Alfvénon, driven reconnection and the direct generation of the field‐aligned current

The patchy and intermittent nature of the solar wind‐magnetosphere interaction suggests that MHD mesoscale processes are important in the description of transport at the magnetopause. In order to deal with the nonlinear electromagnetic interaction of localized fluctuations in a highly inhomogeneous region such as the magnetopause, a quasi‐particle description involving compressional and shear Alfvénons is introduced to give the particle‐like behavior of the corresponding MHD waves. The driven nature of the solar wind‐magnetosphere interaction, and in particular driven reconnection, is discussed in terms of the interactions between these Alfvénons, and between Alfvénons and the ambient magnetic field. The dependence of the threshold conditions for the onset of the driven reconnection on the IMF and the dynamic pressure of the solar wind is calculated by analyzing the generation and interaction of the Alfvénons. The conversion of compressional Alfvénons into shear Alfvénons gives a mechanism for the direct generation of field‐aligned current filaments.