# On Field Line Slippage Rates in the Solar Corona

## TL;DR

This paper introduces a new local method to study magnetic reconnection in the solar corona, focusing on field line slippage rates and their connection to magnetic field geometry.

## Contribution

The paper presents a novel local description of magnetic reconnection, linking field line slippage rates to local magnetic field properties.

## Key findings

- The field line slippage rate is connected to the local geometry of the magnetic field through Lorentz force and current density.
- Anomalous resistivity is mathematically equivalent to the dominant non-ideal term in the solar corona under this new framework.
- The approach is demonstrated using an analytical model and a nonlinear force-free extrapolation of coronal magnetic fields.

## Abstract

Magnetic reconnection is one of the fundamental dynamical processes in the solar corona. The method of studying reconnection in active region-scale magnetic fields generally depends on non-local methods (i.e. requiring information across the magnetic field under study) of magnetic topology, such as separatrix skeletons and quasi-separatrix layers. The theory of General Magnetic Reconnection is also non-local, in that its measure of the reconnection rate depends on determining the maxima of integrals along field lines. In this work, we complement the above approaches by introducing a local description of magnetic reconnection, that is one in which information about reconnection at a particular location depends only on quantities at that location. This description connects the concept of the field line slippage rate, relative to ideal motion, to the underlying local geometry of the magnetic field characterized in terms of the Lorentz force and field-aligned current density. It is argued that the dominant non-ideal term for the solar corona, discussed in relation to this new description, is mathematically equivalent to the anomalous resistivity employed by many magnetohydrodynamic simulations. However, the general application of this new approach is adaptable to the inclusion of other non-ideal terms, which may arise from turbulence modelling or the inclusion of a generalized Ohm’s law. The approach is illustrated with two examples of coronal magnetic fields related to flux ropes: an analytical model and a nonlinear force-free extrapolation. In terms of the latter, the slippage rate corresponds to the reconnection that would happen if the given (static) force-free equilibrium were the instantaneous form of the magnetic field governed by an Ohm’s law with non-ideal terms.