Ellerman bombs and Type II white-light flares share many common features despite the large energy gap between them. Both are considered to result from local heating in the solar lower atmosphere. This paper presents numerical simulations of magnetic reconnection occurring in such a deep atmosphere, with the aim to account for the common features of the two phenomena. Our numerical results manifest the following two typical characteristics of the assumed reconnection process: (1) magnetic reconnection saturates in ～600-900 s, which is just the lifetime of the two phenomena; (2) ionization in the upper chromosphere consumes quite a large part of the energy released through reconnection, making the heating effect most significant in the lower chromosphere. The application of the reconnection model to the two phenomena is discussed in detail.

The effect of heat conduction on 2.5D magnetic reconnection, similar to that in Kopp-Pneuman model, is numerically studied. It is shown that the heat conduction accelerates the reconnection, increases the amount of shrinkage of the closed field lines, and increases the average rise speed of the SXR loop. MHD slow shocks contribute to the SXR loop heating. When the timescale of heat conduction is shorter than the Alfv

Early observations by the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory indicated that propagating diffuse wave fronts, now conventionally referred to as "EIT waves," can often be seen on the solar disk with a propagation velocity several times smaller than that of H Moreton waves. They are almost always associated with coronal mass ejections. We have previously confirmed the existence of such a wave phenomenon with numerical simulations, which indicate that there does exist a slower moving "wave" much behind the coronal counterpart of the H Moreton wave. Further observations have disclosed many new features of the EITwaves: the waves stop near the separatrix between active regions, sometimes they experience acceleration from the active region to the quiet region, and so on. Here we report onMHD simulations performed to demonstrate how the typical features of EITwaves can all be accounted for within our theoretical model, in which the EITwaves are thought to be formed by successive stretching or opening of closed field lines driven by an erupting flux rope. The relationship between EITwaves, H Moreton waves, and type II radio bursts is discussed, with an emphasis on reconciling the discrepancies among different views of the "EIT wave" phenomenon.

EIT waves are often observed to be propagating EUV enhancements followed by an expanding dimming region after the launch of CMEs. It was widely assumed that they are the coronal counterparts of the chromospheric Moreton waves, though the former are three or more times slower. The existence of a stationary "EIT wave" front in some events, however, posed a big challenge to the wave xplanation. Simulations are performed to reproduce the stationary "EIT wave" front, which is exactly located near the footpoint of the magnetic separatrix, consistent with observations. The formation of the stationary front is discussed in the framework of our model where "EIT waves" are supposed to be generated by successive opening of the field lines covering the erupting flux rope in CMEs.

Observations indicate that reconnection-favored emerging flux has a strong correlation with coronal mass ejectons (CMEs). Motivated by this observed correlation and based on the flux rope model, an emerging flux trigger mechanism is proposed for the onset of CMEs, using two-dimensional magnetohydrodynamic (MHD) numerical simulations : when such emerging flux emerges within the filament channel, it cancels the magnetic field below the flux rope, leading to the rise of the flux rope (owing to loss of equilibrium) and the formation of a current sheet below it. Similar global restructuring and a resulting rise motion of the flux rope occur also when reconnection-favored emerging flux appears on the outer edge of the