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NCAR foothills lab weather station (110kb)
The NCAR Foothills Lab weather station is located on a 6 meter tower which is on the roof of a 2 story building. The building is due east of a large highway overpass and near several other large buildings. Our wind speed readings tend to be lower than those from other nearby weather stations during heavy Westerly wind events. Weather is a very local phenomenon and we have our own micro-climate. Limited funding and time have prevented us from moving the station to a location which better represents the local wind speed averages. Temperature readings may read a few degrees high in low wind conditions.
Station Geographical Information
Latitude: 40 degrees 2 minutes 6 seconds
Longitude 105 degrees 14 minutes 35 seconds
Elevation 1625 Meters (5332 Feet)
A Vaisala WXT510 weather transmitter is being used to collect all of the meteorological information. The WXT510 is a self contained weather station which provides an RS-232 data stream containing temperature, humidity, pressure, rain accumulation, wind speed, direction and peak gust speed.
Here is an overview of the WXT510 sensor specifications.
WXT510 weather station on an NCAR PAMII tripod (65kb)
The RS-232 data from the weather station is run through a 1 meter fiber optic lightning isolation link then converted to RS-422 which is used to run the signal from the roof of the building into one of the offices below. There, it is converted to RS-232 again for connection to a Sun Microsystems Sparc 5 computer where it is ingested and made available to our web server machine on the net. The data transmission and isolation hardware was designed and built at NCAR.
Close up of the Coastal Climate weather station (97kb)
The weather station's data stream is collected by a C program called weatherd (the weather daemon), stored in netCDF format files, then plotted using gnuplot which is run from a Perl script called cdf2gplot. Honorable mention should be given to the Zebra program, a very powerful multi-platform data ingest and display system which was used to get the original system up and running.
The wind direction signal is not valid for zero wind speed and the data is removed from the plots in that situation to reduce the number of spikes.
Here is a description of the Peak Gust calculation performed inside of the Coastal weather station.
The rain accumulation data is a plot of "rain events" which are periods where the rain is actually falling. After an hour of no rainfall, the chart resets to zero. The total rainfall over a period of time is a sum of the individual rain events. The textual rain accumulation info at the top of the page represents total rainfall since midnight.
If the air were cooled down, the dewpoint would be the temperature where the moisture in the air would condense and form dew.
Here is formula for the derivation of dewpoint.
Pressure varies with altitude, as you move towards outer space, the pressure moves towards zero. Aeronautical pressure correction is used to remove the altitude information from pressure readings so that comparisons can be made between weather stations at different heights.
Here is formula for the derivation of corrected pressure.
An NCAR meteorologist, Bob Rilling has put together this information on Wind Chill. We are currently using the Court method for calculating wind chill. Note that the wind chill is undefined for wind speeds below 1.9 meters per second and for temperatures above 33 ºC.
The NCAR weather station data is now available at our FTP archive We cannot offer any support for use of the data, please see the README file for details and caveats.
If you bring this page up multiple times using most web browsers, you will probably have to select Reload Images from the File menu to get updated plots. If you are using Netscape, try using the "reload" button or "shift-reload" to get the latest images. Netscape has a reload bug that is related to daylight savings time, if you still can't reload, try going into the "Options" pulldown under "Network Preferences" and push "Clear Disk Cache Now", then press "reload.
Go back to the Foothills Lab weather page.