[ecco-support] How to get the total diffusivity in ECCOv4

[Christopher Wolfe]

Hi all:

I’m trying to figure out what the vertical diffusivity field in ECCOv4r4 is, but I’m a little confused about which input file actually contains this data. 

The ECCOv4 python tutorial (at https://ecco-v4-python-tutorial.readthedocs.io/ECCO_v4_Loading_LLC_compact_binary_files.html#Example-3:-Load-a-3D-'compact'-llc-binary-file-with-3rd-dimension-=-Depth <https://ecco-v4-python-tutorial.readthedocs.io/ECCO_v4_Loading_LLC_compact_binary_files.html#Example-3:-Load-a-3D-'compact'-llc-binary-file-with-3rd-dimension-=-Depth>) says that total_kapredi_r009bit11.bin is the "adjusted GM redi parameter (first guess + adjustments)”, which implies that total_diffkr_r009bit11.bin should be the adjusted diffusivity. 

On the other hand, the README at https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/input_init/README <https://ecco.jpl.nasa.gov/drive/files/Version4/Release4/input_init/README> says that  total_diffkr_r009bit11.bin is the "vert. diff. of release 1 (this field plus xx is the total)”, which means that I should add xx_diffkr.0000000129.data to this to get the full diffusivity. However, the values in this file are order 1, so adding it to total_diffkr_r009bit11 would produce diffusivities far outside the expected range.

The gencost documentation of the ctrl package (https://mitgcm.readthedocs.io/en/latest/ocean_state_est/ocean_state_est.html#ctrl-model-parameter-adjustment-capability <https://mitgcm.readthedocs.io/en/latest/ocean_state_est/ocean_state_est.html#ctrl-model-parameter-adjustment-capability>) says that the xx adjustments are non-dimensional and need to be scaled by one over the square root of the weights, which are in r2.wdiffkrFldv2.data. Using this produces adjustments on the order of 1e-6 to 1e-5, which seems about right. However, the data.ctrl namelist also specifies WC01 smoothing and some thresholding. Do these need to be applied as well?

Is the best way to get this data simply to run the model for a bit and have it dump diffkr? It would be convenient to be able to calculate these quantities without having to run the model, however.

Thanks in advance for your advise,
Christopher

----------------------------------------------------------------------------
Christopher L. Pitt Wolfe
Associate Professor (Physical Oceanography)
School of Marine and Atmospheric Sciences
Stony Brook University
christopher.wolfe at stonybrook.edu <mailto:christopher.wolfe at stonybrook.edu>             631-632-3152
----------------------------------------------------------------------------

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.mit.edu/pipermail/ecco-support/attachments/20210604/79cf2ab1/attachment.html