Detecting temporal shifts in extreme precipitation regime, and the implications for urban locations and major crops in Illinois

Abstract

ABSTRACT The rainfed agricultural system in Illinois is vulnerable to shifts in extreme precipitation (R95), especially during the cropping season. While previous studies have explored the trends of R95, shifts in R95 regimes remain poorly understood. This study introduces Fisher information theory, a novel approach, to identify regime shifts in R95 between 1950 and 2010. Notably, 50% of stations showed a significant shift primarily between 1965–1985, with increased R95 observed in northern and southern Illinois. Some stations evidenced contrasting trends between pre- and post-regime shift periods on annual and seasonal scales. Southern counties face heightened annual vulnerability, while western counties are at risk during winter and spring. Further, cross-wavelet analysis showed a significant coherence between R95 and Niño 3.4. R95 had minimal impact on corn yield but showed a significant positive correlation with soybean yield. Regime shift analysis of R95 can play a crucial role in improving extreme value analysis and informing policy decisions.