{
  "HAPI": "3.3.1",
  "status": {
    "code": 1200,
    "message": "OK"
  },
  "startDate": "1932-01-01T12:00:00Z",
  "stopDate": "2026-09-23T16:00:00Z",
  "cadence": "P1D",
  "timeStampLocation": "center",
  "modificationDate": "2026-09-23T10:35:04Z",
  "title": "Ap Index (Best Available, daily)",
  "description": "Daily planetary geomagnetic index Ap: the arithmetic mean of the eight 3-hourly ap values of the UT day (unit: 2 nT), derived from the Kp index (introduced by Bartels, 1949, and endorsed by IAGA; based on K-values recorded at 13 geomagnetic observatories). Produced by GFZ Potsdam, redistributed by WDC for Geomagnetism, Kyoto. Best Available version: highest processing level per period (currently definitive only). Timestamps are bin centers of the UT day (12:00 UT; timeStampLocation=center).",
  "resourceID": "doi:10.5880/Kp.0001",
  "datasetCitation": "Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O., & Morschhauser, A. (2021). The Geomagnetic Kp Index and Derived Indices of Geomagnetic Activity. Space Weather, 19, e2020SW002641. doi:10.1029/2020SW002641. Kp index data: Matzka, J., Bronkalla, O., Tornow, K., Elger, K., & Stolle, C. (2021), Geomagnetic Kp index, V. 1.0, GFZ Data Services, doi:10.5880/Kp.0001. Redistributed via WDC for Geomagnetism, Kyoto.",
  "licenseURL": "https://creativecommons.org/licenses/by/4.0/",
  "parameters": [
    {
      "name": "Time",
      "type": "isotime",
      "units": "UTC",
      "fill": null,
      "length": 24,
      "label": "Time"
    },
    {
      "name": "apValue",
      "type": "integer",
      "units": null,
      "fill": "999",
      "label": "Ap",
      "description": "Daily equivalent planetary amplitude (unit: 2 nT); mean of the eight 3-hourly ap values."
    },
    {
      "name": "versionCode",
      "type": "integer",
      "units": null,
      "fill": null,
      "label": "Version Code",
      "description": "Processing status code Mm (major*10+minor). Currently a single definitive version (versionCode 20)."
    }
  ],
  "x_LastUpdate": "2026-09-23T15:05:53Z"
}