Recently a big progress has been made on the measurements of magnetic helicity of solar active regions based on photospheric magnetograms . In this paper, we present the details of Chae's method of determining the rate of helicity transfer using line-of-sight magnetograms such as taken by SORO /MDI. The method is specifically applied to full-disk magnetograms that are routinely taken at 96-minute cadence.

• JONGCHUL CHAE(Astronomy Program, School of Earth and Environmental Science, Seoul National University)
• HYEWO JEONG(Astronomy Program, School of Earth and Environmental Science, Seoul National University)