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Surface Wind Profiles of the Coastal Dunes at Ponce de Leon

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

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Surface Wind Profiles of the Coastal Dunes at Ponce de Leon

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  1. 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

  2. Outline • Motivation • Introduction • Background and Objective • Methods • Curve Fit Equations • Time-Centering Procedure • Results • Curve Fits • 2-D reconstruction • Summary

  3. Motivation • Provide insight as to how wind flow is affected by coastal dunes • Vegetated vs. Non-vegetated, does it make a difference • Turbines – estimate wind energy from surface data • “Hurricane Hunter” – estimate surface winds from winds aloft

  4. The Big Picture Emissivity Emily Teske Absorption Skin Temperature Jeremy Fimat & Erik Mackay Surface Energy Budget Heat Flux Turbulent Flow/Drag Skyler Goldman 2-D Wind Flow over Dune

  5. Introduction • Data Collection • Kestrel/Stadia rod • Davis surface station • Objective Using 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

  6. Profile LocationsVegetated Dune 5.19.10 & 5.26.10

  7. Profile LocationsNon-Vegetated Dune 6.9.10 – 6.30.10

  8. Methods • Curve 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

  9. Curve Fit Motivation • There are a lot of surface stations, but not a lot of wind profiles • Allows 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

  10. One-Parameter Logarithmic Law Davis Surface Station z = height above surface z0 = roughness length zR = reference height (6.5 ft) VR = wind speed at reference height

  11. Roughness Length (z0) Increasing Roughness Length

  12. Power Law z = height above surface zR = reference height (6.5 ft) VR = wind speed at reference height α= friction coefficient

  13. Two-Parameter Logarithmic Fit intercept slope z = height above surface A = fitting parameter B = fitting parameter

  14. Two-Parameter Linear Fit z = height above surface C = fitting parameter D = fitting parameter

  15. Curve Fits – Vegetated Dune (5.26.10) Residual = Vobs - Vfit z0 = 1.72E-4 α = 9.02E-2 Best Residual (V2) = 0.2791

  16. Curve Fits - Vegetated Dune (5.26.10) z0 = 4.75 α= 1.34 Best Residual(V2) = 1.01

  17. Curve Fits – Non-Vegetated (6.9.10) z0 = 4.95 E -3 α= 0.1295 Best Residual(V2) = 0.2

  18. Curve Fits – Non-Vegetated (6.9.10) z0 = 1.26 α= 0.45 Best Residual(VL) = 0.42

  19. Time Centering • 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

  20. Wind Flow over Vegetated Dune (5.26.10) East West Valid at 12:30 p.m. Vegetation 1.5 0.5 13.5 12.5 9.5 Wind Speed (m/s) 10.5 11.5 3 2 1

  21. Wind Flow over Non-Vegetated Dune (6.9.10) East West Valid at 4:30 p.m. 15.5 14 11.5 8.5 Wind Speed (m/s) 8 11.5 9.5 3 2 1

  22. Summary • Two-parameter equations had the lowest residuals • Time centered around Station 2 • VR from the Davis Station • Greatest friction and roughness length in lee of dune • larger 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

  23. Questions?? Next: Skyler Goldman

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