Forecasters Hope for New Data From Weather Satellite

NOAA-L is scheduled for launch Sept. 20 from Vandenberg Air Force Base in California. It will replace a six-year-old satellite that is drifting out of orbit as it ages.

John Jones, deputy director of the National Weather Service, said instruments aboard NOAA-L and its sister satellites will provide a more detailed vertical profile of the temperature and moisture in the atmosphere than is currently available.

This information can help researchers understand what triggers the rising air, called convection, that leads to clouds and storms, he said. They will be able to measure the upward motion, the inward movement of cool or warm air and more or less moisture.

This can lead to a better understanding of thunderstorms, he said, ``thunderstorms that can possibly become tornadoes.''

While that is long-term learning, a more immediate gain is also expected.

Instruments will be able to differentiate between clouds and snow cover, a current problem for satellites looking down at white expanses. This new detail will allow hydrologists to better measure the ground snow pack and forecast spring flooding, Jones said.

And with other satellites in similar orbits, NOAA-L will provide worldwide data used in the complex computer programs that help make forecasts by calculating how the weather will change.

Knowing what's happening far away can help in long-range forecasting, since weather tends to travel around the world.

Ajay Mehta of the National Oceanic and Atmospheric Administration added that the new satellite will also be part of the satellite search and rescue system operated by the United States and Russia.

The system uses weather satellites to receive signals from emergency beacons carried by ships, aircraft and individuals on the ground. These are related to ground stations which send rescue teams in the event help is needed.

Another satellite in orbit reduces the time before a receiver may be overhead of someone needing help, he explained, and this can reduce rescue time.

Gary Davis of NOAA's satellite office noted that satellites like NOAA-L also help weather forecasters in other nations because their data is broadcast in a way that anyone with a receiver can use.

``Many third world countries who could not afford satellite data in any other way can get it ... and it's free and open,'' he said.

Flying about 520 miles above the Earth's surface, the satellite will be on an orbit slightly tilted from south-to north. Taking about 100 minutes to complete an orbit, it would cross the equator at 2 p.m. local time on each pass, looking at the whole planet twice a day.

A second NOAA satellite moving north-to-south uses a similar pattern, giving forecasters a look at the planet four times daily.

The new satellite was built by Lockheed Martin and carries instruments designed and built by NASA and NOAA as well as ones provided by meteorological offices in the United Kingdom, Canada and France.

The satellite will be launched using a Titan II rocket, a former intercontinental ballistic missile that once sat in a silo in Arkansas in the event of war. Once in orbit, it will be renamed NOAA-16.