Temporal-spatial variability of modern climate in the Altai Mountains during 1970-2015

Method The treated method (i.e., the Mann-Kendall trend test) was applied to probe the temperature and precipitation trends during the observed period [16, 38–42]. If the slope value is >0, the climate data has a positive trend and the climate data shows a negative trend when the slope value is <0. The data of slope value indicates the rate or the magnitude at which the climate data increases or decreases. Results Temperature trend characters The temperature variations in annual and seasonal scale of the Altai Mountains were showed in Fig 2. The result shows that MAT experienced an increasing trend during the studied inter- val (1970–2015), which had a significance level of 0.01. The increased rate was 0.41˚C/decade in the Altai Mountains during 1970–2015. In the studied interval, about 1.85˚C was the value which the MAT increased (Fig 2A). A significant increase of air temperature was also showed in spring, summer and autumn (Fig 2B–2D), whereas air temperature in winter was statisti- cally insignificant (Fig 2E). Their increased rates were 0.64˚C/decade for spring, 0.43˚C/decade for summer, 0.41˚C/decade for autumn and 0.27˚C/decade for winter, respectively (Fig 2B– 2E). The rising rate of seasonal temperature was the quickest in spring. Fig 3 presented the spatial divergent rates of MAT and seasonal temperature in the Altai Mountains. The significantly positive trends (p<0.05) were observed in MAT among all fifteen stations. The MAT were divergent and the value spanning from 0.28˚C/decade in

Fig 2. Variations of annual and seasonal mean temperature in the Altai Mountains during 1970–2015. https://doi.org/10.1371/journal.pone.0230196.g002 PLOS ONE Modern climate characters in the Altai Mountains PLOS ONE | https://doi.org/10.1371/journal.pone.0230196 March 17, 2020 4 / 15