source: NEMO/trunk/RELEASE_NOTES.rst @ 10201

Last change on this file since 10201 was 10201, checked in by nicolasmartin, 2 years ago

Various modifications related to the setting of a NEMO Quick Start Guide

  • Add missing namelist blocks from ICE and TOP
  • Create a hidden .global.rst to gather common URL links
  • Convert animated gif to frames images for PDF export
  • Place different README.rst appropriately in the code structure and refer to them with symbolic links in doc/rst/source
File size: 11.0 KB
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1======================
2What's new in NEMO 4.0
3======================
4
5.. include:: .global.rst
6
7.. contents::
8   :local:
9     
10Original sea-ice component SI\ :sup:`3`\
11========================================
12
13| Meeting in 2017, the `sea ice working group`_ decided to gather sea ice developers and
14  scientific expertise within the NEMO community in order to build a unified model.
15  The replacement of LIM (Louvain-la-Neuve Ice Model) has required the backport of
16  the desired functionalities from each of CICE, GELATO and LIM into a common code in the NEMO framework.
17| This new model has been named SI\ :sup:`3`\ ("sea ice cubed") and
18  means "**Sea Ice modelling Integrated Initiative**".
19
20- Physics
21
22  * Landfast ice: simple grounding with a "release" stress (not fully operational)
23  * Lateral melting
24  * Melt ponds: constant or `Holland 2012`_ formulation (and soon topographic melt ponds)
25  * Ice-atm. drags from `Lupkes 2012`_ (depending on ice concentration) or `Lupkes 2014`_
26    (Depending on sea ice concentration and atm. stability)
27- Numerics
28
29  * Advection: Ultimate-Macho scheme
30  * Rheology: adaptive EVP (`Kimmritz 2016`_)
31  * Coupling interface: conductivity as surface forcing instead of heat fluxes (Met Office requirement)
32- Performance
33
34  * All thermodynamics in 1D
35  * Reduced mpp communications
36- Users & developers friendly
37
38  * Comprehensive set of outputs (universal units and understandable names + includes limp)
39  * New architecture and namelist
40  * All processes can be decoupled from each other (switch on/off)
41  * Ice categories bounds can be defined by the user or set automatically
42  * For open boundaries, the number of ice categories from the forcing model can be different
43    from the number of categories in the regional simulation
44  * Fully compatible with AGRIF
45
46First Test Cases
47================
48
49Define and install a separate repository for test cases to all easy contributions from the NEMO Users Community
50
51Core components
52===============
53
54Passive tracer TOP and biogeochemical PISCES components
55-------------------------------------------------------
56
57- The passive tracers transport component was redesigned toward a modular structure and
58  users can enable each module directly through logical flags in namelist_top (no more Fortran macros!).
59- TOP on-line user documentation is available on NEMO Trac platform (`TOP User Quick Guide`_)
60- TOP currently accounts for the following 5 modules:
61
62  * ``CFC`` contains inorganic carbon tracers (CFC11/CFC12/SF6)
63  * ``MY_TRC`` is a template for new modules (or external couplings)
64  * ``AGE`` deals with water age tracking
65  * ``C14`` as a radiocarbon passive tracer
66  * ``PISCES`` the companion ecosystem model
67- A generalized infrastructure was developed to handle the prescription of either surface, coastal, or
68  open boundaries conditions for each passive tracer.
69- PISCES model contains new developments and modifications:
70
71  * Particulate Organic Carbon (POC) component comes with a new liability scheme,
72    while the former Kriest parameterisation was superseded;
73  * A complex iron chemistry scheme is now available, with an improved description of ligands for
74    the marine iron cycle
75  * Carbonate chemistry is based on MOCSY 2.0 routines (see `Orr and Epitalon 2015`_),
76    by complying also with CMIP6 standards.
77  * Ecosystem components can be optionally modelled by means of explicit nutrient quotas (PISCES-QUOTA)
78
79AGRIF (embedded zooms)
80----------------------
81
82The NEMO 4.0 includes new capabilities, configurations and test cases with AGRIF:
83
84.. role:: underline
85   :class: underline
86
87:underline:`New capabilities from NEMO 3.6 to NEMO 4.0`
88
89AGRIF is continuously maintained so that it could be activated with all NEMO components (OPA, sea-ice, TOP).
90Depending on NEMO version, it is nevertheless not the case so that some options may not be compatible with
91the use of online grid refinement.
92Check out the table below to know the status according to the NEMO release you may use.
93
94:underline:`Status of available options with AGRIF (if not listed, option is compatible with AGRIF)`:
95
96+--------------------------------------------------------+----------------+---------------------+
97|                                                        | NEMO 3.6       | NEMO 4.0            |
98+========================================================+================+=====================+
99| LIM2                                                   | yes            | ``-``               |
100+--------------------------------------------------------+----------------+---------------------+
101| LIM3/SI3                                               | no             | yes                 |
102+--------------------------------------------------------+----------------+---------------------+
103| TOP                                                    | yes            | yes                 |
104+--------------------------------------------------------+----------------+---------------------+
105| GLS vertical mixing                                    | no             | yes                 |
106+--------------------------------------------------------+----------------+---------------------+
107| z*                                                     | no             | yes                 |
108+--------------------------------------------------------+----------------+---------------------+
109| z~                                                     | no             | no                  |
110+--------------------------------------------------------+----------------+---------------------+
111| Lagrangian icebergs                                    | no             | no                  |
112+--------------------------------------------------------+----------------+---------------------+
113| East-west periodic and/or north fold bcs in zooms      | no             | no                  |
114+--------------------------------------------------------+----------------+---------------------+
115| Online timing                                          | no             | no                  |
116+--------------------------------------------------------+----------------+---------------------+
117| Stochastic parameterization                            | no             | no                  |
118+--------------------------------------------------------+----------------+---------------------+
119| Vertical coordinate change in zooms (``key_vertical``) | no             | yes, but not tested |
120+--------------------------------------------------------+----------------+---------------------+
121| Number of ghost cells                                  | 1 (hard coded) | 3 (parameter)       |
122+--------------------------------------------------------+----------------+---------------------+
123
124[Important notice concerning the change of ghost cells number]
125
126The default number of ghost cells (i.e. the number of cells that serve as open boundary data provision) has been
127increased from 1 to 3 in NEMO 4.0.
128This allows to properly handle boundary conditions for numerical schemes that
129have a discretization order greater than 2.
130On the user point of view this does not change anything++ except in the definition of level 1 grids in
131the ``AGRIF_FixedGrids.in`` file.
132In order to retrieve exactly the position of a nested grid in NEMO 4.0 one has to shift indices by
1332 points to the south-west.
134Taking the ``ICEDYN`` example above for NEMO 4.0, the "old" NEMO 3.6 corresponding file would contain::
135
136   1
137   36 65 36 65 3 3 3
138   0
139
140++ Child grid output files are now greater by 4 points in each direction.
141
142- Now compatible with new sea ice component and z* coordinate
143- Extended ghost cells area to properly handle scheme with spatial order >2
144- Added vertical refinement (beta)
145- Nesting tools for setup now up to date and working
146
147Adding of 3 Reference Configurations
148------------------------------------
149
150- ``AGRIF_DEMO``: 2 interlocked zooms (1:4 & 1:3) in the Nordic Seas + 1 zoom (1:1) at the equator
151- ``ORCA2_OFF_TRC``: a benchmark simulation environment to deal with inert carbon tracers dynamics by
152  exploiting the offline coupling with NEMO.
153- ``SPITZ12``: regional configuration around the Svalbard archipelago.
154
155Misc. improvments
156=================
157
158Physics
159-------
160
161- Bulk formulae : move to aerobulk package (`Brodeau 2017`_), i.e. NCAR, COARE and ECMWF bulk
162  (remove Clio and MFS bulk)
163- Fix for tracer conservation with split explicit free surface
164- Wetting and drying
165- iso-neutral mixing (iso and triad operators): add the Method of Stabilizing Correction (MSC)
166  (more accurate calculation) + add a bilaplacian case
167- Lateral physics (LDF): scale aware setting of eddy viscosity and diffusivity
168- Wave coupling: large scale wave interaction process added in momentum and tracer equations
169- Remove the acceleration of convergence
170
171Numerics
172--------
173
174- Added tidal self attraction and loading either read from a file or from usual "scalar" approximation
175- Vertical physics (ZDF) (modularity, share shear production calculation between TKE and GKS,
176  removal of all ZDF CPP keys, removal of avmu & avmv, minimization of MPP comm.: ~15 removed)
177- Remove the split-explicit ZDF scheme for both TRA and DYN
178- Lateral physics (LDF): simplification of user interface and removal of CPP keys
179- Add a 4th order centered (CEN) and Flux Corrected Transport (FCT) tracer advection
180  (using a 4th compact in the vertical)
181- Generalised lbc_lnk and lbc_nfd
182- Configuration interface completely rewritten (DOM module mainly suppressed,
183  and in place: domain_cfg.nc file, or usr_def module)
184- Vorticity: 2 new energy conserving scheme:  ENT with Coriolis defined at T-point
185  (better for Flux form) and EET a variant of EEN where e3t is used instead of e3f
186  (solved the issue with e3f specification but is not enstrophy conserving)
187- Wave coupling: coupled interface to external wave model
188
189Performances
190------------
191
192- MPI Message passing recoded to reduce number of MPI communications (suppression of redundant communications,
193  gather multiple communications into one)
194- Back to standard dynamical allocation (remove of wrk_alloc/dealloc statements)
195- XIOS software for IOs version 2 as default, and optionally available for restarts
196- Unify mppini
197- Use non uniform jpi/jpj with dynamic allocation to avoid ghost rows/columns
198
199Environment
200-----------
201
202- Revised structure of namelist_ref/_cfg and default reference values.
203- Reorganisation of SVN repository to be compliant with usual directory tree and facilitate building of
204  NEMO executable
205- Improvements of reliability through automatic and regular testing of the changes made in repository
206
207.. _sea ice working group:       http://forge.ipsl.jussieu.fr/nemo/wiki/WorkingGroups/SI3
208.. _TOP User Quick Guide:        http://forge.ipsl.jussieu.fr/nemo/wiki/WorkingGroups/top-dg/TOP-UserQuickGuide
209
210.. _Brodeau 2017:                http://doi.org/10.1175/JPO-D-16-0169.1
211.. _Holland 2012:                http://doi.org/10.1175/JCLI-D-11-00078.1
212.. _Lupkes 2012:                 http://doi.org/10.1029/2012JD017630
213.. _Lupkes 2014:                 http://doi.org/10.1002/2014JD022418
214.. _Kimmritz 2016:               http://doi.org/10.1016/j.ocemod.2016.03.004
215.. _Orr and Epitalon 2015:       http://doi.org/10.5194/gmd-8-485-2015
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