Based on photospheric vector magnetograms obtained at Huairou Observing Station and BBSO, we studied the evolution of magnetic nonpotentiality and energy transport in NOAA AR 10720. Daily changes of vector magnetic field was analyzed. Shear angle, helicity and free energy density which were deduced from the data were examined.
A New EFR on January 13 brought in magnetic nonpotentiality strong shear angle, free energy and complexity(multiple neutral line and opposite sign helicity) which touched off AR activity, support the idea that upper atmospheres critical state may be made by continues changes on the photosphere.
