The National Weather Service (NWS) developed the Radiosonde Replacement System (RRS) to replace its antiquated Microcomputer Automatic Radio-theodolite (Micro-ART) system, which was in operation since the late 1980s. The RRS is comprised of a new Global Positioning System (GPS) tracking antenna referred to as the telemetry receiving system or TRS, 1680 MHz GPS radiosondes, and a new PC workstation. In addition to the deployment of the RRS, a new surface weather observing system and precision digital barometers will be deployed at 92 locations from the Caribbean to Guam and from Alaska to Pago Pago, American Samoa in the Southern Hemisphere.
The figure below delineates the RRS configuration at NWS field sites. The basic system components include: the Telemetry Receiving System (TRS) and an interactive workstation where upper air data is collected, processed and world meteorological Organization (WMO) TEMP messages are prepared and disseminated to data users. The RRS communicates these products through an interface to the NWS Advanced Weather Interactive Processing System (AWIPS) for transmission to the external data user community.
To meet the continuing requirement of a broad base of users for atmospheric sounding data, the NWS replaced its entire current upper air network with RRS to:
Comply with Congressional direction to reduce the use of radio-frequency spectrum and implement the Federal Communications Commission’s (FCC’s) plan to vacate the 1670-1675 MHZ frequency band,
Maintain or increase system availability and data accuracy,
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, and
Provide consistent and accurate measurement of surface weather parameters at the point of balloon release.
Increase amount of data provided to users (at 1 second resolution or about every 5 meters through the atmosphere).
One of the major features of the RRS is its use of state-of-the-art GPS radiosondes operating in the 1680 MHz radiosonde frequency band. RRS sondes use new sensors, which have differing characteristics than the older model sondes used with Micro-ART. As a result, "Data Continuity" studies were done to assess these sensors in a variety of climatic and meteorological conditions.
The RRS radiosonde is prepared for flight in the weather office where the workstation is located, and released at the inflation shelter. Once the radiosonde begins to transmit data, the TRS tracks the signal and sends it to the Signal Processing System (SPS), which is furnished by the radiosonde vendors. The SPS then decodes the transmitted one-second radiosonde telemetry data and computes raw pressure, temperature, humidity and GPS location (for winds) data. From these raw data RRS generates corrected and smoothed data which are used to create the WMO coded messages and archive products.
During the radiosonde flight, the Workstation continuously monitors the course of the flight. The design of the RRS maximizes data acquisition capabilities whether the radiosonde is at low level elevation angles, or at the zenith relative to the ground receiving antenna. The Workstation displays tabular and graphical radiosonde flight data (raw and processed) to aid the operator in evaluating the accuracy and completeness of the meteorological data. The operator can delete poor quality data or choose to perform another flight if the amount of missing or poor quality data is excessive.
The first software builds will provide the standard WMO messages in real-time. Later builds will include a real-time, high resolution (i.e., 1-sec.) data product in the BUFR format.
In addition to the standard archive data set produced for Micro-ART, a high resolution data archive is generated in BUFR format and electronically sent to NCDC. When transmitted to NCDC, it will provide researchers and other users of upper air data a complete summary of all the data collected by the radiosonde. Of special interest, will be the high resolution winds and in-flight radiosonde location data..
The RRS was deployed in a phased approach starting in 2005 and was completed in late 2013.
