Quantifying the effects of nonlinear trends of meteorological factors on drought dynamics

Exploring the effects of meteorological factors on drought dynamic is of important significance for in-depth understanding drought formation mechanism and developing strategies to adapt to climate change. Nevertheless, existing studies have neglected the influence of nonlinear characteristics of meteorological factors on drought evolution, as well as their complex interactions, inhibiting in-depth understanding drought formation mechanism and accurate forecasting. To this end, the standardized precipitation evapotranspiration index (SPEI) is adopted in this study to characterize meteorological drought, and the ensemble empirical mode decomposition (EEMD) is used to explore the nonlinear trend of meteorological factors. Moreover, considering that the interaction between meteorological factors brings some uncertainty in quantifying their individual contributions, a new framework for quantifying drought dynamics taking into account nonlinear trends in meteorological factors and their interactions is proposed based on numerical experiments under eight climate experiments. The Loess Plateau (LP), where drought occurs frequently and its ecological environment is very fragile, is selected as a case study. Results show that: (1) the LP generally shows a drying trend on annual and seasonal scales except for summer especially for its northwest; (2) the interaction between meteorological factors affects the evolution of drought. Eliminating the interactions, the dominant factor on annual SPEI trend is wind speed, both in spring and winter, while sunshine hours and precipitation dominate summer and autumn SPEI trend, respectively; (3) the positive trend contribution of sunshine hours to SPEI is greater than the negative contribution of temperature in summer, and its decline plays an important role in alleviating the drought on the LP in summer. In general, this study sheds a new insight into quantifying the nonlinear effects of meteorological factors to drought dynamics. Relevant findings will help to further understand the mechanism of drought formation under changing environments and provide scientific and technical support for drought early warning and scientific response.

Automated summary

It is important to study the effects of meteorological factors on drought dynamic in order to understand the drought formation mechanism and develop climate change adaptation strategies. However, existing studies have overlooked the nonlinear characteristics and complex interactions of meteorological factors, hindering accurate forecasting and understanding of drought formation mechanism. This study proposes a new framework for quantifying drought dynamics, considering the nonlinear trends and interactions of meteorological factors. The findings provide valuable insights into the nonlinear effects of meteorological factors on drought dynamics, contributing to the understanding of drought formation mechanism and providing scientific support for drought early warning systems.