Can the Uncertainties of Madden-Jullian Oscillation Cause a Significant “Spring Predictability Barrier” for ENSO Events?

With the Zebiak-Cane model and a parameterized stochastic representation of intraseasonal forcing,the impact of the uncertainties of Madden-Jullian Oscillation (MJO) on the "Spring Predictability Barrier(SPB)" for El Nin o-Southern Oscillation (ENSO) prediction is studied. The parameterized form of MJO forcing is added physically to the Zebiak-Cane model to obtain the so-called Zebiak-Cane-MJO model and then the effects of initial error, stochastic model error, and their joint error mode on the SPB associated with El Nin o prediction are estimated. The results show that the model errors caused by stochastic MJO forcing could hardly lead to a significant SPB while initial errors can do; furthermore, the joint error mode of initial error and model error associated with the stochastic MJO forcing can also lead to a significant SPB.These demonstrate that the initial error is probably the main error source of the SPB, which may provide a theoretical foundation of data assimilation for ENSO forecasts.