Opened 7 years ago

Closed 3 years ago

Last modified 3 years ago

#1328 closed Enhancement (fixed)

Bias correcting SST observations in OBS

Reported by: jwhile Owned by: avidard
Priority: low Milestone: Unscheduled
Component: OCE Version: release-3.6
Severity: Keywords: OBS SST
Cc: timgraham Review:
MP ready?:
Progress:

Description

This code change will allow NEMO to read in fields of SST biases and remove theses biases from the observations before the observations are compared to the model.

This is a fairly minor change that has no impact on model dynamics. My plan for testing is to run the standard NEMO SETTE tests, but also conduct a run where the model is given a bias field and show that the observations change appropriately between the input observation files and the output feedback file.

The code will be reviewed by Arthur Vidard (avidard)

Commit History (0)

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Attachments (2)

bias_amm12.png (101.1 KB) - added by jwhile 6 years ago.
demonstration of bias in AMM12 model
bias_orca2.png (87.5 KB) - added by jwhile 6 years ago.
Demonstration of bias in ORCA2 model

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Change History (16)

comment:1 Changed 7 years ago by jwhile

  • Owner changed from NEMO team to jwhile

comment:2 Changed 7 years ago by jwhile

The wiki ticket location for this ticket is https://forge.ipsl.jussieu.fr/nemo/wiki/ticket/1328

comment:3 Changed 7 years ago by jwhile

  • Owner changed from jwhile to avidard

Arthur, Could you confirm that you are happy with my planed tests

comment:4 Changed 6 years ago by avidard

The proposed tests seem appropriate.

The SETTE tests will check that it does not affect the dynamics, and the other test will check that the new feature does what it should.

comment:5 Changed 6 years ago by jwhile

To add more detail about the proposed test for the bias correction:

Two runs will be made in ORCA025, one run will be given a bias field, while the other will not have a bias field. In all other aspects the runs will be the same. If the SST bias correction is working correctly then the difference between the output SST feedback files will be identical to the negative of the bias correction field that was read in. This can easily be check by a visual inspection of a random selection of the observations.

Changed 6 years ago by jwhile

demonstration of bias in AMM12 model

Changed 6 years ago by jwhile

Demonstration of bias in ORCA2 model

comment:6 Changed 6 years ago by jwhile

The updated code has been submitted to ​https://forge.ipsl.jussieu.fr/nemo/browser/branches/2014//dev_r4650_UKMO14.5_SST_BIAS_CORRECTION.

The code passes the SETTE tests as is detailed on the standard wikki page ​https://forge.ipsl.jussieu.fr/nemo/wiki/ticket/1328.

comment:7 Changed 6 years ago by jwhile

To test the new functionality I have done tests in the ORCA2 and AMM12 configurations. In both cases I gave a model a bias field of +5 degrees in one half of the domain and -5 degrees in the other (the division is N/S in AMM12 and E/W in ORCA2). To pass the test this bias should have been subtracted from the observations in the output feedback files. As can be seen in the following images both tests passed:

AMM12 (NOTE: real observations were used for this test)

demonstration of bias in AMM12 model

ORCA2 (NOTE: I used synthetic observations all of the same value)

Demonstration of bias in ORCA2 model

comment:8 Changed 6 years ago by jwhile

Artur, given the above could you please fill out a reviewers twiki for this code change. I have already set one up for you at:

https://forge.ipsl.jussieu.fr/nemo/wiki/ticket/review/1328

comment:9 Changed 6 years ago by jwhile

The code has been approved by the reviewer and will be committed as is.

The reviewer has raised important points about variable names within the OBS code. These should be addressed by a future rationalising of the OBS code.

comment:10 Changed 4 years ago by nicolasmartin

  • Keywords bias removed

comment:11 Changed 4 years ago by nicolasmartin

  • Keywords correction removed

comment:12 Changed 3 years ago by jwhile

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

Ticket closed as code committed long ago.

comment:13 Changed 3 years ago by nemo

  • Keywords Misc. added

comment:14 Changed 3 years ago by nemo

  • Keywords Misc. removed
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