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Abstract

Based on the Solar and Heliospheric Observatory/Michelson Doppler Imager - Debrecen Data (SDD) sunspot catalogue the emergence and decay of the solar active regions and their internal parts, i.e., the leading and following parts will be separately studied on a large number of samples. The growth and decay rates of the sunspot groups depend linearly on their maximum total umbral area. During the development of the groups, the area of the leading parts increases rapidly, and then their decay rates will be smaller. The following parts that contain more but smaller sunspots emerge slower and decay at higher rates. The asymmetry of the compactness is also investigated. At the time of the maximum area, the number of spots is small while their mean area is higher in the leading part. During the decay, this asymmetry varies in three phases and exhibits anticorrelation with size. Hemispheric asymmetry can also be pointed out in the studied sample of solar cycle 23; the asymmetry index and the activity level were higher in the Southern hemisphere. The research leading to these results of the decay has received funding from National Research, Development and Innovation Office - NKFIH, 141895.