How good are remote sensors at measuring extreme winds?

How good are remote sensors at measuring extreme winds?

Sathe, A.R.
Courtney, M.
Mann, J.
Wagner, R.

Aerospace Engineering

Wind Energy

2011-03-14

This article describes some preliminary efforts within the SafeWind project, aimed to identify the possible added value of using wind lidars to detect extreme wind events. Exceptionally good performance is now regularly reported in the measurement of the mean wind speed with some wind lidars in flat terrain. For turbulence measurements, recent theoretical work has revealed that the components of the Reynolds stress tensor are subjected to significant spatial attenuation and contamination by the cross-components of the horizontal and vertical wind speed. Thus, with the conical scanning of the lidar and velocity azimuth display technique of processing data, precision turbulence measurements are not possible. But how faithfully do wind lidars measure extreme wind events? Our study uses mast and wind lidar data from a flat terrain site. The ZephIR is used as a continuous wave lidar and the WindCube as a pulsed lidar. The data analysis consists of cup-lidar comparisons of the mean wind speed, the maximum wind speed, probability distributions of the time difference of the maximum wind speed, and variation of the gust factors with mean wind speed and atmospheric stability. We examine to what degree each of the different instruments are able to detect extreme events, and attempt to identify the differences in the measurements of the extreme events between cups and lidars. The data analysis showed that both lidars are capable of measuring the maximum wind speed within a 10-min period up to an underestimation of about 10% with respect to the cup anemometer. The Windcube is capable of measuring the gust factor that is comparable to that of the cup anemometer, whereas the ZephIR always underestimates it. The conclusion is still speculative and more theoretical work is required to deduce firm conclusions.

http://resolver.tudelft.nl/uuid:9e935a86-2279-4699-919e-cadd37704090

EWEA 2011: Europe's Premier Wind Energy Event, Brussels, Belgium, 14-17 March 2011

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(c) 2011 The Author(s)