Ocean Onslaught
CU-CIRES professor awarded research ship, plane and instruments to study marine gas
In the hunt to track down climate-altering gases it isn’t enough just to stick to dry land. With oceans covering 70% of Earth getting wet feet is a necessity, says Rainer Volkamer, a CU assistant professor of chemistry and biochemistry and fellow at the Cooperative Institute of Research in Environmental Sciences (CIRES).
“The ocean has its own surprises,” Volkamer said. “But the remote ocean atmospheric environment is one of the least studied atmospheric environments on our planet.”
When it comes to tracking down these gases, even the NOAA research ship, is not enough, Volkamer said. From the research ship, scientists can explore the ocean atmosphere interface but miss the action that takes place at higher altitudes, he said. “So we have this beautiful plane and when we fly we’ll take a slice through the atmosphere and get a very detailed view of the composition of the air,” Volkamer said. “This will provide a unique perspective that we currently don’t have.”
The National Science Foundation (NSF) is awarding the use of its High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) plane, the National Ocean Atmosphere Administration (NOAA) is providing access to the research ship, and the National Aeronautics and Space Administration (NASA) is providing use of satellite technology to Volkamer and his group at the University of Colorado Boulder to lead a study called TORERO (Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated Volatile Organic Compounds).
Some 80 researchers from different institutes, including the National Center for Atmospheric Research (NCAR), University of Wisconsin, and researchers from the United Kingdom, Greece and Japan make up the TORERO team which CU heads. TORERO would not be possible without the excellence of its team, Volkamer said.
“The funding is a reflection of a growing need that is recognized in the global scientific community that we understand too little about our oceans and how they affect the atmosphere and climate that we live in,” Volkamer said.
Unmasking mystery molecules
The inspiration for the experiment evolved from the CU group’s attempt to track down a gas called glyoxal that can form aerosols and impact the planet’s climate.
Although scientists hadn’t previously detected the gas in the ocean’s atmosphere, satellite data hinted at its existence. Global models, however, didn’t predict its presence providing a dilemma for the researchers: did it exist or didn’t it? And, if it did, what could the gas reveal about our oceans? “We weren’t clear whether the satellite data was a measurement artifact or whether it was real,” Volkamer said.
To resolve the ambiguity, Volkamer and his group built an instrument—a CU Ship Multi-Axis Differential Optical Absorption instrument—to measure glyoxal and other molecules. They then affixed the instrument to a research ship used for a separate experiment conducted in the Eastern tropical Pacific Ocean between October 2008 and January 2009.
The team also built a second instrument—the Airborne Multi-Axis Differential Absorption Spectroscopy instrument—to measure glyoxal and halogen oxides above the marine boundary layer. They attached this instrument to the wing of NSF’s HIAPER plane that flew over the same region in January 2010.
The team found glyoxal, but that was not all they found.
Using both instruments they discovered a collection of gases that scientists hadn’t expected to find in such environments. “I am not sure yet which are the most intriguing ones,” Volkamer said. “We are in the process of finding out.”
The scientific community is equally intrigued and the group’s innovative technology drew funding to the research. “We have built an instrument that can do things that no one has been able to do before,” Volkamer said.
Ephemeral gases with big impacts
The discovery of these gases 3000km from the land wasn’t simply of interest to curious chemists. The two main gases found in the early studies—glyoxal and iodine oxide—can both influence the chemistry of the atmosphere and contribute to cooling Earth’s climate.
Iodine oxide forms by destroying ozone, a greenhouse gas that warms the climate, Volkamer said. It can also form new particles, or aerosols, which reflect the incoming radiation from the sun thereby reducing the sun’s heating influence. Glyoxal and iodine oxide also can grow smaller particles into the larger ones that eventually precipitate cloud droplets—and clouds play their own role in cooling the climate, he said. "So the gases modify the energy balance of the atmosphere and therefore heating rates.”
Currently, however, the origin and impacts of these gases aren’t understood. Typically, discussions about climate-altering gases have centered on long-lived compounds such as carbon dioxide. Such gases, which remain in the atmosphere for centuries, are those included in the models that attempt to predict future climate scenarios. The role of chemistry that modifies the lifetime of climate relevant gases, or the formation of aerosols, remains a key topic in climate research, Volkamer said.
The scientists have designed the plane’s instruments to constrain the recently found gases on location in the remote ocean. “These only live seconds in the atmosphere so they cannot be transported over long distances,” Volkamer said. The researchers also measure where the gases come from and where they go. Both measurements are relevant for understanding the possible impacts of such gases on climate, he said.
Satellites are the only source of data about the atmosphere over the remote ocean at this point in time, Volkamer said. But the combination of a research ship, a plane and artillery of instruments could change that, he said. “At this point the story remains to be told.”
Rainer Volkamer, CIRES, rainer.volkamer@colorado.edu, 303-492-1843
Karin Vergoth, CIRES, karin.vergoth@colorado.edu, 303-497-5125