Historical trends and future projections of compound cloudy-rainy events during the global winter wheat harvest phase

Abstract

Compound cloudy-rainy events (CCREs), characterized by prolonged rainfall and extensive cloud cover, when occurring during the harvest phase, could adversely affect the drying, harvesting, and transportation of mature grains, and even lead to grain mold and sprouting. However, existing studies have focused more on the growth phases, while trends in CCREs during the harvest phase have been largely undocumented. Here we investigated the spatial-temporal variations of CCREs during the harvest phase of winter wheat globally for the historical (1985–2022) and future (2015–2074) periods. Our results reveal a significant decrease in CCREs during the winter wheat harvest phase on a global scale across the two periods. Spatially, reduced cloudy-rainy days cover about 60 % of the winter wheat-producing area. Additionally, the trend patterns of CCREs exhibit considerable spatial heterogeneity. Specifically, pronounced increases are primarily located in eastern North America, western Europe, and eastern Asia, where agricultural mechanization levels are higher. Meanwhile, the asynchronous trends between cloudy days and rainy days lead to spatial variability in the underlying causes of the observed increases in CCREs across these regions. Overall, the results of this study provide novel insights into agricultural climate mitigation and adaptation for global food security.