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Monitoring the Ozone Layer: A Looming Gap in Data

The monitoring of Earth’s protective ozone layer faces a critical challenge due to the impending shutdown of key satellites. NASA’s Aura and the Canadian Space Agency’s SCISAT are projected to cease operations within the next few years, which raises serious concerns among researchers about the future of ozone layer surveillance and our understanding of atmospheric changes.

The Aura satellite, launched in 2004, and SCISAT, which took to the skies a year earlier, have been instrumental in providing scientists with comprehensive data about the stratosphere, including the presence of compounds that deplete ozone and affect atmospheric circulation patterns. As highlighted in the March issue of the Bulletin of the American Meteorological Society, the expected loss of these satellites, with no current plans for replacements, indicates an imminent “data desert” in the understanding of the stratosphere.

Atmospheric scientist David Fahey from the National Oceanic and Atmospheric Administration, while reflecting on the situation, emphasized the long-standing recognition of this potential gap. He noted, “These satellites…will go dark in the absence of a torchbearer into the future.” This outcome is particularly concerning, as the ozone layer’s recovery appears to have stalled in certain regions, specifically the midlatitude Northern Hemisphere.

Moreover, the increasing risk of space debris from defunct satellites might lead to further complications for ozone-depleting substances. This situation is compounded by other environmental pressures, such as the negative impacts wildfires have on the ozone layer and the risks posed by proposed climate interventions, like stratospheric aerosol injections aimed at reducing global warming effects.

While other instruments will still measure the ozone layer, the unique capacity for detailed monitoring provided by Aura and SCISAT will be sorely missed. Ross Salawitch, an atmospheric scientist at the University of Maryland, likened the loss to replacing advanced imaging techniques with basic X-rays, stating, “We will know what is happening to the ozone. What we’ll lack is why.”

SCISAT orbits Earth at an altitude of 650 kilometers and completes approximately 15 circuits daily. Both satellites, operational since the early 2000s, have contributed to a deeper understanding of atmospheric chemistry and ozone dynamics. However, the impending failure of Aura’s solar panels by mid-2026 and SCISAT’s aging hardware signal a pressing need for successors to continue monitoring efforts.

Recent advancements and findings derived from these satellites are vital, as seen in studies revealing the impact of the 2019-2020 Australian wildfires on ozone depletion. Researchers emphasize the critical need to maintain vigilance, especially given the anticipated increase in wildfire severity linked to climate change and the potential for future stratospheric interventions. Atmospheric chemist Lyatt Jaeglé of the University of Washington pointed out that understanding the effects of such phenomena is still in its early stages.

In response to this impending gap in monitoring capabilities, both NASA and the European Space Agency are evaluating potential successor missions. One initiative, the Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT), would focus on global observations of ozone and associated harmful compounds. A decision from ESA regarding this mission is expected soon, with a targeted launch date around 2032.

Nasa’s alternative concept, the Stratosphere Troposphere Response using Infrared Vertically-resolved light Explorer (STRIVE), promises enhanced monitoring capacity. If either mission proceeds, it could significantly bolster ongoing efforts to understand and protect the ozone layer, as noted by Salawitch, who affirmed the importance of diagnosing atmospheric health through continued monitoring.

As the global community grapples with climate change challenges, maintaining a robust monitoring framework for the ozone layer remains crucial. The outcomes of the proposed missions will be pivotal in ensuring sustained vigilance over this essential atmospheric shield.

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