NASA Sees First Direct Proof Of Ozone Hole Recovery

NASA Sees First Direct Proof of Ozone Hole Recovery

For the first time, scientists have shown through direct observations of the ozone hole by a satellite instrument, built by NASA’s Jet Propulsion Laboratory in Pasadena, California, that levels of ozone-destroying chlorine are declining, resulting in less ozone depletion.

Measurements show that the decline in chlorine, resulting from an international ban on chlorine-containing human-produce chemicals called chlorofluorocarbons (CFCs), has resulted in about 20 percent less ozone depletion during the Antarctic winter than there was in 2005 – the first year that measurements of chlorine and ozone during the Antarctic winter were made by NASA’s Aura satellite.

“We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it,” said lead author Susan Strahan, an atmospheric scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

CFCs are long-lived chemical compounds that eventually rise into the stratosphere, where they are broken apart by the Sun’s ultraviolet radiation, releasing chlorine atoms that go on to destroy ozone molecules. Stratospheric ozone protects life on the planet by absorbing potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and damage plant life.

Two years after the discovery of the Antarctic ozone hole in 1985, nations of the world signed the Montreal Protocol on Substances that Deplete the Ozone Layer, which regulated ozone-depleting compounds. Later amendments to the Montreal Protocol completely phased out production of CFCs.

Past studies have used statistical analyses of changes in the ozone hole’s size to argue that ozone depletion is decreasing. This study is the first to use measurements of the chemical composition inside the ozone hole to confirm that not only is ozone depletion decreasing, but that the decrease is caused by the decline in CFCs.

The study was published Jan. 4 in the journal Geophysical Research Letters.

The Antarctic ozone hole forms during September in the Southern Hemisphere’s winter as the returning Sun’s rays catalyze ozone destruction cycles involving chlorine and bromine that come primarily from CFCs.To determine how ozone and other chemicals have changed year to year, scientists used data from JPL’s Microwave Limb Sounder (MLS) aboard the Aura satellite, which has been making measurements continuously around the globe since mid-2004. While many satellite instruments require sunlight to measure atmospheric trace gases, MLS measures microwave emissions and, as a result, can measure trace gases over Antarctica during the key time of year: the dark southern winter, when the stratospheric weather is quiet and temperatures are low and stable.

The change in ozone levels above Antarctica from the beginning to the end of southern winter – early July to mid-September – was computed daily from MLS measurements every year from 2005 to 2016. “During this period, Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is,” Strahan said. “This is when we want to measure ozone loss.”

They found that ozone loss is decreasing, but they needed to know whether a decrease in CFCs was responsible. When ozone destruction is ongoing, chlorine is found in many molecular forms, most of which are not measured. But after chlorine has destroyed nearly all the available ozone, it reacts instead with methane to form hydrochloric acid, a gas measured by MLS. “By around mid-October, all the chlorine compounds are conveniently converted into one gas, so by measuring hydrochloric acid we have a good measurement of the total chlorine,” Strahan said.

Nitrous oxide is a long-lived gas that behaves just like CFCs in much of the stratosphere. The CFCs are declining at the surface but nitrous oxide is not. If CFCs in the stratosphere are decreasing, then over time, less chlorine should be measured for a given value of nitrous oxide. By comparing MLS measurements of hydrochloric acid and nitrous oxide each year, they determined that the total chlorine levels were declining on average by about 0.8 percent annually.

The 20 percent decrease in ozone depletion during the winter months from 2005 to 2016 as determined from MLS ozone measurements was expected. “This is very close to what our model predicts we should see for this amount of chlorine decline,” Strahan said. “This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs. But we’re not yet seeing a clear decrease in the size of the ozone hole because that’s controlled mainly by temperature after mid-September, which varies a lot from year to year.”

Looking forward, the Antarctic ozone hole should continue to recover gradually as CFCs leave the atmosphere, but complete recovery will take decades. “CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time,” said Anne Douglass, a fellow atmospheric scientist at Goddard and the study’s co-author. “As far as the ozone hole being gone, we’re looking at 2060 or 2080. And even then there might still be a small hole.”

TOP IMAGE….A view of Earth’s atmosphere from space.Credit: NASA

Measuring Cosmic Rays at the Edge of Space

It’s a bird! It’s a plane! It’s a… SuperTIGER?

No, that’s not the latest superhero spinoff movie - it’s an instrument launching soon from Antarctica! It’ll float on a giant balloon above 99.5% of the Earth’s atmosphere, measuring tiny particles called cosmic rays.

Right now, we have a team of several scientists and technicians from Washington University in St. Louis and NASA at McMurdo Station in Antarctica preparing for the launch of the Super Trans-Iron Galactic Element Recorder, which is called SuperTIGER for short. This is the second flight of this instrument, which last launched in Antarctica in 2012 and circled the continent for a record-breaking 55 days.

SuperTIGER measures cosmic rays, which are itty-bitty pieces of atoms that are zinging through space at super-fast speeds up to nearly the speed of light. In particular, it studies galactic cosmic rays, which means they come from somewhere in our Milky Way galaxy, outside of our solar system.

Most cosmic rays are just an individual proton, the basic positively-charged building block of matter. But a rarer type of cosmic ray is a whole nucleus (or core) of an atom - a bundle of positively-charged protons and non-charged neutrons - that allows us to identify what element the cosmic ray is. Those rare cosmic-ray nuclei (that’s the plural of nucleus) can help us understand what happened many trillions of miles away to create this particle and send it speeding our way.

The cosmic rays we’re most interested in measuring with SuperTIGER are from elements heavier than iron, like copper and silver. These particles are created in some of the most dynamic and exciting events in the universe - such as exploding and colliding stars.

In fact, we’re especially interested in the cosmic rays created in the collision of two neutron stars, just like the event earlier this year that we saw through both light and gravitational waves. Adding the information from cosmic rays opens another window on these events, helping us understand more about how the material in the galaxy is created.

Why does SuperTIGER fly on a balloon?

While cosmic rays strike our planet harmlessly every day, most of them are blocked by the Earth’s atmosphere and magnetic field. That means that scientists have to get far above Earth - on a balloon or spacecraft - to measure an accurate sample of galactic cosmic rays. By flying on a balloon bigger than a football field, SuperTIGER can get to the edge of space to take these measurements.

It’ll float for weeks at over 120,000 feet, which is nearly four times higher than you might fly in a commercial airplane. At the end of the flight, the instrument will return safely to the ice on a huge parachute. The team can recover the payload from its landing site, bring it back to the United States, repair or make changes to it, if needed, and fly it again another year!

There are also cosmic ray instruments on our International Space Station, such as ISS-CREAM and CALET, which each started their development on a series of balloons launched from Antarctica. The SuperTIGER team hopes to eventually take measurements from space, too.

Why do we launch from Antarctica?

McMurdo Station is a hotspot for all sorts of science while it’s summer in the Southern Hemisphere (which is winter here in the United States), including scientific ballooning. The circular wind patterns around the pole usually keep the balloon from going out over the ocean, making it easier to land and recover the instrument later. And the 24-hour daylight in the Antarctic summer keeps the balloon at a nearly constant height to get very long flights - it would go up and down if it had to experience the temperature changes of day and night. All of that sunlight shining on the instrument’s array of solar cells also gives a continuous source of electricity to power everything.

Antarctica is an especially good place to fly a cosmic ray instrument like SuperTIGER. The Earth’s magnetic field blocks fewer cosmic rays at the poles, meaning that we can measure more particles as SuperTIGER circles around the South Pole than we would at NASA scientific ballooning sites closer to the Earth’s equator.

The SuperTIGER team is hard at work preparing for launch right now - and their launch window opens soon! Follow @NASABlueshift for updates and opportunities to interact with our scientists on the ice.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

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starsglaxiesspace

7 years ago

NGC 1275

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starsglaxiesspace

7 years ago

Hey!! I find marine biology super cool, but everyone tells me I won't get a stable salary from it. Any advice?

Hello!! So sorry about the late reply. Anyway, I understand your struggle with people constantly wondering about the financial stability of a scientific career. For some scientific careers, especially those relating to marine biology, it is hard to estimate earnings because there are so many different pathways to chose from. What I mean by this is that your could take your passion for the ocean and work in many different places doing vastly different things. For example, you could work at a university teaching students and researching, or you could work in an aquarium taking care of animals, or you could work at a private research company/consulting firm. Each of these paths have different salary ranges. Another thing about marine biology is that it is a highly competitive field (and may be one of the reasons why people see this career as less stable than others.)

I will not lie to you and say that marine biology careers are the most lucrative option out there; however, this does not mean that you cannot make a stable salary! Marine science careers, in my opinion, are more about your passion and drive to discover, educate, or conserve. So my main advice would be to continue doing what you love. If you are passionate about marine biology you will find that the advantages far outweigh the few downfalls. Also if you are not quiet sure if a career in marine sciences is your calling then you still have plenty of time to figure it out. Try interning or volunteering where you may be able to earn some experience.

Sorry about my rambling!! I hope it helped at least.

And if it didn’t I highly suggest you check out SciAll.org’s YouTube channel. He has some cool videos. The video I linked here may help to answer your question.

Thank you so much and have a Thresher Shark for the road!!