Seasonal prediction of Indian summer monsoon in India: The past, the present and the future

Seasonal prediction of summer monsoon in India has had a long history and India has made significant strides in making reliable seasonal predictions. This article provides a detailed review of the progress made in the field of seasonal prediction by India starting from the first attempt of seasonal prediction by India Meteorology Department (IMD) in 1886 based on empirical methods to the present day state-of-the-art coupled dynamical modelling framework developed under "Monsoon Mission". The success and failures of seasonal prediction were amply documented in several articles particularly with more emphasis on its failures. Starting in the early 1900s, the empirical models performed very well for a few decades after which they started failing. As the relationship with predictors underwent significant changes, empirical models were also updated/revamped on several occasions. Prior to Monsoon Mission (before 2010) attempts were made to use dynamical models for seasonal prediction of Indian monsoon, particularly in the tier-II modelling framework, which was based upon the standalone Atmospheric General Circulation Models (AGCMs), albeit with limited success. The immediate need for coupled modelling framework in India was felt in 2008-09 for making seasonal forecasts, primarily to model the dynamical nature of Indian Monsoon and hence, a coupled dynamical modelling framework at a very high atmospheric horizontal resolution of similar to 38 km was implemented to make operational/experimental seasonal forecasts, so far unparalleled. The dynamical modelling framework will be upgraded in the future to contain an earth system framework with aerosols/greenhouse gases, ocean bio-geo chemistry and closed model hydrology.