2017 |
Kent, Christoph; Grimmond, Sue; Barlow, Janet; Gatey, David; Kotthaus, Simone; Lindberg, Fredrik; Halios, Christos Evaluation of Urban Local-Scale Aerodynamic Parameters: Implications for the Vertical Profile of Wind Speed and for Source Areas (Journal Article) Boundary-Layer Meteorol (2017) 164:183–213, Vol: 164(2) , pp. 183-213, 2017. (Abstract | Links | BibTeX | Tags: Aerodynamic roughness length, Anemometric methods, Logarithmic wind-speed profile, Morphometric methods, Source area, Zero-plane displacement) @article{Kent2017, title = {Evaluation of Urban Local-Scale Aerodynamic Parameters: Implications for the Vertical Profile of Wind Speed and for Source Areas}, author = {Christoph Kent and Sue Grimmond and Janet Barlow and David Gatey and Simone Kotthaus and Fredrik Lindberg and Christos Halios}, editor = {Boundary-Layer Meteorology}, url = {http://urbanfluxes.eu/wp-content/uploads/2018/01/2017_Kent_et_al_BLM.pdf}, doi = {10.1007/s10546-017-0248-z}, year = {2017}, date = {2017-04-28}, journal = {Boundary-Layer Meteorol (2017) 164:183–213}, volume = {Vol: 164(2)}, pages = {183-213}, abstract = {Nine methods to determine local-scale aerodynamic roughness length (z0) and zero-plane displacement (zd ) are compared at three sites (within 60 m of each other) in London, UK. Methods include three anemometric (single-level high frequency observations), six morphometric (surface geometry) and one reference-based approach (look-up tables). A footprint model is used with the morphometric methods in an iterative procedure. The results are insensitive to the initial zd and z0 estimates. Across the three sites, zd varies between 5 and 45 m depending upon the method used. Morphometric methods that incorporate roughness-element height variability agree better with anemometric methods, indicating zd is consistently greater than the local mean building height. Depending upon method and wind direction, z0 varies between 0.1 and 5 m with morphometric z0 consistently being 2–3 m larger than the anemometric z0. No morphometric method consistently resembles the anemometric methods. Wind-speed profiles observed with Doppler lidar provide additional data with which to assess the methods. Locally determined roughness parameters are used to extrapolate wind-speed profiles to a height roughly 200 m above the canopy. Wind-speed profiles extrapolated based on morphometric methods that account for roughness-element height variability are most similar to observations. The extent of the modelled source area for measurements varies by up to a factor of three, depending upon the morphometric method used to determine zd and z0}, keywords = {Aerodynamic roughness length, Anemometric methods, Logarithmic wind-speed profile, Morphometric methods, Source area, Zero-plane displacement}, pubstate = {published}, tppubtype = {article} } Nine methods to determine local-scale aerodynamic roughness length (z0) and zero-plane displacement (zd ) are compared at three sites (within 60 m of each other) in London, UK. Methods include three anemometric (single-level high frequency observations), six morphometric (surface geometry) and one reference-based approach (look-up tables). A footprint model is used with the morphometric methods in an iterative procedure. The results are insensitive to the initial zd and z0 estimates. Across the three sites, zd varies between 5 and 45 m depending upon the method used. Morphometric methods that incorporate roughness-element height variability agree better with anemometric methods, indicating zd is consistently greater than the local mean building height. Depending upon method and wind direction, z0 varies between 0.1 and 5 m with morphometric z0 consistently being 2–3 m larger than the anemometric z0. No morphometric method consistently resembles the anemometric methods. Wind-speed profiles observed with Doppler lidar provide additional data with which to assess the methods. Locally determined roughness parameters are used to extrapolate wind-speed profiles to a height roughly 200 m above the canopy. Wind-speed profiles extrapolated based on morphometric methods that account for roughness-element height variability are most similar to observations. The extent of the modelled source area for measurements varies by up to a factor of three, depending upon the morphometric method used to determine zd and z0 |
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