[ecco-support] [EXTERNAL] Perturbing ECCOv4r4 run/relationship between xx_<VAR> and xx_<VAR>.effective

[Wang, Ou (US 329B)]

Dafydd,

This is not the correct way to apply the perturbation to ECCO V4r4 for a few reasons:
1) The xx_<VAR>.effective is the dimensional adjusted field, including the first guess, so using xx_<VAR> would be double counting. Note <VAR> here are control variables for initial conditions (theta, salt, uvel, vvel, and etan) and mixing parameters (diffkr, kapgm, and kapredi).
2) The current V4r4 setup reads in non-dimensional control adjustment (xx_<VAR> files).
3) The model then applies a smoothing operator to the non-dimensional xx, and then rescale it to dimensional xx.

So one way to achieve what you wanted to do is to perturb the dimensional control adjustment and then let the model read in the dimensional adjustment without applying rescaling and smoothing . The steps are as follows.
1) Perturb the dimensional control adjustment for initial theta, xx_theta.dim.0000000129.data that can be found in https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/other/adjustments along with other dimensional control adjustments.
2) Copy the perturbed field to xx_theta.0000000129.data (You may want to keep a copy of the original xx_theta.0000000129.data for later use)
3) Make changes to data.ctrl by replacing
xx_genarr3d_preproc(1,1)='WC01',
with
xx_genarr3d_preproc(1,1)=' noscaling' ,

The part in data.ctrl related to xx_theta is shown below for before and after the change;
Before:
xx_genarr3d_weight(1) = 'Theta_weights_nonseasonal_rmsv2_areascaled.bin',
xx_genarr3d_file(1)='xx_theta',
xx_genarr3d_bounds(1:5,1)=-2.0,-1.9,39.,40.,0.,
xx_genarr3d_preproc(1,1)='WC01',
xx_genarr3d_preproc_i(1,1)=1,
mult_genarr3d(1) = 1.,
After:
xx_genarr3d_weight(1) = 'Theta_weights_nonseasonal_rmsv2_areascaled.bin',
xx_genarr3d_file(1)='xx_theta',
xx_genarr3d_bounds(1:5,1)=-2.0,-1.9,39.,40.,0.,
xx_genarr3d_preproc(1,1)=' noscaling' ,
xx_genarr3d_preproc_i(1,1)=1,
mult_genarr3d(1) = 1.,

Then you can rerun the model with the changes above.

Regards,
Ou


From: <ecco-support-bounces at mit.edu> on behalf of Dafydd Stephenson <dafydd at ucar.edu>
Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu>
Date: Thursday, July 22, 2021 at 2:45 PM
To: "ecco-support at mit.edu" <ecco-support at mit.edu>
Subject: [EXTERNAL] [ecco-support] Perturbing ECCOv4r4 run/relationship between xx_<VAR> and xx_<VAR>.effective

Hi all,

I have managed to re-run the ECCOv4r4 simulation and am now interested in applying perturbations to the run. I have so far modified xx_theta.0000000129.data to increase the temperature everywhere by 1K as a test, but the outcome in xx_theta.effective.0000000129.data and T.0000000001.data is in many places 30+K higher than in the unperturbed run.

My understanding (hopefully correct) is that a rescaling is applied to xx_<VAR> to generate xx_<VAR>.effective, so I should be able to invert this rescaling to apply an “effective” perturbation of my choosing? However, I can’t find a weighting file amongst the input files which in any way resembles the transformation applied to my 1K perturbation.

I’m interested to know (i) whether this is the correct way to apply to a perturbation to the ECCO run and (ii) if so, how to modify xx_<VAR> such that xx_<VAR>.effective corresponds to the perturbation I want.

Thanks!
Dafydd
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