Comprehensive study of heavy precipitation events over land using climate network analysis

Heavy precipitation and its derived disasters have a serious consequence on socioeconomic development. Understanding the spatiotemporal variation in heavy precipitation events (HPEs), the driving factors, and the possible mechanisms that trigger spatial teleconnections between HPEs is helpful in predicting and preventing heavy precipitation-related disasters. Here, the spatial distribution and temporal variation in the frequency and intensity of HPEs are analysed. We employ a time-delayed cross-correlation method and an event synchronization method to quantify the influence of the El Niño southern oscillation (ENSO) and Atlantic multidecadal oscillation (AMO) on the monthly frequency change of HPEs, and to reveal the spatial patterns of teleconnections among heavy precipitation over land, respectively. The results indicate that the mean frequency and mean intensity of HPEs have an upwards trend on the global scale. We find that the AMO is weaker in modulating the frequency change of HPEs than ENSO in the Southwest quadrant, and Southeast quadrant, in which more than 8.8 % of the grid points significantly respond with ENSO, and 7 % of the grid points significantly respond with AMO on the global scale. The distance distribution of the synchronization strength network shows that the teleconnections among heavy precipitation may be related to the Rossby waves, 2,600 km is the threshold distance for the shift from the regional weather system to the teleconnection pattern, and 5,500 km is another turning distance for the teleconnection pattern. Our results provide comprehensive insights into the evolutions and spatial relations of HPEs.