Regional Characteristics of Long-Term Variability of Summer Precipitation in the Poyang Lake Basin and Possible Links with Large-Scale Circulations

Abstract

Understanding the spatiotemporal regime of summer precipitation at local scales plays a key role in regional prevention and mitigation of floods disasters and water resources management. Previous works focused on spatiotemporal characteristics of a region as a whole but left the influence of associated physical factors on sub-regions unexplored. Based on the precipitation data of 77 meteorological stations in the Poyang Lake basin (PYLB) from 1959 to 2013, we have investigated regional characteristics of summer precipitation in the PYLB by integrating the rotated empirical orthogonal function (REOF) analysis with hierarchical clustering algorithm (HCA). Then the long–term variability of summer precipitation in sub-regions of the PYLB and possible links with large–scale circulations was investigated using multiple trend analyses, wavelet analysis and correlation analysis. The results indicate that summer precipitation variations in the PYLB were of very striking regional characteristics. The PYLB was divided into three independent sub-regions based on two leading REOF modes and silhouette coefficient (SC). These sub-regions were located in northern PYLB (sub-region I), central PYLB (sub-region II), and southern PYLB (sub-region III). The summer precipitation in different sub-regions exhibited distinct variation trends and periodicities, which was associated with different factors. All sub-regions show no trends over the whole period 1959–2013, rather they show trends in different periods. Trends per decade in annual summer precipitation in sub-region I and sub-region II were consistent for all periods with different start and end years. The oscillations periods with 2–3 years were found in summer precipitation of all the three sub-regions. Summer precipitation in sub-region I was significantly positively correlated with the previous Indian Ocean Dipole (IOD) event, but negatively correlated with East Asian Summer Monsoon (EASM). While summer precipitation in sub-region II and sub-region III showed weak teleconnections with climate indices. All of the results of this study are conducive to further understand both the regional climate variations in the PYLB and response to circulation patterns variations.

Assessment of Precipitation Variability and Trends Based on Satellite Estimations for a Heterogeneous Colombian Region

“…The principal components (PC) mode one-time series is correlated with rainfall to identify the significant regions over the Magdalena Department. They reflect the spatial and temporal distribution structure of meteorological factors [53]. Mathematically, the EOF analysis can be expressed as:…”

“…where Z(x, y, t) is the function at space (x, y) and at the time (t), the spatial structure concerning the temporal variance of Z is, therefore, represented by EOF (x, y). The key component that explains how each EOF's amplitude varies with time is PC (t) [53]. The eigenvalues provide a percentage measurement of variance explained by each pattern.…”

Rainfall Variability and Teleconnections with Large-Scale Atmospheric Circulation Patterns in West-Central Morocco

“…This warming is often accompanied by precipitation anomalies [2,3] and changes in atmospheric circulation. The link between these precipitation anomalies and global atmospheric circulations has long attracted the attention of researchers, and it is the subject of several studies and investigations in various regions of the world [4][5][6][7][8][9][10][11][12]. In the northern part of the Mediterranean, for example, the results of Tabari and Willems (2018) [13] show a large impact of the winter North Atlantic Oscillation (NAO) and the summer Western Mediterranean Oscillation (WeMO [14]) on the extreme variability of precipitation, with significant relationships of 70% and 45%, respectively.…”