A preliminary study on the characteristics of quiet time and intrinsic dynamic mechanism of precipitation events in the rainy season in eastern China

To explore the inherent nonlinear dynamic mechanism of precipitation, based on daily precipitation data from April to September for the period 1960—2017 in eastern China, the intensity of precipitation is determined by the percentile threshold method, and the time interval between adjacent same-intensity precipitation events is defined as "quiet time" to describe the duration of the recurrence of the same intensity precipitation. The "average quiet time" is then used to characterize the massive feature of precipitation events with different intensities. Specifically, in a certain period, the intervals are shorter (longer) for the recurrence of the same type of precipitation event while the stronger (weaker) the degree of clustering of precipitation events become, if the average quiet time is shorter (longer). Next, spatial and temporal evolution characteristics of the average quiet time of different intensity precipitation events in eastern China are provided. Further in-depth analysis is conducted with the focus on the inherent nonlinear dynamic characteristics of the precipitation. The results show that the massive feature of general intensity precipitation events is stronger in the middle reaches of the Yangtze River than in other areas, and it is weaker in the southeastern part. The massive feature of extreme precipitation events is stronger in the northern part of China but the opposite is true in the south during 1960—2017. As far as the climatic state evolution process is concerned, the massive feature of the general intensity precipitation group shows a certain enhancement to the south of the Yangtze River, and a weakening trend appears in the southeastern part of eastern China. The cluster characteristic of the extreme precipitation events is weakening in the northeastern part of China but the opposite is true in the south. The probability density function of the quiet time of precipitation events at each station shows a power-law distribution pattern and a scale-free feature in space and time, indicating that daily precipitation is a self-organized critical system in the real world, which provides a new perspective for understanding the internal nonlinear dynamic mechanism of precipitation.