The transport of mass, momentum and energy at the magnetopause often occurs in a patchy and time-dependent manner, where MHD mesoscale physics is important. The proposed research is to study the MHD mesoscale physical processes using a recently developed macroparticle concept. In particular, the theory of driven reconnection as a process which occurs due to the dynamic interaction of the solar wind and the magnetosheath with the mangetosphere will be developed. This model will be used to quantitatively determine the threshold for the onset of reconnection, the statistical distribution of mesoscale events, and the solar wind-magnetosphere coupling parameters. When the inhomogeneities of the plasma density, velocity and magnetic field are taken into account, the interaction of magnetofluids can be described as the interaction of a number of localized filaments having a relative velocity and carrying different magnetic fields. The interactions between these filaments and between the filaments and the ambient magnetic field play a key role in the transport processes. A macro-particle description involving compressional and shear Alfvenons in cold plasma limit has been introduced to describe these localized filaments (Song and Lysak, 1994a). The properties of these Alfvenons, such as their magnetic dipole moment and polarization, have been described and it has been shown that their interaction can lead to an onset of reconnection depending on the IMF as well as on the dynamic pressure impinging on the magnetopause. The objective of this proposed research is to extend the concept of Alfvenons, which provides a theoretical basis for patchy and time- dependent driven reconnection, and to pursue further the quantitative evaluation of the solar wind-magnetosphere coupling parameter and the statistical prediction of the transient magnetic field events.
