Temporal–Spatial Distribution Characteristics of Winter Cold Hazards with and without Precipitation in China

According to the nationwide records of cold weather hazards combined with high-precision reanalysis data (NASA MERRA2) during the winter season (November–March) from 1980 to 2020, a daily dataset of low-temperature hazards (including low temperature, abrupt temperature drop, freezing, rain and snow, and snowstorm) in China was constructed. Through linear trend analysis, ensemble empirical mode decomposition, and wavelet analysis, the temporal and spatial distribution characteristics of various cold hazards in China were studied. The results show that cold hazards without precipitation (namely low temperature, abrupt temperature drop, and freezing) are generally caused by a combination of two or more types of cold hazards, while cold hazards with precipitation (namely rain and snow, snowstorm) are generally caused by a single type. The occurrence frequency of various cold hazards exhibits significant regional and seasonal differences. Low-temperature hazards affected the widest area in January, and the occurrence frequency followed a “high–low–subhigh” distribution from south to north. The occurrence frequency of abrupt temperature drop was the highest in December with a distribution pattern of “high-in-the-East and low-in-the-West”. Rain and snow occurred most frequently in southern China from January to February. Snowstorms occur more frequently than other types of cold hazards and are mainly distributed in susceptible regions such as pastoral areas. On the national scale, the occurrence frequencies and affected areas of most cold hazards (except snowstorms) exhibit a long-term increasing trend with time. However, the occurrence of snowstorms exhibits an increasing trend in the affected areas, particularly in January, and a decreasing trend in the occurrence thereafter, particularly in March. The interdecadal variability of the occurrences and affected areas of most cold hazards (except snowstorms) increased after the 2000s, while the interdecadal variability of snowstorms was higher prior to the 2000s. The interannual variability of the frequency of cold hazards (except snowstorms) considerably increased after 2005. Among single-type hazards, only the areas affected due to abrupt temperature drops showed a significantly increasing trend, particularly in January. For the compound-type cold hazards, the combination of abrupt temperature drop and cold hazards with precipitation showed a significant increase.