Acoustic Travel Time Tomography - A Method for Remote Sensingof the Atmospheric Surface Layer

Acoustic travel time tomography is demonstrated as a technique for remote monitoring of near surface air temperature and wind fields. An experimental procedure is presented which provides line-averaged values of the effective sound speed changing with air temperature and wind vector. In this study the travel times of sound signals at defined propagation paths between different acoustic sources and receivers were measured. The travel time data were inverted into effective sound speed values by using a special tomographic algorithm (Simultaneous Iterative Reconstruction Technique) to obtain area-averaged meteorological quantities (air temperature, wind speed). The method of acoustic travel time tomography will be applied to the atmosphere in order to directly provide spatially averaged data which are needed for evaluation of large-eddy simulation and microscale meteorological models as well as to complete conventional point measurements.