Retrieval the statistical–dynamical model of western Pacific subtropical high ridge line index and key members of Asian summer monsoon system

•We establish a nonlinear model of subtropical high ridge line (SHRL) and the East Asian summer monsoon (EASM) system.•Differences of parameters in the models among three types are found out.•Dynamical characteristics of SHRL are analyzed and an aberrance mechanism is developed.•Results show that different parameters can lead to changes of different monsoon factors corresponding to various WPSH activities.•It is revealed that the South China Sea monsoon trough plays an important role in the occurrence and maintenance of the ‘double-ridge’ phenomenon of western Pacific subtropical high (WPSH).

The western Pacific subtropical high (WPSH) is closely correlated with the East Asian climate. To date, the underlying mechanisms and sustaining factors have not been positively elucidated. Based on the concept of dynamical system model reconstruction, this paper presents a nonlinear statistical–dynamical model of the subtropical high ridge line (SHRL) in concurrence with four summer monsoon factors. SHRL variations from 1990 to 2011 are subdivided into three categories, while parameter differences relating to three differing models are examined. Dynamical characteristics of SHRL are analyzed and an aberrance mechanism subsequently developed. Modeling suggests that different parameters may lead to significant variance pertaining to monsoon variables corresponding with numerous WPSH activities. Dynamical system bifurcation and mutation indicates that the South China Sea monsoon trough is a significant factor with respect to the occurrence and maintenance of the ‘double-ridge’ phenomenon. Moreover, the occurrence of the Mascarene cold high is predicted to cause an abnormal northward location of WPSH, resulting in the “empty plum” phenomenon.