  Northeast China is the learding food productive base of China. The extreme
precipitation (EP) event seriously impacts agricultural production and social
life. Given the limited understanding of the EP in Northeast China, we
investigate the trend and potential risk of the EP in Northeast China(107
stations) during 1959-2017, especially in early and later summer. For the first
time, the non-stationary generalized extreme value (GEV) model is used to
analyze the trend and potential risk of EP in Northeast China. Moreover, the
mechanisms of EP trends over Northeast China in early and later summer were
studied separately. Negative trends dominate EP in early summer but positive
trends prevail in last summer. It is reasonable to discuss separately in the
two periods. Meanwhile, all return levels are shown to increase trends in EP in
early summer, corresponding to more frequent EP events. Nevertheless, in later
summer, the 2-year return level decreases in location parameter diminish
slightly, and the rare EP (20, 50, and 100-year return levels) slightly
increase with scale parameter. Also, our results show that normal EP frequently
occurs in Liaoning Province, and extreme EP is more likely to occur in Jilin
Province and Heilongjiang Province. The increase of EP in early summer is
mainly influenced by the northeast cold vortex. However, in later summer, the
effect of cold air on EP is stronger in Northeast China, which gives a clear
explanation that the EP does not increase. This study analyzed the trends and
mechanism of return level and EP, which is beneficial for the development of
policy strategies.
