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Data access via file system: /data/icdc/ocean/esa_cci_sss/
Within the framework of the ESA Climate Change Initiative (ESA-CCI) numerous data sets of so-called Essential Climate Variables (ECV) have been derived during the past decade. A novel data set which is derived by the CCI+SSS project is a global sea surface salinity data set which latest version, v2.31, is offered here.
This level-4 data set is based on space-borne L-Band microwave sensor observations from the satellites SMOS (2010 until today), SMAP (2015 until today), and Aquarius (2011-2015). Input data are level-2 sea surface salinity estimates from SMOS and SMAP and level-3 estimates from Aquarius.
A first step in the generation of the CCI+SSS data set is to bi-linearly interpolate all input data onto a EASE-2 cylindrical grid with about 25 km grid-cell resolution; SMOS sea surface salinity data are already on this grid. The next step is aggregate all input sea-surface salinity data sets in space and time. Because the different input data sets are biased relative to each other, the subsequent steps are a bias correction to harmonize the data sets and the computation of anomalies with respect to climatological sea-surface salinity data on different time scales. With the aid of these anomalies the sea-surface salinity data are finally calibrated - again on different time scales with respect to in-situ sea-surface salinity observations. We refer to the ATBD for further information.
This data set has been included into ICDC's data holding on November 19, 2020.
|Sea surface salinity (SSS)||-- *)|
|Sea surface salinity bias||-- *)|
|Sea surface salinity bias standard deviation||-- *)|
|Sea surface salinity random error||-- *)|
|Percentage of SSS variance explained by the SSS||0 ... 100%|
|Sea surface salinity quality||0 = good, 1 = bad|
|Sea surface salinity contaminaton by ice||0 or 1|
|Sea surface salinity contamination by land||0 or 1|
|Number of observations||--|
|Number of outliers||--|
|*) see Data quality|
Period and temporal resolution:
- 2010-01-01 to 2019-12-31
- Daily as 7-day composit, 15-daily as 30-day composit
Coverage and spatial resolution:
- Spatial resolution: about 50 km x 50 km on an EASE-2 cylindrical grid (equidistant intervals of ~0.26° in longitude, latitude intervals increase nonlinearly poleward from ~0.2° at equator to ~0.5° at 67°N or S), sampled every 25 km
- Geographical latitude: -83.51714°N to 83.51714°N (southern- and northernmost grid-cell center)
- Geographical longitutde: -179.87°E to 179.87°E
- Dimension: 584 rows x 1388 columns
- Altitude: 0.0 m
This new data set of the sea surface salinity includes a suite of uncertainty estimates. The content of this suite ranges from the number of valid satellite observations, over quality flags of the sea surface salinity data set itself and for the impact by sea ice and/or land on the measured L-Band brightness temperatures, to the full error budget (see E3UB report, Product User Guide (PUG) and the parameters list further up): bias, bias standard deviation, random error, explained variance and number of outliers.
A note to *) in the parameters list: In order to comply to CF-conventions we added 1e-3 as unit to every sea-surface salinity variable. All these variables did not have a unit in the original data set.
European Space Agency - ESA Climate Office
email: Mngt_CCI-Salinity (at) argans.co.uk
Institute of Oceanography / CEN / University of Hamburg
email: julia.koehler (at) uni-hamburg.de
- ATBD (Algorithm Theoretical Baseline Document)
- PSD (Product Specification Document)
- PUG (Product User Guide)
- E3UB (End-to-End ECV Uncertainty Budget)
ESA CCI Sea Surface Salinity ECV produced at a spatial resolution of 50 km and time resolution of 1 week / 30 days [select which applies] and spatially resampled on 25 km EASE grid and 1 day / 15 days of time sampling [select which applies], cci.esa.int/salinity , doi.org/10.5285/4ce685bff631459fb2a30faa699f3fc5 [last accessed Nov. 5 2020]