Recent changes in climate seasonality in the inland river basin of Northwestern China

Abstract

Representing regional available water and energy conditions, variations in precipitation (P) and potential evapotranspiration (E0) have received much attention in current studies on climate change. However, the changes in their mismatch, i.e. climate seasonality, have rarely been investigated. Considering the seasonal amplitudes of P and E0 (δP and δE0, respectively), as well as their phase difference, a climate seasonality and asynchrony index (SAI) was used to analyze the seasonal distribution of the available water–energy and their mismatch in the inland river basin of Northwestern China (IRB-NWC) during 1960–2017. We found that the annual δP, δE0, and SAI all decreased during the past few decades, indicating that the mismatch between the seasonal available water and energy in IRB-NWC has improved. Attribution analysis conducted by the elasticity method indicated that the changes in δP controlled the variations in SAI throughout the area, with a relative contribution of 43.7%. Furthermore, wavelet analysis indicated that large-scale ocean-atmosphere circulation patterns (including EI Niño Southern Oscillation, Indian Ocean Dipole, Pacific Decadal Oscillation and East Asian Summer Monsoon) were significantly linked with SAI on 2–6 years scale. Our findings may provide valuable information regarding the trends and causes of climate seasonality and aid in predicting and mitigating the effects of potential future climate changes in the dry region.