Spatio-temporal comparison of temperature and climatic boundary changes between the northern and southern Mts. Qinling from 1971 to 2022

Six meteorological stations on both the northern and southern sides of the Mts. Qinling were selected as the research objects. Based on the daily average temperature， maximum temperature， and minimum temperature data from 1971 to 2022， the trend analysis method and median fluctuation method were adopted to systematically characterize the temperature change trends and fluctuation characteristics of this region. The main conclusions were as follows：（1） The overall temperature in the Mts. Qinling showed a significant increasing trend； The temperature increase rate in the northern foot was relatively fast， while that in the southern foot was slower；（2） The temperature increase range was the largest in spring and the smallest in autumn；（3） During the research period， the temperature change tendency rate of all months was positive， and for most months， the rate in the northern foot was higher than that in the southern foot；（4） Low temperature was the most important indicator affecting the change of the Mts. Qinling temperature boundary effect， and spring was the season with the highest contribution rate to the regional temperature increase. With the accelerated global warming， the temperature boundary function of the Mts.Qinling as the north-south dividing line had shown a tendency of weakening；（5） Compared with other months， the temperature increase in the Qinling region in January was more prominent， especially after 1998， the temperature increase trend was significant. Combined with the spatial difference that the temperature increased faster in the northern foot and slower in the southern foot， the Mts.Qinling might change from the traditional north-south dividing line of China’s 0 ℃ isotherm in the coldest month to the dividing line of the 1 ℃ isotherm.