RS41 GRUAN Data Product Version 1 (RS41-GDP.1)

This dataset comprises reference radiosoundings performed with the Vaisala RS41 radiosonde including subtypes with and without pressure sensor. Reference, in this case, means: correction for all known biases, best possible vertically resolved uncertainty estimates, well-documented correction algorithms, extensive collection of metadata.

The GCOS (Global Climate Observing System) Reference Upper-Air Network (GRUAN) data processing (GDP) for the Vaisala RS41 radiosonde was developed to meet these reference criteria. The algorithms of the RS41-GDP in version 1 include corrections of the raw calibrated data for systematic errors in measurements of pressure, temperature, relative humidity, wind speed and wind direction. The corrections for the most important systematic errors (solar radiative warming of the temperature sensor and increased response time of the humidity sensor at low temperature) are based on extensive laboratory experiments. GRUAN sounding operation includes all manufacturer-prescribed ground checks. Additionally, pre-launch checks using the Standard Humidity Chamber (SHC) are routinely performed in GRUAN, the results of which are however not used for recalibrations or corrections but contribute to the uncertainty budget.

Measurement uncertainties are estimated at the vertical resolution of the measured data. For each main variable, overall uncertainties are given as combinations of individual components using common uncertainty propagation. As a new approach, each of these individual components is assigned one of the three following correlation properties: uncorrelated, spatially correlated, or temporally correlated. This is done comprehensively in the sense that the uncertainties resulting from the combination of the correlated components are consistent with the overall uncertainties that are calculated in the conventional uncertainty evaluation. This facilitates the user to take correlations in uncertainty analyses into account.

The RS41 is in use in GRUAN since late 2014 and is currently launched regularly at 22 sites. As such it is the backbone of radiosounding activities within the network.