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| Titel |
About uncertainties in practical salinity calculations |
| VerfasserIn |
M. Menn |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 7, no. 5 ; Nr. 7, no. 5 (2011-10-17), S.651-659 |
| Datensatznummer |
250004804
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| Publikation (Nr.) |
 copernicus.org/os-7-651-2011.pdf |
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| Zusammenfassung |
| In the current state of the art, salinity is a quantity computed from
conductivity ratio measurements, with temperature and pressure known at the
time of the measurement, and using the Practical Salinity Scale algorithm of
1978 (PSS-78). This calculation gives practical salinity values S. The
uncertainty expected in PSS-78 values is ±0.002, but no details have
ever been given on the method used to work out this uncertainty, and the
error sources to include in this calculation. Following a guide published by
the Bureau International des Poids et Mesures (BIPM), using two independent
methods, this paper assesses the uncertainties of salinity values obtained
from a laboratory salinometer and Conductivity-Temperature-Depth (CTD)
measurements after laboratory calibration of a conductivity cell. The
results show that the part due to the PSS-78 relations fits is sometimes as
significant as the instrument's. This is particularly the case with CTD
measurements where correlations between variables contribute mainly to
decreasing the uncertainty of S, even when expanded uncertainties of
conductivity cell calibrations are for the most part in the order of 0.002 mS cm−1.
The relations given here, and obtained with the normalized GUM
method, allow a real analysis of the uncertainties' sources and they can be
used in a more general way, with instruments having different
specifications. |
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