A comprehensive model of the quiet-time, near-Earth magnetic field: phase 3

T.J. Sabaka, Nils Olsen, R.A. Langel

Research output: Contribution to journalJournal articleResearchpeer-review


The near-Earth magnetic field is caused by sources in the Earth's core, ionosphere, magnetosphere, lithosphere and from coupling currents between the ionosphere and the magnetosphere, and between hemispheres. Traditionally, the main field (low degree internal field) and magnetospheric field have been modelled simultaneously, with fields from other sources being modelled separately. Such a scheme, however, can introduce spurious features, especially when the spatial and temporal scales of the fields overlap. A new model, designated CM3 (Comprehensive Model: phase 3), is the third in a series of efforts to coestimate fields from all of these sources. This model has been derived from quiet-time Magsat and POGO satellite and observatory hourly means measurements for the period 1960-1985. It represents a significant advance in the treatment of the aforementioned field sources over previous attempts, and includes an accounting for main field influences on the magnetosphere, main field and solar activity influences on the ionosphere, seasonal influences on the coupling currents, a priori characterization of the influence of the ionosphere and the magnetosphere on Earth-induced fields, and an explicit parametrization and estimation of the lithospheric field. The result is a model that describes well the 591 432 data with 16 594 parameters, implying a data-to-parameter ratio of 36, which is larger than several popular field models.
Original languageEnglish
JournalGeophysical Journal International
Issue number1
Pages (from-to)32-68
Publication statusPublished - 2002


  • ionosphere
  • lithosphere
  • magnetosphere
  • Earth's magnetic field
  • geomagnetic variation
  • electromagnetic induction

Fingerprint Dive into the research topics of 'A comprehensive model of the quiet-time, near-Earth magnetic field: phase 3'. Together they form a unique fingerprint.

Cite this