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 communications 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 US 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 co-released 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 deg for wind direction. The benefits of using the StreamSonde instrument along with planned improvements to the platform are discussed.
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