{
  "key": "hypoxic_depth_05",
  "slug": "hypoxic_depth_05",
  "label": "Severe hypoxic boundary depth (core of the oxygen minimum zone): the shallowest depth where oxygen falls to 0.5 mL/L",
  "short_label": "Severe hypoxic depth, OMZ core (0.5 mL/L)",
  "description": "Severe hypoxic boundary depth (core of the oxygen minimum zone): the shallowest depth where oxygen falls to 0.5 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 0.5 mL/L), the same rule as hypoxic_depth_24 at the severe boundary, the OMZ core (Rasmus Swalethorp 2026-09-24, questions Q10); most casts stop above it, so it is sparser than the other two",
  "climatology": false,
  "bounds": {
    "valid_min": 0,
    "valid_max": 6500,
    "declared_by": [
      "hypoxic_depth_05"
    ]
  },
  "totals": {
    "n_values": 6144,
    "n_samples": 6144,
    "n_roots": 6144,
    "n_datasets": 1,
    "year_min": 1993,
    "year_max": 2026,
    "depth_min_m": null,
    "depth_max_m": null,
    "qual_ok_n": 6144,
    "n_flagged": 0
  },
  "series": [
    {
      "measurement_type": "hypoxic_depth_05",
      "dataset_key": "calcofi_ctd-derived",
      "source_column": "oxygen_ml_l_ave_sta_corr",
      "qual_column": null,
      "description": "Severe hypoxic boundary depth (core of the oxygen minimum zone): the shallowest depth where oxygen falls to 0.5 mL/L",
      "units": "m",
      "nerc_p01": null,
      "is_canonical": true,
      "n_values": 6144,
      "n_samples": 6144,
      "n_roots": 6144,
      "n_cells": 91,
      "n_cruises": 136,
      "year_min": 1993,
      "year_max": 2026,
      "depth_min_m": null,
      "depth_max_m": null,
      "years": {
        "1993": 96,
        "1994": 178,
        "1995": 171,
        "1996": 199,
        "1997": 215,
        "1998": 289,
        "1999": 188,
        "2000": 206,
        "2001": 192,
        "2002": 205,
        "2003": 193,
        "2004": 167,
        "2005": 186,
        "2006": 187,
        "2007": 201,
        "2008": 193,
        "2009": 209,
        "2010": 176,
        "2011": 198,
        "2012": 198,
        "2013": 224,
        "2014": 175,
        "2015": 206,
        "2016": 224,
        "2017": 219,
        "2018": 202,
        "2019": 155,
        "2020": 160,
        "2021": 129,
        "2022": 124,
        "2023": 159,
        "2024": 156,
        "2025": 111,
        "2026": 53
      },
      "months": [
        1109,
        361,
        232,
        1233,
        64,
        88,
        1036,
        448,
        96,
        677,
        784,
        16
      ],
      "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": 6144
      },
      "qual_ok_n": 6144,
      "n_flagged": 0,
      "observed": {
        "min": 3.72790596430126,
        "p05": 378.495454545455,
        "p50": 455.548900557926,
        "p95": 509.715406836784,
        "max": 615.843930635838
      },
      "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": "The severe boundary, 0.5 mL/L, is the top of the core of the oxygen minimum zone, where little but specialised life persists; most CalCOFI casts stop above it, so it is sparser than the two boundaries above (Rasmus Swalethorp, SIO, 2026-09-24).",
      "bibkeys": [
        "bograd2008"
      ],
      "source_url": null,
      "eov": "Oxygen",
      "goos_doc": "https://goosocean.org/document/17508"
    },
    {
      "rank": 2,
      "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"
}