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spaceexp · 5 years ago

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2019 Ozone Hole is the Smallest on Record Since Its Discovery

NASA logo. Oct. 21, 2019 Abnormal weather patterns in the upper atmosphere over Antarctica dramatically limited ozone depletion in September and October, resulting in the smallest ozone hole observed since 1982, NASA and NOAA scientists reported today.

Unusual Winds Drive a Small 2019 Ozone Hole

Video above: Scientists from NASA and NOAA work together to track the ozone layer throughout the year and determine when the hole reaches its annual maximum extent. This year, unusually strong weather patterns caused warm temperatures in the upper atmosphere above the South Pole region of Antarctic, which resulted in a small ozone hole. Image Credits: NASA Goddard/ Katy Mersmann. The annual ozone hole reached its peak extent of 6.3 million square miles (16. 4 million square kilometers) on Sept. 8, and then shrank to less than 3.9 million square miles (10 million square kilometers) for the remainder of September and October, according to NASA and NOAA satellite measurements. During years with normal weather conditions, the ozone hole typically grows to a maximum area of about 8 million square miles in late September or early October. “It’s great news for ozone in the Southern Hemisphere,” said Paul Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “But it’s important to recognize that what we’re seeing this year is due to warmer stratospheric temperatures. It’s not a sign that atmospheric ozone is suddenly on a fast track to recovery.”

Image above: The 2019 ozone hole reached its peak extent of 6.3 million square miles (16. 4 million square kilometers) on Sept. 8. Abnormal weather patterns in the upper atmosphere over Antarctica dramatically limited ozone depletion this year. Image Credit: NASA. Ozone is a highly reactive molecule comprised of three oxygen atoms that occurs naturally in small amounts. Roughly seven to 25 miles above Earth’s surface, in a layer of the atmosphere called the stratosphere, the ozone layer is a sunscreen, shielding the planet from potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and also damage plants. The Antarctic ozone hole forms during the Southern Hemisphere’s late winter as the returning Sun’s rays start ozone-depleting reactions. These reactions involve chemically active forms of chlorine and bromine derived from man-made compounds. The chemistry that leads to their formation involves chemical reactions that occur on the surfaces of cloud particles that form in cold stratospheric layers, leading ultimately to runaway reactions that destroy ozone molecules. In warmer temperatures fewer polar stratospheric clouds form and they don’t persist as long, limiting the ozone-depletion process. NASA and NOAA monitor the ozone hole via complementary instrumental methods. Satellites, including NASA’s Aura satellite, the NASA-NOAA Suomi National Polar-orbiting Partnership satellite and NOAA’s Joint Polar Satellite System NOAA-20 satellite, measure ozone from space. The Aura satellite’s Microwave Limb Sounder also estimates levels of ozone-destroying chlorine in the stratosphere. At the South Pole, NOAA staff launch weather balloons carrying ozone-measuring “sondes” which directly sample ozone levels vertically through the atmosphere. Most years, at least some levels of the stratosphere, the region of the upper atmosphere where the largest amounts of ozone are normally found, are found to be completely devoid of ozone. “This year, ozonesonde measurements at the South Pole did not show any portions of the atmosphere where ozone was completely depleted,” said atmospheric scientist Bryan Johnson at NOAA’s Earth System Research Laboratory in Boulder, Colorado. Uncommon but not unprecedented This is the third time in the last 40 years that weather systems have caused warm temperatures that limit ozone depletion, said Susan Strahan, an atmospheric scientist with Universities Space Research Association, who works at NASA Goddard. Similar weather patterns in the Antarctic stratosphere in September 1988 and 2002 also produced atypically small ozone holes, she said. “It’s a rare event that we’re still trying to understand,” said Strahan. “If the warming hadn’t happened, we’d likely be looking at a much more typical ozone hole.” There is no identified connection between the occurrence of these unique patterns and changes in climate. The weather systems that disrupted the 2019 ozone hole are typically modest in September, but this year they were unusually strong, dramatically warming the Antarctic’s stratosphere during the pivotal time for ozone destruction. At an altitude of about 12 miles (20 kilometers), temperatures during September were 29 degrees F (16˚C) warmer than average, the warmest in the 40-year historical record for September by a wide margin. In addition, these weather systems also weakened the Antarctic polar vortex, knocking it off its normal center over the South Pole and reducing the strong September jet stream around Antarctica from a mean speed of 161 miles per hour to a speed of 67 miles per hour. This slowing vortex rotation allowed air to sink in the lower stratosphere where ozone depletion occurs, where it had two impacts. First, the sinking warmed the Antarctic lower stratosphere, minimizing the formation and persistence of the polar stratospheric clouds that are a main ingredient in the ozone-destroying process. Second, the strong weather systems brought ozone-rich air from higher latitudes elsewhere in the Southern Hemisphere to the area above the Antarctic ozone hole. These two effects led to much higher than normal ozone levels over Antarctica compared to ozone hole conditions usually present since the mid 1980s. As of October 16, the ozone hole above Antarctica remained small but stable and is expected to gradually dissipate in the coming weeks.

Image above: This time-lapse photo from Sept. 9, 2019, shows the flight path of an ozonesonde as it rises into the atmosphere over the South Pole from the Amundsen-Scott South Pole Station. Scientists release these balloon-borne sensors to measure the thickness of the protective ozone layer high up in the atmosphere. Image Credits: Robert Schwarz/University of Minnesota. Antarctic ozone slowly decreased in the 1970s, with large seasonal ozone deficits appearing in the early 1980s. Researchers at the British Antarctic Survey discovered the ozone hole in 1985, and NASA’s satellite estimates of total column ozone from the Total Ozone Mapping Spectrometer confirmed the 1985 event, revealing the ozone hole’s continental scale. Thirty-two years ago, the international community signed the Montreal Protocol on Substances that Deplete the Ozone Layer. This agreement regulated the consumption and production of ozone-depleting compounds. Atmospheric levels of man-made ozone depleting substances increased up to the year 2000. Since then, they have slowly declined but remain high enough to produce significant ozone loss. The ozone hole over Antarctica is expected to gradually become less severe as chlorofluorocarbons— banned chlorine-containing synthetic compounds that were once frequently used as coolants—continue to decline. Scientists expect the Antarctic ozone to recover back to the 1980 level around 2070. To learn more about NOAA and NASA efforts to monitor the ozone and ozone-depleting gases, visit: https://ozonewatch.gsfc.nasa.gov/ https://www.cpc.ncep.noaa.gov/products/stratosphere/polar/polar.shtml https://www.esrl.noaa.gov/gmd/dv/spo_oz/ Images (mentioned), Video (mentioned), Text, Credits: NASA/Sara Blumberg/Earth Science News Team, by Ellen Gray/National Oceanic and Atmospheric Administration (NOAA), By Theo Stein. Greetings, Orbiter.ch Full article

#space #science

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importanttigercreation · 2 years ago

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Welcome to the news channel of the Angry Nature,Today we will tell you about Tonga Volcano,, The 15 January 2022 eruption of underwater Hunga Tonga–Hunga Ha‘apai volcano triggered a tsunami that flattened buildings, displaced residents, and resulted in at least four deaths across the islands of Tonga. The powerful blast sent waves rippling throughout Earth’s oceans and atmosphere, with tsunami waves causing additional damage and casualties thousands of kilometers away, including two deaths in Peru. Researchers around the world have been studying and learning from the catastrophic event. Now Schoeberl et al. shed light on the fate of a record-breaking amount of water vapor—up to 150 teragrams, or 150,000,000,000 kilograms—shot into Earth’s stratosphere by the eruption. The water vapor was part of a huge plume of ash, gas, and steam that at its highest, billowed 58 kilometers into the sky. Months after the eruption, elevated levels of water vapor and sulfur-rich aerosol particles remained layered in the stratosphere. To clarify how these water vapor and aerosol layers formed and evolved over time, the researchers used data collected from 15 January through 1 July 2022 by NASA’s Microwave Limb Sounder instrument aboard the Aura satellite. They also developed a model incorporating several factors, including tropical atmospheric temperatures, to simulate the posteruption fate of the water vapor. Their analysis suggests that after the eruption, the stratospheric water vapor and sulfate aerosols began to separate from each other, forming two distinct but overlapping layers by mid-February. These layers continued to separate through the end of June, with the water vapor rising in a manner consistent with normal upwelling residual velocity and the aerosols settling gravitationally. A surprising result was that the midstratospheric eruption aerosols and water stayed in the Southern Hemisphere for 5.5 months, with very little material moving north of the equator. The data also revealed the development of an anomalous 3- to 4-kelvin temperature decrease in the midstratosphere through March and April, which appears to have been caused by the infrared cooling effects of the lofted water vapor. The researchers suggest that the high altitude of the eruption plume helps explain why other recent volcanic eruptions have not sent nearly as much water vapor into the stratosphere as Hunga Tonga–Hunga Ha‘apai did. #hunga_tonga_volcano #tonga_volcano #angry_nature ________________________________ The channel lists such natural disasters as: 1) Geological emergencies: #earthquake #volcanic_eruption mudflow, #landslide landfall, avalanche; 2) Hydrological emergencies: #flash_flood #tsunami Limnological catastrophe, floods, flooding; 3) Fires: Forest fire, Peat fire, Glass Fire, Wildfire; 4) Meteorological emergencies: #tornado, #cyclone #blizzard Hail, Drought, Hail, #hurricane #storm, Thunderstorm, typhoon Tempest, Lightning. ATTENTION: All videos are taken from open sources. The selection is based on publication date, title, description, and venue. Sometimes, due to unfair posting of news on social networks, the video may contain frames that do not correspond to the date and place. It is not always possible to check all videos. We apologize for any errors! Thank you for watching, don't forget to subscribe our channel, We Wish you good Weather,

#IFTTT #YouTube

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rodadecuia · 2 years ago

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#ERUPÇÃOVULCÃOTONGA #ILHADETONGA #TONGA

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sciencespies · 4 years ago

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U.S. role in global greenhouse gas constellation still up in the air

https://sciencespies.com/space/u-s-role-in-global-greenhouse-gas-constellation-still-up-in-the-air/

U.S. role in global greenhouse gas constellation still up in the air

The United States is expected to play a supporting role in an international campaign to monitor greenhouse gas emissions from space.

Through the Committee on Earth Observation Satellites, nations are coordinating efforts for space-based monitoring of air quality, greenhouse gases, the ozone layer and natural climate drivers like solar energy. China, Europe and Japan are making major investments in satellites to help verify how well countries are fulfilling commitments they made to reducing greenhouse gas emissions as part of the Paris climate agreement.

The United States, in contrast, is preparing to demonstrate sophisticated greenhouse gas sensor technologies but currently has no plans for ambitious atmospheric monitoring missions.

“Other countries are making great contributions and pushing as hard as they possibly can,” said David Crisp, a NASA Jet Propulsion Laboratory atmospheric physicist helping to coordinate efforts to track carbon dioxide and methane by the 34 space agencies that make up the Committee on Earth Observation Satellites. “We are relying on their contributions. There’s no way around that at this point, but I would like our country to lead.”

Through the Paris climate pact signed in 2015, 174 countries and the European Union agreed to take steps to mitigate global warming and report their progress in reducing greenhouse gas emissions. Those reports, called the global stocktake, are due every five years beginning in 2023.

NEW PRIORITIES

The Trump administration announced plans in 2017 to withdraw the United States from the Paris Agreement and did not support greenhouse-gas monitoring initiatives. It’s not yet clear whether that work will get a significant boost from the Biden administration.

Hours after taking office, President Joe Biden signed an executive order recommitting the United States to the Paris Agreement and Biden often refers to “tackling the climate crisis” as one of his top priorities.

Still, there are many ways the federal government works to address climate change aside from monitoring greenhouse gas in the atmosphere.

NASA develops and demonstrates technology to monitor the ozone layer, air pollution, ocean chemistry, and changes in sea and land ice. The National Oceanic and Atmospheric Administration provides long-term monitoring of those conditions in addition to offering extensive observation of global temperatures, precipitation, ice and ocean conditions.

NASA OR NOAA?

Experts disagree on whether greenhouse gas monitoring is a job for NASA or NOAA.

“NASA is the pathfinder,” said Barry Lefer, NASA’s Tropospheric Composition Program manager. “We build the first one, prove that works and then we hope that there are NOAA follow-ons.”

NASA, for example, proved it could measure carbon monoxide in the troposphere with the Microwave Limb Sounder on the Aura Earth observation satellite launched in 2004. NOAA now provides similar data with the Ozone Mapping Profiler Suite on the Joint Polar Satellite System.

Credit: NOAA

Monitoring carbon dioxide in the atmosphere is trickier. To provide the global stocktake reports mandated by the Paris Agreement, the United States would need to measure atmospheric carbon with great precision and high spatial resolution.

“NASA is probably the only agency that could build that system,” said Crisp, who was the principal investigator for NASA’s first carbon dioxide monitoring mission, the Orbiting Carbon Observatory. “However, once built and launched, it could be delivered to NOAA for use as an operational system.”

Europe plans to make weekly, global measurements of methane and carbon dioxide with the two-satellite Copernicus Anthropogenic Carbon Dioxide Monitoring, CO2M, mission. Japan plans to make similar observations with its GOSAT satellite series as does China with its TanSat satellites.

Neither NASA nor NOAA have similarly ambitious programs underway. That could change if Congress approves the Biden administration’s plan to increase NASA and NOAA budgets.

BIDEN BUDGET

The Biden budget blueprint calls for adding $1.4 billion to NOAA’s 2022 budget partly “to expand its climate observation and forecasting work and provide better data and information to decisionmakers.”

The new administration also proposes a 12.5% increase in NASA Earth science funding, or about $250 million above 2021 levels “to initiate the next generation of Earth observing satellites to study pressing climate science questions,” according to the budget summary released April 9.

It’s too soon to say how the agencies would spend the money.

NASA funding could be directed toward a series of missions recommended in the 2017 Earth Science decadal survey to determine how Earth’s climate, water cycle, soil and vegetation are changing. The decadal survey also mentioned greenhouse gas monitoring as an option for a future Explorer-class mission, but little has been done to flesh out that concept.

Instead, NASA is continuing to gather data with atmospheric sensors in orbit and demonstrating new technologies to measure greenhouse gases.

Two NASA sensors are scheduled to travel to geostationary orbit as hosted payloads on commercial satellites within two years.

The Tropospheric Emissions: Monitoring Pollution sensor, or TEMPO, is designed to provide hourly pollution reports for North America with a resolution of 10 square kilometers during the day.

“If things happen like hurricanes or fires, we can look at part of the field of regard more frequently,” said Kelly Chance, TEMPO principal investigator at the Harvard-Smithsonian Center for Astrophysics. “For example, we can observe a sixth of North America every 10 minutes.”

Geostationary Carbon Observatory, or GeoCarb, is a staring sensor to track atmospheric carbon dioxide, carbon monoxide and methane over North and South America.

NOAA plans to include an instrument similar to GeoCarb on its next generation of geostationary weather satellites scheduled to begin launching in the early 2030s.

For now, NASA identifies CO2 sources and sinks with the Orbiting Carbon Observatory-2 launched in 2014 and the Orbiting Carbon Observatory-3 mounted on the International Space Station in 2019.

OCO-2 and OCO-3 were designed to show that NASA could make measurements from space with the necessary accuracy and precision to monitor global carbon dioxide emissions in areas roughly the size of Texas.

Based on that criteria, the sensors have been extremely effective. To verify Paris Agreement emissions targets, though, the United States would need a satellite constellation offering higher resolution data and greater global coverage.

COMMERCIAL DATA

Could the private sector play a role in making those observations?

“The technology is here today to do that kind of work with very small satellites,” said Charles Beames, chairman of the SmallSat Alliance. “Startups with ambitions to do that are in various phases of fundraising. Frankly, I think the government needs to either buy commercial satellites or buy the data, whichever is in their best interest.”

Commercial small satellites tend to focus on detecting methane rather than carbon dioxide.

“Atmospheric CO2 has a long lifetime,” said Ken Jucks, NASA Upper Atmosphere Research program manager. “You need a very precise measurement because the new CO2 emitted during a particular hour produces a very small change in the total amount of CO2.”

Canada’s GHGSat is identifying important methane sources with 15-kilogram satellites. MethaneSAT LLC, a subsidiary of the nonprofit Environmental Defense Fund, is preparing to launch a 350-kilogram satellite in late 2022 or early 2023 to pinpoint faint methane emissions from oil and gas fields.

All the publicly and privately funded satellites have roles to play in the global greenhouse gas observing system, Lefer said.

Japan’s GOSAT-2 measures CO2 and methane within 10-kilometer-diameter areas that are separated by about 150 kilometers. The Tropospheric Monitoring Instrument on Europe’s Copernicus Sentinel-5 Precursor satellite obtains global, daily observations with 49-square-kilometer resolution.

When those satellites detect atmospheric methane, they can share the data with GHGSat, which can pinpoint sources down to 50 square meters, or MethaneSAT, which will offer 1 kilometer resolution.

UNCERTAIN FUTURE

Beyond TEMPO and GeoCarb, NASA has no greenhouse gas missions underway.

“It’s to be determined what NASA’s next move is going to be after GeoCarb,” Lefer said.

If Crisp could chart the course, he’d encourage the United States to gather and share global greenhouse gas data like it does weather data.

“If we add a U.S. system to the European and Japanese systems just like we do for weather forecasting, we might even get China to share its contributions,” Crisp said. “Once we get some big players involved, there’s more incentive for everyone to share data.”

This article originally appeared in the April 19, 2021 issue of SpaceNews magazine.

#Space

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wigmund · 7 years ago

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From NASA Earth Observatory Image of the Day; February 13, 2018:

Measurements Show Reduction in Ozone-Eating Chemical

Earth’s ozone layer is slowly healing, and we now have proof that policy decisions have helped.

Ever since the Montreal Protocol was drafted in the late 1980s, scientists and policymakers have been looking for signs that their legal curbs on chlorine compounds and related chemicals were stopping the depletion of the ozone layer. They have tracked the amount of chlorofluorocarbons (CFCs) being used in industry and commercial products, while also measuring airborne concentrations near Earth’s surface. They have deployed balloons, instrumented airplanes, and satellites to observe stratospheric ozone over the South Pole (in particular) and around the world.

In each case, they have seen signs of improvement. The concentration of CFCs and other ozone-depleting substances near the ground has decreased, as industry has found replacement chemicals that are less damaging to the atmosphere. The size of the annual ozone hole over Antarctica also has stabilized. Statistical analyses have shown that it peaked in the first half of the 2000s and became less extreme, though there are still large fluctuations from year to year.

But until recently, scientists had not directly measured chlorine compounds at the place where they matter most: inside the ozone hole over the South Pole. New research findings from Susan Strahan and Anne Douglass of NASA’s Goddard Space Flight Center now show that the amount of chlorine in the stratosphere over the South Pole is declining, and that it is happening in conjunction with years of less ozone loss.

This coincidence matters because the severity of an ozone hole in any given year can fluctuate a lot due to weather. Warmer stratospheric temperatures mean less ozone loss and smaller holes, while cooler temperatures breed larger holes and greater ozone loss. Scientists have wanted to know if the Montreal Protocol’s limits on chlorine products were actually driving incremental improvements in the skies over the South Pole.

CFCs were once used for refrigeration, air conditioning cooling, propellants, and solvents. In the 1970s and 80s, these chemicals were found to be accumulating in Earth’s stratosphere, where sunlight breaks them into components that destroy ozone. The ozone layer naturally absorbs ultraviolet radiation from the Sun, so less ozone in the stratosphere means greater risks for sunburn, skin cancer, and cataracts.

The images above depict the atmospheric chlorine reductions as observed by Strahan and Douglass. The globes on the left show the size, shape, and depth of the polar ozone hole in September 2006 and September 2011. The globes on the right show how much ozone was lost each year between July and September; less red and orange means less ozone loss during the southern winter. Note that the numbers between the globes give the averaged concentrations of hydrogen chloride (HCl) in the Antarctic lower stratosphere each year: 3 parts per billion (ppb) in 2006 versus 2.77 ppb in 2011. HCl is produced in the stratosphere when CFCs break down, so less HCl means lower CFCs levels.

The researchers made their discovery with the help of the Microwave Limb Sounder (MLS) on NASA’s Aura satellite. While many satellite instruments require sunlight to measure atmospheric trace gases, MLS detects microwave emissions. As a result, it can measure trace gases over Antarctica during the dark southern winter, when the stratospheric weather is quiet and temperatures are low and stable. This is the best time to detect the effects of chlorine.

In their analysis, Strahan and Douglass found that ozone loss declined by about 20 percent between 2005 and 2016, and the level of hydrogen chloride (HCl) inside the ozone hole had fallen about 9 percent. Most importantly, they found that the reductions in atmospheric HCl coincided with years of less ozone loss.

VIDEO

“The ozone hole is recovering, ozone loss is declining, and it is because of declining chlorine,” said Strahan, an atmospheric chemist for NASA.

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 Douglass, also an atmospheric chemist at NASA. “As far as the ozone hole being gone, we are looking at 2060 or 2080. And even then, there might still be a small hole.”

References and Further Reading

Strahan, S.E., & Douglass, A.R. (2018) Decline in Antarctic ozone depletion and lower stratospheric chlorine determined from Aura Microwave Limb Sounder observations. Geophysical Research Letters, 45, 382–390.

NASA (2018) Ozone Watch. Accessed February 9, 2018.

NASA Earth Observatory (2017) Antarctic Ozone Hole.

NASA Earth Observatory (2017, November 3) Ozone Hole is Smallest Since 1988.

NASA Earth Observatory (2012, September 18) Watching the Ozone Hole Before and After the Montreal Protocol.

NASA Earth Observatory (2009, May 13) The World We Avoided by Protecting the Ozone Layer.

NASA Earth Observatory images by Joshua Stevens, using data courtesy of Strahan, S. E., & Douglass, A. R. (2018)and NASA Ozone Watch. Story by Michael Carlowicz. Instrument(s): Aura - MLS; Model

#earth observatory #satellite data #ozone layer #ozone hole #Montreal Protocol #chlorofluorocarbons #CFC #aura satellite #Antarctica #long post

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kathleenseiber · 4 years ago

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Cosmos Q&A: Cooling the upper atmosphere

The same greenhouse gases that are warming Earth’s surface are cooling the upper atmosphere (the mesosphere) 90 kilometres above Antarctica.

Research released this week precisely measured this cooling rate (putting it at 10 times faster than the average warming at the planet’s surface) and revealed an important discovery: a new four-year temperature cycle in the polar atmosphere.

Cosmos put some questions to John French and Andrew Klekociuk from the Australian Antarctic Division, who carried out the research with Frank Mulligan, from the National University of Ireland Maynooth

In simple terms, the same process that is warming the Earth is cooling the atmosphere less than 100 kilometres above us. How does that work?

This works because of the ability of carbon dioxide (CO2) to absorb infrared radiation, exchange energy with the gases in the atmosphere, and re-emit radiation.

The Sun heats the Earth over a range of wavelengths of the solar spectrum which penetrate through the atmosphere: some wavelengths are absorbed by ozone and water vapour. The warm Earth then re-radiates a lot of this energy as long-wave (infrared or heat) radiation, otherwise we would continue to heat up. While most of the atmosphere (78% nitrogen, 21% oxygen) is transparent to the re-radiated infrared radiation, carbon dioxide is not, and is able to absorb it.

Monitoring equipment at Davis station. Credit: John French

The CO2 molecule can hold on to this absorbed energy only for a short time – its “radiative lifetime” – before it re-emits the radiation in all directions. However, in the dense lower atmosphere it can impact with other molecules in the air (the nitrogen and oxygen), exchanging energy through collisions, thereby increasing the kinetic energy of the air (ie the temperature). This is the “greenhouse effect” of global warming. CO2 essentially transfers more energy to other molecules in the lower atmosphere.

On the other hand, in the upper atmosphere, where the density is very low, the chance of collision is much lower, so the molecule more effectively radiates the energy it absorbs to space, resulting in an overall cooling of this region.

With increasing CO2, both processes occur more effectively. More warming in the lower atmosphere, more cooling in the upper atmosphere. The concentration of CO2 now exceeds 410 parts per million compared to 280 ppm in pre-industrial times. On current trends, this generation will see a doubling of the CO2 concentration compared to the maximum it has ever been over the last 800,000 years – as old ice core data has shown.

Australian scientists have been monitoring the Antarctic for 20+ years. Was this work a Eureka moment or a little more routine?

No Eureka moments were encountered in this discovery! We continually analyse the spectra we measure, meticulously calibrate to derive temperatures, compute nightly and winter averages, and compare with previous years and other measurements to verify the quality of the data.

The variations in temperature we measure are merged responses from seasonal variations, the 11-year solar cycle and the response to changing atmospheric composition (greenhouse gases). We need to untangle these responses to separate the contributions from each. We extract the mean climatology and use a solar activity indicator (the 10.7cm solar radio flux) to extract the solar component. A linear fit to the remainder is the long-term trend.

We have previously reported on the solar cycle and long-term trends in the data. The first of our new papers is an update of these trends with better precision.

On top of that, the new four-year cycle we call the Quasi-Quadrennial Oscillation (QQO) became apparent. As an observer, your eye seeks patterns in the data in order to help forecast what might be coming. After a few cycles of the QQO we could generally predict warmer and colder years. But we needed to verify the QQO with independent data, to have confidence it was not an instrumental anomaly or local effect.

There are not many long-term measurements of temperatures in the mesosphere, particularly in Antarctica. In recent years two satellite instruments have provided global temperature measurements through the atmosphere. These are NASA’s Microwave Limb Sounder (MLS) on the Aura satellite and an instrument called SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) on NASA’s TIMED satellite (Thermosphere Ionosphere Mesosphere Energetics Dynamics).

Although these have fewer years of measurements, both satellites confirmed the QQO pattern over the last three cycles. The second paper is our investigation of the properties, extent and source of the QQO.

Were the results a surprise?

Credit: John French

A four-year cycle is kind of a surprise. The atmosphere undergoes many different cyclic oscillations. Some are obvious like the summer-winter seasonal cycle, some reasonably well know like the El Niño southern oscillation (ENSO) and the solar cycle, and some less well known like the Quasi-Biennial Oscillation (QBO; a two-year variation in equatorial pacific winds), the Pacific Decadal Oscillation (PDO) or the Southern Annular Mode (SAM).

A four-year cycle is unusual in terms of weather and climate modes, and we don’t yet fully understand the source or the mechanism that causes it.

Should we be concerned?

We have measured a three degree Celsius cooling of the upper atmosphere just during the 25-year course of this Australian Antarctic Division project. A consistent 1.2 degrees per decade is a big change in climate terms and is a symptom of the same carbon dioxide problem causing the warming in the lower atmosphere. If the trend continues at the current rate, what will the atmosphere look like in another 25 years?

You talk about the cooling happening at “the edge of space”. Is that significant? Is the location as important as the process itself?

The process is important to demonstrate that it is CO2 that is causing global warming and not some other process. Heating the Earth due to changes in the Sun for example would not lead to cooling in the upper atmosphere.

The upper atmosphere provides a sort of “integrator” of effects occurring closer to the surface. There is a lot of stored energy in the oceans, and this drives variability in weather and climate near the surface that can mask slow changes. The effects of this variability subside at higher altitudes, allowing the longer-term changes to be more clearly seen.

What are the mechanics of the work? What and how do you monitor and how are you able to make such detailed findings?

These observations are based on the remote sensing of hydroxyl airglow. Airglow is similar to aurora, but rather than being produced by charged particle impact on oxygen atoms and nitrogen molecules in the upper atmosphere, airglow is produced by a photochemical reaction. Hydroxyl airglow is actually incredibly bright – about five times brighter than an aurora – but we just can’t see it because it is in the infrared part of the spectrum.

Our spectrometers at Davis Research Station in the Antarctic observe several of these emission lines in the infrared. Simply put, the relative heights of the emission lines in the spectrum are dependent on the temperature of the emission region – kind of like a DNA fingerprint of the airglow, but in temperature.

The technique has been used for decades after the hydroxyl airglow was discovered in the 1950s. We scan a spectrum and obtain a temperature measurement every seven minutes during night hours. Typically, 25,000 measurements per year, for 25 years now.

A large part of the mechanics is continued, careful calibration of the instruments. Running the same instrument for 25 years has its challenges but we do not want to integrate instrumental changes into the temperature results when evaluating long-term changes.

The project also involves monitoring noctilucent or “night shining” clouds. What are they and where do they fit into the picture?

Spectrometer in the optical laboratory at Davis station. Credit: John French

Noctilucent clouds are extremely tenuous, filamental, ice crystal clouds that form in extremely cold temperatures (about minus 130 degrees Celsius) at around 83 kilometres altitude. They are the highest clouds in the atmosphere and only occur at high latitudes in summer when the coldest temperatures occur near the mesopause – the boundary between the mesosphere and the thermosphere and the coldest region anywhere on Earth. Seasonal temperatures are inverted in the mesosphere due to the large scale transport of air, rising and cooling in the summer pole, descending and warming at the winter pole.

Noctilucent clouds sightings are very rare in the Southern Hemisphere due to the fact that there are not many observers in the Southern Ocean or Antarctica where they mostly form. We have about 10 observations of them in our collection between the first one that John saw at Davis in 1998 and this year’s observation by Ashleigh Wilson at Macquarie Island.

They are a phenomenon of the modern world. The first reported sighting of them anywhere was in 1885 after Krakatoa erupted and injected a lot of water vapour into the upper atmosphere.

As a consequence of the CO2 cooling in the region, it is expected that the occurrence of noctilucent clouds will increase, both in brightness and extent. This is the “miner’s canary” reference in two papers by Gary Thomas: the first “Is the polar mesosphere the miner’s canary of global change?” and the second “Are noctilucent clouds harbingers of global change in the middle atmosphere?”

The new findings have global implications. What has been the response from the international science community?

The cooling response of this region to carbon dioxide increases was predicted as far back as 1989 by Roble and Dickinson. Since then, several laboratories around the world have been making measurements to test that forecast. It has taken the best part of three decades to obtain data with the precision needed to quantify the prediction with certainty.

The rates of cooling are an important quantity to measure and monitor and this is of great interest to atmospheric scientists and modellers to confirm and improve our understanding of the physical world. The information is also vital to governments and policy makers as a means of setting and adjusting emission targets based on evidence.

The QQO will be of interest to climate scientists in a wide range of disciplines, from the atmosphere to oceans, and also to the Antarctic ice. As our papers have only recently been published, the international community has yet to apply our results, but with time we expect to see follow-up work investigating this particular aspect further.

Is there any upside to what we now know?

Improved understanding of atmospheric processes and responses is always an upside.

Confirmation of the predicted cooling at 90 kilomere altitude gives us confidence that our global models include the more significant physical mechanisms that control the temperature in our atmosphere. Quantification of the cooling rate enables these models to be refined, which helps to reduce the uncertainty of future model predictions.

Identification of the QQO highlights that processes in the climate system are not fully understood or anticipated. As the processes responsible for the QQO appear to lie near the surface, climate models should be capable of capturing this variability.

We have shown that one leading climate model does not appear to show the signal of the QQO (at least of the magnitude we have observed it). This suggests that the model does not properly capture the physical processes that drive the QQO.

We rely heavily on modelling to predict future climate and to quantify the effect of any mitigation measures that may be adopted. The importance of getting them to capture the atmospheric processes and variability at all levels as accurately as possible cannot be overstated.

Cosmos Q&A: Cooling the upper atmosphere published first on https://triviaqaweb.weebly.com/

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environmentguru · 7 years ago

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Decline in Antarctic Ozone Depletion and Lower Stratospheric Chlorine Determined From Aura Microwave Limb Sounder Observations

Abstract Attribution of Antarctic ozone recovery to the Montreal protocol requires evidence that (1) Antarctic chlorine levels are declining and (2) there is a reduction in ozone depletion in response to a chlorine decline. We use Aura Microwave Limb https://www.environmentguru.com/pages/elements/element.aspx?utm_source=dlvr.it&amp%3Butm_medium=rss&amp%3Bid=6086260&utm_medium=tumblr

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humanitysopenmind-blog · 7 years ago

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Using measurements from NASA’s Aura satellite, scientists studied chlorine within the Antarctic ozone hole over the last several years, watching as the amount slowly decreased. Credit: NASA’s Goddard Space Flight Center/Katy Mersmann

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

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.”

To read the study, visit:

http://onlinelibrary.wiley.com/doi/10.1002/2017GL074830/abstract

For more on MLS, visit:

https://mls.jpl.nasa.gov/index-eos-mls.php

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.

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mystlnewsonline · 7 years ago

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New Post has been published on https://www.stl.news/recent-study-finds-first-direct-proof-ozone-hole-recovery-due-chemicals-ban/61456/

Recent study finds first direct proof of ozone hole recovery due to chemicals ban

Decline in Antarctic Ozone Depletion and Lower Stratospheric Chlorine Determined From Aura Microwave Limb Sounder Observations

WASHINGTON DC/January 4, 2018 (STL.News) — For the first time, scientists have shown through direct satellite observations of the ozone hole that levels of ozone-destroying chlorine are declining, resulting in less ozone depletion.

A new study in Geophysical Research Letters, a journal of the American Geophysical Union, shows the decline in chlorine, resulting from an international ban on chlorine-containing manmade 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 Susan Strahan, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland and lead author of the new study.

Monitoring the ozone hole

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 the 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.

youtube

“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.”

The researchers found 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.

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 co-author of the new study. “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.”

About the American Geophysical Union

The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing 60,000 members in 137 countries. Join the conversation on Facebook, Twitter, YouTube, and our other social media channels.

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Authors:

Susan E. Strahan: Universities Space Research Association, Columbia, Maryland, U.S.A., and Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, U.S.A.;

Anne R. Douglass: Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, U.S.A.

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SOURCE: news provided by American Geophysical Union (AGU), published on STL.News by St. Louis Media, LLC (MS)

#National News Headlines

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