EarthRef.org Digital Archive (ERDA) -- Potsdam Magnetic Model of the Earth

Description
The Potsdam Magnetic Model of the Earth (POMME) is a geomagnetic field model providing an estimate of the Earth's core, crustal, magnetospheric and induced magnetic fields. The internal field is represented to spherical harmonic (SH) degree 90, while the secular variation and acceleration are given to SH degree 16. Static and time varying magnetospheric fields are parametrized in Geocentric Solar-Magnetospheric (GSM) and Solar-Magnetic (SM) coordinates
and include Disturbance Storm-Time (Dst-index) and Interplanetary Magnetic Field (IMF-By) dependent contributions. The model was estimated from five years of CHAMP satellite magnetic data. All measurements were corrected for ocean tidal induction and night-side ionospheric F-region currents.

The model was validated using an independent model from a combined data set of Oersted and SAC-C satellite measurements. For the core field to SH degree 13, the root mean square (RMS) vector difference between the two models at the center of the model period is smaller
than 4 nT at the Earth's surface. The RMS uncertainty increases to about 100 nT for the predicted field in 2010, as inferred from the difference between the two models.

The model estimated from CHAMP data is declared as POMME-3.0. For high internal SH degrees, a superior representation of the field is given by the dedicated lithospheric field model MF4 which was also produced only from CHAMP data. We therefore merge degrees 1 to 24 of POMME-3.0 with degrees 25 to 90 of MF4 to produce the final model POMME-3.1. The spherical harmonic coefficients of these models are available here in POMME-3.zip as two separate files of ascii tables.