Studying storms over the Indian subcontinent

– Kapil Dev Sindhu

In meteorological terms, a storm is a group of cumulonimbus clouds joined together. Extreme rainfall is associated with storms and they account for more than 90% of the total rainfall from convective clouds. Understanding of storm-scale characteristics has implications for short-range weather forecasting as well as improvement in convective parametrization schemes in numerical weather models.

Researchers at the Centre for Atmospheric and Oceanic Sciences (CAOS) at IISc studied the characteristics of storms during pre-monsoon and monsoon seasons using data from Doppler Weather Radars (DWRs) operated by the India Meteorological Department at Bhopal, Lucknow, Nagpur, and Patna. The dependence of the storms’ vertical structure and lifetime on geolocation and season are also reported. A majority of the storms last for less than an hour while a few live for more than 2.5 hours. Pre-monsoon storms are typically shallower and shorter lived compared to those during the monsoon.

One of the major contributions of this work is calculating total precipitation, namely, radar estimated rain volume (RERV; unit m³) resulting from storms during their lifetime. The range of RERV in monsoon storms lies between 2×10⁵ and 2×10⁷ m³. The Tehri Dam in Uttarakhand has a total capacity of ∼4×10⁹ m³ and rain from 200 such big storms can fill the dam to full capacity if there is no other loss of water. The study also established the relationships between RERV and the storms’ area-time integral (ATI; unit km² h) during their lifetime at the four locations. Information about the RERV-ATI relationship is helpful in identifying the nature of precipitation of storms. Overall, these findings enhance the existing knowledge about storm-scale characteristics of atmospheric weather systems.

REFERENCE:

Sindhu, K.D., Bhat, G.S. Seasonal characteristics of storms over the Indian subcontinent. Scientific Reports, 11, 3355 (2021).

https://doi.org/10.1038/s41598-021-82237-w

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