Author: Edward B. Geisler
Publisher:
ISBN:
Category : Automatic meteorological stations
Languages : en
Pages : 32
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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: Edward B. Geisler
Publisher:
ISBN:
Category : Automatic meteorological stations
Languages : en
Pages : 0
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Book Description
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: Edward B. Geisler
Publisher:
ISBN:
Category : Automatic meteorological stations
Languages : en
Pages : 44
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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: James I. Metcalf
Publisher:
ISBN:
Category : Ceilometer
Languages : en
Pages : 0
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This report surveys techniques for cloud detection to assess their suitability for meeting the requirements of the Automated Observation System (AOS). A microwave sensor is essential because of the requirements for observing cloud top heights and documenting multiple cloud layers. Wavelengths between 3 cm and 8.6 mm could be used for this application, and a detailed sensor design study is recommended to evaluate the availability, cost, performance, and reliability of components and systems. Pulsed or continuous-wave radars could meet most of the requirements, although measurements of cloud base with high accuracy at low altitude may be difficult with some pulsed systems. Keywords: Cloud base; Ceilometer; Cloud amount; Automated cloud observation; Remote detection; Ka band radar; X band radar; Lidar.
Author: Frederick J. Brousaides
Publisher:
ISBN:
Category : Ceilometer
Languages : en
Pages : 34
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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: J. E. Shields
Publisher:
ISBN:
Category : Cloud physics
Languages : en
Pages : 33
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Author:
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ISBN:
Category : Science
Languages : en
Pages : 172
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Author:
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ISBN:
Category : Geography
Languages : en
Pages : 1374
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Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 836
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 816
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