He and his team at NASA's Goddard Space Flight Center in Greenbelt, Md., have developed an automated, lightweight, laser-induced fluorescence device that measures the levels of this difficult-to-measure organic compound in the lower troposphere and then again at much higher altitudes. The primary objective is determining how much pollution a storm can transport through convection and then using those insights to improve chemistry-climate models. "It's a major problem in modeling knowing how to treat transport and clouds," Hanisco explained.
University of Maryland graduate student Heather Arkinson is shown here monitoring the In-Situ Formaldehyde Instrument, which she helped to demonstrate on a NASA DC-8. Credit: NASA
This image shows the new air-sampling system that is more efficient at drawing in air and preventing particles from sticking and potentially contaminating formaldehyde measurements. Credit: NASA
In the spring, he flew the In-Situ Airborne Formaldehyde Instrument for the first time on a NASA DC-8 research aircraft, a former passenger airplane that can fly up to 43,000 feet.
Size and Sensitivity
"People like this instrument because it's small, sensitive, and easy to maintain," said Hanisco. The instrument weighs only 60 pounds, and therefore is easily installed inside other research aircraft, including NASA's ER-2, Global Hawk, and WB57, which fly at much higher altitudes. In addition, it's automated and doesn't require anyone onboard to operate it, Hanisco said.
Prior to its development, only one other airborne instrument could measure formaldehyde. That instrument, however, weighed 600 pounds, required an onboard operator, and used a less-sensitive measurement technique -- absorption spectroscopy -- to gather data.
"I've been doing laser-induced fluorescence on other molecules for a while," Hanisco said, explaining why he sought and received Goddard Internal Research and Development funds to apply the measurement technique to a formaldehyde-sensitive instrument. "Formaldehyde isn't measured well at high altitudes. There was a real need for improvement."
With laser-induced fluorescence (LIF), a laser first illuminates the species of interest and "then you watch it fluoresce. It is a single photon-counting instrument," Hanisco said. Consequently, it's faster and more sensitive -- even at concentrations in the parts per trillion, he said.
The DC-8 campaign in Kansas, sponsored by the National Center for Atmospheric Research's Deep Convective Clouds and Chemistry Project, bore out the wisdom of his pursuit, proving that his instrument offered a factor-of-10 improvement in size, sensitivity, and complexity. During that campaign, a DC-8 flew as low as 500 feet above the ground and sampled air entering a storm. It then spiraled up to 30,000 to 40,000 feet and measured the air coming out at the top of the storm.
'Big Step Forward'
The instrument found that 30 to 40 percent of the formaldehyde produced in the "boundary" layer -- the lowest part of the troposphere closest to Earth's surface -- was transported to the upper troposphere during storms. "That number is a rough guideline, but we didn't have it before. Every storm is different, but knowing how much air gets through is a big step forward."
Hanisco attributes the instrument's success to its greatly simplified design and a new fiber-laser system that is smaller and less expensive than those used in other LIF-type instruments. He also attributes its success to a new air-sampling system, which features a glass- and Teflon-coated tube that draws in and directs air into the instrument's detection cell. Though the polymer-coated sampling system allows air to flow quickly, its surface prevents particles from sticking -- particularly useful because they could corrupt results. "We had to work hard to ensure that the sampling system was every bit as good as the detection," Hanisco said.
Hanisco anticipates many other flight opportunities in the future. "There was a real need for this instrument. There aren't a lot of instruments out there doing this."Tiffany Blackburn
Lori Keesey | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine