Baltic Sea - DIVA 4D 6-year analysis of Water body ammonium 1980/2016 v2018

Moving 6-year analysis of Water body ammonium in the Baltic Sea. Four seasons (March-May, June-August, September-November, December-February). Every year of the time dimension corresponds to the 6-year centred average. Periods span between 1980-1985 and 2011-2016. Analyses for depths (m) (HELCOM standard depths): 0, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300. Data Sources: observational data from SeaDataNet/EMODnet Chemistry Data Network. Description of DIVA analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. GEBCO_08 Grid (30 arc-seconds) topography is used for the contouring preparation. Files contain analysed fields, error fields and combined field with the deepest value for each grid point selected. Also pre-masked fields using relative error threshold 0.3 and 0.5 are included. In the analyses the Correlation length and Signal to noise ratio were fixed to 0.7 and 1.0 respectively. Background fields were created using all data (1980-2016) for the given season. Log transformation (option 11) was used in the analyses. No detrending, advection constraints or weighting are applied. Unit is umol/l.