Assessing historical snowfall patterns in Seoul from 1625 to 1907 CE in relation to the Grand Solar Minima

The Sun is the primary energy source driving the Earth's climate system. A prevailing hypothesis suggests that even minor variations in solar activity, when amplified by climate system feedback mechanisms, can induce significant climatic changes on decadal to centennial timescales. However, the limited availability of historical winter climate proxies has impeded consensus on how solar variability influences the long-term winter climate in Northeast Asia, particularly during Grand Solar Minima (GMs). In this study, we analyzed daily-resolution snowfall records in Seoul from 1625 to 1907 CE, derived from the Korean official historical chronicle Seungjeongweon Ilgi. This period encompasses both the Maunder Minimum (1645–1715 CE) and the Dalton Minimum (1790–1830 CE) of solar activity. Our findings indicate that during the GMs, the first date of annual snowfall (FDS) was delayed by approximately 10 days, and the average annual snowfall frequency (ASF) was reduced by half compared to non-GM periods. Additionally, while an 11-year solar cycle was evident in the ASF during non-GM periods, this cycle was replaced by a shortened 8- to 9-year cycle during the GMs. These variations suggest a differential regional climatic response to prolonged changes in solar activity, and provide historical insights that enhance our understanding of the potential impact of low solar activity on the winter climate in Northeast Asia.