Context

• The new monsoon model, called the Coupled Forecast Model (CFS), deployed by the IMD under the National Monsoon Mission (NMM) has failed to forecast the excess rainfall received during August-September 2019.

About National Monsoon Mission

• Under the National Monsoon Mission initiative, the Indian Institute of Tropical Meteorology (IITM), Pune, Indian National Centre for Ocean Information Services (INCOIS), Hyderabad and National Centre for Medium Range Weather Forecasting (NCMRWF), NOIDA have embarked upon to build a state-of-the-art coupled ocean atmospheric model for:-
  • Improved prediction of monsoon rainfall on extended range to seasonal time scale (16 days to one season) and
  • Improved prediction of temperature, rainfall and extreme weather events on short to medium range time scale (up to 15 days) so that forecast skill gets quantitatively improved further for operational services of India Meteorological Department (IMD).

Need for NMM

• El Nino and Southern Oscillation (ENSO) being a dominant mode of global inter-annual variability and due to its vast influence on other regional climates, in last few decades researchers have made large number of studies on the ENSO phenomena and its various impacts using atmospheric and ocean-atmosphere coupled general circulation models.
• In recent decades, dynamical numerical models have considerably improved and most of the global coupled models have shown good prediction skill of ENSO SST with six months lead time.
• The seasonal mean rainfall hindcast skill, at one season lead time, over the central Pacific is also very good. This has been possible due to a concerted effort by a group of devoted scientists.
• However, not much breakthrough has taken place in improving the prediction skill of Indian summer monsoon rainfall, even though it was expected as a prominent heat source over Indian region during summer monsoon period that drives the major atmospheric circulations.

Base Models to be used

• The Ministry of Earth Sciences (MoES) has considered to use the following numerical models :
  • The American model called “Climate Forecast System” (CFS) developed by National Centres for Environmental Prediction (NCEP), NOAA National Weather Service, USA. CFS is a coupled ocean-atmosphere modeling system that combine data from ocean, atmosphere and land for providing long range forecasting (seasonal prediction of Indian Monsoon); [ Model developments on CFS will be implemented by IITM, with atmospheric initial conditions from NCMRWF and Ocean initial conditions from INCOIS]
  • The Unified Model (UM), developed by the United Kingdom Meteorological Office (UKMO), UK. This model will be utilized for short to medium range prediction [and the Model developments on UKMO will be implemented by NCMRWF, in association with IMD.

Source: PIB