The authors thank the German Weather Service (DWD) for funding this work under its Extramural Research Program. Thanks also to Prof. Dr. Klaus D. Beheng for his critical comments on the first draft, and to three anonymous reviewers for their valuable corrections. Especially one anonymous reviewer provided very constructive input and pointed us to a problem in our first implementation of the TORE method. This motivated us to find the ad hoc solution mentioned in section 5.
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Although a radiosonde measures on a spatial scale much larger than the radar wavelength, the data are readily available and are a good source of atmospheric information on temperature and humidity structure. It is assumed that the radiosonde data will at least yield a not-too-bad representation of the n profile in ducting conditions.