Moving 6-year analysis of Water_body_chlorophyll-a in the Black Sea for each season: spring (March-May), summer (June-August), autumn (September-November), winter (December-February). Every year of the time dimension corresponds to the 6-years centred average of each season. 6-years periods span: - from 1990-1995 until 2012-2017 (spring), - from 1990-1995 until 2013-2018 (summer), - from 1990-1995 until 2013-2018 (autumn), - from 1990-1995 until 2011-2016 (winter). Depth range (IODE standard depths): -50.0, -40.0, -30.0, -20.0, -10.0, -5.0, -0.0. Description of DIVA analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. GEBCO 1min topography is used for the contouring preparation. Analysed field masked using relative error threshold 0.3 and 0.5 DIVA settings: signal-to-noise ratio and correlation length were estimated using data mean distance as a minimum (for L) and vertically filtered. Log transformation was used in the analyses. Background field: the data mean value is subtracted from the data. Detrending of data: no, Advection constraint applied: no. Units: umol/l.