Differences in Temperature Variation Between Winter and Summer Across China in Recent Decades

Global warming has attracted widespread attention from scientists and the public. Temperature changes are known to have obvious regional and seasonal characteristics. Here, we explore the spatial and temporal differences in the variation of winter and summer temperatures in China using meteorological observations recorded between 1961 and 2020 to analyse the mean temperature, diurnal temperature range (DTR) and day-to-day temperature variability (DTD). The climatological means, long-term changes and the relationship with the Arctic oscillation (AO) index were detected. The results showed that the mean temperature for the mid-winter days and mid-summer days fluctuated more than those over the entire winter and summer seasons, and both showed regional differences. The average daily temperature increases more in winter than in summer. The DTR decreased in recent decades, with the trend being more pronounced in winter and mid-winter days (−0.19°C/10a and −0.24°C/10a, p < 0.05, respectively) than in summer and mid-summer days (−0.10°C/10a and −0.07°C/10a, p < 0.05, respectively). DTD decreased significantly in winter and mid-winter (−0.016°C/10a and −0.022°C/10a, p < 0.05, respectively) and showed non-significant increasing trends in summer and mid-summer (0.001°C/10a and 0.007°C/10a, respectively). The AO index was shown to be an adequate indicator of variations in average daily temperature, DTR and DTD, being primarily positively correlated with the first parameter and negatively correlated with the latter two. These findings deepen our understanding of the different temperature variations in winter and summer across China.