geopack

Pure Python implementation of Tsyganenko's Earth magnetic field models

The geopack package provides a Python translation of several of Tsyganenko's Earth magnetic field models (originally implemented in FORTRAN). It integrates two modules originally written in Fortran — the geopack coordinate-transformation and internal-field library, and the Tsyganenko external magnetospheric field models T89, T96, T01 and T04 — and is compatible with both geopack05 and geopack08. The package evaluates the internal geomagnetic field from the IGRF and dipole models in GEO, GSM and GSW coordinates; converts cartesian vectors among the GEO, GEI, MAG, GSM, GSE, SM and GSW systems and between geodetic and geocentric coordinates; traces model field lines from an arbitrary point to the Earth's surface or to an outer boundary using any combination of internal and external model; and locates the magnetopause using the Shue et al. (1998) and T96 boundary models. IGRF coefficients are downloaded automatically from NOAA, are represented as time series at millisecond cadence, and are extrapolated outside the tabulated epoch range. All routines take their inputs as arguments and return their outputs, rather than communicating through the shared common blocks of the Fortran and IDL versions. Note that the G parameters of T01 and the W parameters of T04 are not computed by the package and must be supplied by the user; support for T07d is under development.