Asymmetric changes of maximum and minimum temperatures in the Dabie Mountains, China

Abstract. This study used high-quality daily temperature data from 1960–2019, recorded at five observing stations (Huoqiu, Huoshan, Jinzhai, Lu’an, and Shucheng) in the city of Lu’an (China), to study the asymmetric changes of maximum and minimum temperatures in the region of the Dabie Mountains in western Anhui Province (China). Results showed that changes in annual maximum and minimum temperatures over the studied 60 years were asymmetric; the average climatic trend rate of minimum temperature was 0.262 °C/10a, while that of maximum temperature was 0.198 °C/10a, i.e., the temperature increase of the former was approximately 1.3 times that of the latter. Asymmetric changes of maximum and minimum temperatures were evident in winter, summer, and autumn throughout the entire 60-year period and in spring for the first 45 years. The spatial distribution of the asymmetric changes was uneven with decrease both from high latitudes to low latitudes and from high elevations to low elevations. High-elevation high-latitude areas such as Jinzhai, Lu’an, and Huoqiu exhibited the most significant asymmetric changes seasonally and annually. Abrupt changes in the trends of maximum and minimum temperatures occurred in 1994. Three periodicities were found in the maximum temperature series, i.e., 15–18, 32, and 4–6 years, and four periodicities were found in the minimum temperature series, i.e., 9–10, 32, 20–22, and 4 years. The 4–6-year periodicity of maximum temperature and the 4-year periodicity of minimum temperature (which passed the 95% significance test) should be associated with El Niño.