Skip navigationGetting the global picture
POSTED MAR 27, 2003

 

1. Storms of dust and tanks

2. Big eyes upstairs

3. Eyeing melting ice

4. At the big disconnects

5. Finding fish - by satellite

6. Fire and brimstone

 

Under an orange sky, soldiers cover up from a desert sandstorm near Karbala, Iraq on March 26, 2003. The troops, in the 3rd Infantry Division, have been stalled by miserable weather in the desert less than 100 miles from Baghdad. AP Photo/John Moore

 

 

 

 

A group of satellites is taking Earth's temperature - and measuring humidity, chemistry, and heat transfer on the global scale.

  

Battling conditions
War is always hell. Sometimes, it's fought in especially hellish conditions. This week, the newspapers are wrapped in photos of U.S. troops waiting for a dust storm to clear. The dust blocks light, clogs pores, threatens vital electronics and even has caused an occasional mud rain.

Camouflaged soldier squints and covers face in midst of an ominous orange haze. Two out of focus soldiers in background and foreground leave their faces uncovered.Now that Gulf War II has begun, we had to think about dust and deserts. The planet's vast deserts may seem to be entirely natural, but many scientists say part of the blame for their formation is long-term human activity. They call the process desertification.

What role did millennia of grazing and irrigation play in the advance of deserts in the Middle East and elsewhere? How will climate change and rapid population growth affect them in the future?

These are big questions, and we won't answer them in four web pages. Instead, we'll introduce the Earth Observing System satellites. This coordinated set of orbiting observatories has many goals, but none is more important than addressing the many problems of global sustainability by making long-term observations of land, oceans, ice, atmosphere and life. They will, for example, be able to watch deserts expand and, hopefully, contract, and link those changes to changes in weather and human actions.

Call it the global picture
When the early earth-observing satellites looked at weather, they altered meteorology forever. When successive "birds" took photos of land, they revolutionized our view of the human impact on our planet.

The Earth Observing System (EOS) system now has 14 satellites in orbit. Eight more are being readied for launch. Between them, the EOS satellites carry dozens of instruments that look at the oceans, continents and atmosphere.

The new crop of satellites differs from its predecessors in quality and quantity. With their accurate and specialized instruments, they can:

"see" many wavelengths of light at once, to detect individual chemicals with greater accuracy

make finer measurements of the flow of heat from Earth

keep an eye on the sun, to understand how it is affecting global climate change

measure an entire globe's worth of winds in 12 hours

measure the height of the ocean

watch wildfires in action

track pollution drifting across the landscape and

measure soil moisture.

And with multiple and redundant instruments flying carefully defined orbits on many spacecraft, the system produces a torrent of data -- thousands of gigabytes a day -- ready and waiting for earthbound earth scientists.

Satellite image shows sand swirling into a ribbon of dark blue sea between two brown land masses. Green patches line the western coast of one chunk of land, and white lines and patches dot the ocean.
You've seen those gauzy photos of dust-shrouded warriors. In this view of conditions southeast of Iraq , taken from a satellite on March 2, 2003, the light brown plumes show desert dust blowing from the Arabian Peninsula, Iran and Pakistan across the Arabian Sea. Arrows point to lines of clouds at the edge of two weather fronts. Note dust-free air behind the fronts. The vertical line through the center is where two images, made several hours apart, were combined. Jacques Descloitres, GSFC/NASA.

And the so-what?
What's the point? Determining the pace and future of global warming is one obvious goal, but the system is also designed to produce an integrated view of how atmosphere, land, oceans and life interact.

But EOS is expensive, and it could fail if its output is more like a one-time snapshot than a video. Jerry Mahlman, a Princeton University climate modeler who once chaired NASA's advisory panel on earth sciences, told Science magazine in 1999, "EOS doesn't speak to continuity in ... looking at how climate fluctuates. It's up for a few years and then you bag it. And if you don't have continuous measurements, then exactly what are you doing?" (see "Terra Launch..." in the bibliography).

As Mahlman indicated, short- and long-term variability is a given in Earth sciences, and you can't separate noise from long-term trends without long records.

Satellite image shows strong northeast winds blowing white trails of smoke from oil fields over the land of southeast Iraq. Image shows dot representing Baghdad to the northeast and a river to the east.
A satellite spotted this oil-well smoke over southeast Iraq on March 22, 2003. Strong northeast winds blew the smoke into southwest Kuwait. During the last Gulf War, Iraq's military torched more than 700 wells. Image from NOAA.

If our descendants are lucky, the global picture from these satellite-mounted instruments will lead to a smarter, more conservationist approach to planetary management. With luck, in 5,000 years, EOS 101.1 won't show dust storms blanketing regions that were, back in 2003, the global breadbasket.

So how do you measure Earth's heat engine?

 
 
  
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Terry Devitt, editor; Sarah Goforth, project assistant; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

©2003, University of Wisconsin, Board of Regents.