the Automatic Position Reporting System as a WX NETwork

Amateur radio has a long and proud tradition of public service in the United States and around the world. One example is to provide emergency communications in natural disasters such as hurricanes or floods. The Amateur Radio Emergency Service (ARES) is a part of the American Radio Relay League, the national organization of U.S. Amateur Radio Operators, that provides centralized management structure for these emergency services. But, the real heart and soul of amateur radio public service are the ham operators across the country who donate their time, equipment, skills and data.

One aspect of amateur radio public service is supplying atmospheric data to various users, including individuals and federal, state and local governments. Many amateur radio operators operate their own weather stations to collect local weather data and transmit this data for anyone to receive and use. Oftentimes, receivers capable of receiving and displaying this weather information are located at local National Weather Service Offices where forecasters can monitor the data.

The Automatic Position Reporting System (APRS tm) is a part of ham radio that provides an ideal way for weather station operators to distribute their weather data much further than the regions within their transmitter range. APRS was originally intended for position information data but actually provides a means for automatic transmission of all sorts of digital data. This is especially true now that the original APRS packet radio concept has been enhanced to include the capabilities of the Internet. The reporting of citizen weather data is a particularly useful application of the APRS Internet System (APRS IS).

The APRSWXNET/Citizen Weather Observer Program is a group of ham radio operators and other private citizens around the country that have volunteered the use of their weather data for education, research and use by interested parties. The APRS IS collects weather data transmitted from individual weather stations and communicates these data to the findu.com server. The server then organizes the incoming data stream and makes the weather data available to the Forecast Systems Laboratory (FSL) at 15-minute intervals. This is all done in the public service tradition of amateur radio and good citizenship.

The findu.com server acts as a database for APRS position, weather, message, bulletin, satellite and other data. This ham radio server makes weather data available the FSL Central Computer Facility every 5 minutes. This data goes into the RSAS and LAPS data assimilation systems, and also helps initialize the MM5 numerical prediction model, all of which run routinely at FSL. The data are also sent to the National Center for Atmospheric Research and components of the National Weather Service.

The APRSWXNET/CWOP data also goes into the Quality Control and Monitoring System (QCMS) which runs routinely and checks the quality of a large amount of surface data. Standard limit checks are done as well as spatial consistency checks that utilize local observations, and gridded values from the RSAS data assimilation system, to interpolate "synthetic" observations for comparison with the real data. Based on these comparisons, data may be declared questionable. Occasional questionable data is normal. For example, the assimilation system may have placed a cold front incorrectly and if an observer is on the other side of that front, the observed temperature can be correct while the interpolated temperature is in error. A high percentage of questionable data, however, may indicate instrument problems.

The results of this quality checking are then made available to the station operators on the QCMS QC Summary Page and on the Citizen Weather Data Quality web site. This feedback to the weather station owners will alert them when a problem has developed. The goal here is to provide tools to the weather station owners to help them keep the data quality high so that the data can be widely used with confidence. Essentially, the APRSWXNET/CWOP activity can add value to citizen weather data.

For information on how to join APRSWXNET/CWOP, click here.

APRS has been copyrighted by Bob Bruninga, WB4APR.

This description is from Russ Chadwick, KB0TVJ. If you have questions, comments or suggestions, send them to him at
mailto:russ@wxqa.com(home) or at mailto:chadwick@fsl.noaa.gov(work). Last changed August 27, 2002.