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Effects of non-uniform crosswind fields on scintillometry measurements

Ward, H.C.; Evans, J.G.; Grimmond, C.S.B.. 2011 Effects of non-uniform crosswind fields on scintillometry measurements. Boundary-Layer Meteorology, 141 (1). 143-163. 10.1007/s10546-011-9626-0

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Abstract/Summary

The effects of a non-uniform wind field along the path of a scintillometer are investigated. Theoretical spectra are calculated for a range of scenarios where the crosswind varies in space or time and compared to the ‘ideal’ spectrum based on a constant uniform crosswind. It is verified that the refractive-index structure parameter relation with the scintillometer signal remains valid and invariant for both spatially and temporally-varying crosswinds. However, the spectral shape may change significantly preventing accurate estimation of the crosswind speed from the peak of the frequency spectrum and retrieval of the structure parameter from the plateau of the power spectrum. On comparison with experimental data, non-uniform crosswind conditions could be responsible for previously unexplained features sometimes seen in observed spectra. By accounting for the distribution of crosswind, theoretical spectra can be generated that closely replicate the observations, leading to a better understanding of the measurements. Spatial variability of wind speeds should be expected for paths other than those that are parallel to the surface and over flat, homogenous areas, whilst fluctuations in time are important for all sites.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1007/s10546-011-9626-0
Programmes: CEH Topics & Objectives 2009 onwards > Water
CEH Sections: Reynard
ISSN: 0006-8314
Additional Keywords: crosswinds, scintillometry, sensible heat flux, spectra, structure parameter
NORA Subject Terms: Hydrology
Date made live: 29 Sep 2011 10:52
URI: http://nora.nerc.ac.uk/id/eprint/10407

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