(1) What is a radiosonde and how are the data it provides used?

NWS has been using balloon-borne radiosonde instruments for more than 60 years. The data they provide are critical for weather forecasting and research.  Click here to learn more.

(2) What types of radiosondes does the NWS use in its network?

NWS currently uses Vaisala RS-80-57H, Sippican VIZ-B2, Sippican Mark II LORAN-Microsondes, and Sippican MarkIIA GPS radiosondes..

(3) What types of ground equipment does NWS use to track the radiosonde?

A radiotheodolite (i.e., radio direction finder) is used at most stations (see photograph below) to track the radiosonde as it ascends and receive the radiosonde signals.  A computer is used to process, display, and transmit the data.   These systems are now obsolete and are currently being replaced with more modern equipment.  Check out the Radiosonde Replacement System page for more information.

Three other NWS stations use a Sippican W9000 Loran/GPS System.

NWS Radiotheodolite with the fiberglass radome removed.

(4) How are radiosonde data checked for quality?

Quality control of radiosonde data is done at the upper-air station and national centers such as the NOAA National Centers for Environmental Prediction (NCEP) and at the National Climatic Data Center (NCDC).  Click here to learn more.

(5) Why does NWS still use radiosondes? Isn't there another observing system available that can provide the same data?

At the present time, there is no single observing system (e.g., satellites and ground-based remote sensors) that can match the vertical data resolution (about 30 meters or less) and height coverage (more than 30 km) obtained with radiosondes.  NOAA is involved in developing new, cost-effective technologies and methods for obtaining upper-air data to meet future data needs.

(6) What is the difference between a "radiosonde" and a "rawinsonde" observation?

A radiosonde observation provides only pressure, temperature, and relative humidity data. When a radiosonde is tracked so that winds aloft are provided in addition to the pressure, temperature, and relative humidity data, it is called a rawinsonde observation. Most stations around the world take rawinsonde observations. However, meteorologists and other data users frequently refer to a rawinsonde observation as a radiosonde observation.

(7) What should I do if I find a radiosonde?

The radiosonde is harmless and safe to handle. You may detect an odor coming from the instrument, but this is from a sulfur compound used in the battery.  If the radiosonde is not severely damaged, the NWS would be grateful if you return the instrument.  Each radiosonde comes with a mail bag (postage is pre-paid) and mailing instructions. After placing the radiosonde in the mailbag, hand the package to your postal carrier. 

The NWS network releases about 75,000 radiosondes each year, but less than 20 percent are returned to the NWS for reconditioning.  Reconditioned radiosondes are used again, saving the NWS the cost of purchasing a new instrument.

(8) Is there a Federal Handbook on rawinsonde observations?

Yes.  It is called, "Federal Meteorological Handbook #3 (FMH #3)- Rawinsonde and Pibal Observations".

(9) Who do I contact if I have further questions?

Please send an email to upperair@noaa.gov.   We will answer your questions as soon as possible.

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