Development and Validation of the Skyfora StreamSonde—A Lightweight High Frequency Instrument to Measure Atmospheric Soundings

Abstract This study documents the capabilities of the StreamSonde, a lightweight (24 g) instrument manufactured by Skyfora that measures atmospheric temperature, pressure, humidity, and wind velocity. Unique features of the StreamSonde are its wind speed accuracy enabled by a dual-band Global Navigation Satellite System (GNSS) receiver, the ability to vary the terminal fall velocity, a theoretical maximum communication distance between the instrument and the deployment aircraft of 250 km, and the ability to simultaneously operate up to eight instruments (50 in the future). Skyfora’s GNSS receiver receives signals on two bands from U.S. global positioning system (GPS) (L1/L5), European Galileo (E1/E5a), and Chinese BeiDou (B1I/B2a) satellites to calculate the wind speed. The combination of dual GNSS and lower terminal fall velocity results in more accurate wind retrievals than from single-band GPS potentially allowing us calculate turbulence quantities, especially near the surface. StreamSondes were launched as dropsondes from the NOAA P-3 aircraft in both clear-air low-wind testing environments and in Hurricane Nigel (2023). The pressure, temperature, humidity (in clear air), and derived wind velocity collected by the StreamSonde compare favorably to the widely used RD41 dropsonde that was developed at the National Center for Atmospheric Research (NCAR) and is manufactured by Vaisala. At coreleased drops in Hurricane Nigel, mean absolute differences between RD41 dropsondes and StreamSondes are generally below 1°C for air temperature, 1.5 m s −1 for wind speed, and 6° for wind direction. The benefits of using the StreamSonde instrument along with planned improvements to the platform are discussed. Significance Statement This study presents proof of concept for operational deployment of a new, lightweight atmospheric profiler called the StreamSonde in a tropical cyclone. It uses advanced positioning technology to accurately measure three-dimensional wind velocity, has an adjustable terminal velocity, and can be deployed in “swarms” of sensors that have up to eight (50 in the future) instruments simultaneously active. The versatility of this emerging technology makes it useable for many meteorological applications.