Total alkalinity
µmol/kgkey alkalinityNERC P01 MDMAP014P06 units KGUMseries alkalinity
CalCOFI holds 4,063 values of it from 3,382 sampling events in one dataset, 1984–2021, from the surface to 3,542 m. At 10–50 m it has risen 1.74 per decade since 1988.R Alkalinity is the water’s buffer: with dissolved inorganic carbon it fixes pH and how much carbonate is left for shells, which is what decides whether upwelled water is corrosive.C
- 4,063
- values
- 84
- flagged
i
84 of these 4,063 values (2.1 %) 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). - 1984–2021
- years
- 1
- dataset
- 0–3,542 m
- depth
- every month
- months
Measured in
1 dataset
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.
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.
-
series
alkalinity· source columnTA· flag columnta_flag84 flagged · 2.1 %
Explorera depth section vs normaldb-queryERDDAPThis page as JSON R · Python · Parquet
Every way in 8 ways · ERDDAP · Parquet · R · Python · JSON
Read from measurements.json of release v2026.11.05, 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-querySELECT * FROM read_json('…/v2026.11.05/catalog.json')
-- objects[] WHERE table = 'obs_env'
-- AND partition_value = 'alkalinity'library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "obs_env") |> filter(measurement_type %in% c("alkalinity"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM obs_env WHERE measurement_type IN ('alkalinity')").df()The structure 3 structures
ChEBI: “A one-carbon compound with formula CO2 in which the carbon is attached to each oxygen atom by a double bond. A colourless, odourless gas under normal conditions, it is produced during respiration by all animals, fungi and microorganisms that depend directly or indirectly on living or decaying plants for food.” · RDKit 2026.03.6 from the ChEBI SMILES (the molfile is vertical), in the page’s ink · CC BY 4.0. ChEBI’s roles are never shown.
How it is measured CO2 gas analyser (DIC), potentiometric titrator (alkalinity)
Samples drawn from the Niskins at selected stations and analysed ashore; total inorganic carbon and alkalinity are measured, from which pH and pCO2 can be calculated, calibrated to the certified reference materials Scripps prepares for the world. (NCEI accession 0301029 (DIC/alkalinity instruments); calcofi.org Bottle sampling methods)
NCEI accession 0301029 (DIC/alkalinity instruments); Bottle sampling methods on calcofi.org ↗Why it matters 4 ways to say it · EOV Inorganic carbon
the GOOS specification sheet for this Essential Ocean Variable lists it, and asks
GOOS asks
- How is the ocean carbon content changing?
GOOS specification sheet ↗ · quoted, not copied
other ways to say why · 3
- Neither alkalinity nor DIC says much alone; the carbonate system is read from the pair. needs a citation before it can be the pick
- GOOS asks How is the ocean carbon content changing? source
- Wikipedia Alkalinity (from Arabic: القلوية, romanized: al-qaly, lit. 'ashes of the saltwort') is the capacity of water to resist acidification. Alkalinity · CC BY-SA 4.0 · rev. 1377364008
The record’s own history 1 depth band against the 1993–2013 normal
Each year against the normal i
Deeper than the climatology reaches: 818 values at 0–10 m, 374 values at 50–100 m, 679 values at 100–200 m, 683 values at 200–500 m, 364 values at 500–1000 m, 1 values at 1000–2000 m, 16 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.
i
Deeper than the climatology reaches: 818 values at 0–10 m, 374 values at 50–100 m, 679 values at 100–200 m, 683 values at 200–500 m, 364 values at 500–1000 m, 1 values at 1000–2000 m, 16 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.
Units and range µmol/kg · 0 … 5000 declared · 84 flagged
µmol/kg (umol/kg in metadata/measurement_type.csv) · P06 units KGUM
details
- bounds
- The registry declares
0 … 5000 µmol/kgforalkalinity; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- Carbonate Chemistry / DIC
alkalinity2194 · median 2240 · 2437 µmol/kg (5th–95th percentile 2216–2316) - flags
- Carbonate Chemistry / DIC
alkalinityta_flagon 4,063 of 4,063 rows:23,979 ·351 ·433; qual_ok keeps 3,979. 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 × station × the cruise's month × 10 m bin), so the Explorer can draw anomalies against it rather than values.
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.
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.
By depth · by month 0–3,542 m · every month
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).
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.
i
Values per calendar month, one row per series: CalCOFI's quarterly cruises show as peaks in the months the ships sail.
Cite the release, v2026.11.05
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.