Can wind lidars measure turbulence

Modeling of the systematic errors in the second-order moments of wind speeds measured by continuouswave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model captures the effect of volume illumination and conical scanning. The predictions are compared with the measurements from the ZephIR, WindCube, and sonic anemometers at a flat terrain test site under different atmospheric stability conditions. The sonic measurements are used at several heights on a meteorological mast in combination with lidars that are placed on the ground. Results show that the systematic errors are up to 90% for the vertical velocity variance, whereas they are up to 70% for the horizontal velocity variance. For the ZephIR, the systematic errors increase with height, whereas for the WindCube, they decrease with height. The systematic errors also vary with atmospheric stability and are low for unstable conditions. In general, for both lidars, the model agrees well with the measurements at all heights and under different atmospheric stability conditions. For the ZephIR, the model results are improved when an additional low-pass filter for the 3-s scan is also modeled. It is concluded that with the current measurement configuration, these lidars cannot be used to measure turbulence precisely.

[1]  K. A. Browning,et al.  The Determination of Kinematic Properties of a Wind Field Using Doppler Radar , 1968 .

[2]  J. Wyngaard,et al.  Measurement of small-scale turbulence structure with hot wires , 1968 .

[3]  Andrew Oldroyd,et al.  An eight month test campaign of the Qinetiq ZephIR system: Preliminary results , 2007 .

[4]  C. M. Sonnenschein,et al.  Signal-to-Noise Relationships for Coaxial Systems that Heterodyne Backscatter from the Atmosphere. , 1971, Applied optics.

[5]  J. Mann.  The spatial structure of neutral atmospheric surface-layer turbulence , 1994, Journal of Fluid Mechanics.

[6]  Torben Mikkelsen,et al.  Investigation of turbulence measurements with a continuous wave, conically scanning LiDAR , 2009 .

[7]  H. Jørgensen,et al.  Wind lidar evaluation at the Danish wind test site in Høvsøre , 2006 .

[8]  William K. George,et al.  The reduction of spatial aliasing by long hot-wire anemometer probes , 1997 .

[9]  D. Lenschow,et al.  How long is long enough when measuring fluxes and other turbulence statistics , 1994 .

[10]  Torben Mikkelsen,et al.  Comparison of 3D turbulence measurements using three staring wind lidars and a sonic anemometer , 2008 .

[11]  J. Lundquist,et al.  Nocturnal Low-Level Jet Characteristics Over Kansas During Cases-99 , 2002 .

[12]  Torben Mikkelsen,et al.  Spatial averaging-effects on turbulence measured by a continuous-wave coherent lidar , 2009 .

[13]  R. Banta,et al.  Boundary-layer anemometry by optical remote sensing for wind energy applications , 2007 .

[14]  Per Jonas Petter Lindelöw.  Upwind D1. Uncertainties in wind assessment with LIDAR , 2009 .

[15]  V A Banakh,et al.  Representativeness of wind measurements with a cw Doppler lidar in the atmospheric boundary layer. , 1995, Applied optics.

[16]  S. Gryning,et al.  Offshore wind profiling using light detection and ranging measurements , 2009 .

[17]  Igor N. Smalikho,et al.  Measurement of Atmospheric Turbulence by 2-μm Doppler Lidar , 2005 .

[18]  Per Jonas Petter Lindelöw.  Fiber Based Coherent Lidars for Remote Wind Sensing , 2008 .

[19]  Per Jonas Petter Lindelöw,et al.  Testing and comparison of lidars for profile and turbulence measurements in wind energy , 2008 .

[20]  R. E. Cupp,et al.  Doppler lidar measurement of profiles of turbulence and momentum flux , 1989 .

[21]  M. Kallistratova,et al.  Determination of the turbulent fluxes of heat and momentum in the ABL by ground-based remote-sensing techniques (a Review) , 2007 .

[22]  S. Larsen,et al.  On the extension of the wind profile over homogeneous terrain beyond the surface boundary layer , 2007 .

[23]  Rozenn Wagner,et al.  Lidar Scanning of Momentum Flux in and above the Atmospheric Surface Layer , 2010 .

[24]  Rebecca J. Barthelmie,et al.  The influence of non‐logarithmic wind speed profiles on potential power output at Danish offshore sites , 2005 .

[25]  Jakob Mann,et al.  On the length‐scale of the wind profile , 2010 .

[26]  R. Kropfli.  Single Doppler Radar Measurements of Turbulence Profiles in the Convective Boundary Layer , 1986 .

[27]  Alan Genz,et al.  An adaptive algorithm for numerical integration over an n-dimensional rectangular region , 1980 .

[28]  Neil Kelley,et al.  Horizontal-Velocity and Variance Measurements in the Stable Boundary Layer Using Doppler Lidar: Sensitivity to Averaging Procedures , 2008 .

[29]  Mei Xu,et al.  Estimations of atmospheric boundary layer fluxes and other turbulence parameters from Doppler lidar data , 1992 .