Variability of the precipitation over the <scp>Tianshan Mountains, Central Asia</scp> . Part I: Linear and nonlinear trends of the annual and seasonal precipitation

The Tianshan Mountains, with their status as ‘water tower’, receive quantities of precipitation that are among the highest in Central Asia. There considerable knowledge gaps regarding understanding spatial and temporal patterns over this water-scarce region. Based on Global Precipitation Climatology Centre (GPCC) data set, study evaluated variations Mountains different time scales by using Mann-Kendall (M-K) test approaches ensemble empirical mode decomposition (EEMD) method. results show (a) most parts experienced increasing annual during 1950–2016 while Western Tianshan, which is wettest region, faced a downtrend same 67 years; (b) has exhibited high-frequency 3- 6-year quasi-periods low-frequency 12-, 27-year quasi-periods. On decadal scale, had two dry periods (1950–1962 1973–1984) wet (1962–1972 1985–2016) tendency continuous humidification since 2004; (c) shows strong seasonality. In total, 63.6% all falls spring summer. Distinctive differences found seasonal sub-Tianshan regions. Obvious upward trends Eastern were seasons, entering humid period early 1986. Northern decreasing trend summer spring. However, other those regions have been 1990s. showed an autumn. obvious downward winter led to these seasons from 1997–2014 2008–2016, respectively.