Magnetic helicity of global field in cycles 23 and 24

摘要: For the first time we reconstruct magnetic helicity density of global axisymmetric field Sun using method proposed by Brandenburg et al. (2003) and Pipin (2013). To determine components vector potential, apply gauge which is typically employed in mean-field dynamo models. This allows for a direct comparison reconstructed with predictions from We to two different data sets: synoptic maps line-of-sight (LOS) Michelson Doppler Imager (MDI) on board Solar Heliospheric Observatory (SOHO) measurements Vector Spectromagnetograph (VSM) Synoptic Optical Long-term Investigations (SOLIS) system. Based analysis MDI/SOHO data, find that solar cycle 23 had positive (negative) northern (southern) hemisphere. hemispheric sign asymmetry opposite active regions, but it agreement The also suggest rule may have reversed its early late phases 23. Furthermore, indicate an imbalance between southern hemispheres. seem correlate total level activity each hemisphere Magnetic rising phase 24 derived SOLIS/VSM qualitatively, latitudinal pattern similar SOHO/MDI