Tropospheric comparisons of Vaisala radiosondes and balloon-borne frost-Point and Lyman-α hygrometers during the LAUTLOS-WAVVAP experiment

Abstract

The accuracy of all types of Vaisala radiosondes and two types of Snow White chilled-mirror hygrosondes was assessed in an intensive in situ comparison with reference hygrometers. Fourteen nighttime reference comparisons were performed to determine a working reference for the radiosonde comparisons. These showed that the night version of the Snow White agreed best with the references [i.e., the NOAA frost-point hygrometer (FPH) and University of Colorado cryogenic frost-point hygrometer (CFH)], but that the daytime version had severe problems with contamination in the humid upper troposphere. Since the RS92 performance was superior to the other radiosondes and to the day version of the Snow White, it was selected to be the working reference. According to the reference comparison, the RS92 has no bias in the mid- and lower troposphere, with deviations < -50°C. For T > -30°C it is ineffective and does not correct the RS80-A dry bias in high ambient RH. © 2008 American Meteorological Society.