{
  "key": "chl_max",
  "slug": "chl_max",
  "label": "Chlorophyll-a at its maximum: the 3 m running mean at chl_max_depth",
  "short_label": "Chlorophyll maximum",
  "description": "Chlorophyll-a at its maximum: the 3 m running mean at chl_max_depth",
  "units": "ug/L",
  "units_nerc_p06": "http://vocab.nerc.ac.uk/collection/P06/current/UGPL/",
  "nerc_p01": null,
  "category": {
    "key": null,
    "name": "Productivity & Pigments",
    "icon": "cat-productivity",
    "realm": "env",
    "order": 4
  },
  "is_unified": false,
  "derivation": "calcofi4db::ctd_chl_max(window_m = 3): the 3 m running mean of est_chlorophyll_a_sta_corr at chl_max_depth (questions Q02)",
  "climatology": true,
  "bounds": {
    "valid_min": 0,
    "valid_max": 1000,
    "declared_by": [
      "chl_max"
    ]
  },
  "totals": {
    "n_values": 9255,
    "n_samples": 9255,
    "n_roots": 9255,
    "n_datasets": 1,
    "year_min": 1993,
    "year_max": 2026,
    "depth_min_m": null,
    "depth_max_m": null,
    "qual_ok_n": 9255,
    "n_flagged": 0
  },
  "series": [
    {
      "measurement_type": "chl_max",
      "dataset_key": "calcofi_ctd-derived",
      "source_column": "est_chlorophyll_a_sta_corr",
      "qual_column": null,
      "description": "Chlorophyll-a at its maximum: the 3 m running mean at chl_max_depth",
      "units": "ug/L",
      "nerc_p01": null,
      "is_canonical": true,
      "n_values": 9255,
      "n_samples": 9255,
      "n_roots": 9255,
      "n_cells": 109,
      "n_cruises": 136,
      "year_min": 1993,
      "year_max": 2026,
      "depth_min_m": null,
      "depth_max_m": null,
      "years": {
        "1993": 131,
        "1994": 264,
        "1995": 259,
        "1996": 282,
        "1997": 274,
        "1998": 407,
        "1999": 260,
        "2000": 255,
        "2001": 252,
        "2002": 255,
        "2003": 256,
        "2004": 270,
        "2005": 293,
        "2006": 296,
        "2007": 296,
        "2008": 286,
        "2009": 310,
        "2010": 306,
        "2011": 316,
        "2012": 278,
        "2013": 326,
        "2014": 255,
        "2015": 307,
        "2016": 348,
        "2017": 326,
        "2018": 294,
        "2019": 241,
        "2020": 230,
        "2021": 265,
        "2022": 225,
        "2023": 321,
        "2024": 268,
        "2025": 231,
        "2026": 72
      },
      "months": [
        1671,
        552,
        373,
        1923,
        111,
        123,
        1552,
        661,
        117,
        947,
        1201,
        24
      ],
      "depth_bands": {
        "0-10": 0,
        "10-50": 0,
        "50-100": 0,
        "100-200": 0,
        "200-500": 0,
        "500-1000": 0,
        "1000-2000": 0,
        "2000+": 0
      },
      "qual": {
        "none": 9255
      },
      "qual_ok_n": 9255,
      "n_flagged": 0,
      "observed": {
        "min": 0.0059,
        "p05": 0.2528,
        "p50": 0.763066666666667,
        "p95": 6.35628999999998,
        "max": 83.1604666666667
      },
      "out_of_bounds": {
        "n": 0,
        "min": null,
        "max": null
      },
      "flags": [
        "sensor_mean",
        "no_flag_at_grain",
        "no_p01"
      ],
      "grain": "sample"
    }
  ],
  "related": [],
  "flags": [
    "no_label"
  ],
  "face": {
    "kind": "standsin",
    "face_of": "chlorophyll_a",
    "stands_in_note": "stands in: chlorophyll-a's face (the smoothed maximum of the CTD fluorescence profile)",
    "source": "no NERC P01 on this key (D3)"
  },
  "method": [
    {
      "dataset_key": "calcofi_ctd-derived",
      "measurement_type": "chl_max",
      "platform": "ctd",
      "instrument": "Computed from the CTD fluorometer profile (corrected to bottle chlorophyll-a)",
      "nerc_l22": null,
      "principle": "Chlorophyll-a at its maximum: the smoothed value (3 m running mean) at the depth of the maximum.",
      "steps": [
        "smooth the 1 m profile with a 3 m running mean",
        "take the highest smoothed value"
      ],
      "wavelength_nm": null,
      "precision": null,
      "bibkeys": [],
      "calcofi_org_url": null,
      "text_fragment": null,
      "source": "the record's own derivation (measurement_type.csv); questions Q02 (Rasmus Swalethorp, 2026-09-23)",
      "source_url": null
    }
  ],
  "why": [
    {
      "rank": 1,
      "kind": "authored",
      "text": "Chlorophyll peaks at a depth rather than at the surface, and the height of that peak is how much plant life the water column holds at its richest layer: the base of the food web the rest of the survey counts.",
      "bibkeys": [
        "chavez2011"
      ],
      "source_url": null,
      "eov": "Phytoplankton biomass and diversity",
      "goos_doc": "https://goosocean.org/document/17507"
    },
    {
      "rank": 2,
      "kind": "authored",
      "text": "It is the smoothed value at the depth of the maximum, taken from the CTD fluorometer corrected to bottle chlorophyll-a, so a single narrow spike is not read as the peak.",
      "bibkeys": [],
      "source_url": null,
      "eov": "Phytoplankton biomass and diversity",
      "goos_doc": "https://goosocean.org/document/17507"
    },
    {
      "rank": 3,
      "kind": "wikipedia",
      "text": "Deep chlorophyll maximum",
      "bibkeys": [],
      "source_url": "https://en.wikipedia.org/wiki/Deep_chlorophyll_maximum",
      "eov": "Phytoplankton biomass and diversity",
      "goos_doc": "https://goosocean.org/document/17507"
    },
    {
      "rank": 4,
      "kind": "wikipedia",
      "text": "Chlorophyll a",
      "bibkeys": [],
      "source_url": "https://en.wikipedia.org/wiki/Chlorophyll_a",
      "eov": "Phytoplankton biomass and diversity",
      "goos_doc": "https://goosocean.org/document/17507"
    }
  ],
  "grain": "sample"
}