NASA Puzzles Out Ozone’s Ups and Downs

New NASA research on natural ozone cycles suggests ozone levels in the lowest part of Earth’s atmosphere probably won’t be affected much by projected future strengthening of the circulating winds that transport ozone between Earth’s two lowest atmospheric layers.

The finding is good news, since human and plant health are harmed by exposure to ozone near the ground. Significant increases in ozone in Earth’s lowest atmospheric layer, the troposphere, would also lead to additional climate warming because ozone is a greenhouse gas.

The research, which studied the natural ups and downs in ozone in the troposphere and stratosphere, increases our ability to reliably predict future changes in ozone in Earth’s troposphere. This information is useful for developing effective air quality and climate policies.

Jessica Neu, an atmospheric scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and colleagues used NASA satellite observations to show that short-term periodic strengthening and weakening of circulating winds in Earth’s stratosphere — the layer right above the troposphere — account for about half of the observed year-to-year changes in the amount of tropospheric ozone in Earth’s northern mid-latitudes. Those are the same latitudes where North America, most of Europe and Central Asia are located. In a first-of-its-kind estimate, they calculated that a 40-percent change in the strength of stratospheric winds increases tropospheric ozone levels by an average of about two percent over Earth’s northern mid-latitudes at an altitude of about 16,000 feet (5,000 meters). Results are published this month in the journal Nature Geoscience.

While a two-percent change in ozone is small, it does represent a significant natural variation in tropospheric ozone, which has large seasonal changes but only varies by about four percent from year to year at these altitudes in Earth’s northern mid-latitudes. As the human contribution to ozone levels evolves due to increased development and stricter air quality controls, the relative importance of natural sources of tropospheric ozone such as the stratosphere will also shift.

Global climate models project the stratospheric circulating winds of particular interest to Neu and colleagues are expected to strengthen by about 30 percent over the coming century in response to increased greenhouse gas emissions, but the impacts on tropospheric ozone had been highly uncertain.

“If the correlations between tropospheric ozone and changing stratospheric circulation found in this study hold true in the future, the small changes in tropospheric ozone we measured show it’s unlikely the projected long-term changes in stratospheric winds will have a big impact on long-term changes in tropospheric ozone in the future,” said Neu.

The researchers studied changes in the well-established global wind circulation of the stratosphere. Like water in a fountain, winds in the tropics rise up, move toward Earth’s poles, and then descend over middle and high latitudes. In these regions, the descending air carries ozone-rich air from the stratosphere to the troposphere.

To quantify how ozone responds to changes in wind circulation, Neu and colleagues investigated two natural phenomena known to contribute to shorter-term circulation changes: the El Niño/Southern Oscillation and the stratospheric Quasi-Biennial Oscillation. The study focused on the northern mid-latitudes because that is where most stratospheric ozone enters the troposphere.

The researchers used water vapor measurements from the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite from 2005 to 2010 to infer wind circulation changes driven by these two natural phenomena. They compared the magnitude and timing of those changes with measurements of stratospheric and tropospheric ozone from Aura’s MLS and Tropospheric Emission Spectrometer (TES) instruments, respectively. JPL developed and manages both instruments.

“This sort of study is exciting because it reveals connections between the stratosphere and troposphere on timescales of a few years, with implications for connections on multi-decadal — or longer — timescales,” said Anne Douglass, Aura project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “The connections can be quantified only because the observational record from Aura instruments is long.”

While the mechanisms that change wind circulation over the course of six months, such as the El Niño/Southern Oscillation, are different from those that change it over the course of a century, the difference “likely doesn’t matter in terms of the impact on tropospheric ozone,” Neu said. “This study gives us confidence that the impact in the future will be on the same order of magnitude — around two percent.”

NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

The material in this press release comes from the originating research organization. Content may be edited for style and length. Have a question? Let us know.


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5 thoughts on “NASA Puzzles Out Ozone’s Ups and Downs”

  1. Its great to see NASA’s involvement in environmental issues which are extremely pertinent to all of us, but i disagree with the way this research is proceeding. The amount of funds (assuming money from the government, brought forwards by tax payers) being used to conduct the research. NASA should rather cut down expenses on research and use these funds to initiate actions to further processes of environmental rehabilitation and spread awareness.

  2. The innovations from NASA has come in handy in the past and is still coming in handy today. This innovation about using long-term data records to try and predict how the ozone levels in the atmosphere will be affected not only in the present but also how they might be affected in the future will give scientists a better understanding of how this planet’s atmosphere might be changing over the course of the future. This will enable humanity to be better prepared to the changing planet, but it might also ensure a lot of people that research has been done and that both short-term and long-term circulation changes will have an impact on the ozone in the future round about the same order of magnitude. It is thus highly unlikely that these long term changes in circulation will have a large impact on the long term changes in the tropospheric ozone in the future, but this research only tell us that the natural systems have a minimum impact in the process of the changing of planet Earth, but what about the impacts of humanity and the development that we impose on this planet? Surely that must also be taken into account. NASA has thus contributed highly to the study of how planet Earth is changing but it can also contribute to the protection of this planet, by giving useful information about what changes could occur in the future. It is thus important for scientists to study how natural systems are interconnected, so that there can be means identified to preserve planet Earth and to make our actions and development on this planet more sustainable, for a brighter-looking future,

  3. It is a step in the right direction to monitor the Earth with new technologies. I too feel that careful consideration must be taken into account when spending tax payers’ money. I do, however, support NASA’s research on ozone changes. Natural systems are very much interconnected, and therefore one area of study may address a variety of other issues the planet has. The rate of destruction of ozone is symptomatic of life on Earth and therefore needs to be monitored. A broad array of new scientific questions and opinions arise that leads to critical thinking and possible problem solving of current and perceived future issues. Problem solving through the sustainable use of our planet’s resources must get preference, thus the allocation of resources such as time and technology to scientific ventures, must be considered carefully. Studies that lead to better understanding of our planet’s stratosphere and troposphere interconnectedness is broadening our understanding of our chances of survival on Earth.

  4. The technology used here are great and showing how man kind has involved and are truly one of the great miracles of nature, although I personally feel that rather than spending money on trying to see how much we are destroying our planet there must be be looked how we can stop further killing our precious earth and start living green and in harmony with nature. NASA should rather find ways for living sustainable with nature and finding replacements for all the harmful chemicals that is spreading in nature and the high emission rates.

  5. It’s great and all that NASA is monitoring these changes, but I feel that too many of the tax payer’s dollars are being used on technologies and discoveries that are not feasible for humanities’s continuing survival on planet earth. Trillions of dollars every year is being used to build shuttles to explore space and other planets, when we all realistically know that human beings will not be able to live on other planets in our solar system especially not all 8 billion of us. The money can instead be used to develop ways in which the sustainable energy and sustainable water sources can be acquired, because the resources on earth are already scarce and yes in a few years NASA would be able to send some people to Mars, but what about the rest of us ?


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