Propagation threshold from meteorological to agricultural drought and its potential influence factors

Quantifying the propagation threshold (PT) from meteorological drought (MD) to agricultural drought (AD) is vital for constructing resilient agricultural systems. This study quantitatively analyzes the propagation thresholds from MD to MD in different climatic regions of China by using a drought propagation model constructed with Copula. It also reveals the impacts of vegetation types, irrigation methods, and atmospheric circulation on the PT. The study found that (1) both the duration and severity of MD are greater than those of MD. MD duration in northwest China is significantly higher than MD, reaching over six months. In eastern China, the increase in MD duration exceeds that of MD by 25 months, and the increase in MD severity is 10 higher than that of MD. (2) The PT of drought increases with the severity of MD. The MD transmission risk in northeast China is significantly lower than that in the Qinghai-Tibet Plateau and northwest arid regions. The drought propagation threshold (DPT) is highest in Zone II (North China Plain/Mid-east China), ranging from 4.0 to 4.8. Compared to other climate zones, the DPT is lowest in the Qinghai-Tibet Plateau (Zone VII). (3) Vegetation type and irrigation method have a significant impact on the DPT. The DPT is highest in agricultural land among different vegetation types, ranging from 4.0 to 5.0, followed by forest land. While the DPT is lowest in shrubland and grassland. The DPT in double-cropping and triple-cropping irrigated areas is about 0.5 higher than that in rainfed crop areas. Atmospheric circulation negatively influences drought propagation, with La Nina and ENSO both extending the duration by approximately one month. The findings provide theoretical support for exploring the causes of MD and its propagation mechanism, and offer new perspectives for studying the transmission mechanisms among different types of droughts.