Evaluating the Feasibility of the Windsond S1H2 in Severe-storm Environments, a Comparison against the Vaisala RS41-SGP

Sounding systems launched at National Weather Service offices and for field campaigns are crucial for obtaining vertical profiles of the atmosphere. Traditional sounding systems are generally designed to collect one profile of the troposphere at a time, but over the last few decades, the need for higher spatio-temporal resolution observations to analyze fast changing environments has risen. A Swedish company, Sparv Embedded, has developed a low cost sounding instrument and receiver in the last decade that can track multiple sondes simultaneously. Sparv Embedded’s Windsond S1H2 in particular has been used to collect data for severe weather research, but little has been done to directly compare the Windsond S1H2 system to other commonly used radiosondes. This intercomparison sets a foundation for understanding the capabilities of this system, including an exploration of the conditions and portions of the atmosphere that the Windsonds can add value to more traditional sondes in data collection.

More specifically, this study compares the Windsond S1H2 to the Vaisala RS41-SGP through a series of 33 flights launched in a variety of cloud cover conditions and times of day, all within environments supportive of convective storms. The sondes were tethered to the same balloon and the data interpolated to constant height levels (every 10 m) to allow a direct comparison of temperature, dew point temperature, wind speed, and wind direction profiles. The comparisons show that the Windsond’s slower response time and lack of solar radiation correction results in noticeable differences in temperature, particularly during clear daytime flights (with median temperature differences exceeding 3℃) and in dry layers. A difference in the wind smoothing approach between the two instruments results in slower wind speeds output by the Vaisala systems near the surface (0 - 150 m). Even with these differences, many flights within a variety of conditions displayed relatively small differences within the 0-3 km layer. This indicates that Windsondes can be used confidently to supplement more traditional sounding systems for obtaining sub-hourly profiles in lower portions of the atmosphere that are critical for severe weather-related research efforts, but has increasingly less confidence at higher altitudes and in conditions outside of convection. Results from one case study will be shown to highlight the comprehensive results found in the intercomparison.