Evaluation of a ground-based sky camera system for use in surface irradiance measurement

Sabburg, Jeff and Wong, Joe (1999) Evaluation of a ground-based sky camera system for use in surface irradiance measurement. Journal of Atmospheric and Oceanic Technology, 16 (6). pp. 752-759. ISSN 0739-0572

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Abstract

This paper describes the evaluation of a ground-based sky camera system for studying the effect of clouds on the level of the ambient ultraviolet radiation. The system has been developed for research in the characterization of the effect of clouds around the sun. It is the first sky camera system to be used for the assessment of cloud conditions in the vicinity of the sun, rather than a whole-sky assessment. The system features a sun-tracking sky camera with an integrated measurement of horizontally received radiation at the same location. The image-processing algorithm uses solar radiation readings to reduce reflections from the sun on the camera system being mistaken for cloud in the images. Cloud amount was estimated in an angular region of between 12.5°and 37.5° around the sun. The algorithm also estimates the amount of solar obstruction by cloud (sun not covered, partially or totally covered). The system was evaluated during September 1997 at Toowoomba, Australia (27.6°S latitude). Compared to manual assessment of 592 images, 76.5% were identified correctly by the algorithm for the degree of solar obstruction and 81.9% for cloud amount. The behavior of ultraviolet radiation levels with cloud conditions is discussed.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 30 Nov 2007 11:47
Last Modified: 14 Nov 2013 01:48
Uncontrolled Keywords: cloud cover; instrumentation; irradiance; ultraviolet radiation
Fields of Research : 09 Engineering > 0903 Biomedical Engineering > 090303 Biomedical Instrumentation
04 Earth Sciences > 0401 Atmospheric Sciences > 040103 Atmospheric Radiation
04 Earth Sciences > 0401 Atmospheric Sciences > 040106 Cloud Physics
Socio-Economic Objective: D Environment > 96 Environment > 9602 Atmosphere and Weather > 960202 Atmospheric Processes and Dynamics
Identification Number or DOI: 10.1175/1520-0426(1999)016<0752:EOAGBS>2.0.CO;2
URI: http://eprints.usq.edu.au/id/eprint/13827

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