# Trcrad: Bug in ocean.output regarding tracer conservation

**URL:** <https://nemo-ocean.discourse.group/t/trcrad-bug-in-ocean-output-regarding-tracer-conservation/762>\
**Category:** v4.2.x\
**Created:** [25 September 2024 07:54 UTC](https://nemo-ocean.discourse.group/t/trcrad-bug-in-ocean-output-regarding-tracer-conservation/762 "2024-09-25T07:54:12Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![mchoblet](https://yyz2.discourse-cdn.com/free1/user_avatar/nemo-ocean.discourse.group/mchoblet/32/230_2.png) [@mchoblet](https://nemo-ocean.discourse.group/u/mchoblet)\
**Post date:** [25 September 2024 07:54 UTC](https://nemo-ocean.discourse.group/t/trcrad-bug-in-ocean-output-regarding-tracer-conservation/762/1 "2024-09-25T07:54:12Z")

</div>

Good morning,

We noticed a small bug regarding the ocean.output lines written by the trcrad routine ([src/TOP/TRP/trcrad.F90 · main · NEMO Workspace / Nemo · GitLab](https://forge.nemo-ocean.eu/nemo/nemo/-/blob/main/src/TOP/TRP/trcrad.F90?ref_type=heads)). I’m reporting it here before opening an issue on the gitlab as requested.

In line 105:  
` IF( ln_trcrad ) THEN ; WRITE(numout,*) ' ===>> ensure the global tracer conservation'`,

the model writes that global tracer conservation is ensured when using trcrad. However, this is only the case if the PISCES biogeochemical model is used, because in

` SUBROUTINE trc_rad_sms( kt, Kbb, Kmm, ptr, jp_sms0, jp_sms1, cpreserv )`',

cpreserv, which activates the conservative correction is only used with PISCES.  
` IF( ln_pisces ) CALL trc_rad_sms( kt, Kbb, Kmm, ptr, jp_pcs0, jp_pcs1, cpreserv='Y' ) ! PISCES model`  
`IF( ln_my_trc ) CALL trc_rad_sms( kt, Kbb, Kmm, ptr, jp_myt0, jp_myt1 ) ! MY_TRC model `

Note also, that setting negative concentrations exactly to zero as done by the default trcrad routine causes our biogeochemical model to produce NaNs, which is why I use a slightly modified version with a small number instead (e-12). Thanks!