Pinard, J.-P. R. Benoit, and W. Yu, 2005 A WEST Wind climate simulation of the Mountainous
Yukon. Atmosphere-Ocean, 43(3), 259-282
The wind climate of the mountainous terrain in the southern
Yukon is simulated using the Wind Energy Simulation Toolkit (WEST) developed by the Recherche
en Prévision Numérique (RPN) group of Environment Canada and is compared to measurements in
the field. WEST combines two models that operate at different spatial scales. The Mesoscale
Compressible Community (MC2) model is a mesoscale numerical weather prediction model that
produces simulations over large domains of the order of a thousand kilometres. The MC2 model
uses long-term synoptic scale wind climate data from the analysis of radiosonde and other
observations to simulate mean wind fields at tens of metres above the ground using a
horizontal resolution of a few kilometres. The mesoscale results are used as input to
MS-Micro/3 (Mason and Sykes (1979) version of the Jackson and Hunt (1975) model version for
microcomputers/3-dimensional; MS-Micro hereafter), a more computer-efficient, microscale
model with simpler linearized momentum equations and a domain restricted to a few tens of
kilometres with horizontal grid sizes of tens or hundreds of metres. MS-Micro provides wind
field results at specific wind generator hub heights (typically 30 to 50 m above ground
level (AGL)) which are of interest to researchers and developers of wind farms.
WEST shows relatively strong correlations between its simulated long-term mean wind speed
and the measurements from ten wind energy monitoring stations. However, in the mountainous
terrain of the Yukon, WEST tends to predict wind speeds which are about 40% too high. The
model also produces erroneous wind directions and some were perpendicular to valley
orientations. The most likely cause of the wind speed and direction errors is the
substantially modified 5-km grid-spaced mesoscale terrain used in MC2. The WEST simulation
was also found to double the wind speeds observed at airport stations and there was poor
correlation between the simulated and observed wind speeds.
The bias in the model could be attributed to a number of factors, including the use of
smoothed topography by the model, the discrepancy between the neutral atmosphere assumed
in MS-Micro and the normally observed stable atmosphere, the application of MS-Micro to
every third grid point of the MC2 output, abnormally high sea level wind speeds in the
input climate data for MC2, and a certain degree of disagreement between the land surface
characteristics used in the model and those found in the field.
At comparatively low computer cost, WEST predicts a wind climate map that compares
favourably to the wind measurements made in several locations in the Yukon. However,
the problem of the modified terrain in the mountainous regions is the most pressing
problem and needs to be addressed before WEST is used in the mountainous regions of
Canada.
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