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Measurement · Physical Oceanography · PSS-78

Practical salinity (PSS-78)

NERC P01 PSLTZZ01P06 units PSUX PSS-78key salinity_pss78 series salinity_pss78
908
values
8
flagged
i
8 of these 908 values (0.9 %) are flagged by their provider as questionable or bad. The Explorer, the climatology and its anomalies leave them out; do the same when you read the data yourself (cc_qual_ok_sql() in calcofi4r, qual_ok_sql() in calcofi4py).
294
sampling events
1983–2021
years
1
dataset
1–3,500 m
depth
every month
seasons
What

33.66 g of salt in a kilogram of CalCOFI seawater, at the record’s median salinity

Br⁻ 0.2 % · SO₄²⁻ 7.7 % · HCO₃⁻ 0.3 % · Cl⁻ 55.0 % · Mg²⁺ 3.7 % · Na⁺ 30.7 % · K⁺ 1.1 % · Ca²⁺ 1.2 %

The quantity of dissolved ions (predominantly salt in seawater) expressed on a scale (PSS-78) based on the conductivity ratio of a seawater sample to a standard KCl solution.

How
rosette bottle

Guildline Portasal 8410A salinometer, two per cruise

Bottle sampling methods on calcofi.org ↗
Why

EOV Subsurface salinity

CalCOFI holds 908 values of it from 294 sampling events in one dataset, 1983–2021, from the surface to 3,500 m. At 10–50 m it has risen 0.09 per decade since 1984.R Salinity tags the water masses: the California Current carries fresher Subarctic water south and the Undercurrent carries saltier water from the south; with temperature it sets density.C

other ways to say why · 3
  • authored Salinity and temperature together set seawater’s density, which drives the currents and decides how deep winter mixing reaches. needs a citation before it can be the pick
  • Wikipedia Water mass source
  • Wikipedia Salinity is the saltiness or amount of salt dissolved in a body of water, called saline water. It is usually measured in g/L or g/kg. Salinity · CC BY-SA 4.0 · rev. 1368851206

The measurement

Measured in
i

One row per series, one cell per year, darker with more values — the same strip the front door draws per dataset and a species page draws per taxon. Each row is one dataset's own measurement_type; the label is written once, in the title above.

  • Carbonate Chemistry / DIC 908 values · 294 sampling events · 1983–2021 · 1–3,500 m · 26 grid cells · 98 cruises
    series salinity_pss78 · source column Salinity_PSS78 · flag column salinity_pss78_flag 8 flagged · 0.9 %

The structure

O4S2− sulfate CHEBI:16189 · 96.063 g/mol · component
CHO3− hydrogencarbonate CHEBI:17544 · 61.016 g/mol · component

ChEBI: “A sulfur oxoanion obtained by deprotonation of both OH groups of sulfuric acid.” · RDKit 2026.03.6 from the ChEBI molfile, in the page’s ink · CC BY 4.0. ChEBI’s roles are never shown.

How it is measured

Carbonate Chemistry / DIC · rosette bottle
Guildline Portasal 8410A salinometer, two per cruise

About 225 mL drawn from every Niskin into a numbered KIMAX bottle after three rinses; a Guildline Portasal 8410A salinometer compares the sample's conductivity with a reference seawater standard and salinity is computed from the ratio. (calcofi.org Bottle sampling methods)

flag salinity_pss78_flag8 flaggedaccuracy +/-0.003 PSU, precision 0.0003 PSU (Guildline specification)
Bottle sampling methods on calcofi.org ↗

Why it matters

The familiar scale
i

Bars are each series' 5th–95th percentile, the line its minimum to maximum, the ring its median; the marks are metadata/measurement_scale.csv's, each hovering to its own source.

The record’s own history
i

Deeper than the climatology reaches: 132 values at 0–10 m, 56 values at 50–100 m, 108 values at 100–200 m, 109 values at 200–500 m, 63 values at 500–1000 m, 2 values at 2000+ m have no normal to depart from, because the release’s climatology stops at its deepest built bin. Carrying it to the bottom is one argument of build_climatology() and puts these bands on the page too.

Essential Ocean Variable
Subsurface salinity

the GOOS specification sheet for this Essential Ocean Variable lists it

GOOS specification sheet ↗

The record

Ways in
i

Read from measurements.json of release v2026.09.11, written at release by calcofi4db::build_measurements_catalog() beside taxa.json. The catalog's index is /measurements/; the JSON-LD on this page is a schema.org/DefinedTerm in the NERC P01 term set with a PropertyValue per series.

ExplorerExplorer · a depth section vs normaldb-query
ERDDAP · Carbonate Chemistry / DICCalCOFI's own server, the Carbonate Chemistry / DIC table constrained to this series
https://erddap.calcofi.io/erddap/tabledap/calcofi_dic.html?&measurement_type=%22salinity_pss78%22

By depth
i

Values per depth band at the release grain, one thin bar per series. The bands are the record's own (0-10 … 2000+ m).

By month
i

Values per calendar month, one row per series: CalCOFI's quarterly cruises show as peaks in the months the ships sail.

Range & quality

bounds0 … 45 PSS-78observed32.9 … 34.68 PSS-78flagged8baselineclimatology ✓
details
bounds
The registry declares 0 … 45 PSS-78 for salinity_pss78; a value outside it is dropped at the ingest (drop_out_of_bounds()).
observed
Carbonate Chemistry / DIC salinity_pss78 32.9 · median 33.5 · 34.68 PSS-78 (5th–95th percentile 33.12–34.26)
flags
Carbonate Chemistry / DIC salinity_pss78 salinity_pss78_flag on 908 of 908 rows: 2 900 · 3 8; qual_ok keeps 900. The codes are this dataset's own vocabulary, uninterpreted.
baseline
A monthly climatology exists for this measurement (the release's climatology table: 1993–2013, dataset × grid cell × calendar month × 10 m bin), so the Explorer can draw anomalies against it rather than values.

Related measurements
i

The same quantity from another platform or another kind of sample, each its own page and never merged into this one: a dataset's own bottle samples would count that dataset twice, an underway intake is not a cast, and a replicate is not a mean. The reason is the record's (related[].why).

  • Salinity salinity · salinity_ave_corr · Hydrographic Bottle · CTD Cast Files · 1949–2025 · 1,521,289 values · P01 PSLTZZ01 the same casts logged by another instrument on the same station
  • Bottle salinity salinity_btl · CTD Cast Files · 1993–2025 · 150,917 values · P01 PSLTZZ01 the same quantity from the CTD files' own bottle samples — plausibly the same physical bottles, so merging them would count the bottle dataset twice

Cite

Cite the release; each dataset's own citation, licence and DOI are on its page — Carbonate Chemistry / DIC. The Explorer's Share → Cite writes it for the view you make.