Wind Field Characterization from the Trajectories of Small Balloons

Abstract

AbstractThis paper reports the development and application of a new wind sensing system, ValidWind. ValidWind consists of small, helium-filled tracer balloons and an instrument that tracks them with high spatial resolution by means of an eye-safe lidar rangefinder and records 3D balloon position as a function of time. Lightweight retroreflectors attached to the balloons enhance the optical range. Balloon tracking is automatic. The data products include horizontal wind speed, wind direction, and vertical shear as functions of time and geolocation. Vertical wind speeds can be inferred from variations of the balloons’ rate of rise given the balance between buoyancy and aerodynamic drag. Applications of ValidWind include characterization of katabatic and ridge-top wind fields and monitoring of windborne aerosol transport. The capability of ValidWind balloons to provide useful profiles of the wind from the ground up to an altitude of 2 km AGL is presented and analyzed.