Magnetic helicity is a useful quantity in characterizing the magnetic systems of solar active regions. The purpose of the present work is to check for consistency between the local correlation tracking (LCT) method used to measure helicity injection through the photosphere, and the linear force-free field (LFFF) method used to determine helicity in the corona, based on the principle of helicity conservation in the solar corona. We have calculated the amount of magnetic helicity injected through the photosphere during the first disk passage of AR 10696 using the LCT method initially described by Chae. We have also measured the coronal magnetic helicity as a function of time using the LFFF method. With a value for the force-free , the coronal field is constructed from the extrapolation of the Solar and Heliospheric Observatory (SOHO) MDI magnetograms, then compared with the coronal loops in the EUV images taken by the SOHO EIT. The force-free that best fits the loops is used to calculate the coronal helicity. From a careful comparison of different helicity measurements during each time interval, we have reached the core conclusion that our measurements follow the helicity conservation principle with an uncertainty of $15% and hence support the consistency between the two different methods with the same amount of uncertainty. Subject headingg s: Sun: corona -Sun: coronal mass ejections (CMEs) -Sun: magnetic fieldsSun: photosphere
Technical skills of Dr. Yurchyshyn include many-year experience in solar observations with various groundbased solar instruments, substantial experience with acquisition, processing and scientific analysis of space-based observations, and deep physical understanding and broad knowledge of solar phenomena. He actively participated in design and construction of BBSO's full disk Halpha telescope and developed the telescope control and data acquisition software. Managerial performance Dr. Yurchyshyn has organized several successful research teams as evidenced by his full publication list. He also supervised research of several PhD students. For about 5 years and managed the Global Halpha Network. He oversaw network expansion, data flow as well as the network website and maintenance.
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