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A combo (Sonic & 2 x-hot-films or 3D-multisensor probe) setup for atmospheric turbulence measurements Eliezer Kit, Tel Aviv University The fine-scale structure of turbulence is a largely unexplored aspect of the atmospheric boundary layer since it eludes conventional probing techniques. The direct measurement of fine structure using high resolution instruments such as hot-film or hotwire anemometers that can resolve smallest (dissipation) scales has been rare, given the intricacy of the instruments involved. Standard hot film/wire techniques work on the premise that the change of resistance produced in a heated wire due to cooling of a passing flow is a function of velocity. Thus, a reliable calibration procedure is necessary to convert measured voltage to velocity. In addition, more frequent calibrations are necessary in view of slowly changing probe performance due to contamination. In the talk, there is a recall to feasibility study conducted by Kit et al. (2010) where a strikingly successful method, the Neural Network (NN) approach was suggested and applied. By employing an effective velocity approach to mimic behavior of multi-sensor hot-film probe in a given velocity field, a “virtual” probe algorithm was developed. It enabled to study several aspects of the suggested calibration scheme based on NN: determination the turbulence intensity bounds of the flow which permit acceptable calibration, the effect of anisotropy of the flow on calibration quality and the effect of hot-wire nonlinearity on the calibration process. The combos were installed on towers and continuous measurements of the fine turbulence structure were conducted in the frame of MATERHORN-X program during the fall and spring campaigns. The preliminary results from fall campaign are presented. The further data processing is in progress.