We analyze the formation process of delta configuration in some well-known super active regions based on the photospheric vector magnetogram observations. It is found that the magnetic field in the initial developing stage of some delta active regions shows the potential-like configuration in the solar atmosphere, the magnetic shear develops mainly near the magnetic neutral line with the magnetic islands of opposite polarities, and the large-scale photospheric twisted field forms late gradually. Some results are obtained: (1) The analysis of magnetic writhe of whole active regions cannot be limited in the strong field of sunspots, because the contribution of the fraction of decayed magnetic field is non-negligible. (2) The magnetic model of kink magnetic ropes, proposed to be generated in the sub-atmosphere, is not consistent with the evolution of large-scale twisted photospheric transverse magnetic field and the relationship with magnetic shear in some delta active regions completely.

The photospheric current helicity density is a quantity reflected the local twisted magnetic field and relates to the remain of transfered magnetic helicity in the photosphere, even if the mean current helicity density brings the general chiral property in a layer of solar active regions. As the emergence of new magnetic flux in active regions, the changes of photospheric current helicity density with the injection of magnetic helicity into the corona from the sub-atmosphere can be detected. Because the injective rate of magnetic helicity and photospheric current helicity density contain the different means in the solar atmosphere, the injected magnetic helicity probably is not proportional to its remain (current helicity density) in the photosphere. A evidence is that the rotation of sunspots does not synchronize with the twist of photospheric transverse magnetic field in some active regions (such as, delta active regions) completely, as one believes that the rotation of sunspots reflects the magnetic one and connects with the injection of magnetic helicity. They represent different aspects of magnetic chirality. The synthetical analysis of the observational magnetic helicity parameters actually provides a relative complete picture of magnetic helicity and its transfer in the solar atmosphere.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html