Recent variations in the seasonality difference between precipitation and potential evapotranspiration in China

Abstract

AbstractThe seasonality difference between precipitation (P) and potential evapotranspiration (E0) has a significant imprint on ecohydrological processes, but little attention has been given to this difference in China. A climate seasonality and asynchrony index (SAI), considering the amplitude and phase difference (PD) between P and E0, was thus applied to investigate the variation in seasonality difference between P and E0 across China from 1960 to 2017. The main results showed that the mean amplitudes of seasonal P (δP) were larger than that of E0 (δE0). Except for in east and central south China, the peak values of E0 had a time lag of 23 days behind those of P. The annual SAI in China showed a significantly downward trend (p < 0.05), suggesting a reduction in the difference in seasonal P and E0 in China. The attribution results showed that the variation in SAI was mainly controlled by δP changes across China with a relative contribution of 60.5%, followed by δE0 (35.9%) and PD (3.6%). Wavelet analysis showed that the annual SAI had a significant relationship with ocean–atmosphere circulation patterns at a scale of 1–6 years (p < 0.05). As an attempt to investigate the difference in seasonal P and E0 in China, the findings of this study can provide a reference for climate seasonality variations and support for the quantification of its effects on the ecohydrological environment.