Atmospheric Sciences & Global Change
Sharing Space for the Sake of Science
When heaven and earth are your laboratory, how do you narrow down your choices for scientific research? You conduct field work where you can, but to obtain broader information about Earth systems, you build relationships and develop collaborations.
Researchers in the Atmospheric Science and Global Change division are doing just that, providing laboratory space and nearby real estate on south end of the Department of Energy's Pacific Northwest National Laboratory (PNNL) campus in Richland, Washington, for scientific colleagues working on a complex project called the Intercontinental Chemical Transport Experiment, or INTEX. Beginning in April, scientists from the Pennsylvania State University and Washington State University (WSU) began setting up instrumentation at PNNL Annex to collect data focused on the influx of Asian pollution across the Pacific Ocean.
Brett Taubman (holding balloon) and Shannon Michaels (holding sensor package), both from Pennsylvania State University, prepare to launch an ozonesonde as a Tri-City Herald newspaper reporter gets the scoop on their research project. The ozonesonde antenna is located in the foreground, and the team's mobile laboratory is in the background.
"Seattle was too cloudy, and Pullman [Washington] was too cloudy," said Brett Taubman, a post-doctoral student working on the project with Dr. Anne Thompson at Penn State. "The Columbia Basin seemed like the perfect place to get the measurements we're interested in."
Because clouds act as obstacles by absorbing or reflecting light, interpreting data from cloudy skies is more complicated. The research teams preferred to collect their data in clear sky conditions as much as possible.
Their measurements are tied to pollutants contained in the jetstream carried from Asia, across the Pacific Ocean, and into the United States. To catch them as they arrive, research teams from both Penn State and WSU set up shop at the Annex, using different suites of instruments to collect data about specific pollutant constituents, such as sulfur dioxide and carbon monoxide.
Scanning the Sky for Pollutants
Penn State shipped their "mobile laboratory" to PNNL and parked it in the fenced-in area next to the Annex. It contains upward pointing remote sensors and in situ air samplers that take continuous measurements of ozone and other trace gases.
They also are launching ozonesondes (like weather balloons, but designed to reach higher altitudes and measure different properties) once each day to collect in situ measurements from the surface up to altitudes of 35 km (about 115,000 ft.). The balloon launches, which began on April 21 and continued through May 15, are timed to coincide with daily satellite overpasses. In addition, a C-130 aircraft sponsored by the National Science Foundation flew over the Richland area on May 9, collecting in situ data for comparison to the measurement collected by the ground-based instruments and ozonesondes.
Preliminary data from the Penn State instruments at the PNNL Annex show elevated pollution levels between 5 a.m. and 9 a.m. on May 2 (a Tuesday), coinciding with the morning commute (top chart). In the bottom chart, the same pollutants stay at low levels during the same time period on May 7 (a Sunday). The pollutants are noted in the legend above the charts.
On a smaller but no less important scale, WSU is operating a new instrument on the platform above the Annex. The WSU team is led by Dr. George Mount, previously with the National Oceanic and Atmospheric Administration's Aeronomy Laboratory and now in his eighth year as a professor for the Department of Civil and Environmental Engineering at WSU. His graduate student, Elena Spinei, is using this research project for her thesis. Undergraduate students are also involved, helping to monitor the data for anomalies.
WSU undergrad Mary Capiral is gaining research experience by helping monitor data collected by the MF-DOAS instrument.
With funding from the National Aeronautics and Space Administration (NASA), Mount worked with Spinei in building the Multifunction Differential Optical Absorption Spectrometer (MF-DOAS) specifically for INTEX. The instrument will be used to validate measurements obtained by the Ozone Monitoring Instrument onboard NASA's Aura satellite. INTEX-B is the first field campaign for the MF-DOAS instrument.
Typical DOAS instruments measure light scattering as it passes through the atmosphere. By taking measurements at different elevation angles, the concentration of trace gas pollutants is determined based on the path that the light travels. This technique permits simultaneous measurements of several pollutants. With WSU's design, the MF-DOAS instrument allows vertical and horizontal "mapping" of the trace pollutants by taking the measurements in four directions (north, east, south, west) rather a single direction.
"They're all mashed in there together, so we rely on complex computer algorithms to separate them," said Mount. He stressed that the success of the new instrument is dependent on the development of spherical radiative transfer codes—computer algorithms that translate raw data into valid measurements used in computer simulations.
A Foundation for the Future
Both Penn State and WSU are important partnerships for PNNL. A number of scientists formerly with Penn State now work at PNNL, notably Dr. Jim Mather, who manages PNNL's Atmospheric Remote Sensing Laboratory and was instrumental in getting the current collaborators situated at the Annex. Numerous researchers in the Atmospheric Science and Global Change division continue to work with Penn State on other research projects.
In another university connection, many WSU graduates choose to intern and eventually work at PNNL. As PNNL continues to build partnerships with WSU in other key areas of research, the foundation for future research collaborations in aerosol/aerosol chemistry has been laid.
Mather said that there are a number of organizations that specialize in atmospheric chemistry, but PNNL's focus in the Atmospheric and Global Change division has historically been on clouds (as key participants in the Department of Energy's Atmospheric Radiation Measurement Program).
"We're not specifically involved in this part of the INTEX experiment, but are ramping up efforts for aerosol work, both on the observation and modeling side," said Mather. "The aerosol work has an inherent chemistry component, as you can't study aerosol formation without considering chemistry."
"As we get more into aerosol research, it makes sense to develop ties to the chemistry community," Mather added. "The groups over at the Annex represent some of the very active players in that atmospheric chemistry community and so represent potential future collaborators as we head in that direction."
So far, so good.
"The overwhelming success of this activity so far is due in no small part to our facilities and experiment hosts," said Taubman in a presentation to a packed PNNL conference room. He specifically thanked Mather for coordinating the necessary logistics.
Where do they go from here?
"Home," said Taubman. "Then we start analyzing the data."