Analysis of geographical origin of solar terms based on the STTMD method

The 24 solar terms are a significant component of traditional Chinese culture. Amid global warming climate change, research on the Solar Terms has gained increasing prominence. Identifying the geographical origins of the Solar Terms not only provides evidence for studies on the origins of Chinese agricultural civilization but also serves as a critical foundation for the innovative utilization of traditional culture in the modern era. Previous research has primarily relied on historical records, literature review, and field investigation, often challenged by the vast and complex data, the difficulty distinguishing authenticity, the time-consuming nature of the work, and the need for direct scientific evidence. The STTMD (Solar Terms Typical Meteorological Day) method was used for typifying solar term meteorological data sequences, supplemented by isothermal estimation and clustering analysis. This approach was further validated using key crop germplasm sites, phenological indicators, and phenological observation contour maps. The results derived from statistical methods are cross-referenced with historical documents to infer the geographical origins of the 24 Solar Terms. The findings indicate that: (1)On a larger spatial scale, the Solar Terms originated in the middle and lower reaches of the Yellow River; (2)On a smaller spatial scale, the "Luoyang-Zhengzhou-Anyang" triangle is the most probable origin area; (3)The core area of origin is hypothesized to be in present-day Xingyang, Henan Province, or slightly further north. These results are consistent with historical literature and phenological records of crops, offering a novel analysis and transformative insights into the knowledge of Solar Terms. The study provides valuable evidence or methodological inspiration for historical agricultural research in China and offers references for agricultural production and the environmental impacts of global warming.