Understanding the inter-decadal variability of autumn precipitation over North Central China using model simulations

摘要

A recent study has shown a robust relationship between the Pacific Decadal Oscillation (PDO) and inter-decadal variations in autumn precipitation over North Central China (NCC). However, the physical processes underlying these inter-decadal precipitation variations are not fully understood. Here we analyse multi-member ensembles of atmospheric reanalysis and model simulations to examine the atmospheric and precipitation responses to sea surface temperature (SST) forcing. Despite the large inter-member spread resulting from atmospheric internal variability, the model simulations forced by the observed SSTs show an important role of mid-latitude atmospheric circulation in influencing the inter-decadal precipitation variations over NCC. We also analyse the sensitivity experiments using three atmospheric models forced by the Inter-decadal Pacific Oscillation (IPO)/PDO-like SST fields. The results suggest that the SST anomalies associated with a negative IPO phase can induce anomalous positive pressure anomalies over the East Asia-Japan-North Pacific region, which weakens the East Asian trough (EAT) and produces southerly advection of warm and moist air into NCC, leading to increased precipitation there. This study provides a depiction of how the IPO/PDO-associated SSTs induce inter-decadal oscillations in mid-latitude atmospheric circulations, which in turn cause inter-decadal precipitation variations over NCC.