Influences of the North Pacific Victoria Mode on the South China Sea Summer Monsoon

• Main Authors: Ruiqiang Ding, Jianping Li, Yu-heng Tseng, Lijuan Li, Cheng Sun, Fei Xie
• Format: Article
• Language: English
• Published: MDPI AG 2018-06-01
• Series: Atmosphere
• Subjects: Victoria mode; South China Sea summer monsoon; ENSO
• Online Access: http://www.mdpi.com/2073-4433/9/6/229

Using the reanalysis data and the numerical experiments of a coupled general circulation model (CGCM), we illustrated that perturbations in the second dominant mode (EOF2) of springtime North Pacific sea surface temperature (SST) variability, referred to as the Victoria mode (VM), are closely linked to variations in the intensity of the South China Sea summer monsoon (SCSSM). The underlying physical mechanism through which the VM affects the SCSSM is similar to the seasonal footprinting mechanism (SFM). Thermodynamic ocean–atmosphere coupling helps the springtime SST anomalies in the subtropics associated with the VM to persist into summer and to develop gradually toward the equator, leading to a weakened zonal SST gradient across the western North Pacific (WNP) to central equatorial Pacific, which in turn induces an anomalous cyclonic flow over the WNP and westerly anomalies in the western equatorial Pacific that tend to strengthen the WNP summer monsoon (WNPSM) as well as the SCSSM. The VM influence on both the WNPSM and SCSSM is intimately tied to its influence on ENSO through westerly anomalies in the western equatorial Pacific.