Enhanced Accuracy of RASS-Measured Temperatures Due to an Improved Range Correction

Abstract

The accuracy of virtual temperature measurements taken by the Radio Acoustic Sounding System (RASS) has been improved essentially by the application of a more precise range correction that takes into account the profile of reflectivity and the range weighting function of the receiver. Especially, the height dependence of the RASS temperature error compared to radiosondes was significantly reduced. The improved range correction was verified with a 1-yr dataset consisting of more than 1000 comparisons of 482- and 1290-MHz wind profiler/RASS with radiosondes observations. Other corrections discussed in the literature accounting for the displacement of the acoustic source, horizontal wind, and turbulence have been neglected because they are usually not significant. After the application of the improved range correction together with the correction of vertical wind as well as more accurate constants in the temperature retrieval, the bias with respect to radiosondes is smaller than 0.3 K and the standard deviation of temperature differences varies between 0.4 and 0.7 K.