A Systems Approach to the Problems of Solar-Terrestrial Physics

The terrestrial magnetosphere under the influence of the solar wind represents a very complex distributed system. Its evolution involves an enormous number of hydrodynamic and kinetic processes with scales from hundreds of meters to thousands of kilometers. The complexity of the solar terrestrial system is one of the main reasons why comprehensive physical models derived from first principles have not yet been developed. The customary approach adopted in physics is to understand all of the micro-processes involved and then conjugate them into a global model. Currently this ultimate goal is far from being achieved in the case of the terrestrial magnetosphere. Systems science offers a complementary approach. It involves the study of the overall system behaviour and applying knowledge about generic systems in order to advance the understanding of the micro-processes involved. It is shown how the system approach can help to advance the physics of the magnetosphere, or its subsystems (i.e. radiation belts), plasma turbulence and even exotic cases such as the separation of natural signals from interference in spacecraft data. It is also shown that the systems approach and especially frequency domain analysis can be used to validate numerical and analytical models.