Cancellation analysis of current density in solar active region NOAA10019 Gaetano De Vita, Antonio Vecchio, Luca Sorriso-Valvo, Carine Briand, Leonardo Primavera, Sergio Servidio, Fabio Lepreti and Vincenzo Carbone J. Space Weather Space Clim., 5 (2015) A28 Published online: 20 August 2015 DOI: 10.1051/swsc/2015029