A surface acoustic wave hygrometer for high-resolution measurements of atmospheric humidity

Abstract

Weather and climate depend on atmospheric phenomena at all scales, from large-scale atmospheric circulation to microphysical processes. In this talk, a surface acoustic wave (SAW) hygrometer developed at JPL for high-resolution measurements of atmospheric humidity will be discussed. Flight tests of an early prototype on the NASA DC8 showed more than an order of magnitude faster response than chilled-mirror hygrometers. In 1998, a 1-kg reference radiosonde based on the SAW hygrometer was flown on a small balloon to an altitude of 44<th>000 feet, while a mobile ground station recorded telemetered data containing high-resolution measurements of humidity, pressure, temperature, and GPS position. Later in 1998, the SAW hygrometer was deployed on the NASA DC8 to measure humidity in Atlantic hurricanes. In 1999, the SAW hygrometer recorded humidity in the test flight of NASA’s Helios unpiloted aircraft. Currently, this instrument is being modified for incorporation into a hand-held instrument for monitoring environmental humidity on the space station. [The research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, and was jointly sponsored by the National Aeronautics and Space Administration, Earth Science Enterprise, Space Science Enterprise, and Human Exploration and Development of Space Enterprise.]