1. Radiation Dry Bias of the Vaisala RS92 Humidity Sensor
- Author
-
Henry B. Selkirk, Jorge Andres Diaz, Larry M. Miloshevich, J. Valdés, Esko Kyrö, Holger Vömel, Rigel Kivi, W. Stolz, G. S. Peng, and J. Valverde-Canossa
- Subjects
Atmospheric Science ,Hygrometer ,Meteorology ,Instrumentation ,Humidity ,Ocean Engineering ,Atmospheric sciences ,law.invention ,Troposphere ,law ,Radiosonde ,Environmental science ,Relative humidity ,Tropopause ,Zenith - Abstract
The comparison of simultaneous humidity measurements by the Vaisala RS92 radiosonde and by the Cryogenic Frostpoint Hygrometer (CFH) launched at Alajuela, Costa Rica, during July 2005 reveals a large solar radiation dry bias of the Vaisala RS92 humidity sensor and a minor temperature-dependent calibration error. For soundings launched at solar zenith angles between 10° and 30°, the average dry bias is on the order of 9% at the surface and increases to 50% at 15 km. A simple pressure- and temperature-dependent correction based on the comparison with the CFH can reduce this error to less than 7% at all altitudes up to 15.2 km, which is 700 m below the tropical tropopause. The correction does not depend on relative humidity, but is able to reproduce the relative humidity distribution observed by the CFH.
- Published
- 2007