Keynote Lecture by Martin Verlaan, Delft University of Technology & Deltares, The Netherlands at the joint Delft3D User Days and the OpenDA User Day, during Delft Software Days 2016 on Tuesday, 1 November 2016, Delft.
DSD-INT 2016 Keynote Lecture 2016: From global to local: the latest developments - Verlaan
1. November 1st 2016
From global to local:
the latest
developments
Martin.verlaan@deltares.nl
2. Outline
Motivation – global to local
A Global Tide and Surge Model (GTSM): Delft3D FM
Initial model development
Calibration with OpenDA
Applications
Towards the next version
Regional storm surge models
Regional SAL effects
Innundation modelling (local)
Innundation risk in Mozambique
Xynthia flood
6. Grid in Delft3D FM (D-Flow FM module)
This D-Flow FM grid uses triangles and rectangles
for local grid refinement. Resolution is based on Courant number.
Unstructured approach - with grid refinement in shallow areas
13. Calibration of the Model
FES2012
Altimeter observations:
- assimilated FES2012 gridded data
- very accurate on deep water
Calibration parameters:
- Depth & Friction
- 7 regions
Automated calibration:
- 21 parameters
- deep water series Jan2007
347 locations
14. 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
28. IT dissipation – Anisotropic phenomenon
Barotropic tidal dissipation sources:
• Bottom friction (dominant in shallow waters)
• Generation of internal waves when flowing over rough topography in
stratified oceans (dominant in deep waters)
New anisotropic numerical implementation
Dissipation=f(Stratification, bathymetry
gradient, cross-slope flow)
• Mid-ocean ridges and trenches (e.g. Mid-
Atlantic Ridge)
• Continental shelves (e.g. Bay of Biscay)
• Island chains (e.g. Hawaiian Ridge)
Literature values: = 1TW (4TW total)
( )1
ITτ = CρNκ h u h-
Ñ Ñg
29. Model sensitivity to grid resolution
Internal Tides dissipation (W/m2) distribution:
Model is now
sensitive to user
defined parameters
for IT dissipation:
Tuning possible.
RMSE reduction
with IT dissipation:
• Deep waters:~3 cm
• Coast: ~3.2 cm
31. SAL – Implementation in GTSM
SAL is the sum of three effects:
Deformation of the seafloor under the weight of the column
of water (Earth is a elastic body)
Redistribution of Earth mass changes the gravitational field
Gravitational attraction induced by the mass of the ocean on
the ocean itself
LOADING
SELF
ATTRACTION
Literature ~ 10% of astronomical tide Reality: Spatial and
temporal significant variability.
SAL potential in spherical harmonics Calculation of field at
every time step, analogous to Tide Generating Forces
Reduction of errors in tidal representation of ~50 % in coastal
stations and ~60% in deep waters
Minimal increase in computational times.
32. SAL tide spatial distribution
β approximation too simplistic
SAL tide Tide
45. Localization
“OpenDA-NEMO framework for Ocean Analysis and Predictions”,
N. Van Velzen, M. U. Altaf, M. Verlaan, and A.W. Heemink,
submitted to Ocean Dynamics
Sealevel
Observed Sealevel
57. Flooding computations
Grid 90m approx. 700x1000
Computation time (no MPI):
• Delft3D FM (10minutes)
• Lisflood-FP (18minutes)
Results sensitive to:
• DEM
• Boundary conditions
• Friction
58. Future plans
• Complete GTSM version 2 including calibration with OpenDA
• Incorporate real-time satellite observations in Delft-FEWS
• Develop real-time data-assimilation of satellite data
• Incorporate more accurate tropical cyclone estimates in global risk
estimates
• Incorporate wave effects for coastal flood risk
• Develop coastal inundation models
• Develop strategy for systematic validation of inundation models
60. Thanks to …
Arthur van Dam
Dirk Eilander
Edward Melger
Firmijn Zijl
Herman Kernkamp
Hessel Winsemius
Joao Lima Rego
Kun Jan
Maialen Irazoqui Apecechea
Sander van der Pijl
Sanne Muis
Tony Minns
Albrecht Weerts
Alja Vrieling
Annette Zijderveld
Arno Kockx
Arjo Segers
Daniel Twigt
Julius Sumihar
Lora Buckman
Marieke Eleveld
Nils van Velzen
Sandra Gaytan Aguilar
Simone de Kleermaeker
Stef Hummel
…and others…