SST increases unreasonably when run nemo with ERA5 data

Versions v4.2.x
1

Hello, I am doing the global simulation and running the NEMO with ERA5 data. I found the simulation results looks unreasonably in my experiment. Everything went well when I did the spin up with ncar. This is the setting what I use to do spinup

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The tos from spinup is attached here
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After 40 years spinup, I change the atmosphere data to ERA5 data. This is the setting.

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the value is unreasonable after I change the data
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The Anartic Ocean looks crazy warm in my output.

Has anyone met this issue before? Has anyone had experience running nemo with ERA5 data?
I would appreciate anyone could help me out or give me some advice. Thanks in advance!

2

Hei,

The name of your ERA5 files suggests it is hourly data, but then the frequency in hours is set to 3 ?

/robinson

3

Hi robinson,

thanks for your reply！Actually, the ERA5 data is 3 hourly. Sorry for the confusing name.

4

ok, so I’m comparing to my namelist (i also use ERA5), you have set time interp to false, and climatology to true, which are both strange choices since it is a re-analysis.
Then there are all these choices of skin parametrization that i do not have in my nemo version, and also i cannot use dew point temp instead of specific humidity in my namelist. Is this temperature in the right unit for example ?

5

Hi robinson, can you share me your namelist?

6

Have you checked that your weights files are giving you the correct interpolation on the fly? ERA5 has a known warm bias in the Arctic; wonder if your fields are upside down?

7

Hi, the problem is solved. The reason is that Nemo keeps reading the first time step of the atmosphere forcing data during the simulation. I checked the input data and found that my data has a fixed time dimension. The problem was solved after I changed the time dimension to unlimited although I do not really know why it happens like that. Anyway, Thanks for your reply！

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