at the Northern boundary to account for external surges.

Simulated 2D residual velocity fields in the inner German Bight were subjected to Principal Component Analysis (PCA). Residual currents were obtained from coastDat2 barotropic 2D simulations with the hydrodynamic model TRIM-NP V2.1.22 in barotropic 2D mode on a Cartesian grid (1.6km spatial resolution) stored on an hourly basis for the years 1948 - 2012 (doi:10.1594/WDCC/coastDat-2_TRIM-NP-2d) and later extended until August 2015. The present analysis refers to the period Jan 1958 - Aug 2015. The spatial domain considered is the region to the east of 6 degrees east and to the south of 55.6 degrees north. All grid nodes with a bathymetry of less than 10m were excluded. Residual velocities were calculated in two different ways: 1.) as 25h means, 2.) as monthly means. Both types of residual current data are available from * RESIDUAL_CURRENTS_195801_201508 The directory contains sub-directories for years and months. Daily residual currents for the 13th of September 1974, for instance, are stored in * RESIDUAL_CURRENTS_195801_201508/YEAR_1974/MONTH_09/TRIM2D_1974_09_13_means.nc while monthly mean residual currents for September 1974 are stored in: * RESIDUAL_CURRENTS_195801_201508/YEAR_1974/TRIM2D_1974_09_means.nc All current fields provided were interpolated from the original Cartesian model grid to a more convenient regular geographical grid (116x76 nodes). Mean residual currents are stored in: * mean_residual_currents.nc This data set contains residual velocities both on original Cartesian grid nodes and interpolated to the geographical grid. An example plot is provided: * mean_residual_currents.png For PCA, two residual velocity components from each of 12133 Cartesian grid nodes were combined into one data vector (length 2x12133), referring to 21061 daily or 692 monthly time levels. Results of two independent PCAs for either daily or monthly mean fields are stored in: * PCA_daily_residual_currents.nc * PCA_monthly_residual_currents.nc Files contain three leading Principal Components (PCs) and corresponding Emipirical Orthogonal Functions (EOFs). Again EOFs were also interpolated to a regular geographical grid. PC time series are also stored in plain ASCII format: * PCs_daily.txt * PCs_monthly.txt For monthly fields the number N of variables (N=2x12133) is much larger than the number T of time levels (T=692). Therefore, to reduce computational demands, the roles of time and space were formally interchanged. Having conducted the PCA the EOFs were then transformed back to the original spatial coordinates (cf. Section 12.2.6 in von Storch and Zwiers (1999), Statistical Analysis in Climate Research, Cambridge University Press). A much larger number of time levels made even this approach prohibitive for the full set of daily data. Therefore, PCAs were performed for six sub-periods (1958-1965, 1966-1975, 1976-1985, 1986-1995, 1996-2005, 2006-2015(Aug)) independently. EOFs obtained from these six sub-periods were then averaged to obtain EOFs representative for the whole period. Corresponding PCs were calculated by projecting daily fields onto these average EOFs. IMPORTANT: In contrast with PCA of monthly data, the PCA of daily data INVOLVES SOME APPROXIMATIONS! EOFs on the original nodes were normalized to have unit lengths. The following figures, * daily_EOF1.png * daily_EOF2.png * daily_EOF3.png show the first three EOFs obtained from daily data, assuming that corresponding PCs have the value of one standard deviation. The following two plots, * monthly_EOF1.png * monthly_EOF2.png show the leading EOFs for monthly mean data. EOF3 is omitted as it represents just a very small percentage of overall variance (1.7%).

The experiment contains baroclinic hindcast simulations of the North Sea by the hydrodynamic model HAMSOM (Pohlmann, 2006) for the period 1948-2007. HAMSOM was set up at a spatial resolution of 20' x 12' and with 19 vertical levels (5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 75, 100, 150, 200, 250, 350, 600 and 1000m, lower boundary level). The data-set contains hourly output of temperature, salinity, u- and v-component (3-dim) and water level (2-dim). At the open boundaries, lateral boundary conditions are obtained from a coarser, large-scale Northwest-European shelf sea model driven by climatological temperature and salinity obtained from Levitus (1982). For water levels, in addition the eight significant tidal constituents (M2, S2, N2, K2, K1, O1, Q1 and P1) are included and weather effects are accounted for by using wind and pressure fields from the NCEP/NCAR Reanalysis 1 (Kalnay et al., 1996). Due to technical reasons at the lateral boundaries the water level was added by 0.5m. Atmospheric forcing was obtained from NCEP/NCAR Reanalysis 1 data-set comprising near-surface air-temperature, humidity, cloud cover, precipitation, sea level pressure and near surface wind speed and direction. The output format is netCDF.

COSMO-CLM simulation for Bohai, Yellow and East China Sea: System Analysis and Modelling Group at the Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research (referred to hereinafter as data producer) has computed the regional climate simulation. By making these data available, the data producer wishes to stimulate and support climate change and impact research projects. The data producer is aiming to make the results produced on the basis of these data available on its website and in publications as part of an international overview of regional climate change research. All interested users will have access to the simulation data being calculated with high resolution both in space and time. The data were computed at the German Climate Computing Centre (DKRZ) in Hamburg using the regional climate model COSMO-CLM. The simulations were carried out with support by the China Scholarship Council, the Helmholtz Climate Initiative REKLIM and the CLM community.

This is an atmospheric hourly hindcast for Western Europe and the North Atlantic using REMO with spectral nudging from 1948-2007. The model uses a rotated grid with 81 x 91 grid points and a grid point distance of 0.5 degrees, the North pole is located at 170 W, 32.5 N. In rotated coordinates the model area extends from 19.5 W to 20.5 E, 25 S to 20 N, in geographical coordinates this corresponds to about 10.4 W to 70.7 E, 29.6 N to 67.8 N.

This is a North Sea wave hindcast for the period 1949-2014. The simulation has been performed with the wave model WAM Version 4.5.4. The model domain covers the area from 51N to 59N and 4.75W to 13E, with a spatial resolution of 0.05 degree latitude x 0.075 degree longitude (approx. 3 by 3 nautical miles). Integrated parameter derived from 2D spectra are available every hour. Atmospheric forcing was obtained from an atmospheric hindcast with COSMO-CLM (doi:10.1594/WDCC/coastDat-2_COSMO-CLM) driven by the NCEP/NCAR Reanalysis 1 data set. Lateral boundary conditions were obtained from corresponding coarse grid hindcast covering most of the Northeast Atlantic driven by the same atmospheric forcing.

This is a hydrodynamic hindcast for the Baltic Sea over the period 1958-2011. The simulation has been performed with the hydrodynamic model TRIM-NP V2.1 in barotropic 2D mode. Water level and current component fields are stored hourly. The model is set up on an equidistant Cartesian grid cascade with the center near Helgoland (7.88 E, 54.18 N) for the coarsest grid (12.8km resolution) (http://dx.doi.org/doi:10.1594/WDCC/coastDat-2_TRIM-NP-2d). Further model results from three nested grids (6.4km,3.2km, 1.6km resolution) for the Baltic Sea are hourly available for the period 1958-2011.

Regional simulation with the fully coupled physical-biogeochemical model ECOSMO II. Model details and setup specifications are described in Daewel and Schrum (2013). The basis for ECOSMO II is a baroclinic hydrodynamic coupled sea-ice model (Schrum and Backhaus, 1999), which is coupled to a lower trophic level ecosystem NPZD-model. The experiment contains hindcast simulations for the coupled North Sea and Baltic Sea ecosystem for the period 1948-2008 forced by the NCEP/NCAR reanalysis (Kalnay et al., 1996). The spatial resolution is 6’ x 10’ in the horizontal and 20 layers in the vertical. The data-set contains daily averaged data. Data for biological, physical and ice variables are stored in separate files. The 3d model grid is defined in ECOSMOII_NCEP.1948-2008.dm.griddef.000000.nc (https://cera-www.dkrz.de/WDCC/ui/cerasearch/entry?acronym=ECOSMOII_NCEP_griddef ), which contains information on vertical layer thickness in each model grid-box. The output format is netCDF.