{
  "key": "hypoxic_depth_14",
  "slug": "hypoxic_depth_14",
  "label": "Hypoxic boundary depth: the shallowest depth where oxygen falls to 1.4 mL/L",
  "short_label": "Hypoxic boundary depth (1.4 mL/L)",
  "description": "Hypoxic boundary depth: the shallowest depth where oxygen falls to 1.4 mL/L",
  "units": "m",
  "units_nerc_p06": "http://vocab.nerc.ac.uk/collection/P06/current/ULAA/",
  "nerc_p01": null,
  "category": {
    "key": null,
    "name": "Physical Oceanography",
    "icon": "cat-physical",
    "realm": "env",
    "order": 1
  },
  "is_unified": false,
  "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)",
  "climatology": true,
  "bounds": {
    "valid_min": 0,
    "valid_max": 6500,
    "declared_by": [
      "hypoxic_depth_14"
    ]
  },
  "totals": {
    "n_values": 7308,
    "n_samples": 7308,
    "n_roots": 7308,
    "n_datasets": 1,
    "year_min": 1993,
    "year_max": 2026,
    "depth_min_m": null,
    "depth_max_m": null,
    "qual_ok_n": 7308,
    "n_flagged": 0
  },
  "series": [
    {
      "measurement_type": "hypoxic_depth_14",
      "dataset_key": "calcofi_ctd-derived",
      "source_column": "oxygen_ml_l_ave_sta_corr",
      "qual_column": null,
      "description": "Hypoxic boundary depth: the shallowest depth where oxygen falls to 1.4 mL/L",
      "units": "m",
      "nerc_p01": null,
      "is_canonical": true,
      "n_values": 7308,
      "n_samples": 7308,
      "n_roots": 7308,
      "n_cells": 99,
      "n_cruises": 136,
      "year_min": 1993,
      "year_max": 2026,
      "depth_min_m": null,
      "depth_max_m": null,
      "years": {
        "1993": 111,
        "1994": 222,
        "1995": 215,
        "1996": 228,
        "1997": 232,
        "1998": 336,
        "1999": 221,
        "2000": 218,
        "2001": 212,
        "2002": 220,
        "2003": 217,
        "2004": 216,
        "2005": 224,
        "2006": 226,
        "2007": 241,
        "2008": 233,
        "2009": 237,
        "2010": 228,
        "2011": 244,
        "2012": 214,
        "2013": 254,
        "2014": 193,
        "2015": 232,
        "2016": 267,
        "2017": 252,
        "2018": 231,
        "2019": 179,
        "2020": 186,
        "2021": 185,
        "2022": 165,
        "2023": 240,
        "2024": 197,
        "2025": 170,
        "2026": 62
      },
      "months": [
        1337,
        439,
        296,
        1536,
        80,
        97,
        1208,
        532,
        101,
        752,
        910,
        20
      ],
      "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": 7308
      },
      "qual_ok_n": 7308,
      "n_flagged": 0,
      "observed": {
        "min": 3.23813670004354,
        "p05": 197.261932973825,
        "p50": 302.519116067318,
        "p95": 399.284180590117,
        "max": 501.961538461538
      },
      "out_of_bounds": {
        "n": 0,
        "min": null,
        "max": null
      },
      "flags": [
        "no_flag_at_grain",
        "no_p01"
      ],
      "grain": "sample"
    }
  ],
  "related": [],
  "flags": [
    "no_label"
  ],
  "face": {
    "kind": "scale",
    "face_of": null,
    "stands_in_note": null,
    "source": "no NERC P01 on this key; shows its own familiar-scale figure only (D3)"
  },
  "why": [
    {
      "rank": 1,
      "kind": "authored",
      "text": "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.",
      "bibkeys": [
        "bograd2008"
      ],
      "source_url": null,
      "eov": "Oxygen",
      "goos_doc": "https://goosocean.org/document/17508"
    },
    {
      "rank": 2,
      "kind": "authored",
      "text": "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.",
      "bibkeys": [],
      "source_url": null,
      "eov": "Oxygen",
      "goos_doc": "https://goosocean.org/document/17508"
    },
    {
      "rank": 3,
      "kind": "wikipedia",
      "text": "Oxygen minimum zone",
      "bibkeys": [],
      "source_url": "https://en.wikipedia.org/wiki/Oxygen_minimum_zone",
      "eov": "Oxygen",
      "goos_doc": "https://goosocean.org/document/17508"
    }
  ],
  "grain": "sample"
}