Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NASA scientists use satellites to distinguish human pollution from other atmospheric particles

18.09.2002


Driven by precise new satellite measurements and sophisticated new computer models, a team of NASA researchers is now routinely producing the first global maps of fine aerosols that distinguish plumes of human-produced particulate pollution from natural aerosols.



In the current issue of the journal Nature, atmospheric scientists Yoram Kaufman, at NASA’s Goddard Space Flight Center, Greenbelt, Md., Didier Tanré and Olivier Boucher from CNRS (Centre National de la Recherche Scientifique) at the University of Lille, reported in a review paper that these global maps are an important breakthrough in the science of determining how much aerosol pollution comes from human activities. Aerosols are tiny solid or liquid particles suspended in the atmosphere. The authors stated that the next step is to quantify more precisely the roles human aerosol pollution plays in Earth’s weather and climate systems.

"Plumes of smoke and regional pollution are distinguished by their large concentrations of small particles (less than 1 micrometer) downwind of biomass burning sites and urban areas," Kaufman said. "These particles are important because, depending upon the type of particles produced, human pollution can either have a warming or cooling influence on climate, and they can either increase or decrease regional rainfall."


Distinguishing small from large aerosol particles requires good understanding of how aerosols reflect sunlight at key wavelengths of the solar spectrum. For the first time ever, the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument flying aboard NASA’s Terra and Aqua satellites measures precisely the sunlight reflected by aerosols back to space every day over almost the entire planet at wavelengths spanning across the solar spectrum (from 0.41 to 2.2 micrometers).

Aerosol plumes comprised of smaller particles (less than 1 micrometer) reflect light at shorter wavelengths (blue light) much more strongly than plumes comprised of larger particles (greater than 1 micrometer) which scatter and reflect light roughly equally at short and long wavelengths (blue, green, red and near-infrared light). It is this basic understanding that helps scientists use MODIS data to distinguish human-produced aerosol.

However, there are exceptions to this rule. Kaufman noted that nature produces small particles too, while humans can generate large particles by changing land surface cover through agricultural practices and deforestation. Therefore, scientists need additional information-such as land use and fire activities, which are also observed by satellites, as well as information on population and economic activities-that is fed into advanced new computer aerosol models.

"Natural aerosols like salt particles from sea spray are typically widespread over larger areas and not particularly concentrated downwind of urban areas," Kaufman observed. "Or, they are particularly concentrated downwind of obviously natural sources, such as the streams of dust originating from the Sahara Desert."

Conversely, aerosols produced by humans are the result of urban pollution, industrial combustion, or burning vegetation. These plumes of pollutants appear in punctuated bursts of thick and concentrated plumes comprised of small particles. Or, they are concentrated downwind of regions obviously altered by human activities, such as deforested regions.

The authors find surprisingly good agreement between a new aerosol model (developed jointly by NASA Goddard and Georgia Tech) and the measurements now being made by the MODIS sensors. Examining global satellite images in concert with global-scale models and globally distributed ground-based measurements gives scientists the best tools they have ever had to estimate the effects of aerosols on climate and weather patterns around the world.

The new aerosol measurements collected by the Terra and Aqua satellites provide dramatic improvements over the measurements made by previous satellites over the last two decades. Another instrument on Terra, the Multi-angle Imaging SpectroRadiometer (MISR), observes aerosols by looking at the radiation reflected and scattered by aerosols in nine different directions. This multi-angle technique complements the multi-wavelength approach by NASA. NASA plans to further expand global aerosol research with the launch of satellite-based light imaging radars (lidars) that sends bursts of light to Earth and, like a radar signal, provide a measure of the altitude and vertical structure of aerosol plumes and clouds.

The Terra and Aqua satellites are part of NASA’s Earth Science Enterprise, a long-term research effort to understand our home planet.

Lynn Chandler | EurekAlert!
Further information:
http://www.gsfc.nasa.gov/topstory/20020917pollutionpart.html
http://modis.gsfc.nasa.gov
http://earthobservatory.nasa.gov/Library/RemoteSensingAtmosphere/remote_sensing3.html

More articles from Ecology, The Environment and Conservation:

nachricht Despite government claims, orangutan populations have not increased. Call for better monitoring
06.11.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Increasing frequency of ocean storms could alter kelp forest ecosystems
30.10.2018 | University of Virginia

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>