Johns Hopkins Gazette: December 2, 1996 Form

On Technology:
Automated Weather
Station Opens At

Ben Walker
Applied Physics Laboratory
With the installation of an automated weather station and participation in an Internet-linked weather-reporting service, APL has placed itself on the weather map.

"It's something we should have done a long time ago," says Rich Giannola of the Power Projection Systems Department. "The lab is a field test site for many experiments that are affected by the weather, and we need to know what's happening right here-- not at BWI or National [Airport]."

Giannola, a Ph.D. meteorologist, runs the unattended station, which is mounted on a 25-foot tower just north of Building 47 on the APL campus in Rockville, Md. The cluster of automated weather instruments provides continuous readouts of everything from temperature, wind speed and direction, and light intensity to relative humidity, barometric pressure and the amount of rainfall. The station also provides daily minimum and maximum values, and the hourly rate of change in the readings.

The values are updated each second and archived every 15 minutes. Archiving is important because it enables tying past weather conditions to specific experiments or other laboratory events, if necessary.

Weather is a key factor in certain programs using the Global Positioning System and in experiments involving radar and infrared systems. "Infrared sensors are affected by relative humidity, temperature and rainfall," says Giannola. "During a test it could be raining at BWI, but sunny here. That's why we need a local--and I mean APL--weather station." He says that any staff member can use data from the station.

The laboratory is a site in the School WeatherNet system operated by Automated Weather Source of Gaithersburg, Md. Weather stations with AWS software--which include TV Channel 4 in Washington, D.C., TV Channel 11 in Baltimore and more than 1,300 schools nationwide--can tap into each other's data by modem over traditional phone lines.

APL is also one of a growing number of beta test sites using AWS software to place real-time weather observations on the Internet. Anyone in the world with an Internet connection can access these observations.

Each month APL sends a summary of its daily weather observations and special comments to the National Weather Service, which uses the data in compiling their monthly "Metropolitan Washington Climate Review," an analysis of the region's precipitation and temperature statistics.

"It's an exciting time," says Giannola, who helped install the automated weather system at River Hill High School in Clarksville, Md., and is working to locate one in his daughter's elementary school in Olney, Md. "APL is now part of an international network, one of many stations filling in gaps for the National Weather Service so that we can all benefit from more timely and accurate forecasts."

APL weather station readouts appear at Internet address The home page for Automated Weather Source is

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