Cooperative Institute for Research in Environmental Sciences

Scientists with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder (CIRES), the National Oceanic and Atmospheric Administration (NOAA) and colleagues from across the country have gathered in Erie, Colo., for a month-long study of the chemistry of the wintertime atmosphere, which they hope will shed light on some scientific mysteries.

The central question they will tackle: Exactly why and how does a compound usually associated with the atmosphere near oceans — nitryl chloride — also form during the winter nighttime in land-locked regions such as the foothills of the Rocky Mountains? The chemistry involved affects climate and air quality.

The question is important to answer because of the implications for both climate and air quality. Nitryl chloride breaks apart quickly as the sun rises to release chlorine atoms. Chlorine atoms can react with many other compounds, contributing to smog formation, and can also influence chemical cycles that destroy or produce various greenhouse gases, including ozone and methane.

“Nighttime formation of nitryl chloride is a gateway to forming more highly reactive chlorine atoms,” says Steve Brown, the scientist at the NOAA Earth System Research Laboratory (ESRL) in Boulder who is leading the study in Erie. “It changes the atmosphere’s starting point for the next day.”

Brown and colleagues first observed the phenomenon three years ago while testing instruments in Boulder in preparation for an experiment in the Arctic. Brown designed this winter’s comprehensive study, dubbed Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT), which will take place from mid-February to mid-March and will make use of NOAA’s Boulder Atmospheric Observatory, more informally known to locals as the Erie Tower.

Two years ago, Brown and University of Washington scientist Joel Thornton investigated the nitryl chloride mystery a little further and were surprised to find that during the night, chloride compounds in the atmosphere were interacting with nitrogen oxide pollution, ultimately forming the nitryl chloride. Nitrogen oxides are emitted during the combustion of fossil fuels. But exactly where the atmospheric chloride comes from in a region so far from the oceans, and how the nighttime chemistry unfolds to produce nitryl chloride, are not fully understood.

The Erie Tower will give the scientists a distinct advantage in looking at the wintertime atmosphere, which is made up of “layers” that don’t mix well. As a consequence, what’s in the air and its chemical interactions vary with height, and therefore can’t be fully understood by making measurements only at ground level. A new mobile “Tower Laboratory” platform built at NOAA will carry more than one ton of instrumentation up and down the 300-meter tower, characterizing the chemistry at different heights.

Brown and other scientists in ESRL’s Chemical Sciences Division are working with colleagues from the University of Colorado, the University of Washington, the University of Virginia, the University of Toronto, the University of New Hampshire, the National Center for Atmospheric Research, Colorado State University and the Max Planck Institute in Germany.

The NACHTT researchers will bring with them an arsenal of instruments, many of them custom built, to solve the mystery of nitryl chloride. “This time we’ll be able to measure many more compounds, and they should give us the clues we need to pin down the source of the atmospheric chloride,” said Brown. Some of the likely suspects include wood burning, pollution from power plants, and road de-icing chemicals.

De-icing chemicals, for example would be detected by instruments operated by scientists William Keene of the University of Virginia and Ann Middlebrook of ESRL. “By measuring what’s in airborne particles of different sizes, we’ll get a handle on not only the chlorine sources but also the possible climate implications of these particles,” said Keene. Some particles in the atmosphere can act to cool climate by reflecting sunlight, while others such as soot can have a warming effect because they absorb heat.

Whatever the outcome of the NACHTT, the study is sure to advance the understanding of what goes on in the air in the dead of winter, and at night — two little-studied aspects of the chemistry of the atmosphere. It’s possible that the chemistry could apply to other regions and other seasons, even the summertime in Los Angeles.

“This is just the beginning of the story,” notes Brown.

CIRES scientists involved in the study are Roya Bahreini, Agnes Borbon, Bill Dube, Joost deGouw, Jessica Gillman, Martin Graus, Gerd Hübler, Bill Kuster, Brian Lerner, John Trytko, Trevor VandenBoer, Nick Wagner, Carsten Warneke, Eric Williams and Cora Young.

Contact: Katy Human 303-735-0196

The deadly Russian heat wave of 2010 was due to a natural atmospheric phenomenon often associated with weather extremes, according to a new study by scientists at NOAA and the Cooperative Institute for Research in Environmental Sciences (CIRES). And while the scientists could not attribute the intensity of this particular heat wave to climate change, they found that extreme heat waves are likely to become increasingly frequent in the region in coming decades.

The research team drew from scientific observations and computer climate models to evaluate the possible roles of natural and human-caused climate influences on the severity of the heat wave. The study was published in Geophysical Research Letters March 9.

“Knowledge of prior regional climate trends and current levels of greenhouse gas concentrations would not have helped us anticipate the 2010 summer heat wave in Russia,” said lead author Randall Dole, deputy director of research at NOAA’s Earth System Research Laboratory, Physical Science Division and a CIRES Fellow. “Nor did ocean temperatures or sea ice status in early summer of 2010 suggest what was to come in Russia.”

Temperatures in the upper 90s to above 100 F scorched western Russia and surrounding areas from July through mid-August, 2010. In Moscow, the long-term daily average temperatures for July range from 65-67 F; in 2010, daily average July temperatures soared up to 87. Daily average temperatures include the night. The exceptional heat over such a long duration, combined with poor air quality from wildfires increased deaths by at least 56,000 in Moscow and other parts of western Russia, according to Munich Reinsurance, and led to massive crop failures in the region.

While a contribution to the heat wave from climate change could not be entirely ruled out, if it was present, it played a much smaller role than naturally occurring meteorological processes in explaining this heat wave's intensity, the researchers found.

They also cautioned that this extreme event provides a glimpse into the region’s future as greenhouse gases continue to increase, and the signal of a warming climate, even at this regional scale, begins to emerge more clearly from natural variability in coming decades. Climate models evaluated for the new study show a rapidly increasing risk of such heat waves in western Russia, from less than one percent in 2010, to 10 percent or more by the end of this century.

“It appears that parts of Russia are on the cusp of a period in which the risk of extreme heat events will increase rapidly,” said co-author Martin Hoerling, a research meteorologist, also from ESRL.

 Dole called the intensity of this heat wave a “climate surprise,” expected to occur only very rarely in Russia’s current climate. With the possibility of more such events in the future, studying the Russian event better prepares scientists to understand climate phenomena that will affect the U.S. and other parts of the globe.

The team — led by Dole, Hoerling, and Judith Perlwitz from CIRES — sifted through long-term observations and results from 22 global climate models, looking for trends that might help explain the extraordinarily high temperatures in western Russia during the 2010 summer. They also ran atmospheric models that used observed global sea surface temperatures, Arctic sea ice conditions and atmospheric carbon dioxide concentrations in 2010 to assess whether such factors might have contributed to the heat wave.

The heat wave was due primarily to a natural phenomenon called an atmospheric “blocking pattern”, in which a strong high pressure system developed and remained stationary over western Russian, keeping summer storms and cool air from sweeping through the region and leading to the extreme hot and dry conditions. While the blocking pattern associated with the 2010 event was unusually intense and persistent, its major features were similar to atmospheric patterns associated with prior extreme heat wave events in the region since 1880, the researchers found.

They also found that western Russia has not experienced significant climate warming during the summer season over the 130 years from 1880-2009, despite significant warming of globally averaged temperatures during that time. Such a “warming hole” is not unique to that region and is not entirely unexpected, as the Earth is not uniformly warming and experiences distinct geographic areas that may be warmer or cooler than the average trend. 
“We know that climate change is not taking place at the same rate everywhere on the globe,” said Hoerling. “Western Russia is one of the parts of the world that has not seen a significant increase in summertime temperatures. The U.S. Midwest is another.”

Dole compared his team’s findings to trying to hear a quiet conversation underneath the roar of a noisy fan: a summertime signal due to climate change over western Russia was drowned out by the much larger climate “noise,” or variability, resulting from natural processes.

Authors of the new paper, “Was There a Basis for Anticipating the 2010 Russian Heat Wave?” are Randall Dole1, Martin Hoerling1, Judith Perlwitz2, Jon Eischeid2, Philip Pegion2, Tao Zhang2, Xiao-Wei Quan2, Taiyi Xu2, and Donald Murray2. The team is part of a NOAA effort to better understand the underlying causes of high-impact weather and climate events, with the ultimate goal of better anticipating them.

Katy Human, NOAA, 303-735-0196

To a conversation with study lead author and CIRES researcher Joost de Gouw. 6:30

When a team of researchers from NOAA and the Cooperative Institute for Research in Environmental Sciences (CIRES) raced to the scene of the BP Deepwater Horizon oil spill to assess the disaster’s impact on air quality, they found more than they expected. A significant fraction of the oil that surfaced had evaporated. Also, measurements taken onboard the NOAA WP-3D aircraft revealed that organic aerosols – a form of air pollution – formed from the oil vapors. Aside from the common culprits that create organic aerosols, the researchers discovered a new set of chemicals that contribute to diminished air quality – chemicals that also exist in urban environments. 

“It was very clear that the aerosols were formed from compounds not currently measured,” said CIRES Fellow Joost de Gouw, lead author of a new paper published in the journal Science March 10. Discovering these previously unknown sources of aerosols could improve scientists’ understanding of air pollution and how to regulate it in the future, said de Gouw. “This really shows that we need to start paying more attention to these compounds,” he said.

Tiny particles, dire consequences

Aerosols are microscopic particles suspended in the air – in polluted U.S. cities about half of the air pollution particles consists of organic material. Organic aerosols are linked to asthma, cardiovascular disease, and even premature death. But scientists only know the origin of a small fraction of the organic aerosols. “The problem has been that we know there are more organic aerosols than we can account for,” de Gouw said. “So there is a lot of discussion in the literature on where this organic material comes from.”  

The team’s research on the air quality impacts of the oil spill shed new light on this mystery. In early June, a team of scientists from NOAA and CIRES arrived at the scene of the spill to assess how much of the oil was evaporating into the atmosphere, and whether this oil was a concern for air quality. Using a Lockheed WP-3D Orion aircraft, the team flew for about 14 hours directly over and downwind of the oil spill. Instruments on board the aircraft measured many types of air pollution particles, including organic aerosols, and the chemicals from which they are formed in the marine boundary layer – the layer trapping most pollutants.   

Based on the current understanding that the most volatile components of oil form air pollution particles, de Gouw and his colleagues knew where they expected to see the aerosols: exactly where they saw the most volatile components of the oil evaporate. “Our instrument showed a very narrow plume of oil compounds downwind from the spill site,” said de Gouw – so the scientists expected to see the organic aerosols in this same region. 

Explaining the unexpected

But this is not what the scientists observed.

“We detected particles being formed, but over a much wider area,” said de Gouw.  “So that was a big surprise.” 

The scientists realized that other compounds, aside from the highly volatile components of the oil, had to be contributing to the air pollution. Because they recorded organic aerosols over a broad area, they concluded the heavier, less volatile compounds that are slower to evaporate were also forming aerosols. The lighter, highly volatile compounds evaporate quickly from a small area of the ocean and form air particles in that region only, de Gouw said. But heavier compounds have a chance to spread out before they evaporate, giving rise to the much wider band of organic aerosols that the team detected.

In 2007, other atmospheric scientists had proposed that heavier or “less volatile” components could—in theory—help to create organic aerosols. But it had proven to be near impossible to study this process in the real world, de Gouw said. “The problem is that volatile and less volatile species are emitted at the same time from the same combustion sources, so we could not study them separately in the atmosphere,” de Gouw said. “Until Deepwater Horizon.”

When de Gouw and his colleagues ran a series of models showing how spilled oil spread across the water, and how long it should take for various heavy, medium, and light fractions to evaporate, the conclusion was clear: Heavier compounds from the oil that are slower to evaporate were the culprit.

The finding is not one that is specific to catastrophic oil spills, de Gouw said. The oil was not a thick sludge but more similar to the highly refined oil that is used in cars or factories, he said. That means the same heavier compounds that contributed to air pollution over the Gulf Oil Spill, also contribute to air pollution in urban environments.  
But these compounds are not measured in most air-quality monitoring programs designed to capture the conventional contributors to poor air quality. “This chemistry could be a very important source of aerosols in the urban United States and elsewhere,” de Gouw said. “What we learned from this study will help us to improve air quality understanding and prediction.”

Co-authors of the new paper, “Organic Aerosol Formation Downwind from the Deepwater Horizon Oil Spill,” include Ann Middlebrook1, Carsten Warneke1,2 Ravan Ahmadov1,2, Elliot Atlas3, Roya Bahreini1,2, Donald Blake4, Charles Brock1, Jerome Brioude1,2, David Fahey1, Fred Fehsenfeld1,2, John Holloway1,2, Matthiew Le Henaff3, Richard Lueb5, Stuart McKeen1,2, James Meagher1, Daniel Murphy1, Claire Paris3, David Parrish1, Anne Perring1,2, Ilana Pollack1,2, A.R. Ravishankara1, Allen Robinson6, Thomas Ryerson1, Joshua Schwarz1,2, J. Ryan Spackman1,2, Ashwanth Srinivasan3, and Laurel Watts.1,2

1 NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO
2 Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 
3 University of Miami, Miami, FL
4 University of California, Irvine, CA  
5 National Center for Atmospheric Research, Boulder, CO 
6 Carnegie Mellon University, Pittsburgh, PA


Kathleen Human, CIRES, 303-735-0196,

Scientists from NOAA and the Cooperative Institute for Research in Environmental Sciences (CIRES) found a way to use air chemistry measurements taken hundreds of feet above last year’s BP Deepwater Horizon oil spill to estimate how fast gases and oil were leaking from the reservoir thousands of feet underwater. The scientists also determined the fate of most of those gas and oil compounds using atmospheric chemistry data collected from the NOAA WP-3D research aircraft overflights in June. The study, accepted for publication in Geophysical Research Letters, a publication of the American Geophysical Union, is in press.

“We present a new method for understanding the fate of most of the spilled gases and oil,” said Tom Ryerson, lead author of the report, from NOAA’s Earth System Research Laboratory in Boulder, CO. “We found that the spilled gases and oil (spilled fluid) obeyed a simple rule: whether a compound can dissolve or evaporate determines where it goes in the marine environment. That simple rule, and the methods we lay out in this paper, could enable airborne evaluation of the magnitude of future spills.”

Knowing where the spilled gas and oil mixture ended up could also help resource managers and others trying to understand environmental exposure levels.

Using the atmospheric measurements and information about the chemical makeup of the leaking reservoir fluid, Ryerson and his colleagues calculated that at least 32,600-47,700 barrels of liquid gases and oil poured out of the breached reservoir on June 10. This range, determined independently of previous estimates, presents a lower limit. “Although we accounted for gases that dissolved before reaching the surface, our atmospheric data are essentially blind to gases and oil that remain trapped deep underwater,” Ryerson said. Comparison of the new result with official estimates is not possible because this airborne study could not measure that trapped material.

Not including that trapped material, atmospheric measurements combined with reservoir composition information showed that about one-third (by mass) of the oil and gas dissolved into the water column on its way to the surface. The team found another 14 percent by mass (570,000 lbs per day) was lost quickly to the atmosphere within a few hours after surfacing, and an additional 10 percent was lost to the atmosphere over the course of the next 24 to 48 hours.

Among the study’s other key findings:

  • Some compounds evaporated essentially completely to the atmosphere, which allowed scientists to make an estimate of flow rate based solely on atmospheric measurements and reservoir composition information.
  • Airborne instruments picked up no enhanced levels of methane, the lightest-weight hydrocarbon in the leaking reservoir fluid, showing that it dissolved essentially completely in the water column.
  • Benzene — a known human carcinogen — and ethane were found in only slightly elevated concentrations in the air, meaning they dissolved nearly completely in the water.
  • A number of slightly heavier carbon compounds ended up in both the air and water, with the precise fraction depending on the compound.
  • Based on these data, the team inferred different exposure risks of mid- and shallow-water marine species to elevated levels of potentially toxic compounds.

A portion of oil and gas was “recovered” by response activities and piped from the leaking wellhead to the Discoverer Enterprise drill ship on the ocean surface. The research team calculated this recovered fraction by measuring emissions from natural gas flaring aboard the recovery ship. They calculated a recovery rate of 17,400 barrels of reservoir fluid (liquid gas and oil) for June 10, and which accounted for approximately one-third to one-half of the group’s total estimate of 32,600-47,700 barrels of fluid per day.

Ryerson and his colleagues concluded that the technique they developed could be applied to future oil spills, whether in shallow or deep water. The Gulf research flights were possible only because a NOAA WP-3D research aircraft had already been outfitted with sensitive chemistry equipment for deployment to California for an air quality and climate study and was redeployed to the Gulf. NOAA’s Gulf flights were in support of the Unified Area Command’s effort to observe and monitor the environmental effects of the spill.

CIRES scientists involved in the study included Kenneth Atkin, Wayne Angevine, Charles Brock, Fred Fehsenfeld, Joost de Gouw, John Holloway, Daniel Lack, J. Andy Neuman, John Nowak, Jeff Peischi, Anne Perring, Illana Pollack, Joshua Schwartz, J. Ryan Spackman, Harald Stark, Carsten Warneke, and Laurel Watts. 

Co-authors of the new paper, “Atmospheric emissions from the Deepwater Horizon spill constrain air-water partitioning, hydrocarbon fate, and leak rate,” are Kenneth Aikin, Wayne Angevine, Elliot Atlas, Donald Blake, Charles Brock, Fred Fehsenfeld, Ru-Shan Gao, Joost de Gouw, David Fahey, John Holloway, Daniel Lack, Richard Lueb, Simone Meinardi, Ann Middlebrook, Daniel Murphy, J. Andy Neuman, John Nowak, David Parrish, Jeff Peischl, Anne Perring, Ilana Pollack, A.R. Ravishankara, James Roberts, Joshua Schwarz, J. Ryan Spackman, Harald Stark, Carsten Warneke, and Laurel Watts.


Katy Human 303-735-0196 /

Fellow Roger Bilham visits Japan to uncover the causes and impacts of the disaster

Less than three days after a 9-magnitude earthquake struck off the coast of Japan on March 11, geologist Roger Bilham, a fellow of the Cooperative Institute for Research in Environmental Sciences (CIRES), was on a plane to Japan with the NOVA team to investigate the science behind the disaster and its scientific impacts.

In Japan, Bilham visited the Earthquake Research Institute in Tokyo and viewed the devastation of the tsunami by air.  The Honshu earthquake is one of five earthquakes in the world to have exceeded 8.4 since 2004.  The ground along the east side of Japan dropped by almost 10 feet, unleashing a catastrophic tsunami: 30-foot waves reached nearly three miles inland along the country’s northeast coast.

“The science community hasn’t seen many earthquakes this big,” said CIRES graduate student Celia Schiffman, a student of Bilham’s. “Visiting the scene presents an opportunity to learn more about earthquakes.” 

“The earthquake community has failed to forecast the immensity of the world’s last few mega-quakes,” indicated Bilham on his return. “We have been too conservative in our anticipations of seismic futures, basing them on short or incomplete historicial archives of ancient earthquakes.”
On his website, Bilham details the mechanisms behind the earthquake and talks about his visit.  He also has posted photos of the devastation and links to the ERI and United States Geological Survey. For more information, click here:

NOVA is a series of science shows produced by PBS.

Roger Bilham, CIRES, 303-492-6189,
Katy Human, CIRES, 303-735-0196,

CIRES Fellow Veronica Vaida is one of only four University of Colorado Boulder faculty members to receive a Boulder Faculty Assembly Spring 2011 Excellence Award for distinction in "Research, Scholarly and Creative Work."

In the same week Vaida also travelled to the spring meeting of the American Chemical Society (ACS) where she gave an award address – earlier in the year Vaida received the E.Bright Wilson Award in Spectroscopy from the ACS for outstanding accomplishments in spectroscopy in chemistry.

Vaida's research uses spectroscopy to explore different chemical reactions in the atmosphere – many of these reactions having environmental implications.  

Her recent work, accomplished with collaborators Adrian F. Tuck of the NOAA Aeronomy Laboratory and James Donaldson of the University of Toronto has shown that sunlight’s red wavelengths can initiate photochemical reactions not previously known to react in the presence of sunlight. This research revealed new photochemical reactions in the sulphuric, nitric and organic acids that play an important role in the planet’s atmosphere. 

To learn more about Vaida's current research, visit her laboratory homepage at

Katy Human CIRES, , 303-735-0196

CIRES and NOAA scientists study the wake effect of wind turbines to improve efficiency and reduce damage

On the southern edge of Boulder County, Colo., Eldorado Canyon carves a gap through the Rocky Mountains. The canyon funnels prevailing winds, which sweep east over the mountains, smack into the National Wind Technology Center.

Wind turbines, some taller than a 30-story building, stand waiting at the site, which is part of the Department of Energy's National Renewable Energy Laboratory (DOE's NREL).

The turbines not only convert the energy from the wind into wind power, but the rotating blades produce wakes – invisible ripples, waves and other disturbances downstream. Scientists from the Cooperative Institutes for Research in Environmental Sciences (CIRES) and NOAA launched a study of those wakes early this month, with an eye toward improving the productivity of wind farms.

“This turbulence can damage turbines downstream, and harm productivity,” said Bob Banta, an atmospheric scientist with NOAA's Earth System Research Laboratory (ESRL) in Boulder and a leader of the study along with Yelena Pichugina, a research scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES).

Pichugina , Banta and Alan Brewer from NOAA's Earth System Research Laboratory (ESRL) in Boulder, and colleagues from NREL have set up an experiment to make a study of wakes created by wind turbines. The goal of this short term-experiment, funded by the University of Colorado Boulder's Renewable and Sustainable Energy Institute, is to record the important aspects of the wakes created by wind turbines, using NOAA's high-resolution, scanning Doppler lidar.

This experiment is conducted now along with a DOE funded experiment, Turbine Wake and Inflow Characterization Study (TWICS), which is aimed an integrating turbine inflow and wake observations into a wind energy forecasting model.

“Wake study is very important not only for turbine designers but wind farm developers,” Pichugina said. “Turbines that are located behind other turbines can get less energy, so they will generate less power.”

The NOAA Remote Sensing Group has used the Doppler lidar for almost two decades to study wind speeds and directions in the atmosphere. For the turbine project, the scientists hope to capture turbulence and other wake effects in a broad wedge of air up to 7 km (4.3 miles) long and 1 km (3,280 feet) high.

“The wake effect has been modeled in wind tunnel studies and numerical models,” Banta said, “but the atmosphere is different – it's more variable and complicated.”

The team will use the scanning lidar to take a detailed look at the atmosphere in front of and behind one of the large turbines on the NREL site: A 2.3-megawatt graceful giant that stretches 100 m (328 ft) to the central hub and 145 m (492 feet) to the top of a blade.

The researchers hope to be able to capture the effects of ramp up and ramp down events, when winds suddenly gust high or die down, and they will gather data on what happens downstream when winds shift direction quickly.

“This generation of wind turbines are stretching up into a complicated part of the atmosphere,” said Julie Lundquist, TWICS project leader and a professor in the Department of Atmospheric Sciences at the University of Colorado-Boulder and a joint appointee at the National Renewable Energy Laboratory.

“If we can understand how gusts and rapid changes in wind direction affect turbine operations and how turbine wakes behave, we can improve design standards, increase efficiency, and reduce the cost of energy.”

By the end of 2010, wind power provided 2.3 percent of U.S. electricity, up from 1.8 percent the previous year. Researchers have argued that to attain the DOE goal of “20 percent by 2030,” the turbulent lower atmosphere – and its effects on turbines and turbine arrays – must be better understood.

“We have to do everything in our power to promote wind energy,” Pichugina said. “This type of energy is clean and it will provide independence from foreign oil.”


Leaders of TWICS, the Turbine Wake and Inflow Characterization Study:

  • Yelena Pichugina, Cooperative Institute for Research in Environmental Sciences
  • Robert Banta and Alan Brewer, NOAA Earth System Research Laboratory
  • Julie Lundquist, University of Colorado Boulder, National Renewable Energy Laboratory National Wind Technology Center
  • Neil Kelley, National Renewable Energy Laboratory National Wind Technology Center
  • Jeff Mirocha, Lawrence Livermore National Laboratory

Contact: Kathleen Human, CIRES, 303-735-0196,

Cigarette smoking, burning forests and even cooking fires all release a chemical — not previously known to exist in smoke in significant quantities — that may have potential health impacts, according to a new study by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the NOAA Earth System Research Laboratory.

“The molecule has hardly been measured before — certainly not in the atmosphere,” said CIRES Fellow Joost de Gouw, coauthor of the new paper published in the journal Proceedings of the National Academy of Sciences May 16. “ So it was a complete surprise to find it in such large quantities.”

The chemical, isocyanic acid, is similar to methyl isocyanate — the gas that leaked from a pesticide plant in Bhopal, India, in 1984 killing more than 3,000 people within weeks.

De Gouw and his colleagues were first able to detect isocyanic acid when they developed a new instrument, a mass spectrometer designed to measure gaseous acids in the air. In the laboratory, they found biomass burning — burning of trees or plant material—produced levels of this molecule approaching 600 parts per billion by volume (ppbv).

“There is this molecule in smoke that we can now measure and it is there in significant quantities,” de Gouw said. “There are good reasons to believe that it can have significant health impacts.”

In the human body, isocyanic acid dissolves to form cyanate ions and the researchers found that the acid was very soluble at the pH level of human blood. This means it could potentially enter the bloodstream, de Gouw said. At exposure levels of isocyanic acid greater than 1ppbv, the cyanate ion is expected to be present at levels that can contribute to a variety of health problems such as cardiovascular disease, cataracts and rheumatoid arthritis.

Once the researchers discovered that fires produced the gas at the U.S. Forest Service Fire Sciences Laboratory in Missoula MT, they then took their instrumentation out of the lab to see whether smoke in a “real” environment also gave off this chemical. “We had a new tool to look around us and we just explored,” de Gouw said. “It was basically our chemical curiosity at work.”

Previous studies showed that burning coal produces isocyanic acid, and the researchers now discovered this chemical is also present in tobacco smoke and smoke from the combustion of other plant materials. In rural areas of developing countries where biofuels are used for cooking and heating, exposure levels of the acid could be harmful. But does a real, not a laboratory fire, give off the acid?

The team didn’t have to wait long to find out. Starting on Labor Day 2010, the Fourmile Canyon wildfire raged in the foothills above Boulder, CO, burning more than 6,000 sq. acres and destroying 169 homes. Scientists at the Boulder NOAA research facility wasted no time in learning what they could about the tragedy.

“Boulder has a world-class atmospheric chemistry building and only once in its lifetime is it going to have a full-on hit from a wild fire,” de Gouw said. “So just about everyone in that building turned on their instruments.”

The team’s spectrometer detected levels of the acid up to 200pptv in the air at the site, which was downwind from the fire. “So in Boulder we found that not only is it formed in a laboratory fire,” de Gouw said. “It also comes out of a real wild fire.”

One possibility was that the acid could be prevalent immediately in the vicinity of a fire but 20m from the flames the compound could be lost, de Gouw said. “But that didn’t happen,” he said. “We were miles away and it was still there.”

The researchers didn’t constrain their measurements to wildfires. They also used their equipment to find the levels of isocyanic acid in the urban environment of Los Angeles. “In LA we find, wait a minute, even when there are no fires there is a little of this acid,” de Gouw said. “So smoke may not be the only source of it in the atmosphere.”

More isocyanic acid was measured during the day, so sunlight could be sparking the chemical reactions that make it, de Gouw said. Another potential source in urban air could be emissions from diesel engines outfitted with the latest generation of pollution control equipment that is being introduced in California and Europe, he said.

“We know so little about isocyanic acid’s behavior in the atmosphere that we want to do a number of follow-up studies, “ de Gouw said. “We have some data in our paper but that is just the beginning and we need to do a lot more work.”

Other authors of the new paper, “Isocyanic acid in the atmosphere and its possible link to smoke related health effects,” are Jim Roberts, Patrick R. Veres, Anthony K. Cochran, Carsten Warneke, Ian R. Burling, Robert J. Yokelson, Brian Lerner, Jessica B. Gilman, William C. Kuster, and Ray Fall.

Contact: Katy Human, CIRES, 303-492-6289,

The Earth is getting thicker around the middle due to ice loss from the Greenland and Antarctic ice sheets, says a new study by researchers from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

Check out the GRACE Gravity Map Image gallery.

“If you imagine the Earth is like a soccer ball and you push down on the North Pole it would bulge out at its ‘equator’,” said CIRES Fellow Steve Nerem, coauthor of the study with CIRES Fellow John Wahr. “That’s what it looks like —a bit like a slightly squished ball.” We refer to the size of that bulge as the Earth’s ‘oblateness.’”

As the Earth’s shape changes so does its gravity field, a variable that can be measured from satellites, Nerem said. Data from the Gravity Recovery and Climate Experiment (GRACE)—twin satellites launched in 2002 that make detailed measurements of Earth's gravity field to monitor changes in ice mass, the amount of water in the ocean and losses in continental water —enabled Nerem and Wahr to test a theory that the ice loss was changing the oblateness. 

Using the GRACE values for ice loss in Greenland and Anarctica, the scientists predicted how that ice loss has changed the Earth’s oblateness since 2002, and their calculations agreed with the changes recorded by laser ranging measurements from a variety of different satellites. “We found that Greenland and Antarctica cause most of this change,” Nerem said. Their results are currently in press in the journal Geophysical Research Letters.

From the time scientists first began measuring the Earth’s shape, they’ve noted it’s not a perfect sphere, Nerem said. The spinning of the planet means, just like any non-rigid spinning object, material tends to move out to the equator. “There is more mass along the equator than there is at the poles.”

Most of the time the scientists have been taking measurements of its shape the Earth has been changing from this elliptical, or oblate shape, to a rounder one as it readjusts to the end of the ice age 20,000 years ago, Nerem said. Since the downward pressure of land-based ice has reduced as the ice melted, the land underneath has “rebounded” causing the Earth to become more spherical, he said.

In the mid-1990s that trend changed, however, as the planet appeared to start flattening out again, Nerem said. Puzzled by this observation, the scientific community came up with theories as to why this might be the case. “But a lot of it was speculation, albeit informed speculation,” he said. 

That was until the launching of the GRACE satellite mission.  Using the high-resolution GRACE  dataset Nerem and Wahr were able to conduct their experiment confirming the relationship between ice mass loss and the shape of the Earth. But this Nerem says is only a starting point. “People have started to suggest that the melting in Greenland and Antarctica have started to affect the Earth’s rotation,” Nerem said. “That is another thing to think about.”

The study was supported by two separate National Aeronautics and Space Administration GRACE Science Team investigations and a Jet Propulsion Laboratory GRACE MEASURES contract. It will be published online in a future edition of Geophysical Research Letters.


Steven Nerem, CIRES,, 303-492-6721

John Wahr, CIRES,, 303-492-8349

Katy Human CIRES, , 303-735-0196

Chihiko Yamashita, a CIRES graduate student, won the student poster competition at the 26th CEDAR (Coupling, Energetics and Dynamics and Atmospheric Regions) workshop held June 26-July 1. Yamashita’s poster was titled “Physical Mechanisms of Gravity Wave Variations and Their Impacts on the MLT (mesosphere and lower thermosphere) during the 2009 Stratospheric Sudden Warming.” Coauthor, CIRES Fellow Xinzhao Chu, advises Yamahita in her graduate research. The most dramatic phenomenon in the winter polar stratosphere—the layer of air that lies approximately between 10 km and 50 km above the surface of the Earth—is a stratospheric sudden warming. In a single week, the temperature can increase over 25 degrees and the polar jet stream can reverse. Yamashita’s poster describes the use of models to investigate the subsequent changes that take place in the atmosphere, during this sudden warming.