The workshop on Ocean Waves took place at ECMWF from 25-27 June 2012.
Description
The last ECMWF workshop on Ocean Wave Forecasting was held in 2001. Since then, the quality of wind and wave forecasts has steadily improved following advances in many aspects of the atmosphere and wave models. Better forecast guidance can now be issued, including warning about dangerous sea states. Nevertheless, it is now recognised that the modelling interface between the atmosphere and the waves should also include the upper ocean component, leading to a more fully coupled system for air and oceans (water and ice). As far as the waves are concerned, different scales are inherently present with fairly uniform wave fields in the open oceans to rapidly changing wave conditions near coasts and strong surface currents. A truly global operational system should be able to tackle these different scales.
Recent field campaigns and theoretical developments have shown that the parameterisations for the different wave model input source terms might need revision, even more so with the modelling development of fully multi scale integrated systems for air and oceans.
Wave observations from in-situ or space-borne platforms are still relatively sparse. But in line with future deployments, novel approaches on how to best use these different sources of information should be developed.
ECMWF is at the forefront of research on these different aspects and with this workshop, it is actively seeking out advice from the wider community on how to best carry forwards these improvements
Topics
Modelling:
Couplings: Two way coupling with the atmospheric model has been operational since 1998. Overall, it has been beneficial to both atmospheric and wave forecasts. Following developments in ocean circulation modelling, it is now feasible to actively couple the atmosphere and the ocean as well as to provide information from the waves to the oceans and from the ocean to the waves. How to best to develop/prioritise this multi-coupled system should be a topic of discussion.
How to deal with multi scales: Ocean waves have quite different scales, from the generation by the winds, and the propagation across the ocean basins to their interactions with coastal bathymetry and surface currents. Computer resources will always be limited and so the question is how to best use the available resources in order to put the resolution where it matters the most using appropriate numerical techniques.
Dangerous sea states: ECMWF has developed a theory of freak waves, which has resulted in new wave parameters. Within the limit of wave spectral modelling, are there any novel ideas that could be developed to improve on the detection of potentially dangerous sea states?
Physics:
Dissipation: Recent advances in the formulation of wave energy dissipation have been made. It has been achieved on the premise that more physics based formulations should be developed. Keeping in mind that any such parameterizations should be consistent with the physics of the coupled systems, it will be worth exploring their potential benefit. Similarly, with the emphasis of putting more detail in the coastal area, dissipation of wave energy by interaction with the bottom bathymetry should be re-visited.
Non linear source term: Global operational wave forecasting models rely on the DIA approximation for the computation of the non-linear source term. Over the years, alternative methods have been tested but so far none have been applied in an operational environment.
Wave/ocean mixing: In recent years, it has become apparent that wave related processes could be important contributors to the overall upper ocean mixing. ECMWF has developed a mixed layer scheme that accounts for wave effects. What is the view of the community?
Wave/current interaction: With improved representation of surface currents, what could we expect of their impact on the waves? Is the existing formulation in third generation wave models good enough?
Waves under extreme winds: The generation of waves under hurricane force winds is still poorly understood and so is the behaviour of all surface fluxes. In a fully coupled system a better understanding of those might well be needed.
New source terms: Are there any wave processes that have so far been neglected in global wave models that should be considered now (reflection, diffraction, bottom scattering, sea ice/wave interaction, …)?
Data:
Analysis and re-analysis: Operational wave data assimilation techniques are still based on the Optimum Interpolation (OI) method. Even, within the simple framework of the OI method, model background and observation errors are usually specified in a very crude way. Moreover, the impact of wave data assimilation is usually very limited in the forecast range. Is there any novel approach that will improve on that?
Future satellite missions: What could we expect from future satellite missions as far as surface wave observations are concerned?
Validation techniques: The quality of operational wave forecasts is routinely assessed in the framework of the JCOMM Wave Forecast Verification Project maintained by ECMWF. This project has run successfully for quite some time. Nonetheless, it relies on very simple methods for the comparison of the different system and is limited to a small number of buoy observations and to deterministic forecasts. Should it be extended and how?
Forecast products: Are there any new wave model related parameters that should be considered ?
Programme
Presentations
| Monday 25 June | |
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Welcome and introduction Erland Källén (ECMWF) |
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Present Status of wave forecasting at ECMWF Jean Bidlot (ECMWF) |
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Modelling |
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Developments in unstructured grids Aron Roland (University Darmstadt) |
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A global perspective on winds, waves and coupling through the ocean surface boundary layer Stephen Belcher (Hadley Centre) |
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A fully coupled atmosphere-ocean waves ocean model for the Mediterranean Luigi Cavaleri (Inst Marine Sci, Venice) |
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Freak waves Miguel Onorato (University Turin) |
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Effect of ocean waves on ocean circulation Peter Janssen (ECMWF) |
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Physics |
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Update on parametrisation of major source functions, including extreme conditions Alex Babanin (Swinburne Univ Technol) |
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Developments in computational methods for nonlinear energy transfer in deep and shallow water Gerbrant van Vledder (TU Delft) |
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New parameterisations of the source functions Fabrice Ardhuin (Ifremer, Plouzane) |
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Near shore processes André van der Westhuysen (UCAR at NOAA/NCEP) |
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| Tuesday 26 June | |
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Wind-wave interaction under hurricane conditions Jim Doyle (NRL, Monterey) |
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Use of Data for assimilation and verification |
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Current and future verification methods Andy Saulter (Met Office) |
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Latest developments in wave data assimilation Jean-Michel Lefèvre (Météo-France) |
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The MyWave Project Øyvind Sætra (NMI) |
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A US NOPP Project to stimulate wave research Hendrik Tolman (NOAA-NCEP-EMC) |
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Working groups
Proceedings
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Dissipation parameterizations in spectral wave models and general suggestions for improving on today's wave models Fabrice Ardhuin (Ifremer, Plouzane) |
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Observation-based parameterisations of major source functions, their application in extreme conditions Alex Babanin (Swinburne Univ Technol) |
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Present status of wave forecasting at ECMWF Jean Bidlot (ECMWF) |
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On the coupling of COSMO to WAM Luigi Cavaleri (Inst Marine Sci, Venice) |
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Wind-wave interactions under hurricane conditions: a decade of progress Jim Doyle (NRL, Monterey) |
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Freak waves: beyond the Nonlinear Schrodinger breathers Alessandro Iafrati (CNR-INSEAN) |
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Effect of ocean waves on ocean circulation Peter Janssen (ECMWF) |
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Latest developments in wave data assimilation Jean-Michel Lefèvre (Météo-France) |
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Application of Residual Distribution (RD) schemes to the geographical part of the wave action equation Aron Roland (University Darmstadt) |
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Current and future verification of operational wave models Andy Saulter (Met Office) |
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A US NOPP Project to stimulate wave research Hendrik Tolman (NOAA-NCEP-EMC) |
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Efficient algorithms for non-linear four-wave interactions Gerbrant van Vledder (TU Delft) |
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Modelling nearshore wave processes André van der Westhuysen (UCAR at NOAA/NCEP) |
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