Spatial and temporal variability of seasonal precipitation in Poyang Lake basin and possible links with climate indices

Based on the precipitation data of 21 meteorological stations in Poyang Lake basin, the temporal and spatial variability of seasonal precipitation was analyzed by wavelet analysis method. This study adopted the cross wavelet transform to analyze the correlation between the seasonal precipitation and climate indices in time and frequency scales, discussed the possible links between its precipitation variations and climate indices, and preliminarily analyzed its mechanism and regular pattern of variation. The results showed that the oscillations in 2-4 years' and 4-8 years' bands were the main variation periods of seasonal precipitation in Poyang Lake basin. In the 2-4 years' band, the years of rainfall peaks appearing in Poyang Lake were basically consistent with the years when El Nino appeared, and the precipitation oscillations in summer appeared more dramatic in space. According to analysis on the cross wavelet power spectra between different seasonal rainfalls and climate indices, certain correlations between climate factors and seasonal precipitation had existed in specific time periods. Large-scale climate oscillations like the El Nino/Southern Oscillation, North Atlantic Oscillation, Indian Ocean Dipole, and Pacific Decadal Oscillation caused the variability of large-scale circulations through their respective independent or inter-coupled climate systems, and affected the precipitation distribution in Poyang Lake basin by changing local climate conditions like the East Asian Monsoon.