Development of a Balloon-Borne Acoustic Anemometer to Measure Winds for SENSOR Campaign

The stratospheric environmental responses to solar storms (SENSORs) campaign investigates the influence of solar storms on the stratosphere. This campaign employs a long-duration zero-pressure balloon as a platform to carry multiple types of payloads during a series of flight experiments in the mid-latitude stratosphere from 2019 to 2022. This article describes the development and testing of an acoustic anemometer for obtaining
in situ
wind measurements along the balloon trajectory. The anemometer is also equipped with temperature, pressure, and humidity sensors from a temperature–pressure–humidity measurement module (TPH module), inherited from a radiosonde developed for sounding balloons. The acoustic anemometer and other sensors were used in a flight experiment of the SENSOR campaign that took place in the Dachaidan District (95.37°E, 37.74°N) on September 4, 2019. 3-D wind speed observations, which were obtained during level flight at an altitude of around 25 km, are presented. A preliminary analysis of the measurements yielded by the anemometer is also discussed. To our knowledge, this is the first time that wind measurements were obtained by an acoustic anemometer during level flight of the high-altitude balloon and were used to analyze the Lagrangian spectrum in the inertial subrange over the Tibetan Plateau. In addition to wind speed measurements, temperature, pressure, and relative humidity measurements during ascent are compared to observations from a nearby radiosonde launched four hours earlier, and the results show very good agreement.