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GES DISC DAAC Data Guide: Radiosonde Instrument

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Explanation: The Dataset or Sensor Guide Document you are accessing is no longer actively maintained. The Dataset Guide Documents were created for earlier versions of the NASA EOSDIS system. The content of these documents, particularly with regard to characteristics of the data or technical descriptions of a sensor, is likely still accurate. However, information such as contact names, phone numbers, mailing addresses, email addresses, software programs, system requirements, and data access procedures may no longer be accurate. We therefore recommend searching for updated information from other sites to insure that reliable and current information is obtained.

The information in this document has been derived from the National Snow and Ice Data Center's Radiosonde Instrument Document.



Radiosondes carry temperature, pressure and relative humidity sensors and report up to six variables: pressure, geopotential height, temperature, dewpoint depression, wind direction and wind speed.

A typical radiosonde configuration consists of a baroswitch that implements a temperature-compensated aneroid capsule to move a lever arm across a commutator plate, a lead-carbonate coated rod thermistor about 0.7 mm in diameter and 1-2 cm long, and a carbon humidity element that swells with a rise in humidity, made of a glass or plastic substrate thinly coated with a fibrous material.

A radio transmitter and ground-based radar, navagation aid, or other tracking system complete the rawinsonde instrumentation.

Measurements are used in weather forecasting, and are of increasing interest to those studying climate change.


Table of Contents:


1. Sensor/Instrument Overview:

Sensor/Instrument Long Name, Sensor/Instrument Acronym:


Sensor/Instrument Introduction:

Upper air measurements began with temperature soundings made in Glasgow, 1749, using a thermometer attached to a kite. Subsequent efforts in the 18th and 19th centuries progressed through the use of box kites, manned balloons, and free balloons and expanded to include measurements of temperature, pressure, electrical field and humidity.

Early devices were replaced by aircraft carrying first, meteorographs, and then radiosondes. Today, rawinsondes are flown on balloons made of natural or synthetic rubber, which, expanding as they ascend, will eventually burst. Some balloon designs are vented, such that the ballon descends and can be recovered, others are tethered, and other, superpressure balloons are designed to fly anywhere from three days to several months.

Given the limitations of the platform, rawinsondes must be expendable and factor in their design considerations the possibility of being struck by jet aircraft (Lally 1985).

Radiosonde systems comprise pressure, temperature and humidity sensors, c omplemented by transmitting electronics. Winds are calculated based on ascent velocity and air density. As concerns upper air practice, the World Meteorological Organization sets accuracy requirements and performance limits for instruments used to derive these parameters. Pressure must be measured to an accuracy of +/- 1 mb (1 mb = 1 hPa), temperature to an accuracy of +/-.5 degrees Celsius, and relative humidity to an accuracy of +/- 5 percent. 1989 tests of several models of radiosondes used in the United States in the 1980's showed pressure measured to an accuracy of about +/- 2mb, temperature measured to an accuracy of +/-0.3 degrees Celsius, and relative humidity to an accuracy of +/- 2 percent.(Elliott and Gaffen 1991).


Sensor/Instrument Mission Objectives:

Soundings are used in synoptic meteorology and climatology.

Key Variables:

Instrument performance is sometimes seen to degrade in cold, dry regions, because the instrument responds to the number of water molecules present in the atmosphere.


Scanning or Data Collection Concept/Principles of Operation:

The number and variety of instruments in use (see section 4) make it infeasible to describe the particulars of each; the following information, provided courtesy of Vaisala Inc., is representative and does not constitute a product endorsement by GSFC.

The following description is reprinted with permission. Please direct all questions to the manufacturer.


The PTU (pressure, temperature, humidity) measuring system of the Vaisala RS 80 radiosonde is based on a time multiplexing principle. Each of the capacitive sensors controls the frequency of the AF oscillator through an electronic commutator switch. The switch is formed by solid state logic gates. The oscillator frequency is fed through a modulator to the radio transmitter.... A water-activated battery provides power for the radiosonde.

Instrument Layout, Design, and Measurement Geometry

The frequency generated by the transducer is the measure of the meteorological parameters. Relationship between the frequency and corresponding parameter value is established in the calibration process

The set of solid state sensors consists of an aneroid capsule (BAROCAP) with capacitive transducers in the inside vacuum, a ceramic temperature sensor (THERMOCAP) and a thin film humidity sensor (HUMICAP) which is an improved version of the one produced earlier.

All the sensors are capacitive with compatible dynamic ranges which essentially simplifies the transducer electronics.

In the radiosonde only one reference capacitor is needed to eliminate the influence of drift of the transducer electronics. The basic capacitance of the transducer oscillator circuit is used as the second reference.

Other viewpoints when selecting the sensing principle were the existence of the capacitive humidity sensor, a simple stable and frictionless barometer construction and small risk of self-heating problems in temperature and humidity measurements.

The transducer circuit developed for the RS 80 radiosondes is capable of measuring with a resolution of 1 fF. The electronic circuit is insensitive to changes of stray capacitaces between sensor terminals and electrical ground. This is of basic importance for the feasibility of the sensor design.

There is an additional temperature sensor to measure the temperature of the pressure sensor for elimination of its temperature dependence.

from: RS 80 Radiosondes, Vaisala Inc. Upper Air Systems product information, reference no. R0422-2, 26 May 1989.

Data collected in the Historic Arctic Rawinsonde Archive consists of land-based soundings taken one to four times per day for all available Arctic stations poleward of 65 degrees North. Most stations are located between 65 and 78 degrees north. Long term (30) year records are available for about 50 stations, most begin in 1958 and extend through 1987.

Additional soundings obtained from the National Center for Atmospheric Research extend the data base through 1991. Soundings typically extend to at least 300 mb and contain a mixture of reports at mandatory (that is, surface, 1000 mb, 850 mb, 700 mb, 500 mb, 400 mb, 300 mb) and significant levels. Six variables, pressure, geopotential height, temperature, dewpoint depression, wind direction and wind speed are reported with associated quality codes at the 20 to 40 levels usually available per sounding.

2. Sensor/Instrument Layout, Design, and Measurement Geometry:

This information is not available at this time.

List of Sensors:

Radiosondes carry pressure, temperature and humidity sensors.

Sensor Description:

This information is not available at this time.

3. Manufacturer of Sensor/Instrument:

This information is not available at this time.

4. Calibration:



This is not available at this time.

Frequency of Calibration:

This information is not available at this time.

Other Calibration Information:

None other available at this time.

5. References:

Elliott, W. P., and D.J. Gaffen. 1991. On the utility of radiosonde humidity archives for climate studies. Bulletin American Meteorological Society.72(10):1507-1520.

Garand, L., C. Grassotti, J. Halle, and G. L. Klein. 1992. On differences in radiosonde humidity - reporting practices and their implications for numerical weather prediction and remote sensing. Bulletin American Meteorological Society.73(9):1417-1423.

Lally, V. E. 1985. Upper Air in situ Observing Systems. Handbook of Applied Meteorology. David D. Houghton, editor. John Wiley & Sons, Inc. 352 -360.

Vaisala Inc. 1989. RS 80 Radiosondes. Upper-Air Systems product information. Reference No. R0422-2. Vaisala Inc., 100 Commerce Way, Woburn, MA 01801.


6. Glossary of Terms:

EOSDIS glossary

7. List of Acronyms:

EOSDIS acronyms


Uniform Resource Locator

8. Document Information:

Document Revision Date:Fri May 10 11:53:05 EDT 2002
October 5, 1995

Document Review Date:

October 5, 1995

Document ID:

Radiosonde Instrument

Document Curator:

Suraiya Ahmad

Change History

Version 2.0
Version baselined on addition to the GES Controlled Documents List, October 5, 1995.
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Last updated: Jul 19, 2010 03:35 PM ET