Evaluation of the directional bias in the M.S.C. type 45B wind system / by Oscar Koren = Évaluation de la déviation dans le système de mesure des vents M.S.C. de type 45B / par Oscar Koren. : En57-57/750-1971E-PDF

"Preliminary evaluation of the directional bias in the M.S.C. Type 45B wind system shows that the percentage frequency distribution of wind direction is biased toward the intermediate (non-cardinal) wind directions. The analytical evaluation suggests that this bias is due to the relatively long time interval during which the wind direction is sampled. The magnitude of the directional bias is found to be a function of wind speed, stability, and surface roughness. The analysis of the observational data reveals that for most practical purposes the bias toward the intermediate directions may be removed by the use of a pulse-limiter. Furthermore, some evidence is given to suggest that there is a secondary bias, directed toward cardinal wind directions, resulting from the uneven brush-commutator contact. Laboratory tests indicate that the magnitude of the secondary bias is a complex function of time over which the anemometer was used and of the anemometer's initial conditions. It is shown that the secondary bias can be significant when the non-cardinal bias is reduced, and further work remains to be done to reduce it to acceptable limits"--Abstract.

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publications.gc.ca/pub?id=9.938484&sl=1

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