Monsoon prediction in India goes wrong most of the times as the India 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

By Syed Akbar
Hyderabad: Monsoon prediction in India goes wrong most of the
times as the India 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 has been 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
in the country. 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.

The IMD leadership has been taking solace arguing that even weather
centres in advanced countries too fail to predict monsoon rainfalls.
The IMD cited this year’s monsoon prediction by global centres as an
example.

The country’s premier weather prediction body has now proposed to set
up airborne probing of cyclone facility for actual and real time
assessment of cyclones in the Bay of Bengal and the Arabian Sea.