Testing a new approach for event-oriented magnetospheric modelling

Accurate mapping along magnetic field lines using magnetic field models is a crucial problem in all multi-spacecraft or satellite-ground comparison studies. We show test results of a new approach which allows the use of both high-altitude magnetic field and low-altitude particle boundary measurements as input data. This method, being a combination of the traditional approach and novel remote sounding method (Isotropic Boundary Algorithm), utilizes the modified T89 model functions to describe the external field and can significantly improve the constrain of the free model parameters in event studies. Using this new approach, we modelled the magnetospheric configuration for a number of substorm growth phase events and a few steady convection events using either magnetospheric data or energetic particle data. We found that both approaches usually result in similar parameters of magnetospheric models in the domain covered by observations if the utilized data set is sufficiently large. We also discuss the inferred characteristics of the tail current during these events in light of the substorm triggering problem.