Chinese Sunspot Drawings and Their Digitization – (I) Parameter Archives

Based on the Chinese historical sunspots drawings, a data set consisting of the scanned images and all their digitized parameters from 1925 to 2015 have been constructed. In this paper, we briefly describe the developmental history of sunspots drawings in China. This paper describes the preliminary handling processes that start from the initial scanning to the extraction of parameters, and finally summarizes the general features of this data set. It is the first systematic project in the Chinese solar-physics community to digitize the historical series of sunspot drawings. Our data set fills in an almost 90-year historical gap, which originates from an area spanning 60 degrees from east to west and 50 degrees from north to south and has no continuous and detailed digital sunspot observation information. Being complementary to other sunspot observations in the world, our data set provides abundant information to the long-term solar activity cycles research.