Long-term trend of precipitation days for southeast Tibetan Plateau, China

In this paper, the spatiotemporal trend variability of precipitation days (PDs) in the southeast Tibetan Plateau (STP) from 1961 to 2012 is studied on annual and seasonal timescales for the first time. According to the results of the Mann-Kendall (M-K) test, the annual and seasonal area-averaged PDs shows a non-significant tendency except for spring PDs, and the spring PDs shows a significantly increased trend at 95% confidence level during this period. The increase is 6.85 days per 100 years in annual PDs. The maximal increase occurs in spring, which is 7.13 days per 100 years. On the other hand, the PDs and their tendencies have notable spatial distribution variations over the STP. The PDs have some relationship with altitude, but their tendencies are unrelated to altitude in the STP. This study further finds that the Nujiang River is a dividing line for the PDs, and latitude 30 degrees N is such a line for the PDs tendency. The results revealed the local differences of the PDs over the Tibetan Plateau (TP), which is beneficial to understand the variations in precipitation patterns in the STP and gain insights into the change features of the TP under global changes.