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Wind structure in relation to odour plumes in tsetse fly habitats
Author(s) -
GRIFFITHS NIGEL,
BRADY JOHN
Publication year - 1995
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/j.1365-3032.1995.tb00817.x
Subject(s) - anemometer , turbulence , wind speed , wind gradient , meteorology , atmospheric sciences , context (archaeology) , wind direction , wind shear , turbulence kinetic energy , plume , environmental science , wind profile power law , physics , geology , paleontology
. Key characteristics of airflow were measured in the African bush in a study of host odour plume structure. Wind speed, speed variance, direction, and directional variance were measured by conventional cup anemometers plus wind‐vanes and by a solid state ultrasonic anemometer, on time scales from seconds to minutes. The two technologies gave opposite relationships between wind speed and turbulence measured as rate of angular direction change in the wind (° s ‐1 ). A positive correlation between turbulence and wind speed was observed with mechanical anemometers and wind‐vanes, evidently caused by their inherent hysteresis (stalling in weak wind, overswinging after gusts). The same correlation was negative with the solid‐state anemometer which, being hysteresis free, should have measured the true directional turbulence more accurately. Such fine‐scale turbulence at a fixed point in space (on a scale of about ∼15 cm diam.) decreased with wind speed up to ∼1.5 m s ‐1 , as does large‐scale (∼1m diam.) turbulence of air moving through space (Brady et al. , 1989). This decrease occurred both within vegetation and out in the open, but the slope and intercepts of the relationship depended on vegetation and topography. Variables for describing wind speed and turbulence are considered in the context of odour plume structure.