000201558 001__ 201558
000201558 005__ 20180913062652.0
000201558 037__ $$aPOST_TALK
000201558 245__ $$aCanopy wake measurements using multiple scanning wind LiDARs
000201558 269__ $$a2014
000201558 260__ $$c2014
000201558 336__ $$aTalks
000201558 520__ $$aCanopy wakes have been shown, in controlled wind tunnel experiments, to significantly affect the fluxes of momentum, heat and other scalars at the land and water surface over distances of O(1 km), see Markfort et al. (EFM, 2013). However, there are currently no measurements of the velocity field downwind of a full-scale forest canopy. Point-based anemometer measurements of wake turbulence provide limited insight into the extent and details of the wake structure, whereas scanning Doppler wind LiDARs can provide information on how the wake evolves in space and varies over time. For the first time, we present measurements of the velocity field in the wake of a tall patch of forest canopy. The patch consists of two uniform rows of 35-meter tall deciduous, plane trees, which border either side of the Allée de Dorigny, near the EPFL campus. The canopy is approximately 250 m long, and it is 35 m wide, along the direction of the wind. A challenge faced while making field measurements is that the wind rarely intersects a canopy normal to the edge. The resulting wake flow may be deflected relative to the mean inflow. Using multiple LiDARs, we measure the evolution of the wake due to an oblique wind blowing over the canopy. One LiDAR is positioned directly downwind of the canopy to measure the flow along the mean wind direction and the other is positioned near the canopy to evaluate the transversal component of the wind and how it varies with downwind distance from the canopy. Preliminary results show that the open trunk space near the base of the canopy results in a surface jet that can be detected just downwind of the canopy and farther downwind dissipates as it mixes with the wake flow above. A time-varying recirculation zone can be detected by the periodic reversal of the velocity vector near the surface, downwind of the canopy. The implications of canopy wakes for measurement and modeling of surface fluxes will be discussed.
000201558 6531_ $$aTurbulence
000201558 6531_ $$aWind
000201558 6531_ $$aLidars/Lidar observations
000201558 6531_ $$aRemote sensing
000201558 700__ $$0245704$$g240589$$aMarkfort, Corey D.
000201558 700__ $$0247187$$g229721$$aCarbajo Fuertes, Fernando
000201558 700__ $$g206364$$aIungo, Giacomo Valerio$$0244156
000201558 700__ $$aPorté-Agel, Fernando$$g168244$$0243661
000201558 7112_ $$d27 April – 02 May 2014$$cVienna, Austria$$aEuropean Geosciences Union General Assembly 2014
000201558 909C0 $$xU12172$$0252260$$pWIRE
000201558 909CO $$ppresentation$$pENAC$$ooai:infoscience.tind.io:201558
000201558 917Z8 $$x229721
000201558 937__ $$aEPFL-TALK-201558
000201558 973__ $$aEPFL
000201558 980__ $$aTALK