[1] Recently, Cassak and Shay (2007) applied a generalized Sweet‐Parker analysis to derive scaling laws for gross properties of asymmetric magnetic reconnection, including the reconnection rate, outflow speed, and outflow density. This study presents the first comprehensive test of this scaling theory using fully electromagnetic particle‐in‐cell simulations of antiparallel asymmetric magnetic r...

The role of null-point reconnection in a 3D numerical MHD model of solar emerging flux is investigated. The model consists of a twisted magnetic flux tube rising through a stratified convection zone and atmosphere to interact and reconnect with a horizontal overlying magnetic field in the atmosphere. Null points appear as the reconnection begins and persist throughout the rest of the emergence,...

The highly discrete nature of the solar magnetic field as it emerges into the corona through the photosphere, where it is predominantly concentrated into sunspots and magnetic pores, indicates that the magnetic field exists as discrete, isolated flux tubes in the convection zone, and will remain as discrete flux tubes in the corona until it collides and reconnects with other coronal fields. Col...

We present spaceand ground-based observations of the signatures of magnetic reconnection during an interval of duskward-oriented interplanetary magnetic field on 25 March 2004. In situ field and plasma measurements are drawn from the Double Star and Cluster satellites during traversals of the pre-noon sector dayside magnetopause at low and high latitudes, respectively. These reveal the typical ...

Magnetic reconnection is of great interest in many space and laboratory plasmas [1,2], and has been studied extensively for more than four decades. The most important question is that of the reconnection rate. The process of magnetic reconnection, is so complex, however, that this question is still not completely resolved, even within the simplest possible canonical model: twodimensional (2D) i...

Numerical simulations of two-dimensional Magnetohydrodynamic (2D MHD) turbulence reveal the presence of a huge number of sites where magnetic reconnection locally occurs. The properties of this ensemble of reconnection events, that are spontaneously generated by turbulence, have been studied. The associated reconnection rates, computed as the electric field at the neutral points, are broadly di...

Magnetic reconnection is the crucial process in the release of magnetic energy previously stored in the magnetotail in association with substorms. However, energy transfer and dissipation in the vicinity of the reconnection site is only a minor part of the energy conversion. We discuss the energy release, transport, and conversion based on largescale resistive MHD simulations of magnetotail dyn...

This paper presents a numerical model for predicting the evolution of the pattern of ionospheric convection in response to general time-dependent magnetic reconnection at the dayside magnetopause and in the cross-tail current sheet of the geomagnetic tail. The model quantifies the concepts of ionospheric flow excitation by Cowley and Lockwood (1992), assuming a uniform spatial distribution of i...

*Correspondence: Yasuhito Narita, Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz, Austria e-mail: [email protected] Magnetic reconnection in space plasmas remains a challenge in physics in that the phenomenon is associated with the breakdown of frozen-in magnetic field in a collisionless medium. Such a topology change can also be found in superfluid...

We propose a criterion for identifying the orientation of the X-line when two regions of plasma with arbitrary densities, temperatures, and magnetic fields undergo reconnection. The X-line points in the direction that maximizes the (suitably-defined) Alfvén speed characterizing the reconnection outflow. For many situations a good approximation is that the X-line bisects the angle formed by the ...