{
  "key": "buoyancy_n2",
  "slug": "buoyancy_n2",
  "label": "Buoyancy (Brunt-Vaisala) frequency squared N2 (TEOS-10), 10 m running mean",
  "short_label": "Buoyancy frequency N²",
  "description": "Buoyancy (Brunt-Vaisala) frequency squared N2 (TEOS-10), 10 m running mean",
  "units": "1/s2",
  "units_nerc_p06": null,
  "nerc_p01": null,
  "category": {
    "key": null,
    "name": "Physical Oceanography",
    "icon": "cat-physical",
    "realm": "env",
    "order": 1
  },
  "is_unified": false,
  "derivation": "calcofi4db::ctd_n2(smooth_m = 10): gsw_SA_from_SP, gsw_CT_from_t, gsw_Nsquared at the mid-points of the 1 m bins, aligned to the bins by linear interpolation, then a centred 10 m running mean (the CTD team's draft R script, with the running mean in place of its smoothing spline; questions Q11); on the sensor-pair averaged corrected temperature and salinity, final and preliminary_with_bottle casts only; emitted at the depths calcofi_ctd-cast publishes",
  "climatology": true,
  "bounds": {
    "valid_min": -0.2,
    "valid_max": 0.2,
    "declared_by": [
      "buoyancy_n2"
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  "totals": {
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    "n_samples": 9470,
    "n_roots": 9470,
    "n_datasets": 1,
    "year_min": 1993,
    "year_max": 2026,
    "depth_min_m": 6,
    "depth_max_m": 3620,
    "qual_ok_n": 650235,
    "n_flagged": 0
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      "measurement_type": "buoyancy_n2",
      "dataset_key": "calcofi_ctd-derived",
      "source_column": "temperature_ave; salinity_ave_corr; pressure",
      "qual_column": null,
      "description": "Buoyancy (Brunt-Vaisala) frequency squared N2 (TEOS-10), 10 m running mean",
      "units": "1/s2",
      "nerc_p01": null,
      "is_canonical": true,
      "n_values": 650235,
      "n_samples": 9470,
      "n_roots": 9470,
      "n_cells": 113,
      "n_cruises": 139,
      "year_min": 1993,
      "year_max": 2026,
      "depth_min_m": 6,
      "depth_max_m": 3620,
      "years": {
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        "1994": 21114,
        "1995": 19689,
        "1996": 21982,
        "1997": 20852,
        "1998": 30897,
        "1999": 19718,
        "2000": 18847,
        "2001": 18589,
        "2002": 18822,
        "2003": 23201,
        "2004": 23707,
        "2005": 19503,
        "2006": 21280,
        "2007": 20472,
        "2008": 20221,
        "2009": 22684,
        "2010": 21484,
        "2011": 22296,
        "2012": 17980,
        "2013": 20988,
        "2014": 16663,
        "2015": 19738,
        "2016": 22665,
        "2017": 20248,
        "2018": 17672,
        "2019": 14390,
        "2020": 15424,
        "2021": 16414,
        "2022": 14734,
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        "2025": 14435,
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        68806,
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      "depth_bands": {
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        "10-50": 87275,
        "50-100": 106627,
        "100-200": 142171,
        "200-500": 280975,
        "500-1000": 24007,
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        "2000+": 3190
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      "qual": {
        "none": 650235
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      "qual_ok_n": 650235,
      "n_flagged": 0,
      "observed": {
        "min": -0.0181412297844652,
        "p05": 0.00000420523320277488,
        "p50": 0.0000312228836582479,
        "p95": 0.000293151831130287,
        "max": 0.0170579277803867
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      "out_of_bounds": {
        "n": 0,
        "min": null,
        "max": null
      },
      "flags": [
        "no_flag_at_grain",
        "no_p01"
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    }
  ],
  "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 buoyancy frequency squared N² says how strongly the water column resists vertical mixing at each depth: large where layers are stacked tightly, near zero in a mixed layer, so it maps the layers and the mixing between them along a transect.",
      "bibkeys": [],
      "source_url": null,
      "eov": "Subsurface temperature",
      "goos_doc": "https://goosocean.org/document/17501"
    },
    {
      "rank": 2,
      "kind": "authored",
      "text": "TEOS-10 gsw_Nsquared on the 1 m bins of the sensor-pair averaged temperature and salinity, smoothed with a 10 m running mean (Rasmus Swalethorp, SIO, 2026-09-24).",
      "bibkeys": [],
      "source_url": null,
      "eov": "Subsurface temperature",
      "goos_doc": "https://goosocean.org/document/17501"
    },
    {
      "rank": 3,
      "kind": "wikipedia",
      "text": "Brunt–Väisälä frequency",
      "bibkeys": [],
      "source_url": "https://en.wikipedia.org/wiki/Brunt%E2%80%93V%C3%A4is%C3%A4l%C3%A4_frequency",
      "eov": "Subsurface temperature",
      "goos_doc": "https://goosocean.org/document/17501"
    }
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