The Ozone Hole Expands Once More

The Copernicus Sentinel-5P satellite has recently provided measurements that show this year’s ozone hole over Antarctica is one of the largest on record. The hole reached a size of 26 million square kilometers on September 16, 2023, which is approximately three times the size of Brazil. This information raises concerns about the state of our ozone layer and its potential impact on our planet.

The size of the ozone hole fluctuates throughout the year, with its maximum size typically occurring between mid-September and mid-October. During this time, temperatures in the stratosphere start to rise in the southern hemisphere, resulting in a slowdown in ozone depletion. As a result, the polar vortex weakens and eventually breaks down, allowing ozone levels to return to normal by the end of December.

The Copernicus Sentinel-5P satellite, launched in October 2017, is equipped with an advanced multispectral imaging spectrometer called Tropomi. This instrument detects the unique signatures of atmospheric gases in different parts of the electromagnetic spectrum, enabling more accurate and high-resolution imaging of pollutants. The Tropomi total ozone measurements are processed by the German Aerospace Center (DLR) using algorithms developed by DLR and the Royal Belgium Institute for Space Aeronomy (BIRA-IASB).

Diego Loyola, a senior scientist at DLR, emphasizes the accuracy of the Sentinel-5P total ozone products compared to ground-based data, which allows for close monitoring of the ozone layer and its evolution. These measurements extend the global ozone data record of European satellite sensors by almost three decades.

The measurements from Sentinel-5P are provided to the Copernicus Atmosphere Monitoring Service (CAMS) within three hours after measurement time. CAMS, implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF), uses this near-realtime ozone data in their analysis and forecasting system. Antje Inness, a senior scientist at CAMS, highlights the early start and rapid growth of the 2023 ozone hole, which reached a size of over 26 million square kilometers on September 16. She also acknowledges the importance of Tropomi ozone data in their ozone analysis.

The size of the ozone hole is largely influenced by the strength of a wind band that flows around the Antarctic area. The strength of this wind band is determined by Earth’s rotation and the temperature differences between polar and moderate latitudes. If the wind band is strong, it acts as a barrier, preventing the exchange of air masses between polar and temperate latitudes. This isolation results in the cooling down of air masses over the polar latitudes during winter, contributing to the growth of the ozone hole.

Researchers speculate that this year’s unusual ozone patterns could be associated with the eruption of the Hunga Tonga-Hunga Ha’apai volcano in January 2022. The eruption injected a significant amount of water vapor into the stratosphere, which reached the south polar regions after the end of the 2022 ozone hole. This water vapor may have led to increased formation of polar stratospheric clouds, where chlorofluorocarbons (CFCs) can react and accelerate ozone depletion. Additionally, the presence of water vapor may contribute to the cooling of the Antarctic stratosphere, further enhancing the formation of these clouds and resulting in a more robust polar vortex. However, further research is needed to determine the exact impact of the eruption on the ozone hole.

The ozone hole is a consequence of the widespread use of chlorofluorocarbons in products such as refrigerators and aerosol tins during the 1970s and 1980s. These substances damaged the ozone high up in our atmosphere, resulting in a hole in the ozone layer above Antarctica. In response to this issue, the Montreal Protocol was established in 1987 to phase out the production and consumption of these harmful substances. As a result, there has been a gradual recovery of the ozone layer. Scientists predict that, based on the Montreal Protocol and the decrease in ozone-depleting substances, the global ozone layer will return to its normal state by around 2050.

ESA has been actively involved in monitoring ozone for many years. The Copernicus Sentinel-5P satellite, with its advanced instrument Tropomi, provides accurate measurements of atmospheric gases and air pollutants from space. This technology allows for a better understanding of the state of our ozone layer and its evolution.

The recent findings about the size of this year’s ozone hole over Antarctica serve as a reminder of the importance of continued monitoring and protection of our ozone layer. While progress has been made in reducing ozone-depleting substances, it’s important to remain vigilant in order to ensure the full recovery of the ozone layer and the preservation of our planet.