Windsond S1H2 vs Vaisala RS41 Radiosonde Intercomparison
A recent peer-reviewed study published in the Journal of Atmospheric and Oceanic Technology compared the Windsond S1H2 radiosonde from Sparv Embedded with the widely used RS41-SGP radiosonde from Vaisala. The study provides an independent evaluation of Windsond performance in real atmospheric conditions, including environments supportive of convective storms and severe weather.
Researchers conducted 33 paired weather balloon flights, attaching both radiosondes to the same balloon to directly compare measurements of wind, temperature, and humidity throughout the atmosphere. As the use of Windsond radiosonde systems has expanded in recent atmospheric field campaigns — particularly for high-resolution and multi-sonde deployments — this study was conducted to evaluate performance relative to a long-established industry standard.
Strong Performance in the Boundary Layer and Lower Atmosphere
The results show that the Windsond S1H2 performs strongly in the lower atmosphere, the region for which the system was designed and which is most critical for boundary-layer meteorology, severe weather research, and atmospheric profiling.
The intercomparison demonstrated close agreement in wind speed and wind direction between the Windsond S1H2 and the Vaisala RS41 radiosonde. Differences were largely confined to the lowest few hundred meters, where surface effects and turbulence make atmospheric measurements particularly challenging.
For boundary-layer and lower free-tropospheric studies, the findings support Windsond’s role as a reliable and flexible complement to traditional radiosonde sounding systems, especially in research programs requiring higher sampling density or multiple simultaneous launches.
Figure from the paper showing a) an external view and b) an interview of the S1H2
Multi-Radiosonde Swarm Launch Capability
A key strength highlighted by the authors is the Windsond platform’s ability to deploy and track multiple radiosondes simultaneously. This enables coordinated “swarm” weather balloon launches capable of resolving storm-scale atmospheric structure in ways that single-sonde operations cannot.
By lowering cost and increasing operational flexibility, Windsond makes higher-density sampling of convective environments practical for many research programs studying:
- Convective storms
- Boundary-layer processes
- Mesoscale meteorology
- Severe weather environments
- Atmospheric turbulence
The study reported some differences at higher altitudes and during clear daytime conditions, primarily related to humidity sensor response time and solar radiation effects on temperature measurements. The authors also noted occasional telemetry-related data gaps.
We welcome this detailed and thoughtful independent evaluation and would like to clarify several points.
The paper states that Sparv does not apply temperature corrections, smooth wind data, or calculate dewpoint temperature. In fact, all three are part of our standard processing workflow. Windsond data products include temperature corrections, wind-data smoothing, and derived dewpoint temperature as routine outputs available to users.
Since the period covered in the study, we have also implemented an improved solar radiation correction algorithm for the S1H2, further reducing daytime temperature bias. In parallel, we have introduced enhanced telemetry capabilities in updated S1 systems.
In addition, the next-generation Windsond S2 incorporates further refinements in sensor performance, communications reliability, and data processing.
Continuous improvement is central to our development philosophy, and independent radiosonde intercomparison studies such as this one play an important role in advancing atmospheric measurement technology and weather balloon instrumentation.
Diedrichsen, M. R., M. C. Coniglio, and S. Waugh, 2025: An Intercomparison of the Sparv Windsond S1H2 and Vaisala RS41-SGP in Severe Weather Environments. Journal of Atmospheric and Oceanic Technology, 42, 1601–1615. https://doi.org/10.1175/JTECH-D-25-0006.1