Using small, light-weight radiosondes to enhance capacity for in-situ sampling of the lower atmosphere

The state-of-the-art of numerical weather prediction models continue to mature and contribute to better forecast skill at finer spatial and temporal resolutions. Our ability to generate atmospheric observations has not kept pace with these computational advancements, resulting in a “data gap”. There has been a push to develop and advance a broad spectrum of in-situ and remote-sensing atmospheric sampling technologies to address this need. This includes the need to advance and modernize conventional and mature instrumentation. In addition to providing trusted atmospheric measurements, data from these instruments can be used as a reference for newer, emerging technologies or signal-processing methods. Here we focus on recent developments in one such instrument, the rawinsonde (here simply referred to as radiosonde).,

In 2014, Sparv Embedded AB introduced a small, lightweight, and economical radiosonde called the Windsond S1 intended for use in the atmospheric boundary layer and lower free troposphere, typically below 8 km MSL. By focusing on the lower atmosphere, the S1 has been helping to fill one critical aspect of the data gap. As such, the S1 has been successfully used by numerous atmospheric researchers, within the international meteorological community, in fire-weather applications, for educational purposes, and more (e.g., Stouffer et al., 2024: J. Atmos. Oceanic Technol., 41, 1213–1228). Based on the popularity of the S1, Sparv has recently released a successor called the Windsond S2. Like its predecessor, the S2 is small, light-weight, and affordable; however, the new design offers many improvements over the S1. For example, the S2’s new battery and telemetry capabilities facilitate atmospheric soundings up to 10 km MSL. Moreover, the S2’s compact and robust design makes it better suited for launches in challenging environments. With a weight of only 9 g, the S2 requires less helium and smaller balloons than conventional radiosondes, which have typical weights of 60-80 g. As with the S1, the S2 still allows for simultaneous tracking of up to 126 radiosonde units. This feature can be used to map small spatial and temporal variations in atmospheric fields (e.g., Markowski et al., 2018: Bull. Amer. Meteorol. Soc., 99, 711-724). Such observations would also be valuable when validating improved high-resolution weather forecast models. In this presentation, we provide an overview of the Windsond S2, its technical specifications, and highlight several use case scenarios. Additionally we present and discuss S2 data collected under various meteorological conditions.