Hypoxic boundary depth (1.4 mL/L)
Hypoxic boundary depth: the shallowest depth where oxygen falls to 1.4 mL/L
mkey hypoxic_depth_14P06 units ULAAseries hypoxic_depth_14
one value per cast One value per cast. This measurement is worked out once for each cast rather than read at every depth, so it has no depth profile and no anomaly against a normal; its values are rows of sample_measurement, not of obs_env.
CalCOFI holds 7,308 values of it from 7,308 sampling events in one dataset, 1993–2026, one per cast.R Below about 1.4 mL/L of oxygen most fish and crustaceans struggle; how shallow that boundary sits decides how much of the water column they can live in, and off California it has shoaled by tens of metres since the 1980s as the oxygen minimum zone expanded.C
- 7,308
- values
- 0
- flagged
- 1993–2026
- years
- 1
- dataset
- 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
hypoxic_depth_14· source columnoxygen_ml_l_ave_sta_corrone value per cast no flag at this grain no P01 concept
Explorerdb-queryThis page as JSON R · Python · Parquet
Every way in 6 ways · 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.
Explorerdb-querySELECT * FROM read_json('…/v2026.11.05/catalog.json')
-- objects[] WHERE table = 'sample_measurement'
-- then filter the rows:
-- measurement_type IN ('hypoxic_depth_14')library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "sample_measurement") |> filter(measurement_type %in% c("hypoxic_depth_14"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM sample_measurement WHERE measurement_type IN ('hypoxic_depth_14')").df()How it is measured no method registered yet
No method row is registered for this measurement yet (metadata/measurement_method.csv).
Why it matters 3 ways to say it · EOV Oxygen
the GOOS specification sheet for this Essential Ocean Variable lists it
other ways to say why · 2
- The depth at which the station-corrected oxygen first falls to 1.4 mL/L on the way down (Rasmus Swalethorp, SIO, 2026-09-24); the 2.4 and 0.5 mL/L boundaries are published beside it, and because the oxygen minimum can sit mid-profile each is the shallowest crossing. needs a citation before it can be the pick
- Wikipedia The oxygen minimum zone (OMZ), sometimes referred to as the shadow zone, is the zone in which oxygen saturation in seawater in the ocean is at its lowest. This zone occurs at depths of about 200 to 1,500 m (700–4,900 ft), depending on local circumstances. Oxygen minimum zone · CC BY-SA 4.0 · rev. 1320899853
Units and range m · 0 … 6500 declared · 0 flagged
m · P06 units ULAA
details
- bounds
- The registry declares
0 … 6500 mforhypoxic_depth_14; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- CTD Derived Products
hypoxic_depth_143.238 · median 302.5 · 502 m (5th–95th percentile 197.3–399.3) - flags
- CTD Derived Products
hypoxic_depth_14carries no quality code at the release grain; qual_ok keeps all 7,308. - 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.
- derivation
- calcofi4db::ctd_hypoxic_depth(threshold 1.4 mL/L), the same rule as hypoxic_depth_24 at the hypoxic boundary (about 60 umol/kg; Rasmus Swalethorp 2026-09-24, questions Q10)
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 month every month
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 — CTD Derived Products. The Explorer's Share → Cite writes it for the view you make.