PULLMAN, Wash. — With the anticipated July 10 launch of NASA’s Earth Observing System Aura satellite, environmental scientists here and across the globe are expecting to get the clearest space-based views yet of the sources and movement of air pollution in the earth’s lower atmosphere.

The spacecraft will carry into orbit a complex package of four high-tech instruments to conduct a wide range of studies of both the upper and lower atmospheres. Among them will be a device called the Ozone Monitoring Instrument, or OMI (pronounced oh′-mee by project scientists).

Although proposed, constructed and funded largely by the Dutch, OMI utilizes extensive U.S. expertise in ozone-measuring instrumentation and analysis. With funding from NASA, Washington State University’s George Mount, a geophysicist and professor of civil and environmental engineering, has lent his expertise and effort to the project since the early stages of its development nearly eight years ago.

Producing the most advanced spatial resolution available to date, OMI (in conjunction with the other 3 instruments on Aura) is expected to provide the most scientifically useful satellite-gathered data available on the formation and dispersion of weather-borne pollutants within the planet’s troposphere – the near-earth region of the atmosphere extending from the planet’s surface to an altitude of about 14 kilometers. Much of that data will be gathered from within the very lowest atmosphere in which most of the pollution chemistry occurs.

The equipment will analyze the absorption of sunlight in the visible and ultraviolet spectrums as it passes through the atmosphere after being reflected off the surface of the planet, said Mount, a veteran of a number of earlier NASA projects.

“We’re interested in urban air pollution, which is a very, very hard problem to do from space,” Mount said of the work conducted at WSU’s Laboratory of Atmospheric Research (LAR).

 “In 1997, we were selected by NASA to participate in a full range of work on OMI, from design to testing, calibration and data analysis – all as part of the OMI science team. Our work to date has been specifically in the development and calibration of the OMI’s UV spectrometer.”

Launching from California’s Vandenberg Air Force Base, the EOS Aura spacecraft will study the earth’s ozone, air quality and climate from a near-polar orbit completed every 100 minutes. Throughout the projected five-year minimum life of its mission, the satellite will move across the planet in a continuing series of 16-day-long ground-tracking cycles, repeatedly capturing air pollution images from virtually every point on the globe.

OMI will give scientists the ability to measure and map airborne pollutants within individual 64-square-mile segments covering a 1,600-mile long swath representing geographical areas the size of the Pacific Northwest.

While earlier satellite imaging techniques have lacked the necessary definition to give scientists true high-resolution views of pollutants within the troposphere, OMI is expected to allow them to distinguish point sources of air pollution and map the airborne transport of aerosols and chemical pollution on regional and global scales.

In addition to detecting and measuring ozone – a potent byproduct of agricultural burning, deforestation, urban activity and industry – OMI will provide environmental researchers with data on pollutants such as nitrogen dioxide, formaldehyde, sulfur dioxide and other chemical emissions that contribute to the degradation of air quality on a global scale. Data captured by OMI will allow scientists to deduce the amount, type and patterns of air pollution from the molecular concentrations detected in the planet’s lower atmosphere.

Mount credits the Dutch for taking great care to ensure that OMI will be able to function as what he calls “an enlightened instrument.

“The team began working on the design and construction of a development model, which is separate from the flight model that actually goes onto the spacecraft,” he said. “Most satellite projects today don’t begin with the construction of a developmental model that can be used for laboratory testing because that’s a very costly way to work. But that’s how the Dutch did it. And they worked very hard to get substantial blocks of time for testing of both the development model and the flight instrument, so the results of those tests could improve the actual flight instrument.

“The OMI development model was used early on in the Netherlands to perform instrument diagnostics by observing spectroscopic absorption from the sky – looking away from the earth and gathering atmospheric data from the opposite direction in which it will be collected by the orbiting spacecraft,” Mount said.

“At first we couldn’t see what you were supposed to see. Holland has a substantial amount of air pollution, but we couldn’t see it,” he said. “But by fixing problems in the development instrument, we succeeded in producing very nice geophysical data from the sky using the flight model. Some of those changes were very small and easily made. But of course, they wouldn’t have been easy on an instrument that was already in space.”

After the launch of the spacecraft, Mount and his colleagues and graduate students at WSU – along with the entire Puget Sound region – plan to play a continuing role in the mission by assisting in the validation of the data received from the satellite.

Much of that role will be made possible by the work of other WSU researchers, including Brian Lamb, Boeing distinguished professor of civil and environmental engineering, and Joseph Vaughan, a research professor with the university’s LAR.

In collaboration with meteorologists from the University of Washington and elsewhere, the two veteran WSU researchers already have established a sophisticated ground-based air quality forecasting system across the Puget Sound region.

Developed over the past decade, the so-called AIRPACT system – for Air Indicator Reporting for Public Access and Community Tracking – consists of a network of ground sensors used to collect air pollution emissions data, all of which are subsequently correlated with weather forecasting data and used to drive an air-quality model that predicts hourly pollutant levels throughout the region. Data gathered by AIRPACT will play a role in verifying the accuracy of the information received from OMI. Information on the AIRPACT system is available online at http://airpact.ce.wsu.edu/index2.html.   

But as unprecedented as the images provided by OMI are expected to be, NASA has already begun working with Mount and a small group of other scientists and engineers on the next generation of atmospheric-imaging satellite instruments for measurement of air pollution.

“When we ask ourselves what limits air pollution measurements
from OMI, it’s that you get a snapshot of a 1,600-mile long swath beneath the satellite every 100 minutes as the satellite moves on, and that area of the earth rotates away beneath your view,” he said. “And you always need a smaller footprint on the ground to resolve air pollution sources.”

To improve on the capabilities of OMI, Mount and a small team of NASA scientists and engineers have begun working on a $3 million “proof-of-concept” lab prototype instrument for a satellite to be called GeoSpec, or geostationary spectrometer, which will be able to continuously observe an urban airshed from space.

“It’s an instrument that could give us a resolution of six-tenths of a mile and get rid of the problem of orbital sampling by using a geostationary orbit, just like weather satellites that observe the same real estate continuously,” he said.

 “It’s the future for air pollution measurement from space,” Mount said of GeoSpec. “It’s a really exciting project and the lab prototype will come here to WSU for testing in about 18 months”.