[PDF] A Digital Processing And Display System For The Rotating Beam Ceilometer An Gmq 13 eBook

Author : James Weyman
Publisher :
Page : 76 pages
File Size : 16,12 MB
Release : 1981
Category : Cathode ray tubes
ISBN :

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A microprocessor-based automated display system for the Rotating Beam Ceilometer (RBC) was developed to demonstrate the feasibility of modernizing and improving the present display system. The new system consists of a Burroughs self-scan panel display (model number SSD0124-0039) and an Intel 8080A-based microcomputer. The program acquires the signal returns from the RBC, converts the analog signal to a digital value, and displays the most recent scan. The system allows for three modes of operation or processing. Two modes, a one-scan mode and a five-scan mode, require no further inputs from the user once they have been selected. A manual mode which is user-interactive is also available. The basic display capabilities consist of a depiction of signal intensity vs. height, a numerical display of the height of the peak value and an illuminated cursor positioned at the peak value. Evaluation of the system at AFGL and Scott AFB, IL has confirmed that the display is more readable, provides more accurate cloud heights and permits better interpretation of the data obtained than does the current CRT display system. Further considerations which will be incorporated before operational implementation are discussed. (Author).

Author : Edward B. Geisler
Publisher :
Page : 44 pages
File Size : 32,15 MB
Release : 1981
Category : Automatic meteorological stations
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At the Air Force Geophysics Laboratory (AFGL) Weather Test Facility (WTF) at Otis AFB, MA, a network of cloud base height, visibility, and wind measuring instruments were used to explore techniques for the short range prediction of low cloud ceiling. AFGL developed this system in response to the USAF Air Weather Service's requirements to modernize its basic weather support capabilities. This system allowed AFGL to evaluate the ability of statistical forecasting techniques to provide decision assistance significantly improved over the decision assistance currently provided by climatology and persistence. The approach relies upon the use of a hierarchical clustering algorithm to transform the raw cloud base height data into an automated low cloud observation. Four prediction techniques (Regression Estimation of Event Probabilities, Equivalent Markov, climatology, and persistence) yielding probability estimates of low cloud ceiling were evaluated and comparisons made to determine their respective accuracy and reliability. In addition, thresholding techniques were used to convert probability forecasts (unit bias, maximum probability, iterative, and persistence). Analysis of the data collected at the AFGL WTF demonstrates the accuracy and reliability of the automated low cloud prediction system. Regression estimation of event probabilities provided accurate, reliable, high resolution probability forecasts with results superior to climatology, persistence, and Equivalent Markov.

Author : Frederick J. Brousaides
Publisher :
Page : 34 pages
File Size : 17,36 MB
Release : 1982
Category : Ceilometer
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The capability and performance of the AN/GMQ-13 Cloud Height Set, commonly referred to as the Rotating Beam Ceilometer (RBC), was reviewed. Included in the study is an assessment of its ability to meet specific requirements for automting the measurement of cloud field properties, that is, layering and cloud cover, through the application of the hierarchical clustering technique. It is concluded that a single RBC system cannot meet current stated requirements for cloud height measurement. An RBC with a 1600 ft baseline can meet the high altitude requirement but has difficulty with low ceilings that are also associated with conditions of restricted visibility. An RBC with a 400-ft baseline does well at low altitudes but is totally inadequate at high altitudes. An obvious compromise would be the deployment of two RBCS, or one projector and two receivers. The hierarchical clustering technique for the determination of cloud field properties was previously demonstrated in AFGL and AWS field tests. The resolution and accuracy to be obtained is a function of the number of ceilometers available, their orientation, and time averaging considerations.

Author : Edward B. Geisler
Publisher :
Page : 32 pages
File Size : 35,95 MB
Release : 1980
Category : Automatic meteorological stations
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Analysis of cloud base height data collected during a seven-month period from a three Rotating Beam Ceilometer (RBC) network on Otis AFB, Massachusetts, demonstrated the accuracy of an automated cloud observation system. The high degree of correspondence between the automated and human observations of cloud height, low cloud amount, multiple cloud layers, and ceiling confirms the accuracy of the hierarchical clustering technique when applied to a network of RBC's confined to the immediate environs of an airfield. Tests demonstrated only slight improvements in automated cloud observation are realized by incorporating additional information from a second and third RBC on or near an airfield.

Author :
Publisher :
Page : 1370 pages
File Size : 31,87 MB
Release : 1981
Category : Aeronautics
ISBN :

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