Monsoon prediction in India goes wrong most of the times as the Indian Meteorological Department (IMD) uses old technology to track its movement. The accuracy level of long range forecast for seasonal rainfall in the country has been just 50 per cent in the last five years.
At present, the IMD is depending on a suite of statistical models to predict seasonal monsoon rainfall in the country. This leads to error in prediction on several occasions. The IMD does not have a suitable “coupled dynamical ocean-atmospheric model” that helps in accurate prediction of monsoon rainfall at macro and micro levels.
However, the IMD has been near accurate on the arrival of the monsoon. Its long and short range forecasts often fell short of expectations. The average accuracy of short-range forecast has been about 70 per cent. Even the average accuracy of aviation forecast is 77 per cent. Aviation forecast is important for the movement of flights including landing and takeoffs.
The IMD has been planning for long to experiment with the USA and the UK models of monsoon predictions to achieve near accuracy on forecasts. IMD officials claim that the error in the landfall forecast has come down at the rate of 33 km per year in the last eight years, while the accuracy levels in 24 hours forecast of cyclone in the Bay of Bengal increased at the rate of 7.3 km per year during the same period.
Even the skill of district level rainfall forecast has been limited to 75 per cent during the monsoon season. However, the prediction during non-monsoon season is 85 per cent.
Earth sciences minister Vayalar Ravi admitted in Parliament earlier this week that weather being intrinsically variable, its forecast assessment always have a margin of error and the endeavour of IMD has always been to reduce this margin of error through the use of improved observations and advanced models.