Asymmetric Response of Predictability of East Asian Summer Monsoon to ENSO

The connection between the predictability of the East Asian summer monsoon (EASM) and E1 Nino-Southern Oscillation (ENSO) has recently attracted widespread attention. Of particular importance is the effect of E1 Nino and La Nina on EASM predictability. In this paper, the signal-to-noise ratio (SNR) method is used to analyze reanalysis data, and the results show that the EASM potential predictability intensity is much stronger under E1 Nino forcing than that under La Nina forcing. Meanwhile, the asymmetric response of EASM predictability remains within the Community Atmosphere Model (CAM) simulations. The EASM predictability is quantitatively determined using the nonlinear local Lyapunov exponent (NLLE) method. The EASM predict-ability limit under E1 Nino forcing is longer than that for La Nina forcing. Two monsoon indices are used to measure the EASM, the predictability limits of which perform differently because of their particular definitions. However, the asymmetric response of EASM predictability to E1 Nino and La Nina can be verified using observational data and model experiments.