The India Meteorological Department (IMD) will soon adopt the Bharat Forecast System (BFS) which offers the highest resolution among weather models. This move will significantly enhance the IMD’s weather forecasting capabilities, especially with respect to extreme rainfall and cyclones.
On Monday, the BFS will be officially handed over to IMD in New . IMD will operationalise the model starting this monsoon season.
Developed by -based Indian Institute of Tropical Meteorology (IITM), the BFS offers a spatial resolution of 6km x 6km, making it the first weather model with such high resolution. In fact, weather modellers have also been working to fine-tune this resolution to 3km and 1km.
Globally, weather forecasters run multiple models by keying-in the latest atmospheric and/or oceanic initial conditions as data feeds. They use high performance computers to run these models which in turn provide output, whose interpretation is issued as weather forecasts.
Currently, the IMD operates Coupled Forecasting System (CFS) developed under the Monsoon Mission Project. The original model framework of CFS was developed by US-based National Center for Environmental Prediction. For Indian use, it was modified to provide forecasts for the Indian monsoon region for different spatial and temporal resolutions. In addition, it also runs the Global Forecasting System (GFS), which a coupled model (factors-in ocean and atmospheric parameters), for issuing the weather forecasts at time scales ranging from a few hours, to five days, a month to a season.
“The BFS is India’s first indigenously built weather model. It is a deterministic model, that is, it will be a single-model based output,” said Parthasarathi Mukhopadhyay, senior weather modeller formerly with IITM.
The resolution of the existing weather model is 12 km x 12 km, which means forecasters consider 144 sq km area as one unit and the forecast for this unit is considered uniform. And this is also the limitation faced by the IMD, as the current model is unable to pick weather events occurring over smaller areas within this 144 sq km area unit.
“So any variation occurring within this 144 km cannot be captured and that limits the forecasting skills, given that the extreme rainfall events and overall weather extremes are on a rise,” said Mukhopadhyay, adding that BFS has been running at IITM on experimental mode since 2022.
The improved spatial resolution to 6km is expected to improve forecasts, especially for extreme weather events starting the monsoon this year.
