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 'Quartz' crystals at the Earth's core power its magnetic field
23.02.2017 | Tokyo Institute of Technology

nachricht NASA spies Tropical Cyclone 08P's formation
23.02.2017 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>