Estimated chlorophyll-a, cruise-corrected
Est. chlorophyll-a cruise-corrected
µg/Lkey est_chlorophyll_a_cruise_corrP06 units UGPLseries est_chlorophyll_a_cruise_corr
CalCOFI holds 328,439 values of it from 9,490 sampling events in one dataset, 1993–2026, from the surface to 200 m. At 100–200 m it has fallen 0.90 per decade since 1993.R Every phytoplankter carries chlorophyll-a, so it is the standard measure of how much plant life the sunlit layer holds: the base of the food web the rest of the survey counts.C
- 328,439
- values
- 45
- flagged
i
45 of these 328,439 values (under 0.1 %) 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). - 1993–2026
- years
- 1
- dataset
- 1–200 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
est_chlorophyll_a_cruise_corr· source columnest_chl_cruise_corr· flag columnest_chl_cruise_corr_qno P01 concept 45 flagged
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 = 'est_chlorophyll_a_cruise_corr'library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "obs_env") |> filter(measurement_type %in% c("est_chlorophyll_a_cruise_corr"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM obs_env WHERE measurement_type IN ('est_chlorophyll_a_cruise_corr')").df()The structure chlorophyll-a measured fluorometrically’s, standing in
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 CTD-mounted fluorometer, corrected to bottle chlorophyll-a
The CTD fluorometer voltage converted to chlorophyll-a units by regression against that cast's (or cruise's) own bottle chlorophyll-a values. (the record's own derivation (measurement_type.csv))
Why it matters 6 ways to say it · EOV Phytoplankton biomass and diversity
the GOOS specification sheet for this Essential Ocean Variable lists it, and asks
GOOS asks
- Is the biomass of the ocean changing?
GOOS specification sheet ↗ · quoted, not copied
other ways to say why · 5
- The fluorometer reads a profile continuously where the bottles read a handful of depths, so it is what shows the shape of the chlorophyll maximum. needs a citation before it can be the pick
- Chlorophyll is what satellites see as ocean colour, and bottle chlorophyll like CalCOFI’s is among the ground truth their algorithms were fitted to. needs a citation before it can be the pick
- GOOS asks Is the biomass of the ocean changing? source
- Wikipedia Phytoplankton source
- Wikipedia Chlorophyll a is a specific form of chlorophyll used in oxygenic photosynthesis. It absorbs most energy from wavelengths of violet-blue and orange-red light. Chlorophyll a · CC BY-SA 4.0 · rev. 1373717553
The record’s own history 5 depth bands against the 1993–2013 normal
Each year against the normal i
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Units and range µg/L · 0 … 1000 declared · 45 flagged
µg/L (ug/L in metadata/measurement_type.csv) · P06 units UGPL
details
- bounds
- The registry declares
0 … 1000 µg/Lforest_chlorophyll_a_cruise_corr; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- CTD Cast Files
est_chlorophyll_a_cruise_corr0 · median 0.1711 · 210.8 µg/L (5th–95th percentile 0.0155–1.975) - flags
- CTD Cast Files
est_chlorophyll_a_cruise_correst_chl_cruise_corr_qon 340 of 328,439 rows:0149 ·4146 ·828 ·917; qual_ok keeps 328,394. 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.
- derivation
- Fluorometer voltage converted to chlorophyll-a by regression against bottle chlorophyll-a, applied to the 1 m bin-averaged voltage over 0-200 m ONLY - undefined deeper by construction, not by absence of data. Bottle-corrected with ONE regression per cruise, fitted from 4-second-averaged sensor data against all the cruise's bottles (n ~ 1400, fliers omitted).
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 1–200 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).
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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.
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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 Cast Files. The Explorer's Share → Cite writes it for the view you make.