Experiences with Two Hot-Wire Instruments for Measuring the Liquid Water Content in Clouds

摘要

The results of airborne measurements of liquid water content using two hot-wire instruments: the Johnson-Williams (JW) and the Csiro-King (CK) instruments are discussed. Results are very consistent within the 0.04 to 0.46 g/cu m range, subject to correct dry-air calibration and to the exclusion of systematic errors. The dry-air values of the JW instrument are not (or only slightly) affected by variations in airspeed, height, and temperature, while those of the CK instrument are markedly affected. Radio signals have a very noticeable influence on the CK signals. In both instruments, atmospheric turbulence and banking maneuvers produce similar signals to those produced by the liquid water content. In the case of the CK instrument, it is not possible to achieve sufficient accuracy in transferring wind tunnel calibration data to flight measurements.