Long-range prediction of the low-frequency mode in the low-level Indian monsoon circulation with a simple statistical method

The time evolution of the Indian monsoon is closely related to locations of the northward migrating monsoon troughs and ridges which can be well depicted with the 30-60 day filtered 850-mb streamfunction. Thus, long-range forecasts of the large-scale low-level monsoon can be obtained from those of the filtered 850 mb streamfunction. These long-range forecasts were made in this study in terms of the Auto Regressive (AR) Moving-Average process. The historical series of the AR model were constructed with the 30-60 day filtered 850-mb streamfunction [ψ̄ (850 mb)] time series of 4 months. -from Authors