A two-centennial perspective on spatially compounding hydroclimate events in arid and semi-arid north China

Abstract

Spatially compounding hydroclimate events, means the droughts or pluvials occurring concurrently in different areas, are more damaging to society than those occurring locally. However, the short length of instrumental climate data hampers our understanding of the variability and driving mechanism of spatially compounding hydroclimate events in the past. Here, six tree-ring chronologies along a latitudinal gradient from the arid and semi-arid north China were used to analyze the variation of spatially compounding hydroclimate events over the past two centuries (1821–2017 CE). The results show that the frequency of spatially compounding droughts has increased, while that of spatially compounding pluvials has decreased since 1950s. Composite analysis with sea surface temperature indicated that the occurrence of spatially compounding hydroclimate events in the study area was related to El Niño–Southern Oscillation (ENSO) events in the prior winter. Furthermore, we found the phase of Pacific Decadal Oscillation (PDO) modulates the influence of ENSO on spatially compounding hydroclimate events. Compounding drought is most common during El Niño and positive phase of PDO, while compounding pluvials is most common during La Niña and negative phase of PDO. These findings offer a reference for the early warning of drought risk and may benefit disaster prediction and mitigation for the north China.