Changes between Version 105 and Version 106 of Scientific Advisory Board/Agenda/2013-06-18


Ignore:
Timestamp:
2013-07-05T18:26:53+02:00 (7 years ago)
Author:
clevy
Comment:

Legend:

Unmodified
Added
Removed
Modified
  • Scientific Advisory Board/Agenda/2013-06-18

    v105 v106  
    6767'''Session 1: NEMO platform: seamless to what extend? (Leaders: J. Holt and P. Marsaleix)''' 
    6868 
    69 [[BR]]'''Session 2: New dynamical cores, HPC and science     (Leaders: S. Masson & N. Wood)''' 
     69See also table in attached document at bottom of the page.[[BR]]On seemless modelling in NEMO: 
     70 
     71 1. There is not a great drive nor enthusiasm for multi-scale (e.g. unstructured meshes) approaches presently within this community. Personally,  I somewhat disagree with this view of the future but I agree the approaches (e.g. an ocean model within gung-ho) need to be better developed, tested and demonstrated before we might expect substantial community buy in. Certainly , I still see this door as being open. 
     72 1.  There are upscaling issues. These weren’t listed in detail, but include river inputs/coastal currents, dense water formation on shelf seas, frictional processes at shelf slope, dense overflows and ‘pinch points’, and a whole list of BGC/ecosystem processes. These can be addressed to some extent with global high resolution and 2-way nesting (e.g. AGRIF), without resorting to a full multi-scale approach. 
     73 1. There is a clear need for a near coastal capability in nemo – this includes wetting/drying and surface wave coupling. Concerns were expressed (and noted) that the wetting/drying approach should not be obtrusive (at least initially), but methods such moving boundary approaches could be considered in the future for paeleo work. There are many approaches to wave coupling and lots of physical implication to it depending on the problem at hand (ie waves on current, coupled wave-current or coupled wind-wave-current). Curvilinear coordinates are an important capability for near coastal work, and with it nemo has a potential advantage of being much more computationally efficient than unstructured mesh options – very useful for longer term near-coastal simulations. 
     74 1. Resolution and parameterisations need to be considered together and both require development, noting we are moving towards submesoscale permitting models needed to actual resolve the mesoscale, and that observational resolution is increasing to accommodate this. 
     75 
     76 [[BR]]'''Session 2: New dynamical cores, HPC and science     (Leaders: S. Masson & N. Wood)''' 
     77 
     78 * No strong driver to move away from orthogonal curvilinear coordinate with quadrilateral C-grid, together with coupling provided by AGRIF. Question: Does that approach have a finite life time or will it work forever? See also Jason's comments. 
     79 * This means that there is no driver for closer sharing of !GungHo natural science (ie the vast majority of the kernels). 
     80 * However, scalability remains an issue and therefore there is a need to expose as much parallelism as possible (this favours the small kernel approach) and maintain flexibility, as well as protecting parallel code and natural science developers from each other! This favours a layered approach. 
     81 * Scope for sharing this approach with !GungHo most likely lies in the Application Programming Interfaces (APIs) and possibly also in the Parallelisation Systems (PSy) layer (though the extent of the latter is unclear). 
     82 
     83At the meeting I (N. Wood) additionally expressed my personal point of view that having a document, which clearly outlines what the critical scientific properties of NEMO are, could be invaluable, as well as having a clear specification of the scope of applications. In any development there will inevitably be a number of compromises to be made. Having these two documents allows an informed decision over which compromises to make and which not. This allows more progress and less stalemate.'''''' 
    7084 
    7185'''Session 3: Sea-ice and biogeochemical components (Leaders: O. Aumont & M. Vancoppenolle)'''