Sea surface salinity from ESA-CCI

ESA-CCI Sea surface salinity Jan 2010. Copyright: UHH/CEN/AJB

Topics

Access

RESTRICTED: This link to the data set is only available for a restricted user group. The data set is only accessible in CEN/MPI net or accessible from external nets with a customer account. Please contact ICDC if you would like to access this data from outside the network.

View salinity data at LAS
Access salinity data via OPeNDAP
Data access via file system: /data/icdc/ocean/esa_cci_sss/

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Description

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 ESA's CCI+SSS project (see website in references) 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), see websites in references . 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 (see references) for further information.

Last update of data set at ICDC: November 19, 2020.

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Parameters

Parameters of the surface salinity data set
Name	Range / Comments
Sea surface salinity (SSS)	- / see Data quality
Sea surface salinity bias	- / see Data quality
Sea surface salinity bias standard deviation	- / see Data quality
Sea surface salinity random error	- / see Data quality
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	-

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Coverage, spatial and temporal resolution

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:

Global
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

Format:

NetCDF

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Data quality

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) in the references and the parameters list further up): bias, bias standard deviation, random error, explained variance and number of outliers.

Comment on the first 4 parameters listed in the table: In order to comply to CF-conventions we added 1e-3 as unit to every sea-surface salinity variable, these variables did not have a unit in the original data set.

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Contact

CCI+SSS Team
European Space Agency - ESA Climate Office
email: Mngt_CCI-Salinity (at) argans.co.uk

Julia Köhler
Institute of Oceanography / CEN / University of Hamburg
email: julia.koehler (at) uni-hamburg.de

Stefan Kern
ICDC / CEN / University of Hamburg
E-Mail: stefan.kern"AT"uni-hamburg.de

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References

Literature:

ATBD Algorithm Theoretical Development Basis Document, Climate Change Initiative+ (CCI+) Phase 1 , Sea Surface Salinity (pdf, not barrier free)
PSD Product Specification Document (pdf, not barrier free)
PUG Product User Guide (pdf, not barrier free)
E3UB End-to-End ECV Uncertainty Budget (pdf, not barrier free)

Websites:

ESA Sea Surface Salinity, https://climate.esa.int/en/projects/sea-surface-salinity/
ESA SMOS, http://www.esa.int/Applications/Observing_the_Earth/SMOS
NASA Soil Moisture Active Passive, SMAP, https://smap.jpl.nasa.gov/mission/description/
NASA Aquarius Mission, https://www.nasa.gov/mission_pages/aquarius/overview/index.html

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Data citation

Please cite the data as follows:

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]

and with the following acknowledgments:

Thanks to ICDC, CEN, University of Hamburg for data support.

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