ISUS nitrate voltage
- 351,452
- values
- 1,984
- flagged
i
1,984 of these 351,452 values (0.6 %) 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). - 5,300
- sampling events
- 2004–2026
- years
- 1
- dataset
- 1–3,490 m
- depth
- Jan · Feb · Mar · Apr · May · Jun · Jul · Aug · Oct · Nov
- seasons
stands in: nitrate concentration’s face, raw ISUS sensor voltage, pre-conversion
No definition of its own: the estimate is described by its derivation, under How.
Satlantic ISUS ultraviolet nitrate sensor on the CTD
the record's own derivation for est_nitrate_sta_corr (measurement_type.csv), corroborated by the CTD FAQ's bottle-correction description on calcofi.org ↗How do the eutrophication and pollution impact ocean productivity and water quality?
CalCOFI holds 351,452 values of it from 5,300 sampling events in one dataset, 2004–2026, from the surface to 3,490 m. At 200–500 m it has risen 0.09 per decade since 2005.R Nitrate is the fertiliser upwelling lifts into the light; the spring blooms, and the fisheries above them, run on it. At depth it has risen as oxygen fell, the fingerprint of changing source waters.C
other ways to say why · 6
- A sensor on the CTD reads nitrate every metre where the bottles sample a couple of dozen depths, so it resolves the nitracline the bottles straddle. needs a citation before it can be the pick
- Nitrate at the surface is a fingerprint of recent upwelling: where it is high, cold deep water has just arrived and a bloom follows. needs a citation before it can be the pick
- GOOS asks How do the eutrophication and pollution impact ocean productivity and water quality? source
- GOOS asks Is the biomass of the ocean changing? source
- Wikipedia Upwelling source
- Wikipedia Nitrate is a polyatomic ion with the chemical formula NO3−. Salts containing this ion are called nitrates. Nitrate · CC BY-SA 4.0 · rev. 1378622700
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.
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
isus_v· source columnisusv· flag columnisusqno P01 concept 1,984 flagged · 0.6 %
The structure
ChEBI: “A nitrogen oxoanion formed by loss of a proton from nitric acid. Principal species present at pH 7.3.” · 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
The ISUS in-situ ultraviolet nitrate sensor's voltage is converted to nitrate by a per-cast regression fitted against that cast's own bottle nitrates (about 20, fliers omitted) from 1 m bin-averaged sensor data; a 500 m cast with ten or more bottles is required, so shallow or bottle-poor casts carry no estimate by design. (the record's own derivation for est_nitrate_sta_corr (measurement_type.csv), corroborated by the CTD FAQ's bottle-correction description)
the record's own derivation for est_nitrate_sta_corr (measurement_type.csv), corroborated by the CTD FAQ's bottle-correction description 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.
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: 222 values at 1000–2000 m, 10 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: 222 values at 1000–2000 m, 10 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.
the GOOS specification sheet for this Essential Ocean Variable lists it, and asks
GOOS asks
- How do the eutrophication and pollution impact ocean productivity and water quality?
- Is the biomass of the ocean changing?
GOOS specification sheet ↗ · quoted, not copied
The record
Ways in i
Read from measurements.json of release
v2026.10.14, 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-queryi
Read from measurements.json of release v2026.10.14, 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.
SELECT * FROM read_json('…/v2026.10.14/catalog.json')
-- objects[] WHERE table = 'obs_env'
-- AND partition_value = 'isus_v'library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "obs_env") |> filter(measurement_type %in% c("isus_v"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM obs_env WHERE measurement_type IN ('isus_v')").df()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.
Range & quality
details
- bounds
- The registry declares
-1 … 10 Vforisus_v; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- CTD Cast Files
isus_v4.3566e-12 · median 1.169 · 4.097 V (5th–95th percentile 0.1309–2.244) - flags
- CTD Cast Files
isus_visusqon 1,984 of 351,452 rows:8411 ·91,573; qual_ok keeps 349,468. 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.
Cite
Cite the release; each dataset's own citation, licence and DOI are on its page — CTD Cast Files. The Explorer's Share → Cite writes it for the view you make.