A method for rescaling humidity sensors at temperatures well below freezing

Abstract

During 1991, the second field phase of the Stable Antarctic Boundary Layer Experiment (STABLE II) was run at the British Antarctic Survey's Halley station (75°36′S, 26°42′W) on the Brunt Ice Shelf. Vaisala HMP35A humidity instruments were used during the experiment to measure relative humidity (RH) and temperature within the lowest 8m of the boundary layer. The instruments were mounted in naturally ventilated radiation shields (Vaisala type 2212). Halley experiences temperatures from +5° to -50°C and although these instruments are capable of operating over this range, they are only within the manufacturer's calibration between -20° and +65°C. This paper presents a technique for improving the calibration of the HMP35A at low temperatures. -from Author