Improved meteorological measurements from buoys and ships (IMET) : preliminary comparison of humidity sensors

Humidity sensors using various principles of operation are evaluated for the potential use at sea on buoys and ships. Thin film capacitive polymer sensors include the Vaisala Humicap HMP-14U (with WHOI electronics), Hy-Cal Engineerig Ultra-H (also with WHOI electronics), the new Vaisala HMP-35A, and the Rotronic MP-lOOF. Impedance sensors include the Thunder Scientific PC-2101, Phys-Chem PCRC-ll, and the General Eastern 850. The Hygrometrix 8503A is the only organically based cellulose crystallite sensor evaluated. Chilled mirror dew sensors include the EG&G 200M Dewtrak, which was used as a comparative standard, the General Eastern Dew-lO and the WHOI D10IQ Intelligent Dew Point Sensor. The IR-200 infrared optical hygrometer from Ophir is also included in this study. The performance of the EG&G 200M Dewtrak was quite disappointing. Errors of up to 2.5°C in air temperature were observed due to inadequate shielding from solar radiation.Funding was provided by the National Science Foundation under Grant No. OCE-87-09614