Use of 2D ocean surface pco2

Dear Users,

Question of using time-dependent 2D ocean surface pco2 make any difference?
The following figs show the results of the ocean surface CO2 flux by running a version of NEMO 4.0 with the default 2.0 deg resolution forced with ERA5 reanalysis. JMA’s monthly 2D ocean surface pCO2 Map dataset was used in one run, while in another run NOAA’s annual constant values of pco2 were used.

fig.1 Total_flux_of_carbon_out_of_ocn_w_NOAA.cnst.and.w_JMA_w_ERA_s0m_yrmean_yr1985-2021.png

fig.2 DIFF_CO2flx_w-wo_JMA_w_ERA_s0m_yrmean_x12_xy_yr2021.png

The differences are small but how significant are they?

My question is that if the similar experimets were done using a higher resolution configuration such as 0.5 x 0.5 deg, the patterns of the co2 flux would be much different? Perhaps, someone already has done such experiments.


If anyone is interested in doing the similar experiments using a higher model resolution, I’d gladly provide the JMA monthly 2D atmospheric pco2 forcing files that I prepared to run v4 R2 default configuration model.

Hi ukocean, with how many vertical layers did you run your experiment? or did you just run it with the surface layer?. Many thx for you response :slight_smile:

Hi Else,

I used a version of NEMO V4.0 with the default configuration 2x2 deg horizontal grid and
31 vertical levels. I wanted to see if using 2D monthly atmospheric pco2 instead of annual
constant atmospheric pco2 used in NEMO V3.6 will make any differences in the CO2 flux out of the ocean.
With NEMO V4.0 you can use 2D time-dependent atmospheric pco2, while with V3.6 you can use
only annual constant atmospheric pco2.

My finding is that the differences in the amount of global CO2 flux out of the ocean in two cases
are small, but regionally there are locations where it makes some significant differences.
But my experiments were done using the default 2x2-deg, 31-level configuration, so I wondered
if the outcome might be different if the experiments were done using a higher-resolution model
configuration such as a 0.5x0.5 deg horizontal grid.

I’m having difficulties implementing the NEMO V4 with higher spatial resolutions, and that is where
I’m stuck now.

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