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

Abstract

e Asian-Pacific Oscillation (APO) plays an important role in precipitation in Central Eastern China (CEC). is study analyzed observational and reanalysis data to investigate CEC precipitation during autumn and its association with the APO. e APO index (APOI) was redefined, and an autumn CEC precipitation index (CECPI) was calculated to elucidate the relationship between the APO and CEC precipitation. Significant positive correlation (correlation coefficient: 0.60) was found between the APOI and CECPI. Further analysis revealed anomalous southerly winds at 850 hPa over CEC when the APO was strong, which corresponded to anomalous strengthened (weakened) sea level pressure and increased 500-hPa geopotential height over Asia (the Pacific), together with strong meridional shear of the East Asian jet. is configuration is conducive to transportation of warm moist air to CEC during strong APOI years (SAY), but the effect is much diminished during weak APOI years. Moreover, strengthening of both the Walker Circulation of the tropical Pacific and the anomalous upward movement (and convergence) over the Western Pacific (WP) observed during SAY is also conducive to the formation of precipitation in CEC. A possible physical explanation for the close association of the APO with tropical circulation changes is that decreased (increased) sea surface temperature in the tropical eastern Pacific (WP and extratropical Pacific) is beneficial for stimulating a strong APO teleconnection pattern, which further affects precipitation in CEC by strengthening the connection between tropical and subtropical regions.

Linkage Between Preceding August Asian–Pacific Oscillation and September Precipitation Over Southeast China

“…During summer, when the mid-upper troposphere is warmer over Asia, the troposphere above the North Pacific will be colder, and vice versa. The APO can exert substantial impacts on regional-global climatic change via the monsoon circulations and precipitation (Zhao et al, 2007(Zhao et al, , 2012aZhou et al, 2009;Liu et al, 2011;Zou et al, 2015;Hua et al, 2019;Lin et al, 2019Lin et al, , 2021, tropical cyclone activity (Zhou et al, 2008;Zou and Zhao, 2010), and variations in SST (Zhao et al, 2010(Zhao et al, , 2011(Zhao et al, , 2012b. Furthermore, the APO occurs throughout the year, not just in the summertime Lin et al, 2019).…”

“…The APO can exert substantial impacts on regional-global climatic change via the monsoon circulations and precipitation (Zhao et al, 2007(Zhao et al, , 2012aZhou et al, 2009;Liu et al, 2011;Zou et al, 2015;Hua et al, 2019;Lin et al, 2019Lin et al, , 2021, tropical cyclone activity (Zhou et al, 2008;Zou and Zhao, 2010), and variations in SST (Zhao et al, 2010(Zhao et al, , 2011(Zhao et al, , 2012b. Furthermore, the APO occurs throughout the year, not just in the summertime Lin et al, 2019). In light of the findings of previous related studies, it has been suggested that the APO could be regarded as a crucial contributor to engendering climate change on regional-global scales.…”