Author: James I. Metcalf
Publisher:
ISBN:
Category : Ceilometer
Languages : en
Pages : 18
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Book Description
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: Edward B. Geisler
Publisher:
ISBN:
Category : Automatic meteorological stations
Languages : en
Pages : 32
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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: James I. Metcalf
Publisher:
ISBN:
Category : Ceilometer
Languages : en
Pages : 28
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Book Description
Author: Eugene Y. Moroz
Publisher:
ISBN:
Category : Clouds
Languages : en
Pages : 26
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Book Description
Several sensors and techniques currently being investigated at the Air Force Geophysics Laboratory as part of its program to automate the observation of weather parameters are described. Included are a lidar cloud-height measuring system, a laser weather identifier, a decision tree approach for determination of present weather, a lidar slant visual range measuring system, and a tower mounted visibility meter approach for determination of slant visual range. (Author)
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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Book Description
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:
Publisher:
ISBN:
Category : Automated Surface Observing System
Languages : en
Pages : 108
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Book Description
Author: Edward B. Geisler
Publisher:
ISBN:
Category : Automatic meteorological stations
Languages : en
Pages : 44
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Book Description
Author:
Publisher:
ISBN:
Category : Automated Surface Observing System
Languages : en
Pages : 108
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Book Description
Author: JT. Bradley
Publisher:
ISBN:
Category : Air quality
Languages : en
Pages : 18
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Book Description
Traditionally, surface weather observations have been made by human observers. It has been their difficult task to estimate subjective elements such as sky cover (in tenths) and the heights of clouds (often to the nearest 100 ft). Automation has moved slowly to replace subjective methods in the field and, even then, usually only in special areas such as runway visual range (RVR) and runway visibility (RVV). Recent work has demonstrated that automated observations of other subjective elements are feasible and are already operational at two points in the United States.
