Climate change has hampered the ability of forecasting agencies to accurately predict severe events and the India Meteorological Department is installing more radars and upgrading its high-performance computing system to meet the challenge, IMD Director General Mrutyunjay Mohapatra said.
He also said that though the monsoon rainfall has not shown any significant trend in the country, the number of heavy rainfall events has increased and that of light rainfall events has decreased due to climate change.
The impact-based forecast will improve to become “more granular, specific and accurate” by 2025 and IMD will be able to provide forecasts up to panchayat level clusters and specific areas in cities in the coming years, the IMD chief told PTI in an interview.
“Climate change has increased the instability in the atmosphere, leading to an increase in convective activity — thunderstorms, lightning and heavy rainfall. The severity of cyclones in the Arabian Sea is also increasing.”
“This increase in the frequency of extreme weather events is posing a challenge to forecasters. Studies show that the ability to predict heavy rainfall is hampered due to climate change,” he said.
“We have put up six radars in the northwest Himalayas and four more will be installed this year. The procurement process is on for eight radars in the northeast Himalayan region. There are certain gap areas in the rest of the country that will be filled up with 11 radars. The number of radars will increase from 34 at present to 67 by 2025,” the IMD chief said.
Radars are preferred because they have a higher resolution and can provide observations every ten minutes.
The Ministry of Earth Sciences (MoES) also plans to upgrade its high-performance computing system — from a capacity of 10 petaflops currently to 30 petaflops in the next two years — which will help assimilate more data into the model that can then be run at higher resolutions.
The lower the range of a weather model, the higher its resolution and the greater the precision.
At present, the IMD-MoES weather modelling system has a resolution of 12 kilometres. The target is to make it six kilometres.
Similarly, the resolution of the regional modelling system will be improved from three kilometres to one kilometre.
“We are providing forecasts up to the district and block levels currently. Going ahead, we will provide forecasts up to clusters at the panchayat level and specific locations within cities,” Mohapatra said.
On climate change increasing the fragility of the Himalayas, he said, “Climate change is a fact and we need to plan all our activities accordingly.”
A study by the Indian Institute of Tropical Meteorology, MoES says the frequency of mini-cloud bursts (five cm or more rainfall in an hour) is increasing in the Himalayas. And it can also cause damage, Mohapatra said.
Asked about the impact of climate change on the Indian monsoon, he said: “We have got the digital data of the monsoon rainfall since 1901. Parts of north, east and northeast India show a decrease in rainfall, while some areas in the west, such as west Rajasthan, show an increase in precipitation.”
“Thus, there is no significant trend if we consider the country as a whole – the monsoon is random and it shows large-scale variations.”
Mohapatra said an analysis of the day-to-day rainfall data since 1970, however, shows that the number of very heavy rainfall days has increased and that of light or moderate rainfall days has decreased, reads the report.
“That means if it is not raining, it is not raining. If it is raining, it is raining heavily. The rainfall is more intense when there is a low-pressure system.”
“This is one of the most important trends found in the tropical belt, including India. Studies have proved that this increase in heavy rainfall events and decrease in light precipitation are due to climate change,” he said.
The IMD head explained that climate change has increased the surface air temperature, which in turn has increased the evaporation rate. Since warmer air holds more moisture, it leads to intense rainfall. (PTI)