Meandering analysis under low wind conditions in built-up environment

Le résumé fourni par la source

This study investigates meandering under low-wind conditions at the French atmospheric observatory SIRTA using ultrasonic anemometer measurements at two heights in a built-up area and in an open area, allowing comparison under the same mesoscale meteorological conditions. A new data-processing method based on the Eulerian Autocorrelation Function is developed to better characterize oscillations associated with meandering. The results show that buildings reduce the occurrence probability of meandering and shorten oscillation periods. The analysis also highlights the influence of atmospheric stability on the occurrence and characteristics of meandering. Meandering occurs under both stable and unstable conditions, with a higher occurrence probability at night in the built environment. Meandering is less frequent under neutral conditions. Its characteristic time scales are shorter under unstable than under stable conditions. The relationship between meandering and turbulence reveals two distinct meandering–turbulence regimes separated by a Turbulent Kinetic Energy threshold. Above this threshold, meandering intensity is weakly affected by turbulence, whereas below it, its sensitivity increases markedly. A similar behavior is observed for the ratio of the standard deviations of the horizontal and vertical wind components.

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