A study on the precipitation concentration in a Chinese region and its relationship with teleconnections indices

Abstract

• Two annual PC indices, CID year and CIM year , have an obviously positive correlation. • Downward trend of CID year / CIM year becomes more distinct from southwest to northeast. • Winter/autumn PC is higher and more variable than spring/summer PC in the HRB. • PC of the HRB is negatively affected by ENSO/PDO with distinct spatial patterns. • ENSO has more pronounced negative effects on seasonal PCs of the HRB compared to PDO. Investigating precipitation concentration (PC) is significant for a deeper understanding of the formation of floods and droughts. Taking a Chinese region, Huaihe River basin (HRB), as the study area, this study analyzed the spatial and temporal variations of annual/seasonal PCs and their teleconnections with El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). Specifically, the daily and monthly precipitation data are employed to build two annual indices ( CID year and CIM year ) and four seasonal PC indices. The modified Mann-Kendall test is used to identify the significant trends of PC indices. Besides, the correlation test and cross wavelet transform are used to examine the relationship between CID year and CIM year , the spatiotemporal characteristics of PC indices, and the teleconnections of PC indices with ENSO and PDO. The results show that (1) CID year has a significantly positive correlation with CIM year , and shows a dominate downward trend across the HRB; (2) the precipitation temporal distribution in winter and autumn is more variable and more irregular than that in spring and summer at the HRB; (3) the annual and seasonal precipitation temporal distribution of the HRB become more variable and more irregular with increasing latitude, and the downward trends of CID year and CIM year tend to be more significant with increasing latitude and longitude; (4) ENSO and PDO have potentially negative effects on the annual and seasonal PCs of HRB, and their negative impacts on the annual PC significantly strengthen from south to north in the HRB; and (5) Compared with PDO, ENSO has more pronounced negative impacts on seasonal PCs of the HRB, and its negative impacts on summer PC and winter PC decrease and increase from west to east of HRB, respectively. These findings could provide a new perspective for understanding regional precipitation temporal distribution.