• Jacob Bourne

NASA Investigates How Climate Change is Powering Potentially Ozone-Depleting Storms Over the U.S

Although most storms occur in the troposphere, the lowest region of the atmosphere, it’s becoming apparent that more storms than previously thought are overshooting into the higher altitude stratosphere containing the ozone layer.



NASA ER-2 flies to study storms
NASA's ER-2 aircraft flies through stratosphere studying storms. Credit: NASA DCOTSS

There’s evidence that this overshoot could be disrupting the ozone, the protective layer that shields life on Earth from harmful radiation. So on June 16, NASA began deploying its ER-2 aircraft based at the Armstrong Flight Research Center in Edwards, California, as part of the Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) project to understand what this means for climate change and the ozone layer.

“This is the first mission that is specifically designed to look at the impacts of overshooting storms,” said Dr. Kenneth Bowman, DCOTSS principal investigator and a professor of atmospheric science at Texas A&M University.


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The series of flights will continue several times per week during the summer of 2021 and 2022. The ER-2 planes will climb to as high as 70,000 feet above ground in the wake of storms to collect atmospheric samples used in research currently in the preliminary stages.

“One of the things that we're interested in with these severe storms is the fact that they're becoming more frequent as the climate is changing,” said Harvard University scientist David Wilmouth who spoke at a press event for the DCOTSS project on July 27.

A 2017 study conducted by Harvard researchers found that the stratospheric ozone layer above the central U.S. could be eroded by not fully understood chemical reactions during the summer months, exposing the region to UV radiation that a thick blanket of ozone would otherwise block. It’s a phenomenon that caught scientists off guard and warranted the atmospheric missions now underway.

Wilmouth explained that, unlike the troposphere, the stratosphere is very cold and dry — generally about -100 degrees Fahrenheit and with about 1,000 times less water vapor than at the planet’s surface. The stratosphere also contains about 90% of atmospheric ozone. With these severe storms over the central U.S., large fluxes of air are transported from the troposphere to the stratosphere within a matter of minutes, thereby changing the chemical composition of the stratosphere in a process that otherwise wouldn’t happen, Wilmouth said.

Water vapor, which functions as a heat-trapping greenhouse gas in the upper atmosphere, isn’t the only thing pumped into the stratosphere by these storms. Pollutants such as human-made aerosols and particulate matter from dust storms and worsening wildfires in places like the Pacific Northwest are also straying into the stratosphere.



NASA stratosphere storm study
Diagram depicting storm overshoot into the stratosphere. Credit: NASA DCOTSS

“We're very interested in the size of the particles, the composition of those particles and how they participate in Earth's climate,” said Purdue University Professor of Earth, Atmospheric and Planetary Sciences Dan Cziczo. “This was something that was also reinforced because of the wildfires last week. A lot of us saw these very intense brilliant sunrises and sunsets, and that was because there were a lot of the smoke particles in our atmosphere, and they can both absorb and scatter sunlight as it makes its way through the atmosphere.”

Particulate matter from wildfires not only causes cardiovascular disease and premature death for those exposed to high concentrations but can also blanket Arctic ice and snow, reducing the Earth’s albedo effect, or reflectivity, exacerbating global warming.

The particles can also act as seeds for cloud formation, Cziczo said. Following intense thunderstorms, droplets and ice crystals end up condensing on these tiny particles.

So far, the NASA mission hasn’t yielded any specific findings but will be relying on the ER-2s flown by single pilots at up to 450 mph speeds, equipped with 12 robotic instruments to make chemical and meteorological measurements in the stratosphere.

A 2017 paper published in the Proceedings of the National Academy of Sciences had linked the injection of water vapor and aerosols into the stratosphere with chemical reactions that could result in loss of ozone over the central U.S. in the summer. It's a similar process observed in polar regions. The researchers also linked the increased frequency and severity of the storm systems responsible for the stratospheric injections to climate change.

The ozone layer plays a crucial role in Earth’s suitability for life by protecting organisms from cell-destroying UV radiation, which can adversely impact plants, animals and microbes.

“We all are aware that this summer has been quite extraordinary with the wildfires and the extreme drought in the West, and the extreme rainfall we've been getting in the Northeast and eastern part of the country,” said Wilmouth. "It's hard to say that any particular weather event is directly related to climate change, but our thesis is that the thunderstorms over the central U.S. and the resulting convection that lost that air to the stratosphere will be more significant as the climate continues to change.”

As it’s too dangerous to fly during the height of the storms, the flights take off when the weather clears to take stratospheric samples. After that, researchers will take additional samples every few days to track changes over time. This past week, the team flew over the Texas Panhandle and measured very high water vapor concentrations at an altitude of 56,000 feet where the air should be dry.

“The atmosphere in 2021 is different than it was even last year or ten years ago, and it's certainly different than it's going to be next year or ten years from now,” said Cziczo. “So we're really putting together an amazing data set, to which we can compare past data, and we're going to be able to compare future data as well — again in an under-sampled region of the atmosphere.”

Although NASA generally studies space, its suite of satellites can track trends on Earth, such as sea-level rise and methane emissions. However, some measurements are best taken onsite to get the clearest picture of what’s happening in the atmosphere.

The agency recently partnered with the European Space Agency to study climate change. NASA and the ESA are also collaborating on an EnVision mission to study Venus, including past climate change that took place on that planet.



Footage of ER-2 aircraft landing after stratospheric sampling flight:



 

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