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Topic Name: Taking Advantage of Satellite Sensor Capabilities NASA Scientists Measures the Amount of Pollution from East Asia to North America

Category: Geo sciences & technology

Research persons: Hongbin Yu

Location: Goddard Space Flight Center, NASA, United States

Details

In a new NASA study, researchers taking advantage of improvements in satellite sensor capabilities offer the first measurement-based estimate of the amount of pollution from East Asian forest fires, urban exhaust, and industrial production that makes its way to western North America.

China, the world’s most populated country, has experienced rapid industrial growth, massive human migrations to urban areas, and considerable expansion in automobile use over the last two decades. As a result, the country has doubled its emissions of man-made pollutants to become the world’s largest emitter of tiny particles called pollution aerosols that are transported across the Pacific Ocean by rapid airstreams emanating from East Asia.

Hongbin Yu, an associate research scientist of the University of Maryland Baltimore County working at NASA’s Goddard Space Flight Center in Greenbelt, Md., grew up in China and taught there as a university professor, where he witnessed first-hand and studied how pollution from nearby power plants in China affected the local environment. Early this decade, scientists began using emerging high-accuracy satellite data to answer key questions about the role tiny particles play in the atmosphere, and eventually expanded their research to include continent-to-continent pollution transport. So Yu teamed with other researchers to take advantage of the innovations in satellite technology and has now made the first-ever satellite-based estimate of pollution aerosols transported from East Asia to North America.

The new measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Terra satellite substantiate the results of previous model-based studies, and are the most extensive to date. The new study will be published this spring in the American Geophysical Union’s Journal of Geophysical Research-Atmospheres.

“We used the latest satellite capabilities to distinguish industrial pollution and smoke from dust transported to the western regions of North America from East Asia. Looking at four years of data from 2002 to 2005 we estimated the amount of pollution arriving in North America to be equivalent to about 15 percent of local emissions of the U.S. and Canada,” Yu said. “This is a significant percentage at a time when the U.S. is trying to decrease pollution emissions to boost overall air quality. This means that any reduction in our emissions may be offset by the pollution aerosols coming from East Asia and other regions.”

Yu and his colleagues measured the trans-Pacific flow of pollution in teragrams, a unit of measurement of the mass of pollution aerosol (1 teragram is about 2.2 billion pounds). Satellite data confirmed 18 teragrams -- almost 40 billion pounds -- of pollution aerosol was exported to the northwestern Pacific Ocean and 4.5 teragrams – nearly 10 billion pounds -- reached North America annually from East Asia over the study period.

Yu points out, however, that the matter of pollution transport is a global one. “Our study focused on East Asian pollution transport, but pollution also flows from Europe, North America, the broader Asian region and elsewhere, across bodies of water and land, to neighboring areas and beyond,” he said. “So we should not simply blame East Asia for this amount of pollution flowing into North America.” In fact, in a model study published last November in the Journal of Atmospheric Chemistry and Physics, Mian Chin, also a co-author of this study and an atmospheric scientist at NASA Goddard, suggests that European pollution also makes a significant contribution to the pollution inflow to North America.

“Satellite instruments give us the ability to capture more accurate measurements, on a nearly daily basis across a broader geographic region and across a longer time frame so that the overall result is a better estimate than any other measurement method we’ve had in the past,” said study co-author Lorraine Remer, a physical scientist and member of the MODIS science team at NASA Goddard. The MODIS instrument can distinguish between broad categories of particles in the air, and observes Earth’s entire surface every one to two days, enabling it to monitor movement of the East Asian pollution aerosols as they rise into the lower troposphere, the area of the atmosphere where we live and breathe, and make their way across the Pacific and up into the middle and upper regions of the troposphere.

Remer added that the research team also found that pollution movements fluctuate during the year, with the East Asian airstream carrying its largest “load” in spring and smallest in summer. The most extensive East Asian export of pollution across the Pacific took place in 2003, triggered by record-breaking wildfires across vast forests of East Asia and Russia. Notably, the pollution aerosols also travel quickly. They cross the ocean and journey into the atmosphere above North American in as little as one week.

“Using this imaging instrument, we cannot determine at what level of elevation in the atmosphere pollution travels. So, we do not have a way in this study to assess the degree of impact the pollution aerosols from China have on air quality here once they cross over to North America. We need improved technology to make that determination,” said Remer. “Nevertheless, we realize there is indeed impact. For example, particles like these have been linked to regional weather and climate effects through interactions between pollution aerosols and the Sun's heat energy. Since pollution transport is such a broad global issue, it is important moving forward to extend this kind of study to other regions, to see how much pollution is migrating from its source regions to others, when, and how fast,” said Remer.

Note for Moderate-resolution Imaging Spectroradiometer
MODIS (Moderate-resolution Imaging Spectroradiometer) is a payload scientific instrument launched into Earth orbit by NASA in 1999 on board the Terra (EOS AM) Satellite, and in 2002 on board the Aqua (EOS PM) satellite. The instruments capture data in 36 spectral bands ranging in wavelength from 0.4 µm to 14.4 µm and at varying spatial resolutions (2 bands at 250 m, 5 bands at 500 m and 29 bands at 1 km). Together the instruments image the entire Earth every 1 to 2 days. They are designed to provide measurements in large-scale global dynamics including changes in Earth's cloud cover, radiation budget and processes occurring in the oceans, on land, and in the lower atmosphere.

About Goddard Space Flight Center
The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately 6.5 miles northeast of Washington, D.C. in Greenbelt, Maryland, USA.
GSFC has the largest combined organization of scientists and engineers dedicated to increasing knowledge of the Earth, the Solar System, and the Universe via observations from space in the United States. GSFC is a major U.S. laboratory for developing and operating unmanned scientific spacecraft. GSFC conducts scientific investigation, development and operation of space systems, and development of related technologies. Goddard scientists can develop and support a mission, and Goddard engineers and technicians can design and build the spacecraft for that mission. Goddard scientist John C. Mather shared the 2006 Nobel Prize in Physics for his work on COBE.
GSFC also operates spaceflight tracking and data acquisition networks, develops and maintains advanced space and Earth science data information systems, and develops satellite systems for the National Oceanic and Atmospheric Administration (NOAA).
GSFC manages operations for many NASA and international missions including the Hubble Space Telescope (HST), the Explorer program, the Discovery Program, the Earth Observing System (EOS), INTEGRAL, the Solar and Heliospheric Observatory (SOHO), the Rossi X-ray Timing Explorer (RXTE) and Swift. Past missions managed by GSFC include the Compton Gamma Ray Observatory, SMM, COBE, IUE, and ROSAT. Typically, unmanned earth observation missions and observatories in Earth orbit are managed by GSFC, while unmanned planetary missions are managed by the Jet Propulsion Laboratory (JPL).
The Goddard Space Flight Center is named in recognition of Dr Robert H. Goddard, the pioneer of modern rocket propulsion in the United States.
The GSFC Greenbelt facility encompasses the Main Site and adjacent outlying sites. The main campus includes 50 buildings. Additional GSFC facilities are located in New York City, Virginia, and West Virginia. The Greenbelt facility contains two campuses, which were formerly divided by Soil Conservation Road. Soil Conservation Road has recently been diverted to go around the GSFC, and the section that divided the two campuses was turned into Hubble Road.
GSFC operates three facilities that are not located at the Greenbelt site. These facilities are:
The Wallops Flight Facility located in Wallops Island, Virginia was established in 1945, and is one of the oldest launch sites in the world. Wallops manages NASA's sounding rocket program, and supports approximately 35 missions each year.
The Goddard Institute for Space Studies (GISS) located at Columbia University in New York City, where much of the center's theoretical research is conducted. Operated in close association with Columbia and other area universities, the institute provides support research in geophysics, astrophysics, astronomy and meteorology.
The Independent Verification and Validation Facility (IV&V) in Fairmont, West Virginia was established in 1993 to improve the safety, reliability, and quality of software used in NASA missions.

About Terra Satellite
Terra (EOS AM-1) is a multi-national NASA scientific research satellite in a sun-synchronous orbit around the Earth. It is the flagship of the Earth Observing System (EOS).
The name "Terra" comes from the Latin word for earth. The satellite was launched from Vandenberg Air Force Base on December 18, 1999 aboard an Atlas IIAS vehicle and began collecting data on February 24, 2000.
Terra carries a payload of five remote sensors designed to monitor the state of Earth's environment and ongoing changes in its climate system:
ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer)
CERES (Clouds and the Earth's Radiant Energy System)
MISR (Multi-angle Imaging SpectroRadiometer)
MODIS (Moderate-resolution Imaging Spectroradiometer)
MOPITT (Measurements of Pollution in the Troposphere)