Solar radiation in the Arctic during the Early Twentieth Century Warming (1921–1950), presenting a compilation of newly available data

The study was carried out as a part of the scientific project titled ‘‘Causes of the early 20th century Arctic warming,’’ funded by the National Science Centre, Poland (Grant 2015/19/B/ST10/02933), and the Research University—Initiative of Excellence: The Emerging Field ‘‘Global Environmental Changes,’’ Climate Change Research Unit at Nicolaus Copernicus University in Torun.