1. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 COSTA An Introduction Nils van Velzen email: c.vanvelzen@tudelft.nl www.costapse.org

2. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Outline Data assimilation and calibration Existing software and programming issues COSTA Application of COSTA with WAQUA/TRIWAQ Conclusions www.costapse.org

3. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Data assimilation and calibration (Dynamic) simulation models –Weather forecast –Air quality –Shallow water (storm surge) –Ocean modelling –Reservoir Predictions are not perfect!

4. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Data assimilation and calibration Measurements: –Satellites –Buoy –Radar –Weather stations

5. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Data assimilation and calibration –Make model perform better using the available observations: Calibration: change model parameters in order to reduce the difference between the model predictions and observations Data assimilation: combine the model forecast and observations into a mixed forecast

6. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Existing software and programming issues Simulation software is complex More complex is combined with Data assimilation and/or Calibration methods Expensive to develop and maintain Splitting up software is in general a good idea –Less complex –Possible to reuse (parts of) the code

7. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Existing software and programming issues Why people think they have to develop a custom implementation of a DA method: –Computational efficient –Need to handle model specific issues Are these assumptions correct? Issues are: –Which method to implement? –Expensive –Incompatible –Potentially full of bugs

8. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 COSTA A problem solving environment for data assimilation and calibration –Components and their interface –Data assimilation methods –Platform for exchanging models and methods Free software (LGPL)‏

9. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Steps to prepare model codes for implementing data assimilation Identify the state-vector of your model and those parameters and forcing (you think) you want to use Isolate the model time step --This is 90% of the work and has to be done for a custom data assimilation implementation as well --COSTA provides tools to simplify this work

10. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 COSTA A generic environment where user can easily try out different DA-methods to their models A generic environment where method developers can easily implement their method to different models

11. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 COSTA Most data assimilation actually only requires information about model state and observation at the same time. This makes it possible to implement model, observation and data assimilation methods separately as independent components.

12. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 COSTA components Model, observations and DA-method

13. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Model Component Model component in COSTA (formal) State of a model instance Methods to get or change the state of model instance

14. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Model Component Propagate the model state-vector Get, set, axpy for GetObsValues:

15. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Using COSTA

16. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Using COSTA Use the “costawb” program to combine a model with a DA-method without any programming Model components are dynamic libraries and are linked to the “costawb” program

17. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 WAQUA/TRIWAQ Simulation model for shallow water Used operational by the Dutch Rijkswaterstaat Long history of data assimilation –Too expensive –Inflexible

18. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 WAQUA/TRIWAQ Domain decomposition and parallel computing COSTA model component RRSQRT Filter

19. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 The WAQUA/TRIWAQ model Deterministic model: Stochastic model: or

20. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009

21. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009

22. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Deterministic and Stochastic We want a separation between deterministic and stochastic model  Use deterministic model for other applications  Play with alternative noise models

23. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Deterministic and Stochastic WAQUA/TRIWAQ uses ADI-scheme:  One time step consist of two half time steps  Time correlation applied each half time step New approach:  Time correlation each whole time step  Different results!

24. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Challenge Can we:  Separate filter and method Method?  have same results?  Similar performance? Is the COSTA model interface sufficient for this task?

25. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009

26. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Conclusions COSTA offers a flexible framework for using and developing data assimilation methods. Successful coupling with “real” models: –WAQUA/TRIWAQ –Lotos-Euros –Chimere

27. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Conclusions Easy to use Complete basic functionality available: –Implementation available for all basic building blocks –Growing number of available methods Support for parallel computing

28. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Thank you!

29. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Existing software and programming issues

30. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Tools for creating COSTA models Simple model builder –Handles the “object oriented” aspects of the model –You only need to implement 4 functions Model combiner –Combine multiple COSTA models in one composite model –Create a stochastic model from a deterministic model Black Box model builder –Create a COSTA component for a model without changing the model code Support for parallel models

31. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Automatic parallelization

32. Common Set of Tools for Assimilation of Data COSTA Data Assimilation Summer School, Sibiu, 6 th August 2009 Using parallel models