Analysis of Techniques for Describing the State of Sky Through Automation
STANFORD RESEARCH INST MENLO PARK CA PHYSICAL SCIENCES DIV
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The problem of automatically describing cloud amount and cloud base height is studied through the use of statistical analysis and computer simulation. A simulation program is used to determine the response of a set of instruments to simulated cloud conditions. Relations are derived between the accuracy of cloud amount estimation and the number of instruments used, area covered, mean cloud size, cloud speed, sampling interval, and averaging time. Various clustering procedures are evaluated for use in determining the number of cloud layers, the mean height of each layer, and the cloud amount in layers. The physical limitations of such instruments as vertically-pointing ceilometers and scanning lidar systems are discussed. Finally, a simple cost comparison is made between the present manual and a possible automatic system.