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LIDAR Observations of Terrain-induced Flow and Its Application in Airport Wind Shear Monitoring. CM Shun, CM Cheng & O Lee ICAM/MAP 2003. Background. Wind Shear: terrain disrupted flow; thunderstorms; sea breeze. Weather buoy (3). Weather Buoys. (1+2). TDWR. Sham Wat (2). - PowerPoint PPT Presentation
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19-23 May 2003
LIDAR Observations of LIDAR Observations of Terrain-induced Flow and Its Terrain-induced Flow and Its Application in Airport Wind Application in Airport Wind Shear MonitoringShear MonitoringCM Shun, CM Cheng & O LeeCM Shun, CM Cheng & O LeeICAM/MAP 2003ICAM/MAP 2003
19-23 May 2003
BackgroundBackground
Weather Buoys
Automatic WeatherStations over Lantau
TDWR
Weather buoy (3)
(1+2)
Sham Wat (2)
Wind Shear: terrain disrupted flow; thunderstorms; sea breeze
19-23 May 2003
LILIght ght DDetection etection AAnd nd RRanging (anging (LIDARLIDAR) System) System
LIDAR Scanner
ATC Building Roof-top
Installed in mid-2002
IR (2 μm) → eye-safe
19-23 May 2003
LIDAR in Tropical CycloneLIDAR in Tropical Cyclone
19-23 May 2003
Jump Like Feature (11 Nov Jump Like Feature (11 Nov 2002)2002)
465 m
stagnant flow
jump
Lo Fu Tau
N = 0.0135 s-1
h = 465 mU0 ~ 5 ms-1
Nh/U0 ~ 1.3 > 0.85 (wave breaking)Weak inversion (0.4ºC) below 500 m
Inversion near 3 km
100º
19-23 May 2003
Jump Like Feature (20 Jan Jump Like Feature (20 Jan 2003)2003)
reverseflow
reverse flow
jump
Lo Fu Tau
N = 0.013 s-1 h = 465 m U0 ~ 6 ms-1
Nh/U0 ~ 1.0 > 0.85 (wave breaking)Inversion: 1.1&1.5ºC 500-700 m = 3.6 K = 291 K D ~ 600 m Fr = U0 / (g’D)½ ~ 0.7M = h/D ~ 0.8Schär & Smith (1993) Regime IIb
Inversion at 500-700 m
095º
19-23 May 2003
Jump StructureJump Structure22-min Sequence (@ 2 min)22-min Sequence (@ 2 min)
095º
19-23 May 2003
Vortex SheddingVortex Shedding12-minute Sequence (@ 2 min)12-minute Sequence (@ 2 min)
100º
19-23 May 2003
Springtime Wind ShearSpringtime Wind Shear(5 March 2003)(5 March 2003)
19-23 May 2003
Temperature JumpTemperature Jump
Buoy (north)
Buoy (south)
+4ºC
+5ºC
19-23 May 2003
Buoy (north)
Buoy (south)
Land Station (SW1)
Wind Changes (Wind Changes (EESS))
19-23 May 2003
Descent of Warm JetsDescent of Warm Jets
297 K
2025°C
20°C
19°C
00 UTC 0317 UTC
N = 0.02 s-1
h = 934 m (Lantau Peak)U0 19 ms-1
Nh/U0 1 (descending flow / hydraulic jump)
1. How to apply Fr under strong vertical shear?
2. Contribution of gap-flow?3. Interaction between jets?
19-23 May 2003
Time - Azimuth Plot of Time - Azimuth Plot of LIDAR radial velocityLIDAR radial velocity
19-23 May 2003
ConclusionsConclusions
Jump-like features & vortex shedding under Jump-like features & vortex shedding under stable conditions are revealedstable conditions are revealed
Nh/UNh/U00 & Fr able to diagnose jump based on & Fr able to diagnose jump based on Schär & Smith (1993)
Springtime wind shear - interaction of Springtime wind shear - interaction of descending S’ly jet (also a jump?) with surface descending S’ly jet (also a jump?) with surface E’ly jetE’ly jet
More work is needed to better understand More work is needed to better understand phenomena (Nh/Uphenomena (Nh/U00 & Fr in strong vertical shear; & Fr in strong vertical shear; gap-flow dynamics) gap-flow dynamics)
19-23 May 2003
Thank You!