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Objectives of the Radiosonde Replacement Program
To meet the continuing requirement of a broad base of users for atmospheric sounding data, the NWS will replace its entire current network of radiosonde systems with a modern design to:

Maintain or increase system availability and data accuracy
Reduce the use of radio-frequency spectrum
Require less operator interaction and maintenance
Provide a complete high-resolution data set to users
Provide a balloon inflation and launch shelter capable of controlled balloon launches for use at NWS facilities that have space limitations
Provide consistent and accurate measurement of surface weather parameters at the point of balloon release

The NWS must implement and operate an economical and efficient upper air observing system over the next 20 to 25 years to continue meeting the data availability requirements of weather forecasters and climate researchers. The new system must make efficient use of allocated radio frequencies in order to coexist with other users in the same or nearby spectrum band. The system must operate as much as possible in an automated mode, yet allow operator intervention when appropriate.

The current radiosonde system provides for the distribution to users of only a small portion of the data collected. These data sets do not contain sufficient detail to fully meet the needs of today’s numerical prediction models. The replacement system will distribute high-resolution data sets and give users access to the full set of observed data collected by the system. The newer generations of numerical prediction models are now able to apply this high- resolution data. The data sets will include both processed and unprocessed data. The processed data will meet user requirements for the highest quality data (corrected for solar radiation effects on sensors). Unprocessed values will be provided for climate researchers, who require the capability to reprocess old data using newer algorithms to maintain data continuity.

The modernization and restructuring of the NWS has relocated many facilities. Construction of large balloon inflation buildings supporting the current antenna system are impractical in certain cases. Balloon launches from these current structures are performed manually by the observer, who carries the balloon to a suitable launch point to avoid having the radiosonde crash into the launch shelter. Smaller balloon inflation shelters can be used to provide the capability to automatically release the balloon, saving observer time and requiring less obstruction-free real estate surrounding the release site. These new shelters will be used on a case by case basis at locations lacking suitable conventional inflation buildings. Rooftop installation of these shelters will be possible in cases of extreme land restrictions and urban environments.

Radiosonde soundings require the accurate determination of surface weather parameters (temperature, humidity, pressure, and wind) to successfully process the data from the complete sounding. Surface data are used in the calculation of the height of the radiosonde (using pressure measurements from the surface and radiosonde). Small errors in surface pressure, for example, can lead to large height errors later in the sounding. Most NWS automated surface observing equipment (Automated Surface Observing System) is positioned more than a quarter mile from the balloon release point, and is not representative of the upper air site environment. A dedicated suite of instruments will be deployed for consistent measurement of surface weather data supporting the radiosonde operation.


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Date Last Modified: December 6, 2001