Influence of pacific decadal oscillation on decadal precipitation variation over the Yellow River Basin

Precipitation in the Yellow River Basin (YRB) shows contrasting decadal changes from 1961 to 2022, with the northern part becoming drier and the southern part becoming wetter. Based on ensemble empirical mode decomposition (EEMD) method, this study finds that the Pacific Decadal Oscillation (PDO) is a key moderator of the decadal variability of precipitation across the YRB. Specifically, precipitation decreases significantly over most parts of the YRB during positive PDO phase, while it increases during negative phase. Further studies revealed that this distribution is closely related to water vapor transport and atmospheric circulation. During the positive PDO phase, the core of the westerly jet (20°N-60°N, 80°E-160°E) is located over the northwest of the YRB, generating a cyclonic circulation at its southeastern periphery. Meanwhile, the water vapor is dominated by divergence, resulting in insufficient water vapor conditions. This configuration inhibits upward movement and suppresses precipitation in the basin. In contrast, during the negative phase of the PDO, the westerly jet receded to the west and weakened, resulting in increased transport of warm moist air from the ocean to the YRB. Multi-model simulation results from the Coupled Model Intercomparison Project Phase 6 (CMIP6) show that the decadal trends of precipitation in the YRB show opposite patterns during the positive and negative phases of the PDO. The YRB precipitation phase reverses under the SSP585 scenario with respect to the historical period, the SSP126, and SSP245 scenarios, which has a profound impact on the future socio-economic development of the YRB. This study provides new insights into the physical drivers of decadal precipitation variability over the YRB, offering a valuable reference for improving future climate projections and regional water resource management.