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Model Information

OpenGGCM

The OpenGGCM is a global magnetosphere model that uses a semi-conservative form of the MHD equations to move a single-fluid plasma through cells of a 3-D, stretched cartesian grid. The equations are defined such that plasma energy is conserved. It uses an explicit second-order predictor-corrector finite difference scheme for advancing the equations in time and a hybrid flux-limited first/fourth order scheme for spatial discretization.

Ionosphere model

The OpenGGCM calculates the ionosphere potential from conductances and field-aligned currents determined either by empirical relations or the Coupled Thermosphere Ionosphere Model (CTIM). CTIM models the chemical and photo-chemical reactions in the upper atmosphere, primarily using the inputs of solar radiation and auroral precipitation.

Rice Convection Model (RCM)

The Rice Convection Model (RCM) is a ring current model that solves for the motion of plasma flux tubes due to ionosphere potential and magnetic induction and drift forces. It assumes an isotropic particle distribution, and includes electrons and protons of various energies that are defined by an energy invariant.

The RCM maintains ring current flux tube content on an irregular 2-D ionospheric grid that covers a range of latitudes between 45 and 82 degrees in the northern hemisphere. Particle losses due to charge exchange are estimated from the sunspot number.

Model Coupling

The OpenGGCM passes MHD pressure and density is used to set the RCM boundary conditions. When two-way feedback is specified, the RCM-calculated pressure and density is used to nudge the MHD values toward those provided by the RCM.

Ionosphere potential is provided to the RCM model, and precipitation and field-aligned current information is returned. If specified, the RCM-calculated electron precipitation and field-aligned currents are blended with those calculated by the OpenGGCM. In the case of auroral precipitation, the RCM quantities are used in low magnetic latitudes associated with the RCM domain, and MHD quantities are used at latitudes above that. Field-aligned currents can be used in place of MHD currents.