Late-winter hydrographic and geochemical climatology of the Nordic Seas during 2000-2019

Observations of temperature, salinity, oxygen, nitrate, and phosphate during 2000-2019 are used to create a late-winter (February to April) climatology of the Nordic Seas. All observations were modified to represent late-winter conditions, when the mixed layer is deepest and densest, by homogenizing each hydrographic and geochemical profile from the local late-winter mixed-layer depth to the surface (Brakstad et al., 2023: https://doi.org/10.1016/j.pocean.2023.102981). The observations were then interpolated onto a three-dimensional grid with a regular horizontal resolution of 1/3˚ longitude and 1/8˚ latitude, and 46 vertical levels with intervals ranging from 10m near the surface to 250m at depth. The corresponding observational uncertainties were estimated based on the number of observations included in each grid cell and their variance. In general, the uncertainty decreases with depth due to the lower variance at depth and with increased number of observations. The final late-winter hydrographic and geochemical climatology and the associated uncertainties cover the domain 58.5-84.0˚N and 45.0˚W-45.0˚E.