Field distribution of magnetograms from simulations of active region formationS. Dacie, L. van Driel-Gesztelyi, P. Démoulin, M. G. Linton, J. E. Leake, D. MacTaggart and M. C. M. CheungA&A, 606 (2017) A34DOI: https://doi.org/10.1051/0004-6361/201730767