Characteristics and physical mechanisms of the dipole precipitation variations in the Asian drylands over the past millennium based on proxy-model comparisons

Investigating the spatiotemporal variations in hydroclimate is essential for addressing the challenges posed by future climate change. The Asian drylands, encompassing Arid Central Asia (ACA) and West Asia (WA), are regions where water vapor transport is predominantly governed by the westerlies. These regions have exhibited a dipole pattern in precipitation variations over recent decades and throughout the Holocene. However, whether this pattern persisted during the past millennium remains uncertain. Our study reveals that both proxy records and PMIP4 models consistently identify a dipole precipitation pattern between ACA and WA on centennial scales over the past millennium. This pattern is attributed to inconsistent seasonal precipitation changes. During the Medieval Warm Period, ACA experienced decreased winter-spring precipitation, while WA observed increased summer rainfall. This trend reversed during the Little Ice Age. The seasonal shifts in precipitation are likely driven by the migration of the westerlies, influenced by internal variability within the Earth's system, particularly the North Atlantic Oscillation (NAO). These findings provide valuable insights for policymakers aiming to address water management challenges in Asia's drylands, offering a foundation for strategies to mitigate and adapt to the impacts of future climate change.