# Vertical turbulent fluxes from NEMO

**URL:** <https://nemo-ocean.discourse.group/t/vertical-turbulent-fluxes-from-nemo/425>\
**Category:** v4.2.x\
**Created:** [14 January 2023 11:54 UTC](https://nemo-ocean.discourse.group/t/vertical-turbulent-fluxes-from-nemo/425 "2023-01-14T11:54:29Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![qtqw](https://avatars.discourse-cdn.com/v4/letter/q/77aa72/32.png) [@qtqw](https://nemo-ocean.discourse.group/u/qtqw)\
**Post date:** [14 January 2023 11:54 UTC](https://nemo-ocean.discourse.group/t/vertical-turbulent-fluxes-from-nemo/425/1 "2023-01-14T11:54:29Z")

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Is it possible to output vertical fluxes of heat, density and salinity (calculated in NEMO) to NetCDF output files?

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**Author:** ![robinson](https://avatars.discourse-cdn.com/v4/letter/r/848f3c/32.png) [@robinson](https://nemo-ocean.discourse.group/u/robinson)\
**Post date:** [14 January 2023 15:30 UTC](https://nemo-ocean.discourse.group/t/vertical-turbulent-fluxes-from-nemo/425/2 "2023-01-14T15:30:10Z")

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It depends what you mean, but you can output trends in vertical diffusion of T or S. Check trdtra.F90.

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**Author:** ![qtqw](https://avatars.discourse-cdn.com/v4/letter/q/77aa72/32.png) [@qtqw](https://nemo-ocean.discourse.group/u/qtqw)\
**Post date:** [14 January 2023 19:32 UTC](https://nemo-ocean.discourse.group/t/vertical-turbulent-fluxes-from-nemo/425/3 "2023-01-14T19:32:57Z")

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I mean flux variables, which is calculated as follows:  
flux\_t = - avt \* grad\_t  
flux\_s = -avs \* grad\_s,  
where avt, avs - vertical coefficients,  
grad\_t, grad\_s - vertical gradients of temperature and salinity

From trdtra.F90 it seems that ttrd\_evd and strd\_evd are the flux variables I need.  
Am I correct?

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<div class="post-metadata">

**Author:** ![robinson](https://avatars.discourse-cdn.com/v4/letter/r/848f3c/32.png) [@robinson](https://nemo-ocean.discourse.group/u/robinson)\
**Post date:** [15 January 2023 07:50 UTC](https://nemo-ocean.discourse.group/t/vertical-turbulent-fluxes-from-nemo/425/4 "2023-01-15T07:50:09Z")

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The trends in trdtra are the time variation of the process for T & S, which equals the divergence of fluxes for a given grid cell. But if you start from the bottom grid cell upward I guess you can deduct the fluxes as you define them  
Then which variable you need is a big question, it depends a bit what you want to include or not. ttrd\_zdf  
seems the obvious choice, but it is not purely vertical. ttrd\_zdfp is better I guess. ttrd\_evd is for convection (when N2 becomes negative), so not related with avt/avs computed by the vertical turbulence model.