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| Titel |
Absolute Salinity, ''Density Salinity'' and the Reference-Composition Salinity Scale: present and future use in the seawater standard TEOS-10 |
| VerfasserIn |
D. G. Wright, R. Pawlowicz, T. J. McDougall, R. Feistel, G. M. Marion |
| 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. 1 ; Nr. 7, no. 1 (2011-01-06), S.1-26 |
| Datensatznummer |
250004428
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| Publikation (Nr.) |
 copernicus.org/os-7-1-2011.pdf |
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| Zusammenfassung |
Salinity plays a key role in the determination of the thermodynamic
properties of seawater and the new TEOS-101 standard provides a consistent and effective
approach to dealing with relationships between salinity and these
thermodynamic properties. However, there are a number of practical
issues that arise in the application of TEOS-10, both in terms of
accuracy and scope, including its use in the reduction of field data
and in numerical models.
First, in the TEOS-10 formulation for IAPSO Standard Seawater, the Gibbs
function takes the Reference Salinity as its salinity argument,
denoted SR, which
provides a measure of the mass fraction of dissolved material in
solution based on the Reference Composition approximation for Standard
Seawater. We discuss uncertainties in both the Reference Composition
and the Reference-Composition Salinity Scale on which Reference Salinity
is reported. The Reference Composition provides a much-needed
fixed benchmark but modified reference states will inevitably be
required to improve the representation of Standard Seawater for some
studies. However, the Reference-Composition Salinity Scale should remain
unaltered to provide a stable representation of salinity for use with
the TEOS-10 Gibbs function and in climate change detection studies.
Second, when composition anomalies are present in seawater, no single
salinity variable can fully represent the influence of dissolved
material on the thermodynamic properties of seawater. We consider
three distinct representations of salinity that have been used in
previous studies and discuss the connections and distinctions between
them. One of these variables provides the most accurate representation
of density possible as well as improvements over Reference Salinity
for the determination of other thermodynamic properties. It is
referred to as "Density Salinity" and is represented by the symbol
SAdens; it stands out as the most appropriate
representation of salinity for use in dynamical physical
oceanography. The other two salinity variables provide alternative
measures of the mass fraction of dissolved material in
seawater. "Solution Salinity", denoted SAsoln, is
the most obvious extension of Reference Salinity to allow for
composition anomalies; it provides a direct estimate of the mass
fraction of dissolved material in solution. "Added-Mass Salinity",
denoted SAadd, is motivated by a method used to
report laboratory experiments; it represents the component of
dissolved material added to Standard Seawater in terms of the mass of
material before it enters solution. We also discuss a constructed
conservative variable referred to as "Preformed Salinity", denoted
S∗, which will be useful in process-oriented numerical
modelling studies.
Finally, a conceptual framework for the incorporation of composition
anomalies in numerical models is presented that builds from studies in
which composition anomalies are simply ignored up to studies in which
the influences of composition anomalies are accounted for using the
results of biogeochemical models.
1TEOS-10:
international Thermodynamic Equation of Seawater 2010,
http://www.teos-10.org/. |
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