Baltic Sea - Gulf of Riga - DIVAnd 4D seasonal analysis of Water body dissolved oxygen concentration 1995/2021 v2023

Water body dissolved oxygen concentration - Seasonal Climatology for Gulf of Riga for the period 1995-2021. Four seasons (March-May, June-August, September-November, December-February). Analyses for depths (m) (HELCOM standard depths): 0, 5, 10, 15, 20, 25, 30, 40, 50. Data Sources: observational data from SeaDataNet/EMODnet Chemistry Data Network. Description of DIVAnd analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. GEBCO_04 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 horizontal correlation length is fixed to 25 km and decreasing towards the coastline, the vertical correlation length is varying with depth. Signal to noise ratio were fixed to 1.0. Log transformation was used in the analyses. No detrending, advection constraints or weighting are applied. The horizontal resolution of the produced DIVAnd maps grids is 0.01 degrees. Unit is umol/l.

1995-2021年里加湾水体溶解氧浓度季节气候学数据集。涵盖4个季节：3-5月、6-8月、9-11月、12-2月。分析深度（单位：米）采用HELCOM标准深度：0、5、10、15、20、25、30、40、50。数据来源：SeaDataNet/EMODnet化学数据网络的观测数据。DIVAnd分析说明：采用DIVA（Data-Interpolating Variational Analysis，数据插值变分分析）工具开展地统计数据分析。制图等值线绘制时采用GEBCO_04网格（30弧秒）地形数据。数据文件包含分析场、误差场，以及各网格点选取的最深值组合场；同时包含采用相对误差阈值0.3和0.5进行预掩膜处理的场。分析过程中，水平相关长度固定为25 km，并向海岸线方向递减；垂直相关长度随深度变化。信噪比固定为1.0，分析过程采用对数变换，未进行去趋势、平流约束或加权处理。生成的DIVAnd映射网格水平分辨率为0.01度，单位为微摩尔每升（umol/l）。