A New Perspective on the Climate Prediction of Asian Summer Monsoon Precipitation

Abstract

A new paradigm for climate (one month and longer) prediction is developed and is applied to the 5-day-averaged Asian summer monsoon (ASM) precipitation. The foundation of the method is to identify climate signals (deterministic components) that constitute the ASM system and predict the temporal fluctuations of the amplitudes (stochastic components) of the individual signals. Climate signals were identified via cyclostationary empirical orthogonal function (CSEOF) analysis of the Xie?Arkin pentad precipitation in this study and include the annual cycle, El Niño/La Niña, and the intraseasonal oscillations of the 40?50-day period band (the Madden?Julian oscillation). Prediction is much facilitated by forecasting the slowly undulating amplitude time series of each climate signal rather than the raw precipitation data directly. The new prediction method results in reasonable forecasts of the pentad precipitation for the test period of 1999?2001. Specifically, the propagation of the intraseasonal oscillations is predicted successfully 60 days in advance. The performance of the new method is significantly better than persistence and that of conventional prediction methods in which raw data is predicted directly.