Coupling Between the Solar Convection Zone and Corona by Shear Flows Driven by the Lorentz Force

It has long been know that magnetic field near polarity inversion lines (PILs) is nearly horizontal and parallel to the PIL. Observations are showing in increasing detail that vigorous shearing motions in active regions proceed CMEs and produce the build up of energy that drives the eruption. It has recently been shown that such shearing motions are driven by the Lorentz force that naturally arises when bipolar magnetic fields emerge through the photosphere. Here, we examine the degree to which these shear flows couple the convection zone to the corona with a series of larger-scale MHD simulations of emerging magnetic flux ropes. Shearing motions transport flux, energy and magnetic helicity from the submerged portion of the field to the expanding coronal portion, causing a build up which may cause coronal mass ejections.