source: NEMO/trunk/RELEASE_NOTES.rst @ 10187

Last change on this file since 10187 was 10187, checked in by nicolasmartin, 2 years ago

Push draft versions of RST root files

File size: 16.8 KB
Line 
1======================
2What's new in NEMO 4.0
3======================
4
5.. contents::
6   :local:
7     
8Original sea-ice component SI\ :sup:`3`\
9========================================
10
11| Meeting in 2017, the `sea ice working group`_ decided to gather sea ice developers and
12  scientific expertise within the NEMO community in order to build a unified model.
13  The replacement of LIM (Louvain-la-Neuve Ice Model) has required the backport of
14  the desired functionalities from each of CICE, GELATO and LIM into a common code in the NEMO framework.
15| This new model has been named SI\ :sup:`3`\ ("sea ice cubed") and
16  means "**Sea Ice modelling Integrated Initiative**".
17
18- Physics
19
20  * Landfast ice: simple grounding with a "release" stress (not fully operational)
21  * Lateral melting
22  * Melt ponds: constant or `Holland 2012`_ formulation (and soon topographic melt ponds)
23  * Ice-atm. drags from `Lupkes 2012`_ (depending on ice concentration) or `Lupkes 2014`_
24    (Depending on sea ice concentration and atm. stability)
25- Numerics
26
27  * Advection: Ultimate-Macho scheme
28  * Rheology: adaptive EVP (`Kimmritz 2016`_)
29  * Coupling interface: conductivity as surface forcing instead of heat fluxes (Met Office requirement)
30- Performance
31
32  * All thermodynamics in 1D
33  * Reduced mpp communications
34- Users & developers friendly
35
36  * Comprehensive set of outputs (universal units and understandable names + includes limp)
37  * New architecture and namelist
38  * All processes can be decoupled from each other (switch on/off)
39  * Ice categories bounds can be defined by the user or set automatically
40  * For open boundaries, the number of ice categories from the forcing model can be different
41    from the number of categories in the regional simulation
42  * Fully compatible with AGRIF
43
44First Test Cases
45================
46
47Define and install a separate repository for test cases to all easy contributions from the NEMO Users Community
48
49+-------------------+--------------------------------------------------------+------------------------------------+
50| Name              | Purpose                                                | References                         |
51+===================+=================+======================================+====================================+
52| ``CANAL``         | East-west periodic canal of variable size with several |                                    |
53|                   | initial states and associated geostrophic currents     |                                    |
54|                   | (zonal jets or vortex).                                |                                    |
55+-------------------+--------------------------------------------------------+------------------------------------+
56| ``ICEDYN``        | East-west + north-south periodic channel.              |                                    |
57|                   | The common configuration includes an AGRIF zoom (1:3)  |                                    |
58|                   | in the middle of the basin to test how an ice patch is |                                    |
59|                   | advected through it but one can also test the          |                                    |
60|                   | advection schemes (Prather and Ultimate-Macho) by      |                                    |
61|                   | removing the ``key_agrif`` in the CPP keys.            |                                    |
62+-------------------+--------------------------------------------------------+------------------------------------+
63| ``ISOMIP``        | Simple box configuration with an iceshelf with simple  | `Hunter 2006`_                     |
64|                   | geometry on top.                                       |                                    |
65|                   | The purpose of this test case is to evaluate the       |                                    |
66|                   | impact of various schemes and new development with     |                                    |
67|                   | iceshelf cavities.                                     |                                    |
68+-------------------+--------------------------------------------------------+------------------------------------+
69| ``LOCK_EXCHANGE`` | Classical fluid dynamics experiment that has been      | - `Haidvogel and Beckmann 1999`_   |
70|                   | adapted for testing advection schemes in ocean         | - `Burchard and Bolding 2002`_     |
71|                   | circulation models.                                    | - `Ilıcak 2012`_                   |
72|                   | This experiment can in particular illustrate the       |                                    |
73|                   | impact of different choices of numerical schemes       |                                    |
74|                   | and/or subgrid closures on spurious interior mixing.   |                                    |
75+-------------------+--------------------------------------------------------+------------------------------------+
76| ``OVERFLOW``      | Adapted from the non-rotating overflow configuration   | - `Haidvogel and Beckmann 1999`_   |
77|                   | Illustrates the impact of different choices of         | - `Ilıcak 2012`_                   |
78|                   | numerical schemes and/or subgrid closures on spurious  |                                    |
79|                   | interior mixing close to bottom topography.            |                                    |
80+-------------------+--------------------------------------------------------+------------------------------------+
81| ``VORTEX``        | Illustrates the propagation of an anticyclonic eddy    | - `Debreu 2012`_                   |
82|                   | over a Beta plan and flat bottom.                      | - `Penven 2006`_                   |
83|                   | It is implemented here with an online refined          | - `Spall and Holland 1991`_        |
84|                   | subdomain (thanks to AGRIF library) out of which the   |                                    |
85|                   | vortex propagates and serves as a benchmark to         |                                    |
86|                   | diagnose nesting errors.                               |                                    |
87+-------------------+--------------------------------------------------------+------------------------------------+
88| ``WAD``           | Set of simple closed basin geometries for testing the  |                                    |
89|                   | wetting and drying capabilities.                       |                                    |
90|                   | Examples range from a closed channel with EW linear    |                                    |
91|                   | bottom slope to a parabolic EW channel with a Gaussian |                                    |
92|                   | ridge.                                                 |                                    |
93+-------------------+--------------------------------------------------------+------------------------------------+
94
95-----------
96Improvments
97-----------
98
99Core components
100===============
101
102Passive tracer TOP and biogeochemical PISCES components
103-------------------------------------------------------
104
105- The passive tracers transport component was redesigned toward a modular structure and
106  users can enable each module directly through logical flags in namelist_top (no more Fortran macros!).
107- TOP on-line user documentation is available on NEMO Trac platform (`TOP User Quick Guide`_)
108- TOP currently accounts for the following 5 modules:
109
110  * ``CFC`` contains inorganic carbon tracers (CFC11/CFC12/SF6)
111  * ``MY_TRC`` is a template for new modules (or external couplings)
112  * ``AGE`` deals with water age tracking
113  * ``C14`` as a radiocarbon passive tracer
114  * ``PISCES`` the companion ecosystem model
115- A generalized infrastructure was developed to handle the prescription of either surface, coastal, or
116  open boundaries conditions for each passive tracer.
117- PISCES model contains new developments and modifications:
118
119  * Particulate Organic Carbon (POC) component comes with a new liability scheme,
120    while the former Kriest parameterisation was superseded;
121  * A complex iron chemistry scheme is now available, with an improved description of ligands for
122    the marine iron cycle
123  * Carbonate chemistry is based on MOCSY 2.0 routines (see `Orr and Epitalon 2015`_),
124    by complying also with CMIP6 standards.
125  * Ecosystem components can be optionally modelled by means of explicit nutrient quotas (PISCES-QUOTA)
126
127AGRIF (embedded zooms)
128----------------------
129
130The NEMO 4.0 includes new capabilities, configurations and test cases with AGRIF:
131
132.. role:: underline
133   :class: underline
134
135:underline:`New capabilities from NEMO 3.6 to NEMO 4.0`
136
137AGRIF is continuously maintained so that it could be activated with all NEMO components (OPA, sea-ice, TOP).
138Depending on NEMO version, it is nevertheless not the case so that some options may not be compatible with
139the use of online grid refinement.
140Check out the table below to know the status according to the NEMO release you may use.
141
142:underline:`Status of available options with AGRIF (if not listed, option is compatible with AGRIF)`:
143
144+--------------------------------------------------------+----------------+---------------------+
145|                                                        | NEMO 3.6       | NEMO 4.0            |
146+========================================================+================+=====================+
147| LIM2                                                   | yes            | ``-``               |
148+--------------------------------------------------------+----------------+---------------------+
149| LIM3/SI3                                               | no             | yes                 |
150+--------------------------------------------------------+----------------+---------------------+
151| TOP                                                    | yes            | yes                 |
152+--------------------------------------------------------+----------------+---------------------+
153| GLS vertical mixing                                    | no             | yes                 |
154+--------------------------------------------------------+----------------+---------------------+
155| z*                                                     | no             | yes                 |
156+--------------------------------------------------------+----------------+---------------------+
157| z~                                                     | no             | no                  |
158+--------------------------------------------------------+----------------+---------------------+
159| Lagrangian icebergs                                    | no             | no                  |
160+--------------------------------------------------------+----------------+---------------------+
161| East-west periodic and/or north fold bcs in zooms      | no             | no                  |
162+--------------------------------------------------------+----------------+---------------------+
163| Online timing                                          | no             | no                  |
164+--------------------------------------------------------+----------------+---------------------+
165| Stochastic parameterization                            | no             | no                  |
166+--------------------------------------------------------+----------------+---------------------+
167| Vertical coordinate change in zooms (``key_vertical``) | no             | yes, but not tested |
168+--------------------------------------------------------+----------------+---------------------+
169| Number of ghost cells                                  | 1 (hard coded) | 3 (parameter)       |
170+--------------------------------------------------------+----------------+---------------------+
171
172[Important notice concerning the change of ghost cells number]
173
174The default number of ghost cells (i.e. the number of cells that serve as open boundary data provision) has been
175increased from 1 to 3 in NEMO 4.0.
176This allows to properly handle boundary conditions for numerical schemes that
177have a discretization order greater than 2.
178On the user point of view this does not change anything++ except in the definition of level 1 grids in
179the ``AGRIF_FixedGrids.in`` file.
180In order to retrieve exactly the position of a nested grid in NEMO 4.0 one has to shift indices by
1812 points to the south-west.
182Taking the ``ICEDYN`` example above for NEMO 4.0, the "old" NEMO 3.6 corresponding file would contain::
183
184   1
185   36 65 36 65 3 3 3
186   0
187
188++ Child grid output files are now greater by 4 points in each direction.
189
190- Now compatible with new sea ice component and z* coordinate
191- Extended ghost cells area to properly handle scheme with spatial order >2
192- Added vertical refinement (beta)
193- Nesting tools for setup now up to date and working
194
195Adding of 3 Reference Configurations
196------------------------------------
197
198- ``AGRIF_DEMO``: 2 interlocked zooms (1:4 & 1:3) in the Nordic Seas + 1 zoom (1:1) at the equator
199- ``ORCA2_OFF_TRC``: a benchmark simulation environment to deal with inert carbon tracers dynamics by
200  exploiting the offline coupling with NEMO.
201- ``SPITZ12``: regional configuration around the Svalbard archipelago.
202
203Misc. improvments
204=================
205
206Physics
207-------
208
209- Bulk formulae : move to aerobulk package (`Brodeau 2017`_), i.e. NCAR, COARE and ECMWF bulk
210  (remove Clio and MFS bulk)
211- Fix for tracer conservation with split explicit free surface
212- Wetting and drying
213- iso-neutral mixing (iso and triad operators): add the Method of Stabilizing Correction (MSC)
214  (more accurate calculation) + add a bilaplacian case
215- Lateral physics (LDF): scale aware setting of eddy viscosity and diffusivity
216- Wave coupling: large scale wave interaction process added in momentum and tracer equations
217- Remove the acceleration of convergence
218
219Numerics
220--------
221
222- Added tidal self attraction and loading either read from a file or from usual "scalar" approximation
223- Vertical physics (ZDF) (modularity, share shear production calculation between TKE and GKS,
224  removal of all ZDF CPP keys, removal of avmu & avmv, minimization of MPP comm.: ~15 removed)
225- Remove the split-explicit ZDF scheme for both TRA and DYN
226- Lateral physics (LDF): simplification of user interface and removal of CPP keys
227- Add a 4th order centered (CEN) and Flux Corrected Transport (FCT) tracer advection
228  (using a 4th compact in the vertical)
229- Generalised lbc_lnk and lbc_nfd
230- Configuration interface completely rewritten (DOM module mainly suppressed,
231  and in place: domain_cfg.nc file, or usr_def module)
232- Vorticity: 2 new energy conserving scheme:  ENT with Coriolis defined at T-point
233  (better for Flux form) and EET a variant of EEN where e3t is used instead of e3f
234  (solved the issue with e3f specification but is not enstrophy conserving)
235- Wave coupling: coupled interface to external wave model
236
237Performances
238------------
239
240- MPI Message passing recoded to reduce number of MPI communications (suppression of redundant communications,
241  gather multiple communications into one)
242- Back to standard dynamical allocation (remove of wrk_alloc/dealloc statements)
243- XIOS software for IOs version 2 as default, and optionally available for restarts
244- Unify mppini
245- Use non uniform jpi/jpj with dynamic allocation to avoid ghost rows/columns
246
247Environment
248-----------
249
250- Revised structure of namelist_ref/_cfg and default reference values.
251- Reorganisation of SVN repository to be compliant with usual directory tree and facilitate building of
252  NEMO executable
253- Improvements of reliability through automatic and regular testing of the changes made in repository
254
255.. _sea ice working group:       http://forge.ipsl.jussieu.fr/nemo/wiki/WorkingGroups/SI3
256.. _TOP User Quick Guide:        http://forge.ipsl.jussieu.fr/nemo/wiki/WorkingGroups/top-dg/TOP-UserQuickGuide
257
258.. _Hunter 2006:                 http://staff.acecrc.org.au/~bkgalton/ISOMIP/test_cavities.pdf
259.. _Brodeau 2017:                http://doi.org/10.1175/JPO-D-16-0169.1
260.. _Haidvogel and Beckmann 1999: http://hdl.handle.net/10013/epic.11761
261.. _Burchard and Bolding 2002:   http://www.researchgate.net/publication/258128069_GETM_A_General_Estuarine_Transport_Model_Scientific_Documentation
262.. _Ilıcak 2012:                 http://doi.org/10.1016/j.ocemod.2011.10.003
263.. _Debreu 2012:                 http://doi.org/10.1016/j.ocemod.2012.03.003
264.. _Penven 2006:                 http://doi.org/10.1016/j.ocemod.2005.05.002
265.. _Spall and Holland 1991:      http://www.researchgate.net/publication/232101325_A_Nested_Primitive_Equation_Model_for_Oceanic_Applications
266.. _Holland 2012:                http://doi.org/10.1175/JCLI-D-11-00078.1
267.. _Lupkes 2012:                 http://doi.org/10.1029/2012JD017630
268.. _Lupkes 2014:                 http://doi.org/10.1002/2014JD022418
269.. _Kimmritz 2016:               http://doi.org/10.1016/j.ocemod.2016.03.004
270.. _Orr and Epitalon 2015:       http://doi.org/10.5194/gmd-8-485-2015
Note: See TracBrowser for help on using the repository browser.