Diurnal variation

{
  "id": "MLC-T-OAG-001129",
  "term": "Diurnal variation",
  "field": "Oil and gas",
  "definition": "A regular, daily fluctuation in the Earth's magnetic field, primarily caused by solar radiation affecting the ionosphere. This natural variation is recorded during magnetic surveys and must be removed from the observed data to isolate anomalies related to subsurface geology. Diurnal corrections are applied using data from a stationary base station magnetometer or from global magnetic observatories.",
  "subject": "Geophysics",
  "url": "https://mlchart.com/terminology/oil-and-gas/diurnal-variation/"
}