26 April 2002 Effects of low clouds on terrestrial free-space optics availability
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Proceedings Volume 4635, Free-Space Laser Communication Technologies XIV; (2002) https://doi.org/10.1117/12.464098
Event: High-Power Lasers and Applications, 2002, San Jose, California, United States
Abstract
Meteorological visibility data are the most commonly used data to estimate terrestrial Free Space Optics (FSO) availability in a given city. Visibility data can be used to estimate transmission efficiency at desired IR wavelengths using a semi-empirical equation, and are often archived over many years allowing the calculation of long-term averages of availability. However, these data are taken at near-surface levels (historically within a few meters of the surface) and are therefore only appropriate for estimating FSO availability near the surface. Examination of long term cloud observations, including percent frequency of cloud ceilings occurring at various heights above the ground, show the importance of including low clouds into the consideration of FSO availability for any situation above about 30-m above ground level (AGL). In most locations, low clouds occurring very near the surface are relatively common -- more so than surface-based fog (which is measured in terms of visibility). Thus, FSO availability will decrease with height, sometimes dramatically, in most cities. Cloud data is also archived over long periods of record and can thus be used to calculate long-term averages of availability.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jeff Baars, Michael Witiw, Ammar Al-Habash, Kenneth W. Fischer, "Effects of low clouds on terrestrial free-space optics availability", Proc. SPIE 4635, Free-Space Laser Communication Technologies XIV, (26 April 2002); doi: 10.1117/12.464098; https://doi.org/10.1117/12.464098
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