Surface Wind Profiles of the Coastal Dunes at Ponce de Leon

Sarah CollinsDepartment of Marine and Environmental Systems

Florida Institute of TechnologyMelbourne, FL 32901

Surface Wind Profiles of the Coastal Dunes at Ponce de Leon

OutlineMotivationIntroduction

Background and ObjectiveMethods

Curve Fit EquationsTime-Centering Procedure

ResultsCurve Fits2-D reconstruction

Summary

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

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

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

Profile LocationsVegetated Dune 5.19.10 & 5.26.10

Profile LocationsNon-Vegetated Dune 6.9.10 – 6.30.10

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

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

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

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

Power Law

z = height above surfacezR = reference height (6.5 ft)VR = wind speed at reference

heightα = friction coefficient

Two-Parameter Logarithmic Fit

z = height above surfaceA = fitting parameterB = fitting parameter

slope

intercept

Two-Parameter Linear Fit

z = height above surface

C = fitting parameterD = fitting parameter

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

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

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)

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

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

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.

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.

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

Questions??

Next: Skyler Goldman