The influence of the Pacific Decadal Oscillation on North Central China precipitation during boreal autumn

Decadal variations in autumn (September-October-November, SON) precipitation over North Central China since the 1940s are investigated using observations and reanalysis data. They are found to be significantly correlated negatively with the Pacific Decadal Oscillation (PDO). Further analyses indicate that the inter-decadal changes in SON precipitation over North Central China result from anomaly patterns in the large-scale atmospheric circulation in the mid-latitude Northern Hemisphere associated with the PDO. Specifically, during the negative phase of the PDO (1945-1976 and 2003-2014), an anomalous low pressure and cyclonic circulation are seen west of Lake Baikal, while positive pressure anomalies are located over the East Asia-Japan-North Pacific region, which weakens the East Asian trough (EAT). The weakened EAT favours southerly winds over North Central China. The negative pressure anomalies around Mongolia and Lake Baikal induce large-scale ascent motion to the west of the EAT, which also produces southerly advection of warm and moist air into North Central China, leading to increased precipitation there. These results reinforce the notion that PDO has a large impact on SON rainfall over North Central China on decadal timescales and highlight the need to further examine how the PDO induces the Eurasia atmospheric teleconnection pattern (e.g. East Atlantic/Western Russia pattern).