Quantifying the Trends and Variations in the Frost-Free Period and the Number of Frost Days across China under Climate Change Using ERA5-Land Reanalysis Dataset

Understanding the spatio-temporal variations in frost-free period (FFP) and number of frost days (FD) is beneficial to reduce harmful effects climate change on agricultural production enhancing adaptation. However, FFP FD their response remain unclear across China. To investigate impact FD, trends China from 1950 2020 were quantified using ERA5-Land, a reanalysis dataset with high spatial temporal resolution. The results showed that ERA5-Land has good applicability quantifying under change. distribution multi-year average significant latitudinal zonality altitude dependence, i.e., decreased increasing latitude altitude, while increased altitude. As result warming China, an trend increase rate 1.25 d/10a maximum individual region was 6.2 d/10a, decreasing decrease 1.41 −6.7 d/10a. Among five major zones subtropical monsoon zone (SUMZ) greatest 1.73 FFP, temperate (TEMZ) −1.72 FD. In addition, coefficient variation (Cv) greater variability at higher altitudes, Cv lower latitudes southern Without considering adaptation temperature crops, general both terms promoting longer growing reducing damage crops. This study provides comprehensive understanding change, which great scientific significance for adjustment layout adapt