Mediterranean Sea - Po River - DIVAnd 4D seasonal analysis of Water body dissolved inorganic nitrogen (DIN) 1980/2020 v2023

Dissolved inorganic nitrogen (DIN) - Seasonal Climatology for Po River for the period 1980-2020 on the domain: Lon E12.0-14.0deg., Lat N44.0-46.0deg.
Data Sources: observational data from SeaDataNet/EMODNet Chemistry Data Network.
Description of DIVA analysis: The computation was done with the DIVAnd (Data-Interpolating Variational Analysis in n dimensions), version 2.7.9, using GEBCO 30sec topography for the spatial connectivity of water masses.
The horizontal resolution of the produced DIVAnd maps grids is dx=dy=0.009 degrees (around 975m and 708m accordingly).
The vertical resolution is 14 depth levels: [0., 2., 4., 6., 8., 10., 15., 20., 25., 30., 40., 50., 60., 70.].
A relative correlation length used based on topography gradients and the horizontal correlation length varies from 25 km to 12.5 km. The vertical correlation length (in meters) is:  [4.,4.,4.,4.,4.,10.,10.,10.,10.,20.,20.,20.,20.,20.]. 
Duplicates check was performed using the following criteria for space and time: dlon=0.01deg., dlat=0.01deg., ddepth=0.01m, dtime=1min, dvalue=0.01.
The error variance (epsilon2) was set equal to 1. Data weight was reduced at shallow waters. Data weighting was applied with the following threshold values: lon=0.03, lat=0.03, depth=2.
An anamorphosis transformation was applied to the data (function DIVAnd.Anam.loglin) to avoid unrealistic negative values: threshold value=200.
The mean value was used as background analysis field.
Quality control of the observations was applied using the interpolated field (QCMETHOD=3). Residuals (differences between the observations and the analysis (interpolated linearly to the location of the observations) were calculated. Observations with residuals outside the minimum and maximum values of the 99% quantile were discarded from the analysis. 
Seasons definition: Winter=Jan-Mar, Spring=Apr-Jun, Summer=Jul-Sep, Autumn=Oct-Dec.
Originators of Italian data sets-List of contributors:
- Brunetti Fabio (OGS)
- Cardin Vanessa, Bensi Manuel doi:10.6092/36728450-4296-4e6a-967d-d5b6da55f306
- Cardin Vanessa, Bensi Manuel, Ursella Laura, Siena Giuseppe doi:10.6092/f8e6d18e-f877-4aa5-a983-a03b06ccb987
- Cataletto Bruno (OGS)
- Cinzia Comici Cinzia (OGS)
- Civitarese Giuseppe (OGS)
- DeVittor Cinzia (OGS)
- Giani Michele (OGS)
- Kovacevic Vedrana (OGS)
- Mosetti Renzo (OGS)
- Solidoro C.,Beran A.,Cataletto B.,Celussi M.,Cibic T.,Comici C.,Del Negro P.,De Vittor C.,Minocci M.,Monti M.,Fabbro C.,Falconi C.,Franzo A.,Libralato S.,Lipizer M.,Negussanti J.S.,Russel H.,Valli G., doi:10.6092/e5518899-b914-43b0-8139-023718aa63f5
- Celio Massimo (ARPA FVG)
- Malaguti Antonella (ENEA)
- Fonda Umani Serena (UNITS)
- Bignami Francesco (ISAC/CNR)
- Boldrini Alfredo (ISMAR/CNR)
- Marini Mauro (ISMAR/CNR)
- Miserocchi Stefano (ISMAR/CNR)
- Zaccone Renata (IAMC/CNR)
- Lavezza, R., Dubroca, L. F. C., Ludicone, D., Kress, N., Herut, B., Civitarese, G., Cruzado, A., Lefèvre, D.,Souvermezoglou, E., Yilmaz, A., Tugrul, S., and Ribera d'Alcala, M.: Compilation of quality controlled nutrient profiles from the Mediterranean Sea, doi:10.1594/PANGAEA.771907, 2011.