Magnetic energy injection mechanism via flux emergence
Flux emergence is a dynamic process involving interactions between surface flow and magnetic field, injecting magnetic energy into a solar atmosphere. To make a quantitative evaluation of the energy injection via the flux emergence, we defined the emergence velocity vemg, a physical quantity based on the angle
between velocity field vector and magnetic field vector. A key feature of this quantity is that it represents the net effect of the surface flow (= vertical flow + horizontal flow) on the energy injection (net emergence when vemg > 0; net submergence when vemg < 0). Using the emergence velocity, we demonstrated that geometric
shape of emerging field line plays an important role in the energy injection.
Reference
Magara, T. 2011 ApJ, 731, 122
net emergence (left panel; vemg > 0) and net submergence (right panel; vemg < 0)
Energy injection at early and late phases of flux emergence
