Tsyganenko Magnetic Field

The Tsyganenko models are semi-empirical best-fit representations for the magnetic field, based on a large number of satellite observations (IMP, HEOS, ISEE, POLAR, Geotail, GOES, etc). The models include the contributions from major external magnetospheric sources: ring current, magnetotail current system, magnetopause currents, and large-scale system of field-aligned currents.

The T89 model was primarily developed as a simple empirical approximation for the global magnetosphere, binned into several intervals of the disturbance index Kp. The T96 model has an explicitly defined realistic magnetopause, large-scale Region 1 and 2 Birkeland current systems, and IMF penetration across the boundary. The model was parameterized by the solar wind ram pressure, Dst-index, and transverse components (By and Bz) of the IMF. The T02 model represents the variable configuration of the inner and near magnetosphere for different interplanetary conditions and ground disturbance levels. It also takes into account the observed dawn-dusk asymmetry of the inner magnetosphere due to the partial ring current that develops during magnetospheric disturbances. The TS05 model is a dynamical model of the storm-time geomagnetic field in the inner magnetosphere, based on space magnetometer data taken during 37 major events in 1996-2000 and concurrent observations of the solar wind and IMF.

The Tsyganenko model suite also includes GEOPACK library with 20 FORTRAN subroutines. The GEOPACK-2008 library includes subroutines for the current (IGRF) and past (DGRF) internal geomagnetic field models, a group of subroutines for transformations between various coordinate systems, a field line tracer, and two magnetopause model codes.

CCMC Web interface for instantaneous calculation of external and internal geomagnetic field along a field line and at a specified point is based on T96 and Geopack08.

The model returns magnetic field for an instance of solar wind and geomagnetic indices. In addition, the TS05 model uses parameters based on time integrals of solar wind data that create an appearance of physical transitions between the magnetic fields returned for each time step.

T89, T96, T02, TS05 use the solar wind ram pressure (nPa), Dst index (nT), IMF By and Bz components (nT), the Earth's dipole tilt angle (radians), and X,Y,Z - GSM position (Re).

Input for the T02 and TS05 models also includes special indices, quantifying the intensity of the solar wind driving of the magnetosphere during the preceding 1-hour interval (T02) or during the entire period from the beginning of a storm (TS05). More information can be found at Nikolai Tsyganenko website, http://geo.phys.spbu.ru/~tsyganenko/empirical-models.

When using the web interface for instantaneous calculation of external and internal geomagnetic field along a field line and at the specified point the user sets the date and time (year, day of the year, UT hour, minute, and second).

The primary output from Tsyganenko models are geomagnetic field components at the selected point in 3D space in GSM coordinates.