= Name and subject of the action

Last edition: '''[[Wikinfo(changed_ts)]]''' by '''[[Wikinfo(changed_by)]]'''

The PI is responsible to closely follow the progress of the action, 
and especially to contact NEMO project manager if 
the delay on preview (or review) are longer than the 2 weeks expected.

[[PageOutline(2, , inline)]]

== Summary

||=Action       || rearangemnt of the pressure gradient according to A19 from NEMO book 4.0.1                        ||
||=PI(S)        || Sibylle & Gurvan                                                 ||
||=Digest       || In accordance with NEMO documentation, using using the density anomaly in dynhpg routines avoid computing a surface presure gradient that is removed afterwards     ||
||=Dependencies || If any                                                ||
||=Branch       || source:/NEMO/branches/2020/dev_r13333_techene_gm_HPG_SPG ||
||=Previewer(s) || Names                                                 ||
||=Reviewer(s)  || Names                                                 ||
||=Ticket       || #2506                                                 ||

=== Description

{{{#!box width=25em help
Describe the goal of development and the methodology, \\
add reference documents or publications if relevant.
}}}
Current implementation of the pressure gradient... blablabla... 
We modify the implementation of the pressure gradient according to A19 from NEMO book 4.0.1 :
in dynhpg routines we compute the specific pressure gradient with the density anomaly : when possible we merely remove the znad, otherwise we remove explicitely the surface pressure gradient (dynhpg_prj, dynhpg_djc).
in dynspg routines we compute the surface pressure gradient with constant density systematically

Note that using a density anomaly only in dynhpg_isf, requires also changes in isfload and isfstp.

''...''

=== Implementation

{{{#!box width=35em help
Describe flow chart of the changes in the code. \\
List the Fortran modules and subroutines to be created/edited/deleted. \\
Detailed list of new variables to be defined (including namelists), \\
give for each the chosen name and description wrt coding rules.
}}}

''...''

Index: src/OCE/DYN/dynspg_exp.F90
compute the surface pressure gradient with constant density systematically

Index: src/OCE/oce.F90
Index: src/OCE/DYN/dynspg.F90
Index: src/OCE/DYN/dynspg_ts.F90
formatting and some optimisation 

Index: src/OCE/DYN/dynhpg.F90
we compute the specific pressure gradient with the density anomaly
dynhpg_zco
dynhpg_zps
dynhpg_sco
dynhpg_djc
dynhpg_prj
dynhpg_isf


Index: src/OCE/ISF/isf_oce.F90
Index: src/OCE/ISF/isfload.F90
Index: src/OCE/ISF/isfstp.F90



=== Documentation updates

{{{#!box width=55em help
Using previous parts, define the main changes to be done in the NEMO literature 
(manuals, guide, web pages, …).
}}}

''...''

== Preview 

{{{#!box width=50em info
[[Include(wiki:Developers/DevProcess#preview_)]]
}}}

''...''

== Tests

{{{#!box width=50em info
[[Include(wiki:Developers/DevProcess#tests)]]
}}}

''...''
GYRE_PISCES for zco, sco, prj
ISOMIP for isf

Because we change the arrangement of adding and subtractig the "surface pressure gradient" we do not expect to have the same results as before. 

== Review

{{{#!box width=50em info
[[Include(wiki:Developers/DevProcess#review)]]
}}}

''...''