Preprints
https://doi.org/10.5194/amt-2021-337
https://doi.org/10.5194/amt-2021-337

  21 Oct 2021

21 Oct 2021

Review status: this preprint is currently under review for the journal AMT.

Intercomparison of Vaisala RS92 and RS41 radiosonde temperature sensors under controlled laboratory conditions

Marco Rosoldi1,, Graziano Coppa2,, Andrea Merlone2, Chiara Musacchio2, and Fabio Madonna1 Marco Rosoldi et al.
  • 1Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l’Analisi Ambientale (CNR-IMAA), Tito Scalo, Italy
  • 2Istituto Nazionale di Ricerca Metrologica (INRiM), Torino, Italy
  • These authors contributed equally to this work.

Abstract. Radiosounding profiles are essential for weather and climate applications, as well as for the calibration and validation of remote sensing measurements. Vaisala RS92 radiosondes have been widely used on a global scale until 2016, although in the fall of 2013 Vaisala introduced the RS41 model to progressively replace the RS92. To ensure homogeneity and the highest quality of data records following the transition from RS92 to RS41, intercomparisons of the two radiosonde models are needed. An intercomparison experiment has been performed where, for the first time and independently of the manufacturer, RS92 and RS41 radiosondes have been simultaneously tested and compared inside climatic chambers in order to characterize the noise, the calibration accuracy and the bias of their temperature measurements. A pair of RS41 and RS92 radiosondes has been tested at ambient pressure under very different temperature and humidity conditions. The results reveal that the temperature sensor of RS41 is less affected by noise and more accurate than that of RS92, with noise values less than 0.06 °C for RS41 and less than 0.1 °C for RS92. The error corrected by means of calibration, evaluated as the deviation from a reference value and referred as calibration error, is within ±0.1 °C for RS41 and the related uncertainty (hereafter with coverage factor k = 1) is less than 0.06 °C, while RS92 is affected by a cold bias in the calibration, which ranges from 0.1 °C up to a few tenths of a degree, with a calibration uncertainty less than 0.1 °C. Under conditions similar to those that radiosondes meet at the ground in nighttime radiosoundings, the temperature bias between RS41 and RS92 is within ±0.1 °C, while its uncertainty is less than 0.1 °C. The radiosondes have also been tested before and after fast (within ≈ 10 s) temperature changes of about ±20 °C, simulating a scenario similar to steep thermal changes that radiosondes may meet when passing from indoor to outdoor environment during the pre-launch phase. The results reveal that such thermal changes may increase the noise of temperature sensors during radiosoundings, up to 0.1 °C for the RS41 and up to 0.3 °C for the RS92, with a similar increase in the calibration uncertainty of temperature sensors, as well as an increase in the uncertainty of their bias up to 0.3 °C. However, the thermal changes do not appear to affect sensors’ calibration error and temperature bias.

Marco Rosoldi et al.

Status: open (until 23 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-337', Anonymous Referee #1, 24 Nov 2021 reply

Marco Rosoldi et al.

Marco Rosoldi et al.

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Short summary
A methodology based on tests in climatic chambers was proposed to evaluate the effect of radiosonde models’ change on radiosounding stations’ data series, in terms of measurements accuracy and homogeneity. For Vaisala radiosonde models RS92 and RS41, the noise, the calibration accuracy and the bias of their temperature sensors were quantified independently of the manufacturer. The potential effects of steep thermal changes during radiosondes’ pre-launch phase were also investigated.