surface wind profiles of the coastal dunes at ponce de leon
DESCRIPTION
Surface Wind Profiles of the Coastal Dunes at Ponce de Leon . Sarah Collins Department of Marine and Environmental Systems Florida Institute of Technology Melbourne, FL 32901. Outline. Motivation Introduction Background and Objective Methods Curve Fit Equations Time-Centering Procedure - PowerPoint PPT PresentationTRANSCRIPT
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Sarah CollinsDepartment of Marine and Environmental Systems
Florida Institute of TechnologyMelbourne, FL 32901
Surface Wind Profiles of the Coastal Dunes at Ponce de Leon
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OutlineMotivationIntroduction
Background and ObjectiveMethods
Curve Fit EquationsTime-Centering Procedure
ResultsCurve Fits2-D reconstruction
Summary
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MotivationProvide insight as to how wind flow is
affected by coastal dunesVegetated vs. Non-vegetated, does it make
a differenceTurbines – estimate wind energy from
surface data“Hurricane Hunter” – estimate surface
winds from winds aloft
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Emissivity
Absorption
Skin Temperature
Surface Energy Budget
Heat Flux
Turbulent Flow/Drag
The Big Picture
2-D Wind Flow over Dune
Emily Teske
Jeremy Fimat & Erik Mackay
Skyler Goldman
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IntroductionData Collection
Kestrel/Stadia rod Davis surface station
ObjectiveUsing the surface wind speed observations and curve fitting to reconstruct and compare the two-dimensional wind field over the vegetated and non-vegetated dunes at Ponce de Leon Landing.
Davis surface station
Kestrel/Stadia Rod set-up. Picture courtesy of
Sarah Tyson
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Profile LocationsVegetated Dune 5.19.10 & 5.26.10
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Profile LocationsNon-Vegetated Dune 6.9.10 – 6.30.10
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MethodsCurve Fitting Equations
One-Parameter Logarithmic Law (z0)Power Law (α)Two-Parameter Logarithmic Fit (A and B) Two-Parameter Linear Fit (C and D)
Time Centering
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Curve Fit MotivationThere are a lot of surface stations, but not a
lot of wind profilesAllows the ability to take a single wind
speed value from the surface and create a vertical profile of the wind
With 1-minute resolution data from the Davis stations we have the ability to create a separate profile for each minute
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One-Parameter Logarithmic Law
z = height above surfacez0 = roughness length
zR = reference height (6.5 ft)VR = wind speed at reference height
Davis Surface Station
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Roughness Length (z0)
Typical ValuesClassification z0 (ft)
Open Ocean 0.0004Onshore Flow 0.03Hedges, Tall Vegetation 3Mountainous, Center of Large Cities 20
Increasing Roughness Length
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Power Law
z = height above surfacezR = reference height (6.5 ft)VR = wind speed at reference
heightα = friction coefficient
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Two-Parameter Logarithmic Fit
z = height above surfaceA = fitting parameterB = fitting parameter
slope
intercept
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Two-Parameter Linear Fit
z = height above surface
C = fitting parameterD = fitting parameter
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Curve Fits – Vegetated Dune (5.26.10)
0 5 10 1505
1015202530
Station 2
Wind SpeedVLOGVPOWV2VL
Wind Speed (m/s)
Hei
ght (
ft)
z0 = 1.72E-4 α = 9.02E-2
9.5 10 10.5 1105
1015202530
Station 2
Wind SpeedVLOGVPOWV2VL
Wind Speed (m/s)
Hei
ght (
ft)
Best Residual (V2) = 0.2791
Residual = Vobs - Vfit
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Curve Fits - Vegetated Dune (5.26.10)
0 5 10 1505
1015202530
Station 3
Wind SpeedVLOGVPOWV2VL
Wind Speed (m/s)
Hei
ght (
ft)
z0 = 4.75 α = 1.34 Best Residual(V2) = 1.01
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Curve Fits – Non-Vegetated (6.9.10)
z0 = 4.95 E -3 α = 0.1295 Best Residual(V2) = 0.2
0 1 2 3 4 5 6 7 8 9 1005
1015202530
Station 2
Wind SpeedVLOGVPOWV2VL
Wind Speed (m/s)
Hei
ght (
ft)
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Curve Fits – Non-Vegetated (6.9.10)
0 1 2 3 4 5 6 7 8 9 1005
1015202530
Station 3
Wind SpeedVLOGVPOWV2VL
Wind Speed (m/s)
Hei
ght (
ft)
z0 = 1.26 α = 0.45 Best Residual(VL) = 0.42
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Time Centering
3
2
Backward in TimeForward in Time
12:30 1
• Station 1 – curve fit ascending profile• Station 3 – curve fit descending profile• Station 2 – average of the ascending and descending observed profiles
Davis Station 6.5 ft velocity at 12:30
Davis Station 6.5 ft velocity at 12:30
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Wind Flow over Vegetated Dune (5.26.10)
Wind Speed (m/s)123
Vegetation
West
East
0.5
1.5
9.5 10.5
11.5
12.5
13.5
Valid at 12:30 p.m.
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Wind Flow over Non-Vegetated Dune (6.9.10)
Wind Speed (m/s)
123
11.5
15.5
14
11.5 8.
5
9.5
8
EastWest
Valid at 4:30 p.m.
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SummaryTwo-parameter equations had the lowest
residualsTime centered around Station 2VR from the Davis StationGreatest friction and roughness length in
lee of dunelarger at vegetated dune
Impact will likely be situational (i.e., flow dependent) – for easterly flow the largest impact on the wind field occurred at the vegetated dune to the west of the dune crest.
For easterly flow
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Questions??
Next: Skyler Goldman