ISO 8932-1:2025

International
Standard
ISO 8932-1
First edition
Meteorology — Radiosonde —
2025-10
Part 1:
Laboratory test method for
calibration error of temperature
sensor in radiosonde
Météorologie — Radiosonde —
Partie 1: Méthode d'essai en laboratoire pour l'erreur
d'étalonnage du capteur de température dans la radiosonde
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and subscripts . 3
4.1 Symbols .3
4.2 Subscripts . .4
5 Technical requirements for the laboratory setup . 4
5.1 Test chamber .4
5.2 Reference thermometers .4
6 Test procedure for radiosonde temperature sensors . 5
6.1 Environmental conditions .5
6.2 Preparation of radiosonde .5
6.3 Installation of radiosonde.5
6.4 Examination of laboratory setups .6
7 Test methods and procedures . 7
7.1 Test conditions .7
7.2 Testing sequence .7
7.3 Data collection .7
7.4 Finalization of the test .8
8 Data processing . 8
8.1 Calculation of the reference temperature .8
8.2 Calculation of the measurement error .9
9 Evaluation of measurement uncertainty . 9
9.1 General .9
9.2 Mathematical model of measurement .9
9.3 Formula for combined standard uncertainty .9
9.4 Calculation of expanded uncertainty .10
10 Test report .11
Bibliography .12

iii
Foreword
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The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
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This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 5,
Meteorology.
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Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
Temperature and water vapour (i.e. humidity) are two of the basic atmospheric state variables and
important initialization for weather and climate prediction models. In order to measure the temperature
and humidity in the upper-air atmosphere, radiosondes are widely used. Radiosonde is an instrument
intended to be carried by a balloon through the atmosphere, equipped with devices to measure one or
several meteorological variables (such as pressure, temperature and humidity), and provided with a radio-
[1]
transmitter for sending this information to the observing station . Radiosonde observations are often
used in conjunction with other measurement techniques such as remote sensing using satellites in order to
provide comparative data. For radiosonde-derived data to be useful, the measurement accuracy of the radio-
soundings needs to be known.
Thermistors, thin-film platinum resistance thermometers (PRTs), and thermocouples are mostly used as
temperature sensors for radiosonde. Temperature from radiosonde is mainly affected by temperature
sensor calibration and long and short-wave radiation correction. The impact of radiation correction on the
[2],[3] [4]
temperature is treated in a separate document . The temperature-dependent physical quantities, such
as resistance or thermoelectric voltage, have peculiar formulae as a function of temperature. Thermistor
[5]
uses the Steinhart-Hart equation, and Callendar van Dusen (CVD) formula is applied for the PRTs .
Therefore, the temperature accuracy in ground condition mainly depends on the sensor calibration and
thus an essential prerequisite to improve the measurement reliability of radiosondes is to calibrate the
radiosonde sensors using ground-based facilities.
The temperature generated by a laboratory setup can be traceable to the SI via International Temperature
[6]
Scale of 1990 . The SI traceability of the setup should then be transferred to radiosonde temperature
sensors through calibration by manufacturers. This document is mainly focused on testing the calibration
error of temperature sensors in radiosondes sampled from a batch of mass production.
The Standing Committee on Measurements, Instrumentation and Traceability (SC-MINT) at the World
Meteorological Organization (WMO) urges users to test selected samples of radiosondes under laboratory
conditions in order to ensure that the calibrations supplied by the manufacturer are valid. Unless
radiosonde sensors can be produced in large batches to give the reproducibility and accuracy required
by users, it is necessary to calibrate the instruments and sensors individually. Even if the sensors can be
produced in large batches to meet an agreed set of standardized performance checks, it is necessary for
[1]
representative samples, selected at random, to be checked in more detail . This independent testing would
further improve the reliability of radiosonde measurements by verifying the calibration results applied by
the manufacturers. Despite the importance of the testing, the test setup in the guide by SC-MINT are limited
to stability (±0,25 °C/min) and systematic errors less than ±0,1 °C, and more detailed methodologies or test
procedures for the testing of radiosonde temperature sensors have not yet been reported.

v
International Standard ISO 8932-1:2025(en)
Meteorology — Radiosonde —
Part 1:
Laboratory test method for calibration error of temperature
sensor in radiosonde
1 Scope
This document specifies a test method in terms of calibration error for radiosonde temperature sensors
sampled from a batch of mass production, with varying temperature in laboratory setups at ground level
pressure. This document elaborates on:
a) the technical requirements for test chamber and reference thermometers as essential laboratory setups
to evaluate the calibration errors of radiosonde temperature measurement;
b) a test procedure including the installation of radiosondes in the test chamber, the operation of laboratory
setups and the comparison between radiosonde and the temperature references for evaluating
1)
calibration errors of radiosonde temperature sensors for a temperature range of −85 °C to 50 °C at
laboratory conditions; at
c) a method for evaluating the uncertainties related to the references and the radiosonde sensors for the
measured radiosonde temperature calibration error.
NOTE Calibration error of radiosonde treated in this document fo
...