Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Measuring earthshine: How new terra data are improving weather and climate forecast models

12.07.2002


A sensor aboard NASA’s Terra satellite is helping scientists map how much sunlight the Earth’s surface reflects back up into the atmosphere, and this new detailed information should help to greatly improve weather and forecast models. The Moderate Resolution Imaging Spectroradiometer (MODIS) now routinely provides daily global and local measurements of albedo, or the total amount of light reflected from Earth’s surface out to space. These precise data may allow scientists to better understand and predict how various surface features absorb and reflect solar radiation, which influence both short-term weather patterns and longer-term climate trends.

In a May 2002 issue of Geophysical Research Letters, a team of scientists at Boston University reported that the new albedo measurements match up well with the wide variance of geological features found across the Earth’s barren landscapes.

"Zooming in on Africa’s Sahara Desert and the Arabian Peninsula, for instance, MODIS observed considerable variability in reflectance across the region-from the darkest volcanic terrains to the brightest sand sheets," said Elena Tsvetsinskaya, the paper’s lead author and a researcher at Boston University. "So we can relate specific soil groups and rock types to MODIS-derived albedo measurements."



This correlation is important because most current weather forecast models treat this region as if the surface is uniform and therefore reflects the same amount of light all across its wide expanse. However, the terrain across the Sahara Desert and Arabian Peninsula is actually quite varied. Darker surface features (like rocks and plant canopies) absorb more light than lighter surfaces (like sand) and therefore get hotter in the afternoon. Over the course of a day, these heating differences can set up atmospheric motions that influence clouds and rain.

By coupling the MODIS measurements with geologic information, Tsvetsinskaya and her colleagues have provided weather and climate modelers with a new map of albedo across Northern Africa and the Arabian Peninsula that they can use to fine-tune their models. The team classified the region into eight categories, each of which has a distinct reflectivity range.

"There is a certain scientific beauty in deriving albedos from something else in the model (such as geologic information)," said Robert Dickinson, project lead at the Georgia Institute of Technology. "But the more practical reason is for ’what if’ studies. For example, what if the wind in Africa blew so hard it covered all the black rocks with white sand?"

This scenario hints at what both meteorologists and climate researchers alike know well: albedo for a given region can change relatively quickly. For example, the bright white snow- and ice-covered landscapes of Canada and Siberia during the winter and early spring reflect most incoming solar radiation back up into space, thereby helping to keep the surface cold.

But as the snow melts with the gradual onset of summer, the boreal forest canopy is exposed to the sunlight. The vegetated surface is much darker and strongly absorbs light, which helps to warm the surface.

NASA scientists discovered recently that once the snow melts in the Earth’s boreal regions, densely-vegetated surfaces begin to release a significant amount of heat into the overlying atmosphere. Yufang Jin, a Boston University graduate student, uses MODIS albedo data to document the difference between snow covered and snow-free vegetated surfaces in a related paper in another May issue of Geophysical Research Letters.

Over the longer term, regular MODIS albedo measurements will allow scientists to monitor how the Earth’s reflectivity changes on a global scale. "This will help us determine how the Earth’s climate is changing, both globally and locally," said Crystal Schaaf, co-author and research professor at Boston University. "When humans convert a vegetated region to a more reflective surface type (such as an urban area), the albedo changes."

Similarly, Schaaf added, when places like the grasslands of the African Sahel contract, they leave more reflective, barren deserts, which increases albedo.

###

Launched December 18, 1999, Terra is the flagship of the Earth Observing System series of satellites and a central part of NASA’s Earth Science Enterprise. The mission of the Earth Science Enterprise is to develop a scientific understanding of the Earth system and its response to natural and human-induced changes to enable improved prediction capability for climate, weather, and natural hazards.

For more information and images: http://www.gsfc.nasa.gov/topstory/20020624earthshine.html

Lynn Chandler | EurekAlert

More articles from Earth Sciences:

nachricht World’s oldest known oxygen oasis discovered
18.01.2018 | Eberhard Karls Universität Tübingen

nachricht A close-up look at an uncommon underwater eruption
11.01.2018 | Woods Hole Oceanographic Institution

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>