Decoding Weather and Climate by Using Global Positioning Systems Technology

By Knox, John | National Forum, Spring 1999 | Go to article overview
Save to active project

Decoding Weather and Climate by Using Global Positioning Systems Technology


Knox, John, National Forum


The U.S. military created it decades ago, but now it is exploding onto the civilian scene with seemingly limitless applications. The Internet? No, it is global positioning system technology, better known simply as GPS. If you have heard of GPS, it is probably because you have seen a newspaper item on how it will guide cars of the future to the nearest gas station, or point recalcitrant husbands to the laundry room (see comic strip below). In this column, we will examine a more exotic, but potentially even more revolutionary application of GPS: the improvement of weather forecasts and climate observations.

WHAT IS GPS?

PS works like this: the U.S. military has placed about two dozen satellites in orbit around the earth, roughly halfway between the surface and where weather satellites typically reside. This network of satellites routinely checks each others positions and then transmits this information to receivers via radio waves. If a receiver intercepts signals from four or more satellites, then it can calculate its own location very accurately. How accurately? Amazingly, to within about a foot and a half, or just the size of the little saucer-shaped antenna! Little wonder, then, that everyone from aviators to seismologists to foresters is snapping up this technology; wherever precise locations matter, GPS is the wave of the future.

GPS AND WEATHER

The application of GPS to weather forecasting, like weather radar, transforms a fly-in-theointment into a scientific bonanza.

Radar was invented to detect enemy aircraft during World War II. However, the military soon discovered that weather conditions interfered with aircraft detection. But this wartime drawback could pay peacetime dividends, because severe weather is a mortal foe, too. Weather radar was born, and with it came the improved detection of thunderstorms and tornadoes.

In the case of GPS, the accuracy of an estimate of location depends just as with radar - on the transmission of radio waves through the earth's atmosphere. Thunderstorms and tornadoes are invisible to GPS, but the continuous changes in atmospheric temperature, pressure, and especially moisture delay GPS signals on their route to Earth by tiny fractions of a second - just enough to reduce the accuracy of navigation.

This navigator's headache is the meteorologist's "Eureka." The delay in GPS signals can be "inverted" to infer the conditions of the atmosphere around the globe. This information is the Holy Grail of weather forecasting, especially when it comes to moisture, which is the energy source for storms. Many (if not most) of the glitches in weather forecasting today result from our imperfect knowledge of what the atmosphere is doing overhead, over the entire globe. Currently our best sources of such information are weather balloons; but few of them are launched over the oceans, and even in the United States only one balloon is launched every twelve hours at about one site per state. GPS technology promises much more continuous and global information.

GPS AND CLIMATE

The debate over "global warming" pivots on a few key issues: Is the atmosphere really warming globally? If so, will atmospheric moisture increase and wreak havoc via more severe storms? Can we trust our data sources, which often are based on a variety of incompatible methods? And do weather and climate phenomena get in the way of the reliability of the data-gathering methods?

GPS can make a solid contribution to this debate through a technique called "radio occultation," in which the radio signals are received by another satellite in a low orbit over Earth. As a global data source, GPS can avoid the bias of observing temperature only in populated regions over land. GPS is especially sensitive to water-vapor concentrations in the atmosphere, so changes can be detected rapidly and reliably.

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
Loading One moment ...
Project items
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited article

Decoding Weather and Climate by Using Global Positioning Systems Technology
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

While we understand printed pages are helpful to our users, this limitation is necessary to help protect our publishers' copyrighted material and prevent its unlawful distribution. We are sorry for any inconvenience.
Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.

Are you sure you want to delete this highlight?