Abstract:

To enhance the understanding of regional winter temperature variations and provide a scientific basis for optimizing water transfer and management during the ice period of the South-to-North Water Diversion Middle Route Project, we analyzed the daily mean winter temperatures from 1981 to 2021. Data were gathered from 10 national meteorological stations located along the section north of the Anyang River within the main canal of the Middle Route Project. We investigated winter temperature changes over the past 41 years using various methods, including the climate tendency rate method, cumulative anomaly method, Mann-Kendall mutation test, and Morlet wavelet analysis. The results are as follows: 1) From 1981 to 2021, mean winter temperatures at stations north of the Anyang River declined gradually from south to north. This trend is strongly synchronized especially among adjacent stations, with correlation coefficients exceeding 0.9. 2) Over the past 41 years, mean winter temperatures at each station showed a clear warming trend with fluctuations. Significant temperature changes occurred notably in the mid-late 1980s, early 2000s, and early-mid 2010s. 3) Within the analyzed time domain, most stations north of Anyang River followed a 40-year cycle as the primary temporal scale. Mean winter temperatures displayed a cyclical pattern of low→high→low→high and are expected to remain elevated for a period in the future. Such conditions facilitate effective dynamic scheduling during the winter ice period.

Key words: winter temperature, trend analysis, Mann-Kendall (M-K) mutation test method, wavelet analysis, Middle Route of South-to-North Water Diversion Project