When we think of the ozone layer, we usually imagine a protective shield high above Earth, stretching across the atmosphere and absorbing harmful ultraviolet rays from the Sun. However, scientists in India have just discovered a very unusual feature: an unexpectedly low and thicker-than-normal ozone pocket above the North Bay of Bengal during winter.
This discovery, published in Earth and Space Science by the American Geophysical Union, is giving researchers fresh insight into how air currents shuffle ozone around the Stratosphere, and why the atmosphere over India behaves in such surprising ways.
Normally, the ozone layer peaks at altitudes of 25–30 km. But during a nationwide campaign called NetRAD-ASMA, scientists found an unusually thick ozone layer between 21 and 23 km above the Bay of Bengal.
The ozone abnormality was immediately apparent: partial pressure levels were > 50 nbar above the climatological median for that latitude level, forming a layer of7 km thick between altitudes of 2.1 and at least as high as ~2.4 kilometers. Surprisingly, it lasted longer than a day without changing through the daytime and nighttime.
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This was no fleeting glitch. Balloons, radars, and satellites all confirmed the same thing: a sporadic ozone structure that had never been documented so clearly before.
The campaign was a massive collaboration, involving radars at Nainital, Haringhata, Gadanki, and Kochi, plus weather balloons and satellites like Aura MLS and INSAT-3DR.
Central to the effort was one of India’s biggest indigenously developed radars, the Backscatter VHF Radar (BVHF), or Stratosphere–Troposphere Radar, at the Aryabhatta Research Institute for Observational Sciences (ARIES), Nainital, providing high-temporal-resolution vertical air-motion profile data.
Two main Atmospheric processes were identified for the peculiar ozone enhancement. In the lower Stratosphere, downward air motion compressed ozone-rich air to form a layer. During this period, transport of ozone into the area, or advection as it is also known, resulted in further enhancement. Combined, these mechanisms produced the persistent anomaly observed in maintaining a higher partial pressure and enduring such cycles of day and night.
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To protect life on Earth, we have the ozone layer, which protects us from ultraviolet rays. Exploring how it changes shape and density in unexpected regions will help scientists understand how both climate change and shifting atmospheric circulation patterns influence where ozone is distributed. These insights also enhance models of stratospheric chemistry and dynamics and strengthen global monitoring of ozone health.
Dr. Manish Naja and Dr. Samaresh Bhattacharjee from ARIES, who played key roles in the study, emphasize that this is quantitative experimental evidence of ozone redistribution in the Indian subtropics, something researchers had long suspected but never captured so clearly.
This finding emphasizes the coordinated force of science throughout India. Using combined data from radars, balloons, satellites, and models, researchers observed a rare atmospheric phenomenon.
It also highlights the need for domestic technology. The radar and balloon-based measurements by ARIES were vital in detecting the anomaly, indicating how India’s scientific infrastructure can play a major role in furthering global atmospheric research.
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The pocket of ozone over the Bay of Bengal is no mere curiosity. It is also a reminder that the Earth’s atmosphere is constantly in motion and layered. By unveiling these concealed matrices, scientists are securing a UV-deflecting protective layer above our planet and broadening the scientific exploration of the invisible processes that dictate what happens in our skies.
Journal Reference:
- Siddharth Shankar Das, N. Poddar, A. K. Ghosh, M. V. Ratnam et al. Unusual Enhancement of Stratospheric Ozone Observed Over the North Bay of Bengal: Results Inferred From NetRAD-ASMA Campaigns-2024. Earth and Space Science. DOI: 10.1029/2025EA004791
