IMD looking to create common alert protocol: Mrutyunjay Mohapatra

Mrutyunjay Mohapatra, director general of Indian Meteorological Department, speaks to Indulekha Aravind about the country’s changing rainfall patterns, the effect of global warming and how his department is preparing for better forecasting. Edited excerpts:

Why was there such heavy rainfall in certain regions? Is it unusual?
The excess rainfall was due to a depression over the Bay of Bengal near the Odisha coast. The depression moved across Odisha, Chhattisgarh and Madhya Pradesh and along the path triggered extreme rainfall — all the way to Gujarat.


If there is a low pressure area over the Bay of Bengal, the winds blowing towards the peninsula will strengthen, especially over the Arabian Sea. Rainfall also increases over Kerala and Karnataka. Now the question of whether this is unusual.

It is not. But what is unusual is that in central India and in Kerala, studies show the frequency of light to moderate rainfall is decreasing while the frequency of very heavy to extremely heavy rainfall is increasing.

Why is this happening?
Another study indicates that if there is a rise in land temperature — and we know temperatures are rising in the Indian subcontinent because of global warming — temperatures rise in the atmosphere as well. Due to this, the capacity of the troposphere (atmosphere’s lowest region) to hold moisture also goes up. Thus, the rate of absorption is increasing because of rising temperatures. As a result, moisture in the atmosphere increases. And in certain pockets, in the zone of low pressure, you can expect heavy to extremely heavy rainfall.

How is the weather department dealing with these changes?
Since there is an increase of heavy to extremely heavy rainfall in certain pockets, what you need is to detect these pockets and improve the forecasting of the rainfall occurrence.

To improve our observational systems, we will increase the number of Doppler radars, automatic rain gauge systems and stations over the next year. We are planning for a common alert protocol so that our warnings reach these locations on time. Our website already provides districtlevel warning for the entire country. We are giving colour-coded forecasts and providing now-casts — three-hour forecasts — for 605 cities.

Was the flooding due to excess rain alone?
Rainfall is the first trigger. Flooding happens due to many factors, such as dam and water bodies’ management and past rainfall. For example, if you compare rainfall in Kerala this year to last year, in 2018 Kerala continued to receive excess rainfall June onwards. This year, there was a rainfall deficit in June. That is why this year’s flooding is not as extreme as last year’s.