[MITgcm-support] Questions about the calculation method of downloaded wind stress data(tau) on LLC4320 MITgcm website

[刘钰勋]

Hi everyone,



I want to calculate wind work on ocean surface currents in LLC4320 MITgcm model. I downloaded the wind stress from the model data list on the website, but I am not sure how it is calculated in the model.

Some papers about LLC4320 model introduce that 10-m wind velocities are from the 0.14°/6 h ECMWF atmospheric operational model analysis and are converted to surface fluxes using the bulk formulae of Large and Yeager 2004 (/tau =ρa * Cd * |ΔU|*ΔU, where \tau is the wind stress and ΔU is the difference between the 10-m wind and sea surface current).

I tried to confirm this calculation method, so I linearly interpolated ECMWF 10-m wind data into the resolution of the surface velocity u in the 4320 model. Then I used LY04's method to calculate wind stress. The temporal trend of the calculated results was consistent with the downloaded data. But my results seem to be ahead of the downloaded wind stress by a lag of 6 hours.

My question is how the 4320 model calculated the wind stress affect the ocean surface. I am confused because the U_ocean in the model is affected by the wind stress, but wind stress is calculated using the U_ocean and U_wind. In the 4320 model, does it calculate U_ocean first, then calculate \tau, and then calculate the effect of \tau on U_ocean? How long is the calculation interval?

Thank you for your time and patience!

Sincerely,

Yuxun
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