Test Flight of a Stratospheric Sonic Anemometer Prototype

Stratospheric sonic anemometers are an emerging technology for making wind velocity measurements in low pressure environments. This paper explores the challenges, design, and high-altitude testing of a digital sonic anemometer for applications including high-altitude balloon navigation, atmospheric gravity wave research, solar activity research, and planetary science on Mars. The system was fl own on NASA's Sensor Package for Attitude, Rotation, and Relative Observable Winds (SPARROW-3) balloon test fl ight out of Fort Sumner, New Mexico, in August 2022. The mission recorded relative wind data throughout the fl ight at temperatures as low as-408C and at the balloon's fl oat altitude of 38 km (3.8-mb pressure; 1 mb 5 1 hPa). The device surpassed all previous sonic anemometers regarding maximum operational altitude. However, only two of the three axes operated well above 32 km, leading to some validation challenges. The system achieved a velocity resolution of 0.1 m s-1 (standard deviation) and recorded three-dimensional wind measurement every 2.25 s. Future plans anticipate addressing the faulty axis and increasing performance to a resolution of 0.01 ms-1 and a wind sampling rate of 10 Hz.