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. 2015 Oct 13:2:150054.
doi: 10.1038/sdata.2015.54. eCollection 2015.

Sea surface temperature and salinity from French research vessels, 2001-2013

Fabienne Gaillard  1 , Denis Diverres  2 , Stéphane Jacquin  2 , Yves Gouriou  2 , Jacques Grelet  2 , Marc Le Menn  3 , Joelle Tassel  3 , Gilles Reverdin  4
Affiliations

Sea surface temperature and salinity from French research vessels, 2001-2013

Fabienne Gaillard et al. Sci Data. .

Abstract

French Research vessels have been collecting thermo-salinometer (TSG) data since 1999 to contribute to the Global Ocean Surface Underway Data (GOSUD) programme. The instruments are regularly calibrated and continuously monitored. Water samples are taken on a daily basis by the crew and later analysed in the laboratory. We present here the delayed mode processing of the 2001-2013 dataset and an overview of the resulting quality. Salinity measurement error was a few hundredths of a unit or less on the practical salinity scale (PSS), due to careful calibration and instrument maintenance, complemented with a rigorous adjustment on water samples. In a global comparison, these data show excellent agreement with an ARGO-based salinity gridded product. The Sea Surface Salinity and Temperature from French REsearch SHips (SSST-FRESH) dataset is very valuable for the 'calibration and validation' of the new satellite observations delivered by the Soil Moisture and Ocean Salinity (SMOS) and Aquarius missions.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. Thermo-salinometer delayed mode processing workflow.
On French research vessels, data acquisition relies on the ship operator and the calibration laboratory. The data centre collects real time data and full resolution archives. The delayed mode processing team assembles the necessary information to provide qualified and adjusted data sets to the GOSUD database.
Figure 2
Figure 2. Effect of bubbles on the salinity reported by the TSG.
When the ship is heading into strong waves, air bubbles on the conductivity cell decrease the true salinity value. We show here the full resolution salinity data (in blue) and the reduced data (in red), in PSS as a function of time, given in seconds.
Figure 3
Figure 3. Difference between the salinity reported by the TSG and the external measurements.
During the Strasse cruise on board the Thalassa in 2012 a large number of CTD data were collected (in red), they are in excellent agreement with the daily water samples (in blue) collected by the ship crew and reveal a 0.01 offset of the TSG, with very low standard deviation. Argo measurements show a strong dispersion.
Figure 4
Figure 4. Difference between the TSG temperature and the laboratory reference temperature.
The temperature sensors (SBE-38 and SBE-3S) used on the research vessels are regularly controlled in the SHOM metrology service. The sensor drift observed on all instruments from 2002 to 2014 is within the specifications declared by the manufacturer (0.001 °C in 6 months).
Figure 5
Figure 5. Difference between the TSG salinity measurements and the salinity gridded field from ISAS-13 monthly analysis.
ΔS is defined as the salinity difference with ISAS-13, computed at each TSG data position. In blue |ΔS|≤0.5, in green 0.5<|ΔS|≤2, in red |ΔS|>2. |ΔS| is expressed in PSS. The period considered is defined by ISAS-13 availability and runs from 2002 to 2012.
Figure 6
Figure 6. Difference between the TSG salinity and ISAS-13 monthly analysis in coastal areas.
This figure is a zoom of Fig. 4 in the North-East Atlantic showing that the higher values of salinity anomalies relative to ISAS-13 are found in coastal areas. Note also the dense sampling in the North Sea, Bay of Biscay and Gulf of Lion.
Figure 7
Figure 7. Distribution of TSG-ISAS-13 differences for each ship.
The distribution is shown only for the values |ΔS|≤0.5.
See this image and copyright information in PMC

References

Data Citations

    1. Gaillard F. 2015. Pôle Océan. http://doi.org/z79
    1. Gaillard F. 2015. Pôle Océan. http://doi.org/z77

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