Doppler radar to predict monsoon rainfall more accurately

A new study has revealed that a doppler radar would significantly improve forecasting models used to track monsoon systems, influencing the monsoon in and around India.

The research was a collaboration of Purdue University, the National Centre for Atmospheric Research, and the Indian Institute of Technology, Delhi.

Dev Niyogi of Purdue University said modelling of a monsoon depression path could have marginal error of about 200 kilometres for landfall, which could be significant for storms that produce as much as 20-25 inches of rain as well as inland floods and fatalities.

"When you run a forecast model, how you represent the initial state of the atmosphere is critical.

"Even if doppler radar information may seem highly localised, we found that it enhanced the regional atmospheric conditions, which, in turn, could significantly improve the dynamic prediction of how the monsoon depression will move as the storm makes landfall," said Niyogi.

Niyogi, Mohanty of the IIT, and Mohanty's doctoral student, Ashish Routray, collaborated with scientists at the National Centre for Atmospheric Research and gathered information such as radial velocity and reflectivity from six doppler weather radars that were in place during storms.

Using the weather research and forecasting model, they found that incorporating the doppler radar-based information decreased the error of the monsoon depression's landfall path from 200 kilometres to 75 kilometres.

Mohanty said that more accurate predictions could better prepare people for heavy rains that account for a number of deaths during the monsoon season.

"Once a monsoon depression passes through, it can cause catastrophic floods in the coastal areas of India.

"Doppler radar can be a very useful tool to help assess these things," he said.

Future studies will incorporate more simulations and advanced models to test the ability of the radar to track monsoon processes.

The findings were published in the quarterly Journal of the Royal Meteorological Society.