Indian researchers uncover an enhanced ozone layer at 21–23 km altitude, offering new insights into atmospheric circulation

New Delhi, August 10, 2026: 

Indian scientists have identified an unusually strong concentration of ozone in the lower stratosphere over the North Bay of Bengal, providing new evidence about how ozone-rich air can be transported and redistributed through the atmosphere.

The unusual ozone enhancement was detected at an altitude of approximately 21 to 23 kilometres and persisted for more than a day. Researchers say the event provides an opportunity to better understand the atmospheric processes that influence ozone distribution over the Indian region.

Ozone Layer Found at Unusual Altitude

Ozone is a critical component of Earth's atmosphere because it absorbs a significant portion of the Sun's harmful ultraviolet radiation. Under normal conditions, the highest concentrations of stratospheric ozone are generally found around 25–30 kilometres above Earth's surface.

The newly observed enhancement over the North Bay of Bengal occurred somewhat lower, making the event particularly interesting to atmospheric scientists.

Researchers found that ozone concentrations in this layer were substantially higher than typically observed over eastern India.

Nationwide Atmospheric Observations

The investigation was conducted as part of the Phase-I NetRAD-ASMA campaign, a coordinated scientific programme involving atmospheric research institutions across India.

Scientists used observations from several complementary sources, including:

  • Stratosphere–Troposphere (ST) radars

  • Weather balloons equipped with scientific instruments

  • Satellite observations

  • Atmospheric measurements

  • Advanced atmospheric modelling

The Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital was an important participant in the research programme.

Researchers including Dr Manish Naja and Dr Samaresh Bhattacharjee from ARIES contributed to the campaign.

ARIES Radar Helps Track Atmospheric Movement

During the experiment, the indigenously developed 206.5 MHz Stratosphere–Troposphere Radar at ARIES, Nainital, collected atmospheric data along with similar radar systems located at Haringhata, Gadanki and Kochi.

Weather balloons were also launched to obtain detailed measurements of ozone concentrations and atmospheric conditions at different heights.

The simultaneous observations from multiple locations enabled researchers to compare wind behaviour and vertical atmospheric movements across the country.

Why Did Ozone Accumulate?

One of the major questions raised by the observation was why such a large amount of ozone accumulated between 21 and 23 kilometres over the North Bay of Bengal.

Researchers compared balloon observations with data from the Aura MLS and INSAT-3DR satellites, radar measurements and atmospheric models.

The ozone enhancement was detected during both day and night. This indicated that sunlight-dependent chemical reactions were unlikely to be the main explanation for the unusual increase.

Scientists subsequently examined several atmospheric processes, including convection, wind shear, horizontal transport and vertical air movement.

Ozone-Rich Air Was Transported Downward

The combined observations indicated that the event was primarily linked to the movement of ozone-rich air into the region, followed by downward movement of the air mass.

Persistent downward air motion was observed in the lower stratosphere. As the ozone-rich air descended, compression of the air mass contributed to the enhanced ozone concentration detected by the researchers.

In simple terms, the study suggests that the unusual ozone layer was not simply produced locally. Instead, atmospheric circulation transported ozone-rich air to the region and subsequent downward movement helped concentrate it.

Importance for Atmospheric Research

The findings provide quantitative evidence of how stratospheric ozone can be redistributed over the Indian subtropical region during winter.

The study also demonstrates the importance of combining observations from multiple atmospheric monitoring systems. Radar measurements, balloon observations, satellite data and numerical models each provided different pieces of information needed to explain the event.

The research highlights the role of India's atmospheric observation infrastructure in studying complex processes occurring high above the Earth's surface.

Study Published in International Journal

The findings have been published in Earth and Space Science, a journal of the American Geophysical Union (AGU).

The research was conducted under the Phase-I NetRAD-ASMA campaign, which brought together scientists and institutions from across India to investigate atmospheric processes.

What the Discovery Means

The unusual ozone enhancement over the North Bay of Bengal provides researchers with a valuable case study for understanding how atmospheric circulation influences the distribution of ozone in the stratosphere.

The study could contribute to improved understanding of:

  • Stratospheric ozone transport
  • Atmospheric circulation over India
  • Vertical air movements
  • Wintertime atmospheric dynamics
  • Ozone distribution in subtropical regions
  • Interaction between horizontal and vertical atmospheric transport

The research also demonstrates how coordinated national observation networks can help scientists investigate short-lived and unexpected atmospheric events.

Source: Press Information Bureau (PIB), Government of India
Publication: Earth and Space Science, American Geophysical Union
DOI: 10.1029/2025EA004791