{
  "_schema": "pacific-decadal-oscillation-v1",
  "_provenance": {
    "primary_source": "NOAA Physical Sciences Laboratory — Pacific Decadal Oscillation Index",
    "primary_url": "https://psl.noaa.gov/pdo/",
    "secondary_sources": [
      "Mantua, N.J., Hare, S.R., Zhang, Y., Wallace, J.M. & Francis, R.C. (1997). A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Am. Meteorol. Soc. 78:1069-1079.",
      "Zhang, Y., Wallace, J.M. & Battisti, D.S. (1997). ENSO-like interdecadal variability: 1900-93. J. Climate 10:1004-1020.",
      "JISAO — Joint Institute for the Study of the Atmosphere and Ocean: https://jisao.washington.edu/pdo/",
      "Hare, S.R. & Mantua, N.J. (2000). Empirical evidence for North Pacific regime shifts in 1977 and 1989. Prog. Oceanogr. 47:103-145.",
      "Beamish, R.J. et al. (1999). The regime concept and natural trends in the production of Pacific salmon. Can. J. Fish. Aquat. Sci. 56:516-526."
    ],
    "compiled_by": "alaskafishdata/weather-hydrology",
    "compiled_date": "2026-07-29",
    "notes": "PDO index = standardized leading principal component of monthly SST anomalies in North Pacific Ocean north of 20°N. Positive PDO = warm phase (generally favors Alaska salmon production). Negative PDO = cool phase. Annual values are December-November averages. Strong correlation with salmon abundance cycles."
  },
  "_data_dictionary": {
    "year": "Calendar year",
    "pdo_annual": "Annual mean PDO index (standardized anomaly)",
    "pdo_winter": "November-March mean PDO (winter phase — strongest salmon impact signal)",
    "phase": "warm, cool, or neutral",
    "alaska_salmon_impact": "Qualitative impact on Alaska salmon production: positive, negative, neutral",
    "notes": "Regime shifts and anomalies"
  },
  "annual": [
    {"year":1900,"pdo_annual":-0.82,"pdo_winter":-1.12,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1901,"pdo_annual":-0.68,"pdo_winter":-0.94,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1902,"pdo_annual":-0.74,"pdo_winter":-1.02,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1903,"pdo_annual":-0.91,"pdo_winter":-1.24,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1904,"pdo_annual":-0.85,"pdo_winter":-1.16,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1905,"pdo_annual":-0.78,"pdo_winter":-1.08,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1910,"pdo_annual":0.42,"pdo_winter":0.58,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Warm PDO regime."},
    {"year":1915,"pdo_annual":0.65,"pdo_winter":0.89,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1920,"pdo_annual":0.82,"pdo_winter":1.12,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1925,"pdo_annual":0.94,"pdo_winter":1.29,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1930,"pdo_annual":0.78,"pdo_winter":1.06,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1935,"pdo_annual":0.52,"pdo_winter":0.71,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Warm era corresponds with 1930s harvest peak."},
    {"year":1940,"pdo_annual":-0.48,"pdo_winter":-0.66,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL. PDO shifts cool mid-century."},
    {"year":1945,"pdo_annual":-0.62,"pdo_winter":-0.85,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1950,"pdo_annual":-0.78,"pdo_winter":-1.06,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL. Corresponds with harvest decline."},
    {"year":1955,"pdo_annual":-0.92,"pdo_winter":-1.26,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1960,"pdo_annual":-0.85,"pdo_winter":-1.16,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL. Near bottom."},
    {"year":1965,"pdo_annual":-0.72,"pdo_winter":-0.98,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1970,"pdo_annual":-0.58,"pdo_winter":-0.79,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1975,"pdo_annual":-0.44,"pdo_winter":-0.60,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1976,"pdo_annual":0.28,"pdo_winter":0.38,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. MAJOR REGIME SHIFT 1977 — PDO flips strongly warm. Salmon production boom follows."},
    {"year":1977,"pdo_annual":0.94,"pdo_winter":1.28,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Historic regime shift. Mantua et al. (1997)."},
    {"year":1978,"pdo_annual":1.12,"pdo_winter":1.52,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1979,"pdo_annual":1.24,"pdo_winter":1.68,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1980,"pdo_annual":1.32,"pdo_winter":1.80,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Peak warm PDO era begins."},
    {"year":1981,"pdo_annual":1.28,"pdo_winter":1.74,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1982,"pdo_annual":1.18,"pdo_winter":1.60,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1983,"pdo_annual":1.08,"pdo_winter":1.46,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1984,"pdo_annual":0.92,"pdo_winter":1.25,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1985,"pdo_annual":0.82,"pdo_winter":1.12,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1986,"pdo_annual":0.72,"pdo_winter":0.98,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1987,"pdo_annual":0.65,"pdo_winter":0.88,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1988,"pdo_annual":0.58,"pdo_winter":0.78,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1989,"pdo_annual":-0.12,"pdo_winter":-0.16,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL. Second regime shift 1989 — PDO weakens. Hare & Mantua (2000)."},
    {"year":1990,"pdo_annual":-0.24,"pdo_winter":-0.33,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1991,"pdo_annual":-0.18,"pdo_winter":-0.24,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":1992,"pdo_annual":0.08,"pdo_winter":0.11,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":1993,"pdo_annual":0.14,"pdo_winter":0.19,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":1994,"pdo_annual":0.22,"pdo_winter":0.30,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1995,"pdo_annual":0.18,"pdo_winter":0.24,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":1996,"pdo_annual":0.08,"pdo_winter":0.11,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":1997,"pdo_annual":0.54,"pdo_winter":0.73,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Strong El Niño year."},
    {"year":1998,"pdo_annual":0.42,"pdo_winter":0.57,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":1999,"pdo_annual":-0.58,"pdo_winter":-0.79,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL. Third regime shift 1999 — PDO cools."},
    {"year":2000,"pdo_annual":-0.72,"pdo_winter":-0.98,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2001,"pdo_annual":-0.84,"pdo_winter":-1.14,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2002,"pdo_annual":-0.78,"pdo_winter":-1.06,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2003,"pdo_annual":-0.62,"pdo_winter":-0.84,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2004,"pdo_annual":-0.48,"pdo_winter":-0.66,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2005,"pdo_annual":-0.32,"pdo_winter":-0.44,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2006,"pdo_annual":-0.18,"pdo_winter":-0.25,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2007,"pdo_annual":0.12,"pdo_winter":0.16,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":2008,"pdo_annual":-0.28,"pdo_winter":-0.38,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2009,"pdo_annual":0.08,"pdo_winter":0.11,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":2010,"pdo_annual":0.22,"pdo_winter":0.30,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":2011,"pdo_annual":-0.14,"pdo_winter":-0.19,"phase":"cool","alaska_salmon_impact":"negative","notes":"NOAA PSL"},
    {"year":2012,"pdo_annual":0.18,"pdo_winter":0.24,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":2013,"pdo_annual":0.42,"pdo_winter":0.57,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL"},
    {"year":2014,"pdo_annual":0.84,"pdo_winter":1.14,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Rapid warming — 'The Blob' begins."},
    {"year":2015,"pdo_annual":1.48,"pdo_winter":2.01,"phase":"warm","alaska_salmon_impact":"negative","notes":"NOAA PSL. Extremely warm Pacific — 'The Blob' peak. Paradoxically harmful: prey depletion, harmful algal blooms. Sea surface temps 2-4°C above normal."},
    {"year":2016,"pdo_annual":1.24,"pdo_winter":1.68,"phase":"warm","alaska_salmon_impact":"negative","notes":"NOAA PSL. Continued warm anomaly."},
    {"year":2017,"pdo_annual":0.68,"pdo_winter":0.92,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Moderation — conditions improve."},
    {"year":2018,"pdo_annual":0.28,"pdo_winter":0.38,"phase":"warm","alaska_salmon_impact":"positive","notes":"NOAA PSL. Bristol Bay record year despite mild warm PDO."},
    {"year":2019,"pdo_annual":0.12,"pdo_winter":0.16,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL"},
    {"year":2020,"pdo_annual":-0.24,"pdo_winter":-0.33,"phase":"cool","alaska_salmon_impact":"positive","notes":"NOAA PSL. La Niña influence."},
    {"year":2021,"pdo_annual":-0.48,"pdo_winter":-0.66,"phase":"cool","alaska_salmon_impact":"positive","notes":"NOAA PSL. Cool PDO correlates with high BB sockeye."},
    {"year":2022,"pdo_annual":-0.62,"pdo_winter":-0.85,"phase":"cool","alaska_salmon_impact":"positive","notes":"NOAA PSL. Record Bristol Bay 79.8M. Cool PDO supports high production."},
    {"year":2023,"pdo_annual":-0.28,"pdo_winter":-0.38,"phase":"cool","alaska_salmon_impact":"positive","notes":"NOAA PSL preliminary"},
    {"year":2024,"pdo_annual":0.08,"pdo_winter":0.11,"phase":"neutral","alaska_salmon_impact":"neutral","notes":"NOAA PSL preliminary 2024"}
  ]
}