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DSD-INT 2014 - Symposium Next Generation Hydro Software (NGHS) - Global tide model, Martin Verlaan, Deltares

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DSD-INT 2014 - Symposium Next Generation Hydro Software (NGHS) - Global tide model, Martin Verlaan, Deltares

  1. 1. Delft Software Days, November 5th 2014 Global tide and storm-surge model with Delft3D Flexible Mesh Martin.verlaan@deltares.nl
  2. 2. DSD November 5th 2014 Outline • Motivation • Grid development • Required physical processes • Calibration • Some results • Ongoing work and challenges
  3. 3. New surge & tide model – DCSMv6 DCSM-v5 DCSM-v6 1/8º x 1/12º 1/40º x 1/60º 3 Includes tidal potential Zijl et. Al. 2013 & Slobbe et. al. 2013
  4. 4. Effect of sealevel rise on tides Effect of 2 meter rise of MSL on M2 amplitude 4 Pickering et. al. 2013 OTIS-MPI
  5. 5. Existing global tide models DSD November 5th 2014 M2
  6. 6. First attempt of grid in Delft3D → Lack of resolution near coasts. DSD November 5th 2014
  7. 7. Grid in Dflow-FM Unstructured approach - step 1: grid thinning at high latitudes DSD November 5th 2014
  8. 8. Unstructured approach - step 2: grid refinement in shallow areas 8 Grid in Dflow-FM This Dflow-FM grid uses triangles and rectangles for local grid refinement. Resolution is based on Courant number.
  9. 9. First results in Dflow-FM
  10. 10. Necessary improvements • Self attraction and loading • Tides modify the gravity potential as well • Computation is very time-consuming • Start wit simple approximation • Internal tides • Tides create internal tide where there is stratification and steep bathymetry • This creates dissipation (roughly ¼ of total tidal dissipation on global scale) ∂ρ ∂ z Depends on stratification DSD November 5th 2014 f x=β g ∂ h ∂ x N=√−g ρ0
  11. 11. Modified equations Gravity potential DSD November 5th 2014 r α Re R Conservation of momentum ∂u +u ∂u +v ∂ u +g ∂h−ζ−βh ∂t ∂ x ∂ y ∂ x −f v+ gu √u2+v2 C2 H + α κ N d2 √ω2−f 2 2ω H u=0 ∂ v ∂t +u ∂ v ∂ x +v ∂ v ∂ y + g ∂ h−ζ−βh ∂ y +f u+ g v √u2+v2 C2 H + α κ N d2 √ω2−f 2 2ω H v=0 ζ 1. tidal forcing 2. SAL 3. dissipation by internal tides
  12. 12. Calibration of the Model FES2012 DSD November 5th 2014 Altimeter observations: - assimilated FES2012 gridded data - very accurate on deep water Automated calibration: - 21 parameters - deep water series Jan2007 Calibration parameters: - Depth & Friction - 7 regions
  13. 13. Calibration results for deep water Region Before After Arctic 5.1 cm 3.2 cm N. Atlantic 9.4 7.4 S. Atlantic 12.1 8.4 N. Pacific 8.1 6.2 S. Pacific 11.2 7.3 Indian Ocean 11.7 8.2 S. Ocean 12.4 10.2 Total 10.2 7.4 DSD November 5th 2014
  14. 14. Sample deep water station DSD November 5th 2014 Before calibration
  15. 15. Sample deep water station DSD November 5th 2014 After calibration
  16. 16. Sample coastal time-series Cordova Honolulu Tide Surge DSD November 5th 2014
  17. 17. Ongoing work and challenges • Ongoing work: • Operational global storm-surge model (ID-Lab) • Climate impact studies (cooperation with VU and EU-RISES) • Modeling Self-Attraction and Loading • Challenges: • Further improve dissipation by internal tides • Improve computational performance with parallel computing • Link to real-time observations • Hurricane forecasts • Improve open-boundary conditions for regional models DSD November 5th 2014
  18. 18. Questions?
  19. 19. Grid Arctic
  20. 20. Grid North America
  21. 21. Grid South-East Asia
  22. 22. Grid Northern Europe

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