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  • Author or Editor: F. O. Guiraud x
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D. C. Hogg, F. O. Guiraud, and E. B. Burton

Abstract

An example of measurement of liquid water in a cool cloud deck by microwave radiometry and simultaneous observation of icing of aircraft is given. Implications in use of microwave radiometers for warning of icing conditions, and in weather-modification application, are discussed. The liquid in the cloud is shown to be supercooled by supporting evidence from the National Weather Service radiosondes at Denver, Colorado.

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J. B. Snider, F. O. Guiraud, and D. C. Hogg

Abstract

We report on observations of liquid water in clouds made by two independent ground-based microwave instruments. One system is a dual-frequency (20.6, 31.65 GHz) microwave radiometer designed to measure emission from the precipitable water vapor and from liquid in the zenith direction; we refer to this as System 1. The other system is a combination receiver-radiometer that utilizes absorption of a 28 GHz signal from the COMSTAR satellite to measure the liquid content of clouds; we refer to this as System 2. Comparative measurements on liquid-bearing clouds in Colorado are given.

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M. T. Decker, E. R. Westwater, and F. O. Guiraud

Abstract

Profiles of atmospheric temperature and water vapor derived from ground-based microwave radiometric measurements are compared with concurrent rawinsonde profiles including both clear and cloudy cases. Accuracies of the temperature profiles including the cloudy cases are quite close to predicted accuracies. Mean virtual temperatures between commonly used pressure levels are also compared and resulting rms accuracies are 1.1, 1.6, 2.0 and 2.8°C for the 1000–850, 850–700, 700–500 and 500–300 mb layers, respectively. The microwave technique is potentially useful in applications requiring high time resolution or in data-sparse regions of the oceans that might be covered by an ocean data buoy system.

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D. C. Hogg, F. O. Guiraud, J. B. Snider, M. T. Decker, and E. R. Westwater

Abstract

An instrument that remotely senses the integrated amounts of water vapor and liquid on a path through the atmosphere is discussed. The vapor and liquid are measured simultaneously but independently by microwave radiometers. Comparison of the accuracy in measurement of vapor is made with radiosondes, and of liquid with an independent method employing transmission from a geosynchronous satellite. The instrument is designed for unattended operation; examples of measured data are given. Applications including observations for weather forecasting, weather modification, solar-radiation studies, and instrumentation for geodetic metrology are also discussed.

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D. C. Hogg, M. T. Decker, F. O. Guiraud, K. B. Earnshaw, D. A. Merritt, K. P. Moran, W. B. Sweezy, R. G. Strauch, E. R. Westwater, and C. G. Little

Abstract

A remote-sensing system for continuously profiling the troposphere is discussed; the prototype Profiler utilizes radio wavelengths, thereby achieving essentially all-weather operation. Designed for unattended operation, the Profiler employs radiometric and Doppler radar technology. Design, construction and calibration of the instruments composing the Profiler system are described along with some of the physics and mathematics upon which their operation is based. Examples of profiles and other variables of meteorological interest are given, and comparisons are made with simultaneous data from colocated operational (NWS) sondes. An algorithm based on climatological statistics of measurements by radiosonde is used in the radiometric retrieval process, but there is no reliance of the products of the Profiler upon any current radiosonde data. The role of the Profiler in mesoscale and synoptic weather forecasting and its relationship to systems employing sounders on satellite platforms are also discussed.

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