= REPORT OF THE WORKING GROUP MEETING (January 30, 2014) = Participants : Rachid Benshila, Daley Calvert, Julien Calandreau, Jérome Chanut, Laurent Debreu, Christian Ethe, Rachel Furner, Claire Levy, Gurvan Madec, Sébastien Masson == 1) Discuss the update of the 3.6 version == ==== History : ==== * [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] version (and corresponding NEMO subroutines) has been updated by Julien Calandreau (INRIA) and Laurent Debreu * Jérome Chanut has made a lot of improvements and bug fixes in his Gilbraltar Strait configuration * Same for Sébastien Masson in the Pulsation ANR project * Other developments in LIM, PISCES ==== Bugs that have been identified and corrected since version 3.4 : ==== * zwork array (J. Chanut): a global array « zwork » was defined in the libmpp module and (due to a bug in the [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] converter) this led to several problems and in particular the update step was not performed … * Diffusion coefficients in the corners of the sponge layern were wrong (J. Chanut) * Scale factors were not correctly computed in the ghost cells (where it is assumed that we are in full steps) (J. Chanut) -> same problem for OBC * TKE (S. Masson): near the boundaries, spatial averaging operations led to wrong Kz in the first cell inside the high resolution domain. Extrapolation is possible but does not fulfill the requirement that with, a mesh refinement factor of 1, the obtained solution of the HR grid is identical to a solution computed without a zoom. S. Masson has implemented exchanges of TKE between coarse and fine grids. -> Same problem for GLS and for OBC * Asselin Filter (J. Chanut) : when updating the « after » (n+1) fields, the corresponding corrections of the « now » fields were not done. * arrays out of bound in procnames in MPI (wrong declarations of [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] profiles in agrif_declare_variables: jpi, jpj have been replaced by ncli,nlcj) ==== Bugs / Problems that have been identified ==== #BugsProblemsthathavebeenidentified · The bathymetry connection check is not complete (add a check that the coarse grid bathy have been correctly updated) · Reproducibility is not guaranteed (due to MPI problem) when ln_spc_dyn is set to true in namelist (which means that we take 0 as special value for dynamics in interpolations/updates). · Recursive updates. When more than 1 zoom level are set, the update should start from the highest resolution grid and go recursively to the root grid. Laurent implemented changes that makes this possible. * Use of [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] for degradation online (problème de north pole, coarsening) * Average operators with update values * High order operators with coastlines * BDY problem have been solved ==== Improvements ==== #Improvements * [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] and time splitting (OK for version 3.6, end of the year, Jérome) * only consider forward integration of the forcing mode permits to ensure volume conservation * without update of the parent grid right hand side * Performance of parallel runs * allows the distribution of the processors among the fine grids '''''Rachid Benshila''' is ready be in charge of the merge'' == 2) What are the known open problems ? (not to be solved for 3.6) == * Number of ghost cells ('''''L. Debreu''''') * Antartic problem (periodicity): require only one ghost cell instead of 2 * Number of required ghost cells for high order advection schemes may be larger than 2 * -> Remove hardcoding of the number of ghost cells, do the required modifications to the [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] “profiles” (Laurent) * North fold problem * Timings for each grid == 3) What are the main next developments? == * Coupling between grids at the level of the barotropic mode (in time splitting version) (Jérome) * requires some modification in the organization of the step routine of NEMO * Vertical grid refinement (Laurent) * Online coarsening for tracers using [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] (L. Debreu, G. Madec) * [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] with variable volume == 4) Nesting tools: == Two stages: a) for 3.6 version * agree on all the points: bathymetry smoothing, update of coarse grids (take the maximum as default) * Incorporate corrections done by Jean Marc * The nesting tools are only essential for the creation of bathymetry: * forcings can be interpolated on the fly * -> Do a list available tools for 3D interpolation (initialization / restart fields) * For 3.6 keep the 3D fields interpolation in nesting tools b) next version * The definition of vertical coordinates should be done outside NEMO * Nesting tools for the s coordinates == 5) Documentation: == * Update of the nesting tools 3.6 documentation * Update of the users guide: describes what is possible or not with [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF]. * Documentation for nesting in NEMO/[http://www-ljk.imag.fr/MOISE/AGRIF AGRIF]: starts from the notes of Sebastien, then circulate the powerpoint * GMD paper == 6) Standard configuration and sanity tests == The standard configuration should: * Include more than one level of embedding (test of the recursive update starting from the finer resolution grid(s)) * Uses time splitting * Include a zoom in a sea ice area (Labrador Sea, LIM3) * Include a zoom with PISCES * Zoom in Perou Chili Sanitiy tests * Zoom with a mesh refinement of 1 * Test constancy preservation for tracers Longer visions of having [http://www-ljk.imag.fr/MOISE/AGRIF AGRIF] zoom in AMM S coordinates zoom inside a z coordinate parent grid.