Efficient data assimilation with OpenDAAn introduction

10-06-11

Nils van Velzen, Martin Verlaan, Stef Hummel, Julius Sumihar, Erwin Loots, Albrecht Weerts, Ghada El Serafy, Herman Gerritsen

Outline

● What is OpenDA● How to link models to OpenDA● Example of Calibration● Example of Data assimilation● Parallel computing● Ongoing developments

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OpenDA

• A generic toolbox for data-assimilation

– (real time) data assimilation

– model calibration

– impact observations

– reconstruction of sources

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OpenDA

• Content:

– set of interfaces that define interactions between components

– library of data-assimilation algorithms

– philosophy

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OpenDA

• Open source (LGPL)

• Why OpenDA?

– More efficient than development for each application

– Shared knowledge between applications

– Development of algorithms with e.g. universities

– Easier to test, which should result in fewer bugs

– Optimized building blocks

– Development template

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www.openda.org

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• Downloads

– Users

– Developers

• Documentation

• Wrappers for models

• OpenDA association

OpenDA Main Application

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Single program for:

Editing input files● Running simulations and calibrations● All models and observation sources● Gui and command line, sequential and parallel

Object Oriented Approach

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Models in OpenDA

• A model wrapper is needed for each model:

– Blackbox

– Native:

• Simple, only a few functions

• Full, the (whole) interface

• parallel

– Java

• Simple java models for testing and research

• Direct implementation of java interface

• Stochastic extension

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Black Box Wrapper

• Uses input and output files of the model

• No source code of the model is needed

• Well suited for calibration

• Sometimes suited for Data Assimilation

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Native Wrapping

• Implement a specified set of functions (C/Fortran)

• Create a dynamic library

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SWAN 3rd generation wave model

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Wave breaking and interaction over a bar

0.4

0.3

0.2

0.1

0

0.5m

X

Z0

1:20

10

1:10

20 30m

WAVES

STATIONS01 02 0403 0705 06 08

totS =wind input+ non-linear interactions (quadruplets & triads)+ whitecapping + bottom friction+ depth induced wave breaking

SWAN 3rd generation wave model

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SWAN 3rd generation wave model

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Operational storm surge forecasting

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Operational Storm-Surge Model Steady-state Kalman Filter

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OpenDA

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New operational model DCSMv6-Zuno

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Parallel Computing

• Model timestepping often most time consuming part of algorithm (90-99%)

• Often natural parallelism in the model timestepping

• Parallel time stepping for all native OpenDA models (OO)

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Parallel computing

• Parallelized using threads

• Parallelized using multiple processes

– master worker

– worker worker

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1x 2x 3x

4x 5x 6x

Ongoing Developments

• OpenDA core:

– New major release of OpenDA

– Development of course material

– Parallelization of the algorithms

• With OpenDA

– Operational wind induces waves forecasting with swan

– Coupling with FEWS

– Observation sensitivity and design of monitoring networks

– Lotos-Euros

– Coupling with OpenFOAM, …..etc

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