GUIDE
Our simple GUIDELINES approach to estimation of wind speed variation in complex terrain is
based on simple analytic models of internal boundary layer development downstream of single
or multiple roughness changes and model results of flow over idealised topographies.
Earlier versions were described in papers by Taylor and Lee (1984), Walmsley et al (1989) and
Weng et al (2000).. A software package based on these guidelines, called GLW, has been
developed by Zephyr North Canada. (http://www.zephyrnorth.com/products.html#GLW).
Multiple roughness changes are a new addition, based on work described in a submitted paper
(Weng et al, 2009).
References
Taylor, P.A. and Lee, R.J., 1984: Simple Guidelines for estimating wind speed variations due to
small scale topographic features. Climatological Bulletin, 18(2), 3-32.
Walmsley, J.L., Taylor, P.A. and Salmon, J.R., 1989: Simple Guidelines for Estimating Wind
Speed Variations due to Small-Scale Topographic Features - An Update, Climatological
Bulletin, 23(1), 3-14.
Weng, W., Taylor, P.A. and Walmsley, J.L., 2000, Guidelines for airflow over complex terrain;
model developments, Journal of Wind Engineering and Industrial Aerodynamics, 86, 169-186.
Weng, W., Taylor, P.A. and Salmon, J.R., 2009, A 2-D numerical model of boundary-layer flow
over single and multiple surface condition changes. Submitted to J. Wind Eng. and Ind. Aerodyn.
Participants:
Jim Salmon1,2, Peter Taylor1,2 and Wensong Weng2
1
Zephyr North Canada, Burlington, Ontario, Canada
2
Centre for Research in Earth and Space Science, York University, Toronto, Canada
MSMICRO
MS-Micro/3 is a software package for estimating wind speed variations in complex terrain. It has
been developed by Zephyr North Canada (http://www.zephyrnorth.com/products.html#GLW)
based on the MS3DJH model reported by Walmsley et al (1986). This is itself based on an
extension of models developed by Jackson and Hunt (1975), Mason and Sykes (1979) and
Taylor et al (1983) but with the addition of spatially heterogeneous roughness lengths. The
analytic solution for flow perturbations caused by flow over topography is treated in a linear
fashion using Fourier components. The analytic solutions can be replaced by numerical solutions
for variations in the vertical while Fourier transforms remain a powerful technique for the
horizontal structure of the perturbed flow. This approach is used in the MSFD model (Beljaars et
al, 1987).
In a new version of MSMICRO we will use the MSFD model for topographic effects coupled
with numerical solutions of internal boundary-layer development downstream of single or
multiple roughness changes. The treatment is linear – based on a linearised topographic
perturbation model combined, linearly, with the roughness change perturbations.
References
Beljaars, A.C.M., Walmsley, J.L. and Taylor, P.A., 1987: A mixed spectral, finite difference
model for neutrally stratified boundary-layer flow over roughness changes and topography,
Boundary-Layer Meteorology. 38, 273-303
P.S. Jackson, J.C.R. Hunt, 1975, Turbulent wind flow over a low hill, Quart. J. Roy. Met. Soc.
101 929-955.
P.J. Mason, R.I. Sykes, 1979, Flow Over an Isolated Hill of Moderate Slope, Quart. J. Roy. Met.
Soc. 105, 383-395.
Taylor, P.A., Walmsley, J.L. and Salmon, J.R., 1983: A simple model of neutrally stratified
boundary-layer flow over real terrain incorporating wavenumber dependent scaling. Boundary-
Layer Meteorology 26, 169-189.
Walmsley, J.L., Taylor, P.A. and Keith, T., 1986: A Simple Model of Neutrally Stratified
Boundary-Layer Flow over Complex Terrain with Surface Roughness Modulations. Boundary-
Layer Meteorology, 36, 157-186.
Participants:
Peter Taylor1,2 , Wensong Weng2 and Jim Salmon1,2,
1
Zephyr North Canada, Burlington, Ontario, Canada
2
Centre for Research in Earth and Space Science, York University, Toronto, Canada
NLMSFD
The original NLMSFD model of flow over topography is described in papers by Xu and Taylor
(1992) and Xu et al (1994). It is an iterative solution of the steady state Reynolds Averaged
Navier Stokes equations (RANS) for topographically induced perturbations to turbulent, constant
flux layer flow over a plane homogeneous surface of uniform roughness. It works well for
moderate slope hills (slope < 0.3) and improvements are currently in hand to increase the range
of slopes for which it can be applied and to produce a PBL version.
It can be coupled to models of internal boundary-layer flow over roughness changes to predict
flow perturbations in moderately complex terrain.
References
Xu, D. and Taylor, P. A., 1992, A non-linear extension of the Mixed Spectral Finite Difference
model for neutrally stratified flow over topography, Boundary-Layer Meteorol. 59, 177-186.
Xu, D., Ayotte, K.W. and Taylor, P.A., 1994, Development of the NLMSFD model of turbulent
boundary-layer flow over topography, Boundary-Layer Meteorol, 70, 341-367.
Participants: Peter Taylor1,2 , Wensong Weng2, Xiao (Frank) Yu2 and Dong Liang2
1
Zephyr North Canada, Burlington, Ontario, Canada
2
Centre for Research in Earth and Space Science, York University, Toronto, Canada