Hemispheric Sunspot Numbers 1945-2004: Data Merging from Two Observatories

For the time span 1945 - 2004 from daily sunspot drawings northern and southern relative sunspot numbers are extracted using drawings provided by Kanzelhoehe Solar Observatory, Austria, and Skalnate Pleso Observatory, Slovak Republic. The derived data will be used to improve and extend an already existing catalogue of hemispheric sunspot numbers (Temmer et al., 2002). Since northern and southern solar hemispheres do not evolve in phase during the cycle, hemispheric data are very important for activity studies. In the present paper the compilation of the data for the period 1945 - 2004 is described. Furthermore as a quality check of the derived hemispheric data a regression analysis and the comparison to the international hemispheric sunspot numbers from the Sunspot Index Data Center for the time span 1992 - 2004 is presented.