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

Abstract

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).

Analysis for Spatio-Temporal Variation Characteristics of Droughts in Different Climatic Regions of the Mongolian Plateau Based on SPEI

“…Before 1999, PDO is the dominant factor. After year 1999, AMO is deemed more relevant to drought in MP, especially in summer [51], supported by a significant Pearson's r in Table S1. Droughts in summer have an adverse impact on vegetation growth, especially in agricultural and pastoral areas, which are totally dependent on natural precipitation.…”

An assessment of the impact of Pacific Decadal Oscillation on autumn droughts in North China based on the Palmer drought severity index

“…Additionally, differences might exist between our results and the results for drought events defined using only precipitation data, which might mostly represent the precipitation conditions during SON (e.g.Gao and Yang, ; Qian and Zhou, ; Qin et al ., ). To further understand these differences, a precipitation index (PI) is constructed using the normalized area‐averaged SON precipitation over North China (PI).…”

“…Therefore, drought events will intensify in some areas. Previous studies have revealed that North China, a semiarid region, has experienced severe and prolonged dry periods since the late 1990s (e.g., Zou et al, 2005;Qin et al, 2018). In the study by Wang and Zhai (2003), all of the grades of droughts measured by the "Z" index, which is used by the National Climate Center of China as a tool for the operational real-time monitoring of drought and flood events, showed expanding trends in the main agricultural areas of North China.…”

“…Mantua et al, 1997 ;Mantua and Hare, 2002). Previous studies have shown that the PDO can impact the climate over East Asia (e.g., Zhu and Yang, 2003;Wang et al, 2008;Jia and Ge, 2017;Qin et al, 2018). The influence of the PDO on rainfall anomalies in North China has also been investigated.…”

Influence of Asian-Pacific Oscillation on Precipitation in Central Eastern China during Autumn (1960–2016)

“…Moreover, numerical simulation based on the downscaling method has also shown that both the SST and the 500-hPa geopotential height can act as prediction factors, considerably improving predictions of autumn precipitation [10]. In addition, other studies have shown that certain oscillation patterns (e.g., the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO)) can play a crucial role in modulation of regional-scale autumn precipitation over China [11][12][13][14].…”