1 Scope

This document specifies a test method for estimating the magnitude of radiosonde temperature sensor warming, induced by direct solar radiation, based on variations in air pressure, temperature, ventilation speed, tilt angle of its supporting sensor boom, and light illumination angle on the boom through a laboratory evaluation. This document provides the following:

1. technical requirements for a laboratory setup to measure the effect of direct solar radiation on radiosonde temperature measurement under simulated sounding conditions;

2. a test procedure for estimating radiosonde temperature measurement errors due to direct solar radiation in the air pressure range of 3 hPa to 1 000 hPa, temperature range1 of −70 °C to 50 °C, ventilation speed range of 3 m∙s⁻¹ to 7 m∙s⁻¹ at a specified irradiance (e.g. 1 000 W⋅m−2 or higher), sensor boom tilt range2 from 0° to 45° with respect to the air ventilation direction and the range of light illumination3 angle from 0° to 90° with respect to the sensor boom plane;

3. a method to evaluate uncertainty in the results under the test conditions.