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 Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

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: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Fraunhofer ISE Pushes World Record for Multicrystalline Silicon Solar Cells to 22.3 Percent

25.09.2017 | Power and Electrical Engineering

Usher syndrome: Gene therapy restores hearing and balance

25.09.2017 | Health and Medicine

An international team of physicists a coherent amplification effect in laser excited dielectrics

25.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>