At sunspot minimum, the solar wind is highly structured by solar latitude. The structure of the solar wind, and of the magnetic field it drags from the Sun to form the heliosphere, varies in a fundamental way with the phase of the sunspot cycle. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. 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.ĬCMC 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 most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. The Tsyganenko model suite also includes GEOPACK library with 20 FORTRAN subroutines. 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. 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 T01 model represents the variable configuration of the inner and near magnetosphere for different interplanetary conditions and ground disturbance levels.

The model was parameterized by the solar wind ram pressure, Dst-index, and transverse components (By and Bz) of the IMF. 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 T89 model was primarily developed as a simple empirical approximation for the global magnetosphere, binned into several intervals of the disturbance index Kp. 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 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).

Solar wind ram pressure