Simulation study on the relationship between East Asian Summer Westerly Jet and Summer Monsoon at different time scales in Holocene

The East Asian Summer Westerly Jet (EASWJ) and East Asian Summer Monsoon (EASM) are important components of the East Asian monsoon system. In this study, the MV-EOF method and exponential analysis method were used to study the temporal and spatial co-evolution relationship between EASWJ and EASM at different time scales in the Holocene by using TraCE-21ka data, and the single-factor sensitivity test was used to analyze the mechanism of the evolution relationship between the two. The results show that EASWJ and EASM are dominated by intensity-intensity and position-intensity relationships in Holocene from the interannual time scale to the millennium time scale. Among them, the intensity-intensity relationship is that the EASWJ and EASM are opposite in the temperate zone and same in the subtropical zone; the position-intensity relationship is corresponding to the weakening/strengthening of EASM when EASWJ moves southward/northward on the interannual-multiannual and interdecadal-multidecadal scales, and the corresponding subtropical EASM strengthens/weakens when EASWJ moves southward/northward on the centennial-millennial scale. The relationship between the Holocene interannual and millennial time scales is mainly affected by internal variability. The PDO-like, ENSO-like and North Atlantic sea surface temperature changes will affect the intensity change relationship between the two through thermal, dynamic and teleconnection effects. The North Pacific sea surface temperature tripole also affects the relationship between EASWJ position and EASM through thermal effect. On the suborbital scale, the relationship between the two is dominated by the inverse change of intensity, which is mainly affected by the change of external forcing orbital parameters.