Abstract: Based on the daily precipitation observation dataset of stations from 1951-2004 in China, gamma function was used to define the extreme precipitation event and calculate the probability distribution of daily precipitation; then, relationship between ENSO and seasonal frequency of extreme precipitation events in China was studied. Results reveal that ENSO events are able to impact China'sextreme precipitation events in different regions, at different seasons. Generally, during winter and spring, extreme precipitation events may come forth in more regions during El Nino events than during La Nina events; while during summer and autumn, the opposite is true. Meanwhile, as for the time-lag relationship between ENSO and extreme precipitation frequency, the extreme precipitation events more easily occur in several regions if the central-eastern tropical Pacific is in ENSO warm phase two seasons ago. Therefore, the impact of El Nino and La Nina on the frequency of China's extreme precipitation events is asymmetrical.

Key words: extreme precipitation, gamma function, ENSO, Nino 3.4, sea surface temperature (SST)