Scientists detect unusual ozone layer over North Bay of Bengal

Convener News Desk

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New Delhi, Aug 10: Scientists have detected an unusually high concentration of ozone in the upper atmosphere over the North Bay of Bengal, providing new insights into how atmospheric circulation transports and redistributes ozone through the stratosphere.

 

The unusual ozone layer was observed at an altitude of around 21 to 23 kilometres above the North Bay of Bengal, where the concentration was significantly higher than normally recorded over eastern India. The layer persisted for more than a day, prompting scientists to investigate the atmospheric processes responsible for its formation.

The study, published in Earth and Space Science by the American Geophysical Union, provides quantitative experimental evidence of the redistribution of stratospheric ozone over the Indian subtropical region during winter.

Scientists from several Indian institutions participated in the Phase-I NetRAD-ASMA campaign, a nationwide programme aimed at understanding complex atmospheric processes. The Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous institute under the Department of Science and Technology (DST), was an important participant. Researchers Dr Manish Naja and Dr Samaresh Bhattacharjee from ARIES were involved in the study.

As part of the campaign, scientists used observations from a nationwide network of atmospheric radars, weather balloons, satellites and advanced atmospheric models. The indigenously developed 206.5 MHz Stratosphere–Troposphere (ST) Radar at ARIES, Nainital, collected data alongside similar radars at Haringhata, Gadanki and Kochi.

Weather balloons equipped with instruments to measure atmospheric conditions and ozone levels were also launched from different locations. The coordinated observations enabled researchers to compare wind patterns and vertical air movements across the country.

The enhanced ozone layer was observed both during daytime and nighttime, indicating that sunlight-driven photochemical processes were unlikely to be the main cause. Satellite observations from Aura MLS and INSAT-3DR also confirmed the unusual ozone structure.

Researchers subsequently examined convection, atmospheric wind shear, horizontal transport and vertical air movement. The observations revealed persistent downward motion of air in the lower stratosphere.

By combining evidence from the different observation systems, scientists concluded that the unusual ozone enhancement was primarily caused by the transport of ozone-rich air, followed by downward movement and compression of the air mass.

The findings underline the importance of coordinated atmospheric observations in understanding India’s complex atmospheric dynamics. They also highlight the role of indigenous scientific capabilities, particularly the ARIES Stratosphere–Troposphere Radar and balloon-based measurements, in advancing atmospheric research and improving understanding of processes that influence the distribution of ozone.

The ozone layer normally reaches its maximum concentration at altitudes of around 25–30 kilometres and plays a crucial role in protecting life on Earth by absorbing harmful ultraviolet radiation from the Sun.

The study is available through the publication DOI: Earth and Space Science study. – (PIB)