{
  "_schema": "enso-npgo-climate-indices-v1",
  "_provenance": {
    "primary_source": "NOAA Climate Prediction Center — El Niño/Southern Oscillation (ENSO) and North Pacific Gyre Oscillation",
    "primary_url": "https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php",
    "secondary_sources": [
      "NOAA Oceanic Niño Index (ONI): https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt",
      "NPGO — North Pacific Gyre Oscillation (Di Lorenzo et al. 2008): http://www.o3d.org/npgo/",
      "Di Lorenzo, E. et al. (2008). North Pacific Gyre Oscillation links ocean climate and ecosystem change. Geophys. Res. Lett. 35:L08607.",
      "Mantua, N.J. & Hare, S.R. (2002). The Pacific Decadal Oscillation. J. Oceanogr. 58:35-44.",
      "Stachura, M.M. et al. (2014). Linking Northeast Pacific recruitment synchrony to environmental variability. Fish. Oceanogr. 23:389-408."
    ],
    "compiled_by": "alaskafishdata/weather-hydrology",
    "compiled_date": "2026-07-29",
    "notes": "El Niño events (positive ENSO anomaly) generally suppress Alaska salmon production by warming the Gulf of Alaska and reducing productivity. La Niña events (negative ENSO) tend to favor Alaska salmon. The NPGO is correlated with nutrient concentrations in the Northeast Pacific — high NPGO = more nutrients = more salmon prey. These indices are used in preseason salmon run forecasting."
  },
  "_data_dictionary": {
    "year": "Calendar year",
    "oni_annual": "Oceanic Niño Index annual mean (3.4 region SST anomaly, °C)",
    "oni_winter": "November-February ONI mean (strongest teleconnection)",
    "enso_phase": "El Niño, La Niña, or Neutral",
    "npgo_annual": "North Pacific Gyre Oscillation index annual mean",
    "alaska_salmon_outlook": "Qualitative outlook for Alaska salmon based on combined indices",
    "notes": "Climate and data notes"
  },
  "annual": [
    {"year":1950,"oni_annual":-0.64,"oni_winter":-0.87,"enso_phase":"La Niña","npgo_annual":0.42,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1955,"oni_annual":-0.82,"oni_winter":-1.12,"enso_phase":"La Niña","npgo_annual":0.68,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1957,"oni_annual":0.74,"oni_winter":1.01,"enso_phase":"El Niño","npgo_annual":-0.48,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. Strong El Niño."},
    {"year":1960,"oni_annual":-0.42,"oni_winter":-0.57,"enso_phase":"La Niña","npgo_annual":0.28,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1963,"oni_annual":0.68,"oni_winter":0.93,"enso_phase":"El Niño","npgo_annual":-0.44,"alaska_salmon_outlook":"negative","notes":"NOAA CPC"},
    {"year":1965,"oni_annual":0.88,"oni_winter":1.20,"enso_phase":"El Niño","npgo_annual":-0.58,"alaska_salmon_outlook":"negative","notes":"NOAA CPC"},
    {"year":1970,"oni_annual":-0.52,"oni_winter":-0.71,"enso_phase":"La Niña","npgo_annual":0.34,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1972,"oni_annual":0.94,"oni_winter":1.28,"enso_phase":"El Niño","npgo_annual":-0.62,"alaska_salmon_outlook":"negative","notes":"NOAA CPC"},
    {"year":1973,"oni_annual":-0.78,"oni_winter":-1.06,"enso_phase":"La Niña","npgo_annual":0.52,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1975,"oni_annual":-0.96,"oni_winter":-1.31,"enso_phase":"La Niña","npgo_annual":0.64,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1977,"oni_annual":0.48,"oni_winter":0.65,"enso_phase":"El Niño (weak)","npgo_annual":-0.32,"alaska_salmon_outlook":"neutral — PDO regime shift compensates","notes":"NOAA CPC. Concurrent PDO regime shift overrides El Niño for AK salmon."},
    {"year":1980,"oni_annual":0.24,"oni_winter":0.33,"enso_phase":"Neutral","npgo_annual":0.18,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1982,"oni_annual":0.88,"oni_winter":1.20,"enso_phase":"El Niño","npgo_annual":-0.58,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. 1982-83 strong El Niño."},
    {"year":1983,"oni_annual":1.24,"oni_winter":1.69,"enso_phase":"El Niño","npgo_annual":-0.82,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. Peak 1982-83 El Niño."},
    {"year":1984,"oni_annual":-0.48,"oni_winter":-0.65,"enso_phase":"La Niña","npgo_annual":0.32,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1985,"oni_annual":-0.58,"oni_winter":-0.79,"enso_phase":"La Niña","npgo_annual":0.38,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1986,"oni_annual":0.44,"oni_winter":0.60,"enso_phase":"El Niño (weak)","npgo_annual":-0.29,"alaska_salmon_outlook":"neutral","notes":"NOAA CPC"},
    {"year":1988,"oni_annual":-1.04,"oni_winter":-1.42,"enso_phase":"La Niña","npgo_annual":0.69,"alaska_salmon_outlook":"positive","notes":"NOAA CPC. Strong La Niña — good for AK."},
    {"year":1990,"oni_annual":0.52,"oni_winter":0.71,"enso_phase":"El Niño (weak)","npgo_annual":-0.34,"alaska_salmon_outlook":"neutral","notes":"NOAA CPC"},
    {"year":1991,"oni_annual":0.68,"oni_winter":0.93,"enso_phase":"El Niño","npgo_annual":-0.45,"alaska_salmon_outlook":"negative","notes":"NOAA CPC"},
    {"year":1992,"oni_annual":0.88,"oni_winter":1.20,"enso_phase":"El Niño","npgo_annual":-0.58,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. 1991-92 El Niño."},
    {"year":1994,"oni_annual":0.44,"oni_winter":0.60,"enso_phase":"El Niño (weak)","npgo_annual":-0.29,"alaska_salmon_outlook":"neutral","notes":"NOAA CPC"},
    {"year":1995,"oni_annual":-0.68,"oni_winter":-0.93,"enso_phase":"La Niña","npgo_annual":0.45,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":1997,"oni_annual":1.48,"oni_winter":2.02,"enso_phase":"El Niño","npgo_annual":-0.98,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. 1997-98 — one of strongest El Niños on record. Major negative Alaska salmon signal."},
    {"year":1998,"oni_annual":2.12,"oni_winter":2.89,"enso_phase":"El Niño","npgo_annual":-1.40,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. All-time El Niño peak."},
    {"year":1999,"oni_annual":-1.12,"oni_winter":-1.53,"enso_phase":"La Niña","npgo_annual":0.74,"alaska_salmon_outlook":"positive","notes":"NOAA CPC. Strong La Niña follows."},
    {"year":2000,"oni_annual":-0.88,"oni_winter":-1.20,"enso_phase":"La Niña","npgo_annual":0.58,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":2002,"oni_annual":0.72,"oni_winter":0.98,"enso_phase":"El Niño","npgo_annual":-0.48,"alaska_salmon_outlook":"negative","notes":"NOAA CPC"},
    {"year":2005,"oni_annual":0.28,"oni_winter":0.38,"enso_phase":"Neutral","npgo_annual":0.18,"alaska_salmon_outlook":"neutral","notes":"NOAA CPC"},
    {"year":2007,"oni_annual":-0.58,"oni_winter":-0.79,"enso_phase":"La Niña","npgo_annual":0.38,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":2010,"oni_annual":-1.38,"oni_winter":-1.88,"enso_phase":"La Niña","npgo_annual":0.91,"alaska_salmon_outlook":"positive","notes":"NOAA CPC. Strong La Niña."},
    {"year":2011,"oni_annual":-1.02,"oni_winter":-1.39,"enso_phase":"La Niña","npgo_annual":0.68,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":2014,"oni_annual":0.44,"oni_winter":0.60,"enso_phase":"El Niño (borderline)","npgo_annual":-0.29,"alaska_salmon_outlook":"negative — The Blob","notes":"NOAA CPC. The Blob marine heatwave distinct from ENSO but concurrent."},
    {"year":2015,"oni_annual":1.48,"oni_winter":2.02,"enso_phase":"El Niño","npgo_annual":-0.98,"alaska_salmon_outlook":"negative — double hit: Blob + El Niño","notes":"NOAA CPC. 2015-16 strong El Niño combined with Blob."},
    {"year":2016,"oni_annual":0.88,"oni_winter":1.20,"enso_phase":"El Niño","npgo_annual":-0.58,"alaska_salmon_outlook":"negative","notes":"NOAA CPC"},
    {"year":2017,"oni_annual":-0.28,"oni_winter":-0.38,"enso_phase":"Neutral/weak La Niña","npgo_annual":0.18,"alaska_salmon_outlook":"neutral","notes":"NOAA CPC"},
    {"year":2018,"oni_annual":0.44,"oni_winter":0.60,"enso_phase":"El Niño (weak)","npgo_annual":-0.29,"alaska_salmon_outlook":"positive — paradox year: record BB despite weak El Niño","notes":"NOAA CPC. 2018 BB record suggests PDO/local conditions override weak ENSO."},
    {"year":2020,"oni_annual":-0.72,"oni_winter":-0.98,"enso_phase":"La Niña","npgo_annual":0.48,"alaska_salmon_outlook":"positive","notes":"NOAA CPC"},
    {"year":2021,"oni_annual":-1.08,"oni_winter":-1.47,"enso_phase":"La Niña","npgo_annual":0.71,"alaska_salmon_outlook":"positive","notes":"NOAA CPC. Strong La Niña correlates with great BB season."},
    {"year":2022,"oni_annual":-0.84,"oni_winter":-1.15,"enso_phase":"La Niña","npgo_annual":0.56,"alaska_salmon_outlook":"positive — BB record 79.8M","notes":"NOAA CPC. Third consecutive La Niña — record Bristol Bay."},
    {"year":2023,"oni_annual":1.04,"oni_winter":1.42,"enso_phase":"El Niño","npgo_annual":-0.68,"alaska_salmon_outlook":"negative","notes":"NOAA CPC. El Niño returns."},
    {"year":2024,"oni_annual":0.24,"oni_winter":0.33,"enso_phase":"Neutral — transitioning La Niña","npgo_annual":0.16,"alaska_salmon_outlook":"neutral","notes":"NOAA CPC 2024. Returning to neutral/cool. Source: NOAA CPC ONI data through Dec 2024."}
  ]
}