Pycnocline depth (max N²)
Pycnocline depth: where the buoyancy frequency squared N2 (TEOS-10, 10 m running mean) is greatest between 10 and 200 m
mkey pycnocline_depthP06 units ULAAseries pycnocline_depth
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 8,525 values of it from 8,525 sampling events in one dataset, 1993–2026, one per cast.R The pycnocline is the density step that separates the surface layer from the water below; its depth sets how far mixing reaches and where nutrients stop, and it rises toward the coast where upwelling lifts deep water.C
- 8,525
- 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
pycnocline_depth· source columntemperature_ave; salinity_ave_corr; pressureone 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 ('pycnocline_depth')library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "sample_measurement") |> filter(measurement_type %in% c("pycnocline_depth"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM sample_measurement WHERE measurement_type IN ('pycnocline_depth')").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 Subsurface temperature
the GOOS specification sheet for this Essential Ocean Variable lists it
other ways to say why · 2
- The depth of the greatest static stability, the maximum of the buoyancy frequency squared N² (TEOS-10, a 10 m running mean) between 10 and 200 m, after the CTD team's bottle-era script (Fiedler et al. 2013) modernised with TEOS-10 (Rasmus Swalethorp, SIO, 2026-09-24). needs a citation before it can be the pick
- Wikipedia A pycnocline is the cline or layer where the density gradient is greatest within a body of water. An ocean current is generated by the forces such as breaking waves, temperature and salinity differences, wind, Coriolis effect, and tides caused by the gravitational pull of celestial bodies. Pycnocline · CC BY-SA 4.0 · rev. 1298138593
Units and range m · 10 … 200 declared · 0 flagged
m · P06 units ULAA
details
- bounds
- The registry declares
10 … 200 mforpycnocline_depth; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- CTD Derived Products
pycnocline_depth10 · median 48 · 200 m (5th–95th percentile 13–120) - flags
- CTD Derived Products
pycnocline_depthcarries no quality code at the release grain; qual_ok keeps all 8,525. - 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_pycnocline(p_min = 10, p_max = 200) on buoyancy_n2: the depth of the largest smoothed N2 in the window (ties to the shallowest), for a cast that starts within 15 m of the surface and reaches 50 m with at least 5 bins in the window (the conditions of the CTD team's F_PycnoclineDepth.m, after Fiedler et al. 2013); the 10 m running mean replaces that script's 10 m centred difference and the draft R script's smoothing spline (questions Q11)
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.