The role of magnetic reconnection in the onset of solar flares and CMEs

K. Kusano

Earth Simulator, JAMSTEC

As understanding the onset mechanism of flares and CMEs is crucially important for the task of forecasting space weather, it still remains in a developing stage and very much in dispute. In this talk, we will give a brief review of the onset models, and discuss about the role of reconnection based on the results of the new numerical modeling.

Since it is likely in complicated dynamical systems that the interaction between different modes of different scales controls the transition process from a static state to a dynamic state, we have to investigate not only the detail dynamics at respective scale, but also the mutual feedback between different scales, in order to understand the physical mechanism of sudden onset of flares and CMEs. From this point of view, we are developing the several types of simulations for magnetic reconnection-related phenomena. In this talk, we present the current status of our attempt for three types of simulation studies: First, the kinetic-MHD coupling simulation, second, the high-resolution MHD simulation of nonlinear tearing mode instability, and third, the large-scale global simulation of solar eruption.

Based on the results, we will discuss about the possibility that magnetic reconnection may play different roles in the onsets of flares and CMEs, and propose a physical scenario, in which the mutual feedback between the resistive and ideal MHD instabilities may control the onset of flares and CMEs. Finally, we will try to mention also about similarity between the onset of solar eruption and that of geomagnetic substorm.