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Offline MOC calculation

Y

younglan_shin@utoronto_ca

New Member
Hi.

When calculating ocean meridional overturning circulation offline from pop history files, does it matter if I use VVEL instead of WVEL? (I know that for the modern pop configuration for CCSM3, both variables are used for calculating MOC for the Atlantic). My configuration is the simplest one, the ocean covered configuration. My question is whether the calulated MOC values are the same (or equivalent ) between the case of using VVEL and the case of using WVEL. Any clarification on this MOC matter will be greatly appreciated.

Thanks and Happy holidays!!


young
 
B

bates

Member
Are you aware that there is a variable (called MOC) output by CCSM3? You'll find it in the ocean history files. If there is a reason you are calculating this variable offline, write back and I'll look into your question.
 
Y

younglan_shin@utoronto_ca

New Member
bates said:
Are you aware that there is a variable (called MOC) output by CCSM3? You'll find it in the ocean history files. If there is a reason you are calculating this variable offline, write back and I'll look into your question.
Click to expand...

Hi.

Thank you for your reply. Dr. Shields from NCAR gave me good advice on how to set up POP and sent me the fortran code for offline moc calculation.

In order to calculate MOC online (for my (paleo)geographical configuration), I needed to modify 'lat_aux_grid_type' , 'lat_aux_begin', 'lat_aux_end', 'n_lat_aux_grid' and 'n_transport_reg' in my pop_in.

I also calculated MOC offline using the fortran code. I calculated two differen ways: using (1)VVEL and UVEL and (2) WVEL . These two results were almost identical. Just for my curiosity, in your opinion, which one produces more accurate results?

Thank you. Also, I'd like to thank Dr. Shields' help.


Young
 
B

bates

Member
I have spoken with an MOC expert here at NCAR (I am the ocean model science liaison here at NCAR) and here is the answer I got to your question:

Either method you use should be near equivalent in accuracy. MOC can be computed either by
integrating VVEL or by integrating WVEL appropriately. Either way will work in the Atlantic interior; BUT, at the southern boundary of the Atlantic (30S), VVEL must be used to get inflow/outflow through the southern latitude wall.

Hope this helps!
Susan
 
L

lehner@climate_unibe_ch

New Member
Young said:
Thank you for your reply. Dr. Shields from NCAR gave me good advice on how to set up POP and sent me the fortran code for offline moc calculation.

In order to calculate MOC online (for my (paleo)geographical configuration), I needed to modify 'lat_aux_grid_type' , 'lat_aux_begin', 'lat_aux_end', 'n_lat_aux_grid' and 'n_transport_reg' in my pop_in.

I also calculated MOC offline using the fortran code. I calculated two differen ways: using (1)VVEL and UVEL and (2) WVEL . These two results were almost identical. Just for my curiosity, in your opinion, which one produces more accurate results?
Click to expand...

Is this fortran code available on the NCAR homepage or through some other channels?

Appreciate it,
Flavio
 
zdliu

zdliu

Member
Dear Susan,Now I want to get the fortran code for offline MOC calculation , so would you like to email it to me? (and my email is : zdliu@ouc.edu.cn)And I am using CESM1.0.Thanks.zedong
 
zdliu

zdliu

Member
Dear Suan，Thank you very much. I knew the NCL script, and I have used it for calculation once. But there is a question, for example, I use the tx0.1v2 POP, there is no MOC output, so I cannot find the template of MOC and its associated auxilary latitudinal grid(lat_aux_grid). Before, I choosed some arbitrary lat_aux_grid, such as (-90:0.1:90), but the result of MOC is very different with the grid I choosed. So would you give me some comments about how to choose the lat_aux_grid?And also I have noticed that in the cesm/pop code there are some routines to compute some diagnostics on an auxilary latitudinal grid, so now I am now working hard at the fortran code.
Thanks again.
zedong
131004
 
A

afrigola@marum_de

New Member
Dear all, I would need to adapt the function moc_globe_atl.shtml to get it working for CCSM3. This function uses model output variables such as: WISOP, WSUBM, VISOP, VSUBM, which are not available from CCSM3. I would also like to ask whether this function is appropriate for runs with a region_mask and kmt files significantly different from present day. I am only interested in calculating Global MOC (not AMOC),  maybe this is an important detail to answer the question.Any help would be appreciated.Best wishes,Amanda
 
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