Indian scientists detect unusually thick ozone layer over North Bay of Bengal
The ozone-rich layer was found at 21-23km above the North Bay, lower than the altitude where ozone normally reaches its highest concentration.
Indian scientists have detected an unusually thick layer of ozone at an unexpected altitude over the North Bay of Bengal, offering new insights into how ozone moves through the upper atmosphere.
The ozone layer, which protects life on Earth by absorbing harmful ultraviolet (UV) radiation from the Sun, normally reaches its highest concentration at an altitude of around 25-30km.
However, the unusually thick ozone layer detected by the scientists was found at around 21-23km above the North Bay of Bengal. The amount of ozone was significantly higher than normally observed over eastern India, and the layer persisted for more than a day, India's Science and Technology Ministry said in a statement today (10 August).
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The discovery has raised questions about how such a large amount of ozone accumulated at the relatively low altitude and is helping scientists better understand how atmospheric currents transport ozone through the stratosphere, the ministry said.
Scientists from several Indian institutions, including the Aryabhatta Research Institute of Observational Sciences (ARIES), conducted the study using data from atmospheric radars, weather balloons, satellites and advanced atmospheric models.
The findings, published in Earth and Space Science by the American Geophysical Union, provide quantitative experimental evidence of the redistribution of stratospheric ozone over the Indian subtropical region during winter.
Researchers launched weather balloons equipped with instruments to measure atmospheric conditions and ozone concentrations. Simultaneous observations from different parts of India allowed them to compare wind patterns and vertical air movements and investigate the conditions behind the unusual ozone event.
To identify the processes responsible, the researchers combined measurements from ozone and weather balloons with observations from a nationwide radar network, the Aura Microwave Limb Sounder (MLS) and INSAT-3DR satellites, as well as atmospheric models.
The enhanced ozone layer was detected during both daytime and nighttime. This suggested that sunlight-driven photochemical processes were unlikely to have been the primary cause of the unusual ozone concentration.
Satellite observations also detected the unusual ozone structure, supporting the measurements recorded by the weather balloons.
The researchers then examined the possible roles of sea convection, atmospheric wind shear, horizontal transport and vertical air movement.
Their observations showed persistent downward air movement in the lower stratosphere.
By combining evidence from the different observation systems, the scientists concluded that the unusual ozone enhancement was mainly caused by the transport of ozone-rich air, followed by downward movement and compression of the air mass.
