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Changelog – NEMO

Version 2 (modified by clevy, 7 years ago) (diff)


NEMO Release notes

Last edition: Wikinfo(changed_ts)? by Wikinfo(changed_by)?

2005-2006 From Tag nemo_v1 to nemo_v2

New science:

  • Add the 1D configuration option
  • KPP turbulent closure scheme implementation
  • Implement CFC tracers and p4z
  • Add new surface pressure gradient algorithms and its interface to Open Boundary Conditions module
  • First implementation of AGRIF 2 ways nesting tool
  • Implement overturning computation for main basins
  • Implement ice damping in buffer zones
  • Implement 1D on-line & off-line passive tracers
  • Implement new tracers advection scheme UBS
  • Implement computation of mean trends in the mixed layer taking into account the asselin time filter

New High Performance Computing:

  • Implementation of a hierarchy of debugging levels
  • Rewriting of NEMO-TOP biogeochemistry component
  • Remove some of the bio models (p3zd,npzd, hamocc3, age, gosac)
  • Switch to IOIPSL-3-0 new input output library
  • Switch rigid lid to option rather than default
  • Re-organization of coordinate definition, scale factors are now 3d by default, include file for partial steps has been removed
  • Implement IO Manager module
  • Enables bit comparison between single and multiple processor runs
  • Implement OASIS3 and OASIS4 interfaces to buid coupled ocean-atmosphere configurations

2007 From tag nemo_v2 to nemo_2_3

New science:

  • Implement non linear free surface (variable volume)
  • Implement Kriest parameterization in NEMO-TOP
  • Implement AGRIF 2 ways nesting for passive tracers
  • Implement quickest scheme for tracers

New High Performance Computing:

2008 From tag nemo_v2.3 to nemo_v3_1

New science:

  • Open Boundaries BDY package as unstructured boundaries, and OBCs pakage entirely cleaned and documented,
  • New TKE physics
  • New sea-ice NEMO-LIM 3.0 (key_lim3) component including: ice-thickness categories, EVP rheology on C-Grid, ice salinity variations interfaced with the new surface module

New High Performance Computing:

  • New surface module in NEMO-OPA
  • Namelists entire re-organisation, improve readability and coherence
  • Improvement of IOManager now able to handle long simulations and so to manage successive input files from one year to an other
  • Improvements of AGRIF performance and users interface
  • improved vectorial performances (~5%) of the rheology module in LIM 2.0
  • TOP reorganisation with one directory by model Fully written in Fortran 90, include all SMS models ( PISCES, LOBSTER, CFC ...) and interface for users developemnt through the MY_TRC directory)
  • Update IOM modules for OFFLINE tracers
  • Interpolation On the Fly
  • Passive tracers used with AGRIF package

2009 From tag nemo_v3_1 to nemo_v3_2

This release has been mainly designed for climate models, with enhanced coupling interface and implementation of AR5 diagnostics.

New science:

  • tidal mixing parametrization (bottom intensification) + Indonesian specific tidal mixing
  • RGB light penetration and optional use of ocean color
  • vvl option has been restored, including revisit free-surface time-splitting algorithm to reach stability and satisfying result and have vvl option available for all type of coordinates (z, zps, s)
  • TKE change in the surface boundary condition, especially in coupled mode (mean stress module send by the atmosphere)

New High Performance Computing:

  • the way to handle outputs has been improved
  • implementation of IOM for output with the following functionalities : allows to output at few frequencies during same simulation, e.g both monthly and daily; output vectors/scalars is also available (for a strait transport calculation or for a vertical profile associated to buoys location for instance), and make easier the way to add an output everywhere in the code
  • Suppression of rigid-lid option and no more island specific treatment
  • Cleaning of lib_mpp
  • SHMEM option has been removed
  • north fold treatment is now done once for all in a new routine lbcnfd.F909 instead of being duplicated
  • suppression of redundant east-west communication phase (ORCA grid case)

2010 From tag nemo_v3_2 to nemo_v3_3

  • introduction of a modified leapfrog-Asselin filter time stepping scheme [Leclair and Madec 2009] ;
  • additional scheme for iso-neutral mixing [Griffies et al. 1998], although it is still a ”work in progress” ;
  • a rewriting of the bottom boundary layer scheme, following Campin and Goosse [1999] ;
  • addition of a Generic Length Scale vertical mixing scheme, following Um- lauf and Burchard [2003] ;
  • addition of the atmospheric pressure as an external forcing on both ocean and sea-ice dynamics ;
  • addition of a diurnal cycle on solar radiation [Bernie et al. 2007] ; river runoffs added through a non-zero depth, and having its own temperature and salinity ;
  • CORE II normal year forcing set as the default forcing of ORCA2-LIM configuration ;
  • generalisation of the use of fldread.F90 for all input fields (ocean climatology, sea-ice damping...) ;
  • addition of an on-line observation and model comparison (thanks to NEMOVAR project) ;
  • optional application of an assimilation increment (thanks to NEMOVAR project) ;
  • coupling interface adjusted for WRF atmospheric model ;
  • C-grid ice rheology now available for both LIM-2 and LIM-3[Bouillon et al. 2009] ;
  • LIM-3 ice-ocean momentum coupling applied to LIM-2 ;
  • a deep re-writting and simplification of the off-line tracer component (OFF SRC) ;
  • the merge of passive and active advection and diffusion modules ;
  • Use of the Flexible Configuration Manager (FCM) to build configurations, generate the Makefile and produce the executable ;
  • Linear-tangent and Adjoint component (TAM) added, phased with v3.0

In addition, several minor modifications in the coding have been introduced with the constant concern of improving the model performance.

2011 From tag nemo_v3_3 to nemo_v3_4

This is a major release and the documentation has been updated in consequence.

Major improvements

New physics and numerics

  • new pressure gradient suitable for s-coordinate
  • completion of Griffies iso-neutral diffusion
  • back to a semi-implicit bottom friction
  • add Pacanowski-Philander scheme for computation of Ekman depth
  • add a new bulk formulae (so called MFS)
  • introduce a drag coefficient compute by wave model
  • add tidal potential forcing
  • Netpune effect parametrization
  • point to point MPI communication for north fold
  • allow sub timestepping for biogeochemistry models when using non-linear free surfac
  • Improvement in PISCES (light limitation ; quota model for iron ; use Pa in gas exchange ; fldread for all data ; calcite dissolution & calcon salinity dependence )

Configurations, diagnostics and tools

  • suppression of POMME configuration
  • addition of a regional configuration AMM12
  • improvement of format for lagrangian floats
  • online computing of transport across sections
  • tidal harmonic analysis
  • tools to prepare input files for observation operator
  • timing functionality

System simplification

  • simplification of dynamic allocation
  • end of merge TRA/TRA (no more separate 3d arrays for tracers, only 4d)
  • suppression of obsolete hpg options
  • more flexible definition of BDY input data
  • simplification of interfaces toward biogeochemical models
  • interface with CICE in coupled mode
  • Use of fldread to read/interpolate data for passive tracers and dynamical input data for OFFLINE configurations

2012 From nemo_v3_4 to nemo_v3_5

Brief overview of the v3_5_alpha majors improvements and developments:

The new Input/Output? server XIOS is a major evolution including a versatile xml interface, the dedicated processors for I/O functionality allowing improved scalability, and a large performance improvement on massively parallel platforms. This option is now set as the default one. The previous IOIPSL code and interface are kept as backup options at this stage.


  • Ocean/ice/biogeochemistry/atmosphere: revisit heat/salt(tracers)/mass fluxes ; new levitating & embedded sea-ice (for LIM & CICE)
  • AGRIF is now sea-ice (LIM) compatible using a new AGRIF package shared with other GCMs
  • Compilation with external biogeochemistry model
  • Improved CICE-NEMO interface
  • ICB module (Bigg et al 1997, Martin and Adcroft 2010): icebergs as lagrangian floats (~200,000!) allowing improved fresh water input especially in the Southern ocean
  • SAS: Stand Alone Surface module allowing testing of forcing set with bulk formulae, to run sea-ice models without ocean, to run ICB icebergs module alone, and to test AGRIF with sea-ice
  • Biogeochemical component NEMO-TOP: PISCES will now include the LOBSTER functionalities, becoming more general and allowing a simplification and reduction of code size
  • Open boundaries module: merging the two existing options (OBC and BDY) has made some important progress (end of the work expected for 2013)
  • Wave-NEMO interface module has been further developed with the introduction of the reading of the 2D stoke drift and wave number and the on-line computation of the 3D stoke drift current.


  • A new vertical sigma coordinate stretching function (Siddorn and Furner OM 2012r)

Smagorinsky eddy coefficients: Smagorinsky type diffusivity/viscosity for lateral mixing has been introduced

  • Analytical tropical cyclones taken in account using track and magnitude observations (Vincent et al. JGR 2012a,b)
  • MUSCL: an option for local up-stream advection schemes which are useful in case of rivers, straits and in proximity of open lateral boundary conditions. The possibility to switch from MUSCL to a standard up-stream scheme has been included in the MUSCL advection routine
  • NEMO-OBS: observation operators. Add a model equivalent of SST at night
  • Log layer for bottom friction is now added (sigma coordinates only)
  • Evolution of SETTE validation tool

2014 From nemo_v3_5 to nemo_v3_6

Includes all the developments of 3_5 (especially the new XIOS IO system) , and new features:

  • Open boundaries: completion of BDY/OBC merge
  • Solved 2 time stepping issues
  • Faster split-explicit time stepping, Z-tilde ALE coordinates, implicit bottom friction
  • First version of Configuration Manager
  • Major evolution of LIM sea-ice model (including towards LIM2/LIM3 merge)
  • Standalone OBS component and improvements in OBS&ASM
  • Coupled interface for next IPCC requirements (multi category sea-ice, calving and iceberg module)
  • Runoff improved and SBC with BGC
  • MPP assessment and optimisation
  • Standard Fox Kemper parametrisation
  • First steps of wave coupling
  • On line coarsening of ocean I/O
  • Solar flux filtering at daily frequency to force BGC component
  • Atmospheric forcing at land-ocean interface

2015: From nemo_v3_6 to nemo_v3_6_STABLE: the release from CMIP6 experiments:

Main new features

  • Coupled interface for next IPCC requirements (multi category sea-ice, calving and iceberg module)
  • Runoff improved and SBC with BGC
  • Solar flux filtering at daily frequency to force BGC component
  • Major evolution of LIM sea-ice model (including LIM3 in mono category, i.e. similar to LIM2)
  • On line coarsening of ocean I/O
  • Ocean and ice allowed to be explicitly coupled through OASIS, using StandAlone? Surface module)
  • First steps of wave coupling
  • MPI optimisation
  • XIOS new IO system
  • Standard Fox Kemper parametrisation
  • Atmospheric forcing at land-ocean interface
  • Open boundaries: completion of BDY/OBC merge
  • Solved 2 time stepping issues
  • Faster split-explicit time stepping, Z-tilde ALE coordinates, implicit bottom friction
  • First version of Configuration Manager
  • Standalone OBS component and improvements in OBS&ASM

Features becoming obsolete:

  • LIM2 (replaced by LIM3 monocategory)

List of associated branches

  • On line coarsening of biogeochemistry