This is version v1.1 of the hydrographic part of the "Baltic and North Sea Climatology (BNSC)". It turned out that the original hydrographic data product of the BNSC (BNSClim hydrographic part (Version 1.0)) was erroneous. The errors occurred by accidentally reading obsolete files in two of the intermediate steps of the production procedure. By this, the basis of observations was altered. This happened after the quality control and interpolation of the observations on standard depths, in the step where the observations are sorted into the chosen grid (this affects temperature and salinity) and in the following step, the correction of the temporal sampling error (this affects only salinity). These errors were corrected in this Version 1.1. The parameters provided are water temperature and salinity on 105 depth levels. The data product comprises the time period from 1873-2015 and is based on more than one million observational profiles, which were obtained from several different data sources in the region of the Baltic, the North Sea and adjacent areas of the North Atlantic Ocean (15°W-30°E, 47°N-66°N). Intersection of observational data from different data sources is avoided and the in situ data were objected to an elaborate automatic quality control to identify erroneous observations that would bias the data product. Additionally, a correction of the temporal sampling error was applied to minimize the impact of the temporal distribution of the observations on the created temporal mean fields. The data product consists of gridded mean fields of water temperature and salinity. The spatial resolution is 0.25° in meridional and zonal direction. The depth levels are irregularly distributed: for the depth interval from 0 to 50m the distance between the single depth levels is 5m. Below 50m, the distance increases progressively by 1m to the last depth level of 4985m. The dimensions of the data product are 180*76*105 (longitude, latitude, depth). The BNSC climatology consists, on the one hand, of time series of monthly and annual mean values of the hydrographic parameters as fields of box averages. Grid boxes that show no observations are left empty. Based on these time series, decadal monthly mean fields are created for the decades 1956-1965, 1966-1975, 1976-1985, 1986-1995, 1996-2005, 2006-2015 as another part of the data product. Again, gaps remain in observational data-void regions. The third part of the data product results from above mentioned decadal mean fields: horizontally interpolated fields by application of the method of objective analysis. Consequently, this subset does not contain gaps. Available parameters: box averages: monthly and annual mean, resp. standard deviation, number of observations decadal box averages: decadal monthly mean, resp. standard deviation, mean year, standard deviation to mean year, number of years decadal interpolated mean: interpolated monthly mean, absolute median deviation, number of bins, first guess, relative interpolation error, mean year, mean distance The products and a description of the differences between v1.0 and v1.1 are publicly available at the ICDC portal ( https://icdc.cen.uni-hamburg.de/1/daten/ocean/bnsc/)

EKF400 version 2 is a monthly resolved paleo-reanalysis covering the period 1603 to 2003. Early instrumental temperature, surface pressure and precipitation (new in version 2) observations, temperature indices derived from historical documents and temperature and moisture sensitive tree-ring measurements (largely increased number in version 2) were assimilated into an atmospheric general circulation model ensemble using a Kalman filtering technique. This data set combines the advantage of traditional reconstruction methods of being as close as possible to observations with the advantage of climate models of being physically consistent and having 3-dimensional information about the global state of the atmosphere at 2x2 degree resolution for various variables and at all points in time. While version 1 was using time-dependent covariances from the 30-member ensemble, version 2 uses a blended covariance matrix. It consists of 50% time-dependent and 50% climatological covariances. This leads to a better covariance estimation, not only between various locations in space but in between various variables, too.

The assessment of climate change impacts on the North Sea and the overlying atmosphere requires reliable reference data in order to identify change and impacts against a highly variable background with time scales from hours to multi-decadal. Therefore, in the frame work of the research programme "KLIWAS - Impacts of climate change on waterways and navigation - Searching for options of adaptation" of the German Federal Ministry of Transport, Building and Urban Development (BMVBS), a new climatology was developed in a close co-operation of the Federal Maritime and Hydrographic Agency (BSH), the German Meteorological Service (DWD) and the Integrated Climate Data Center (ICDC) of the University Hamburg. All available oceanographic in-situ data for temperature and salinity have been carefully checked for quality before further processing, while the atmospheric data had already been quality controlled by the DWD. More than 13 million temperature and 12 million salinity (starting in 1890) as well as more than 19 million atmospheric data (air temperature, dew point and air pressure starting in 1950) have been processed. Monthly averages have been created on specified grids for the ocean and atmosphere. For the first time oceanographic and meteorological climatologies are provided on a coordinated grid. The climatological data set is supposed to be growing with time and new data can be implemented as they are collected. it is planned to add additional parameters in future. The climatologies will be used to analyse the temporal and spatial variability in the North Sea area and deduce long-term trends. Additional the data sets will be needed for the validation of regional climate scenarios. The products are publicly available at the ICDC portal ( http://icdc.cen.uni-hamburg.de/1/projekte/knsc.html ). A corrected version of the climatology is available. For more information see Accuracy report.

The assessment of climate change impacts on the North Sea and the overlying atmosphere requires reliable reference data in order to identify change and impacts against a highly variable background with time scales from hours to multi-decadal. Therefore, in the frame work of the research programme "KLIWAS - Impacts of climate change on waterways and navigation - Searching for options of adaptation" of the German Federal Ministry of Transport, Building and Urban Development (BMVBS), a new climatology was developed in a close co-operation of the Federal Maritime and Hydrographic Agency (BSH), the German Meteorological Service (DWD) and the Integrated Climate Data Center (ICDC) of the University Hamburg. All available oceanographic in-situ data for temperature and salinity have been carefully checked for quality before further processing, while the atmospheric data had already been quality controlled by the DWD. More than 13 million temperature and 12 million salinity (starting in 1890) as well as more than 19 million atmospheric data (air temperature, dew point and air pressure starting in 1950) have been processed. Monthly averages have been created on specified grids for the ocean and atmosphere. For the first time oceanographic and meteorological climatologies are provided on a coordinated grid. The climatological data set is supposed to be growing with time and new data can be implemented as they are collected. it is planned to add additional parameters in future. The climatologies will be used to analyse the temporal and spatial variability in the North Sea area and deduce long-term trends. Additional the data sets will be needed for the validation of regional climate scenarios. The products are publicly available at the ICDC portal ( http://icdc.cen.uni-hamburg.de/1/projekte/knsc.html ).

EKF400 version 2 is a monthly resolved paleo-reanalysis covering the period 1603 to 2003. Early instrumental temperature, surface pressure and precipitation (new in version 2) observations, temperature indices derived from historical documents and temperature and moisture sensitive tree-ring measurements (largely increased number in version 2) were assimilated into an atmospheric general circulation model ensemble using a Kalman filtering technique. This data set combines the advantage of traditional reconstruction methods of being as close as possible to observations with the advantage of climate models of being physically consistent and having 3-dimensional information about the global state of the atmosphere at 2x2 degree resolution for various variables and at all points in time. While version 1 was using time-dependent covariances from the 30-member ensemble, version 2 uses a blended covariance matrix. It consists of 50% time-dependent and 50% climatological covariances. This leads to a better covariance estimation, not only between various locations in space but in between various variables, too.

This is version v1.1 of the hydrographic part of the "Baltic and North Sea Climatology (BNSC)". It turned out that the original hydrographic data product of the BNSC (BNSClim hydrographic part (Version 1.0)) was erroneous. The errors occurred by accidentally reading obsolete files in two of the intermediate steps of the production procedure. By this, the basis of observations was altered. This happened after the quality control and interpolation of the observations on standard depths, in the step where the observations are sorted into the chosen grid (this affects temperature and salinity) and in the following step, the correction of the temporal sampling error (this affects only salinity). These errors were corrected in this Version 1.1. The parameters provided are water temperature and salinity on 105 depth levels. The data product comprises the time period from 1873-2015 and is based on more than one million observational profiles, which were obtained from several different data sources in the region of the Baltic, the North Sea and adjacent areas of the North Atlantic Ocean (15°W-30°E, 47°N-66°N). Intersection of observational data from different data sources is avoided and the in situ data were objected to an elaborate automatic quality control to identify erroneous observations that would bias the data product. Additionally, a correction of the temporal sampling error was applied to minimize the impact of the temporal distribution of the observations on the created temporal mean fields. The data product consists of gridded mean fields of water temperature and salinity. The spatial resolution is 0.25° in meridional and zonal direction. The depth levels are irregularly distributed: for the depth interval from 0 to 50m the distance between the single depth levels is 5m. Below 50m, the distance increases progressively by 1m to the last depth level of 4985m. The dimensions of the data product are 180*76*105 (longitude, latitude, depth). The BNSC climatology consists, on the one hand, of time series of monthly and annual mean values of the hydrographic parameters as fields of box averages. Grid boxes that show no observations are left empty. Based on these time series, decadal monthly mean fields are created for the decades 1956-1965, 1966-1975, 1976-1985, 1986-1995, 1996-2005, 2006-2015 as another part of the data product. Again, gaps remain in observational data-void regions. The third part of the data product results from above mentioned decadal mean fields: horizontally interpolated fields by application of the method of objective analysis. Consequently, this subset does not contain gaps. Available parameters: box averages: monthly and annual mean, resp. standard deviation, number of observations decadal box averages: decadal monthly mean, resp. standard deviation, mean year, standard deviation to mean year, number of years decadal interpolated mean: interpolated monthly mean, absolute median deviation, number of bins, first guess, relative interpolation error, mean year, mean distance The products and a description of the differences between v1.0 and v1.1 are publicly available at the ICDC portal ( https://icdc.cen.uni-hamburg.de/1/daten/ocean/bnsc/)

The assessment of climate change impacts on the North Sea and the overlying atmosphere requires reliable reference data in order to identify change and impacts against a highly variable background with time scales from hours to multi-decadal. Therefore, in the frame work of the research programme "KLIWAS - Impacts of climate change on waterways and navigation - Searching for options of adaptation" of the German Federal Ministry of Transport, Building and Urban Development (BMVBS), a new climatology was developed in a close co-operation of the Federal Maritime and Hydrographic Agency (BSH), the German Meteorological Service (DWD) and the Integrated Climate Data Center (ICDC) of the University Hamburg. All available oceanographic in-situ data for temperature and salinity have been carefully checked for quality before further processing, while the atmospheric data had already been quality controlled by the DWD. More than 13 million temperature and 12 million salinity (starting in 1890) as well as more than 19 million atmospheric data (air temperature, dew point and air pressure starting in 1950) have been processed. Monthly averages have been created on specified grids for the ocean and atmosphere. For the first time oceanographic and meteorological climatologies are provided on a coordinated grid. The climatological data set is supposed to be growing with time and new data can be implemented as they are collected. it is planned to add additional parameters in future. The climatologies will be used to analyse the temporal and spatial variability in the North Sea area and deduce long-term trends. Additional the data sets will be needed for the validation of regional climate scenarios. The products are publicly available at the ICDC portal ( http://icdc.cen.uni-hamburg.de/1/projekte/knsc.html ). A corrected version of the climatology is available. For more information see Accuracy report.

The assessment of climate change impacts on the North Sea and the overlying atmosphere requires reliable reference data in order to identify change and impacts against a highly variable background with time scales from hours to multi-decadal. Therefore, in the frame work of the research programme "KLIWAS - Impacts of climate change on waterways and navigation - Searching for options of adaptation" of the German Federal Ministry of Transport, Building and Urban Development (BMVBS), a new climatology was developed in a close co-operation of the Federal Maritime and Hydrographic Agency (BSH), the German Meteorological Service (DWD) and the Integrated Climate Data Center (ICDC) of the University Hamburg. All available oceanographic in-situ data for temperature and salinity have been carefully checked for quality before further processing, while the atmospheric data had already been quality controlled by the DWD. More than 13 million temperature and 12 million salinity (starting in 1890) as well as more than 19 million atmospheric data (air temperature, dew point and air pressure starting in 1950) have been processed. Monthly averages have been created on specified grids for the ocean and atmosphere. For the first time oceanographic and meteorological climatologies are provided on a coordinated grid. The climatological data set is supposed to be growing with time and new data can be implemented as they are collected. it is planned to add additional parameters in future. The climatologies will be used to analyse the temporal and spatial variability in the North Sea area and deduce long-term trends. Additional the data sets will be needed for the validation of regional climate scenarios. The products are publicly available at the ICDC portal ( http://icdc.cen.uni-hamburg.de/1/projekte/knsc.html ).