Theory, Electro-Optical Design, Testing, and Calibration of a Prototype Atmospheric Supersaturation, Humidity, and Temperature Sensor.

摘要

A new infrared differential absorption - passive thermal emission based instrument designed to make accurate in-cloud measurements of absolute humidity, air temperature, relative humidity, and ice and water supersaturations has been developed. Absolute humidity is measured by the differential infrared absorption of a broad-band light beam between 2.45 microns wavelength and the strongly absorbing water vapor band at 2.67 microns. Air temperature is sensed by a passive radiometric measurement of the Planck's law radiance emitted by carbon dioxide molecules in their very intense emission band at 4.25 microns. Significant operational advantages over previous 14-16 micron band radiometers are achieved. These non-contact optical measurements of absolute humidity and true air temperature can then be combined to yield relative humidity values with respect to both water and ice which remain valid in condensing supersaturated conditions and in spite of hydrometeors in the sample volume. (Author)