Arctic ozone soars in 2024 due to series of extraordinary atmospheric events
Ocean-Land-Atmosphere Research (OLAR)
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The graph depicts the total column ozone (TCO), or the total amount of ozone in a vertical column extending from the Earth's surface to space, over time. The annual (blue) and March month (red) TCO measurements are illustrated in the graph by satellite (top panel), reanalysis (second from the top), and ground-based (Lerwick, Oslo, Sodankylä, and Scoresbysund) observations in the Arctic between 1978–2024. The pink lines in the background show the observed high TCO years.
view moreCredit: Authors and OLAR
Scientists discover the atmospheric processes behind the highest Arctic stratospheric ozone levels observed in more than 45 years, providing new insight into how large-scale climate variability shapes the ozone layer.
The Arctic ozone layer is a protective layer of gas that sits in the stratosphere above the North Pole, filtering ultraviolet radiation from the sun. Recently, scientists discovered that the Arctic ozone layer recorded its highest ozone levels in March 2024 since satellite observations began in 1979. What puzzled researchers was why.
Ozone is a molecule of three highly reactive oxygen atoms (O3). In the atmosphere, it serves a protective function, but on the ground, ozone is a harmful gas that forms when pollutants from tailpipes, power plants and factories react with sunlight. Inhaling ozone can cause severe respiratory issues.
The researchers found record-high total column ozone of 477 Dobson Units (DU), a standard measure of the total amount of ozone, from merged satellite observations, supported by exceptionally high measurements from monitoring stations across the Arctic, including Lerwick, Scotland; Oslo, Norway; Sodankylä, Finland; and Scoresbysund, a deep inlet in the Greenland Sea. Balloon observations and satellite measurements also confirmed unusually high ozone concentrations throughout the lower and middle stratosphere.
Rather than simply reporting these observations, a team of scientists from CORAL at the Indian Institute of Technology Kharagpur in Kharagpur, India, investigated what caused the record-setting levels of ozone above the Arctic.
The team published their paper, entitled “Intense Wave Activity and Climate Oscillations Drive Record-High Arctic Ozone in March 2024,”on July 21st in Ocean-Land-Atmosphere Research.
“Although the record ozone values were evident in satellite and ground-based observations, the atmospheric processes responsible for this extraordinary event were not well understood. Our goal was to identify the mechanisms that led to this unprecedented increase and determine how large-scale climate variability influenced the Arctic ozone layer,” said Jayanarayanan Kuttippurath, associate professor at CORAL, IIT Khargapur and lead scientist of the research study.
The team performed a comprehensive dynamical analysis, which uses mathematical, analytical, and numerical methods to model how a system evolves over time, that showed exceptionally strong planetary waves, or large, meandering waves that form naturally in rotating fluids like the Earth's atmosphere and oceans, propagating from the lower atmosphere into the stratosphere, triggering three warming events during the winter of 2023–2024. These warming events weakened and disturbed the Arctic polar vortex, allowing ozone-rich air to accumulate over the polar region.
The study further demonstrated that this sequence of events was amplified by the combined influence of a strong El Niño, or warmer than average water across the equatorial Pacific; the Madden–Julian Oscillation, a massive, eastward-moving atmospheric disturbance that travels along the equator, circling the entire globe every 30 to 60 days; and the Quasi-Biennial Oscillation, a regular variation of stratospheric winds over the equator that alternate between easterlies and westerlies.
The team’s integration of advanced wave diagnostics with observations from multiple independent datasets has provided the most robust explanation of the atmospheric mechanisms responsible for the record-breaking Arctic ozone levels to date.
"This was not simply an unusual ozone year," said Kuttippurath. "It was the result of an exceptionally rare alignment of atmospheric processes operating from the Earth's surface to the upper atmosphere."
The findings highlight the growing importance of atmospheric dynamics in controlling Arctic ozone variability. “As the recovery of the ozone layer continues under the Montreal Protocol [a 1987 global treaty designed to protect Earth's ozone layer], year-to-year ozone levels will increasingly depend on natural climate variability and large-scale atmospheric circulation rather than changes in ozone-depleting substances alone,” said Anjali Sathyanath, research scholar at CORAL, IIT Kharagpur and lead author of the study.
The research also has broader implications for seasonal climate prediction. Improving our understanding of how planetary waves, tropical climate modes that determine the recurring shifts in temperature, atmospheric pressure, and rainfall patterns between the Tropic of Cancer and the Tropic of Capricorn, and the polar vortex interact could improve forecasts of Arctic stratospheric conditions and their influence on global weather patterns.
“In the longer term, we hope this research will contribute to a new generation of Earth System Models capable of providing more reliable predictions of atmospheric extremes in a warming climate,” said Kuttippurath.
This study did not receive any specific funding.
Journal
Ocean-Land-Atmosphere Research
Method of Research
Observational study
Article Title
Intense Wave Activity and Climate Oscillations Drive Record-High Arctic Ozone in March 2024
Article Publication Date
21-Jul-2026
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