The Ministry of Earth Sciences (MoES) has proposed a National Mission on monsoon towards developing reliable dynamic models for forecasting the monsoon over the next three to five-year period through a multi-institutional effort.
Though the focus will chiefly be on seasonal forecast, the mission will include aspects of short (up to 3 days) and medium-range (up to a week) predictions as well.
The currently operational model for long-range or seasonal forecast used by the India Meteorological Department (IMD) is not a dynamic one but a statistical one. It uses a set of historically determined atmospheric variables with significant statistical correlations to the total rainfall received by the country as a whole during June-September.
However, improving and perfecting statistical models will not form part of the mission, Dr. Ajit Tyagi, Director-General of the IMD, clarified. The IMD has also been using open source dynamic models such as the Global Forecasting System (GFS) and the Weather Research & Forecasting (WRF) System of the U.S. for limited area 3-day forecast as well as 5-day forecast, with some success.
The mission is yet to be formalised for it to be approved by the Planning Commission and then the Cabinet. “The details are being worked out,” said Shailesh Nayak, Secretary, MoES. “The project proposal is being prepared. In January, we had a meeting of people involved in model development and have a working knowledge of models. Mostly these are models developed elsewhere, such as the Climate Forecasting System (CFS) of the U.S. or that of the U.K. Met Office, but have been slightly modified to be applicable for monsoon prediction. All that activity is slowly getting into frame. But these atmospheric or ocean-atmosphere coupled models need to be improved greatly through a coordinated effort. We have to create a forum for that,” he added.
“There are enough models and enough people around. We are almost a critical mass [of atmospheric scientists] now. It is the right time to put in a concerted effort to improve monsoon prediction. Nobody else is going to do it for us,” said Sulochana Gadgil, honorary professor at the Centre for Atmospheric and Oceanic Sciences (CAOS), Indian Institute of Science (IISc), Bangalore. According to her, the initial focus of the mission will be atmospheric models. “Coupled models are not yet good enough. They get wrong sea-surface temperatures [SSTs] and predict more rain over cold oceans,” she added.
“There has also been no progress in the predictability of inter-seasonal and intra-seasonal variability in most models. They are not able to anticipate extremes of droughts and excess. For example, as Professor Nanjundiah has shown, as late as May, all except one atmospheric model predicted 2009 to be a normal to above normal monsoon, even though the El Nino predictions were right,” she points out.
“If we look at the [prediction] skill of most numerical models, we find that it is one of the lowest over the Indian region,” points out Professor Ravi Nanjundiah of the CAOS/IISc. “This certainly implies that a lot needs to be done in improving these models. This would involve a lot of experimentation with models, identify processes that are going wrong and try and fix them. This is easier said than done. Monsoon mission is a step in the right direction. But don't expect miracles overnight. This is going to be a long and hard grind. Today, the major problem we could be facing in tackling the problem is not of financial or computational resources; it is one of human resources,” he adds.
“I feel, it is a good initiative,” said M. Rajeevan of the National Atmospheric Research Laboratory of ISRO at Gadanki and formerly of the National Climate Centre at the IMD, Pune.
Last year Dr. Rajeevan and Professor Nanjundiah had shown how the various coupled models used in the Fourth Assessment Report (AR4) of the Inter-governmental Panel on Climate Change (IPCC) for projecting climate change failed to correctly reproduce the monsoon behaviour.
