Opened 11 years ago

Closed 5 years ago

#637 closed Bug (fixed)

big bugs on ORCA025 and ORCA12 grid on the north pole

Reported by: smasson Owned by: cbricaud
Priority: normal Milestone: Unscheduled
Component: OCE Version: release-3.4
Severity: Keywords:
Cc:

Description

Following ticket:613 Ian Culverwell checked coordinates files of other resolutions and found several error for ORCA025.
A careful review of those files are therefore needed.

ORCA2:
I checked again coordinates_ORCA2_v3.2.nc. It looks OK. NO lbc errors and no errors visible around the geographical north pole (see attached pdf)

ORCA05
I checked a file called coordinates_ORCA_R05.nc.
There is 1 error for the norh pole folding of the arrays gphif, e1f and e2f. However this error is located on i = 360 that correspond to a pole of ORCA grid located on land ⇒ no impact.
Visual check of the geographical north pole looks OK (see attached pdf)

ORCA025
I checked a file called coordinates_ORCA_R025.nc.
There is big problems on the north pole folding of gphi[uvf], e1[uvf] and e2[uvf]. gphi[vf] are completly wrong! See detailed report bellow. In addition geographical north pole shows several bugs (see attached pdf)

gphiu : north pole periodicity (1) : 4 errors (located on : 718, 719, 720, 721)
e1u : north pole periodicity (1) : 4 errors (located on : 718, 719, 720, 721)
e1u : north pole periodicity (2) : 8 errors (located on : 1, 2, 3, 4, 656, 657, 658, 659)
e2u : north pole periodicity (1) : 4 errors (located on : 718, 719, 720, 721)
e2u : north pole periodicity (2) : 8 errors (located on : 1, 2, 3, 4, 656, 657, 658, 659)
gphiv : north pole periodicity (1) : 1441 errors
e1v : north pole periodicity (1) : 5 errors (located on : 3, 658, 720, 782, 1437)
e1v : north pole periodicity (2) : 4 errors (located on : 3, 658, 782, 1437)
e2v : north pole periodicity (1) : 5 errors (located on : 3, 658, 720, 782, 1437)
e2v : north pole periodicity (2) : 4 errors (located on : 3, 658, 782, 1437)
gphif : north pole periodicity (1) : 1441 errors
e1f : north pole periodicity (1) : 20 errors
e1f : north pole periodicity (2) : 16 errors
e2f : north pole periodicity (1) : 20 errors
e2f : north pole periodicity (2) : 16 errors

ORCA12
I checked a file called coordinates_ORCA_R12_lbclnk.nc
As its name is suggesting, north pole folding has no error in this file (but there is a minor error on the east-west periodicity for e1v and e2v locate dat j=3058)
However, plot of TUVF points position around the geographical north pole show very big problems! See attached pdf

Conclusion: big bugs on ORCA025 and ORCA12 around the geographical north pole. We must understand why…

seb

Commit History (0)

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Attachments (6)

ORCA2_NP.pdf (58.1 KB) - added by smasson 11 years ago.
ORCA2 grids points position around the geographical north pole
ORCA05_NP.pdf (62.8 KB) - added by smasson 11 years ago.
ORCA05 grids points position around the geographical north pole
ORCA025_NP.pdf (55.3 KB) - added by smasson 11 years ago.
ORCA025 grids points position around the geographical north pole
ORCA12_NP.pdf (59.6 KB) - added by smasson 11 years ago.
ORCA12 grids points position around the geographical north pole
north_fold4_old.jpg (70.1 KB) - added by idcatukmo 11 years ago.
Old ORCA025 coords near N pole
north_fold4_new.jpg (70.5 KB) - added by idcatukmo 11 years ago.
New ORCA025 coords near N pole

Download all attachments as: .zip

Change History (14)

comment:1 Changed 11 years ago by idcatukmo

Just to check: coordinates_ORCA2_v3.2.nc means the original (pre NEMO vn2) ORCA2 coords file, as ticket:613 suggests, right? Otherwise I suspect it's still wrong.

As for ORCA025: I have a hand-made fix for these coords, but I don't know why the original coords are wrong.

Changed 11 years ago by smasson

ORCA2 grids points position around the geographical north pole

Changed 11 years ago by smasson

ORCA05 grids points position around the geographical north pole

Changed 11 years ago by smasson

ORCA025 grids points position around the geographical north pole

Changed 11 years ago by smasson

ORCA12 grids points position around the geographical north pole

comment:2 Changed 11 years ago by smasson

I updated the pdf files that where not really visibles!

coordinates_ORCA2_v3.2.nc is the one coming with version 3.2 that corresponds pre NEMO vn2. By the way, we also found a minor problem in this file: in the southern hemisphere, glamt is not exactly equal to glamv (and same problem with gkamu and glamf…).

Regarding ORCA025, how do you fix the problem? It is not only a problem of LBC. Some points are not properly positioned (gphi is wrong). Scale factors have some LBC errors too but I didn't checked if the values itself have errors…

seb

Changed 11 years ago by idcatukmo

Old ORCA025 coords near N pole

Changed 11 years ago by idcatukmo

New ORCA025 coords near N pole

comment:3 Changed 11 years ago by idcatukmo

Thanks for ORCA2 clarification, Sebastien.  Didn't realise that glamt ne glamv etc in S Hem - bit worrying that there's a problem even where grid is regular!

As for ORCA025 - I made polar stereo projection of (glamx,gphix), noted (by eye) which points didn't lie on the regular lattice, calculated their correct posns in polar stereo space from those of the T-points (which look OK), and then derived the corresponding (glmax,gphix). Not as good as correcting the grid generation code, but then I couldn't get that to work at all.m Before and after pics attached.

Scale factors looked OK to me - certainly I didn't correct them.

Regards,

Ian.

comment:4 Changed 8 years ago by vichi

  • Owner changed from NEMO team to smasson
  • Version changed from nemo_v3_2 to nemo_v3_4

comment:5 Changed 7 years ago by clevy

  • Owner changed from smasson to ??

comment:6 Changed 7 years ago by cbricaud

  • Owner changed from ?? to cbricaud

comment:7 Changed 5 years ago by cbricaud

ORCA025 and ORCA12 grid have been corrected to the north pole.

Last edited 5 years ago by cbricaud (previous) (diff)

comment:8 Changed 5 years ago by cbricaud

  • Resolution set to fixed
  • Status changed from new to closed
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