Induction studies with satellite data

摘要: The natural variations of the Earth's magnetic field periods spanning from milliseconds to decades can be used infer conductivity-depth profile interior. Satellites provide a good spatial coverage measurements, and forthcoming missions will probably allow for observations lasting several years, which helps reduce statistical error estimated response functions. Two methods are study electrical conductivity mantle in period range hours months. In first, known as potential method, spherical harmonic analysis geomagnetic is performed, Q-response, transfer function between internal (induced) external (inducing) expansion coefficients determined specific frequency. second approach, depth sounding C-response, vertical component horizontal derivative components, determined. If one these functions frequencies, models interior constructed. This paper reviews discusses possibilities induction studies using high-precision measurements low-altitude satellites. different various presented, with special emphasis on differences analysing data ground stations results scalar satellite (from POGO satellites) vector Magsat mission) demonstrate ability probe space. However, compared obtained much noisier, presumably due shorter time series studies. new indicate higher resistivity oceanic areas than continental areas. since this holds whole 2 20 days, difference not caused purely by (for would expect less longer periods). Further recently launched future satellites needed.