# \[v4.2.x\] BUG Double allocation of memory in bdydyn ln\_trddyn=true

**URL:** https://nemo-ocean.discourse.group/t/v4-2-x-bug-double-allocation-of-memory-in-bdydyn-ln-trddyn-true/938
**Category:** v4.2.x
**Created:** [8 August 2025 16:19 UTC](https://nemo-ocean.discourse.group/t/v4-2-x-bug-double-allocation-of-memory-in-bdydyn-ln-trddyn-true/938 "2025-08-08T16:19:35Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![johannestimm](https://avatars.discourse-cdn.com/v4/letter/j/5f9b8f/32.png) [@johannestimm](https://nemo-ocean.discourse.group/u/johannestimm)
#### Post date: [8 August 2025 16:19 UTC](https://nemo-ocean.discourse.group/t/v4-2-x-bug-double-allocation-of-memory-in-bdydyn-ln-trddyn-true/938/1 "2025-08-08T16:19:35Z")

</div>

In the current 4.2 branch my colleague and I found the following bug.IT seems to be recently introduced with [Update Momentum Trends to Work with Split Explicit Timestepping (6a1e8701) · Commits · NEMO Workspace / Nemo · GitLab](https://forge.nemo-ocean.eu/nemo/nemo/-/commit/6a1e8701dfb8259abe9b6e865710f80ce92d455c)

On first glance it doesn’t seem to be included in the 5 branch.

In the bdydyn.F90 there are two times calls to ALLOCATE zbdytrdu and zbdytrdv.

If one runs a configuration with l\_trddyn and ll\_dyn3d nemo crashes due to trying to allocate the fields twice.

Furthermore the definitions for :

maxdzT ,utrd\_bdy,utrd\_bdy2d,utrd\_bdy\_e3u,utrd\_bdy2d\_hu,vtrd\_bdy,vtrd\_bdy2d,vtrd\_bdy\_e3v,vtrd\_bdy2d\_hu

are forgotten to be provided in the cfgs/SHARED/field\_def\_nemo-oce.xml which are required for the xios calls in trddyn.F90

For our setup we now use the following modified version of bdydyn.f90 and field\_def\_nemo-oce.xml

> **bdydyn.f90**
>
> ```auto
> MODULE bdydyn
> !!======================================================================
> !! ***MODULE bdydyn***
> !! Unstructured Open Boundary Cond. : Apply boundary conditions to velocities
> !!======================================================================
> !! History : 1.0 ! 2005-02 (J. Chanut, A. Sellar) Original code
> !! - ! 2007-07 (D. Storkey) Move Flather implementation to separate routine.
> !! 3.0 ! 2008-04 (NEMO team) add in the reference version
> !! 3.2 ! 2008-04 (R. Benshila) consider velocity instead of transport 
> !! 3.3 ! 2010-09 (E.O'Dea) modifications for Shelf configurations 
> !! 3.3 ! 2010-09 (D.Storkey) add ice boundary conditions
> !! 3.4 ! 2011 (D. Storkey) rewrite in preparation for OBC-BDY merge
> !!----------------------------------------------------------------------
> !! bdy_dyn : split velocities into barotropic and baroclinic parts
> !! and call bdy_dyn2d and bdy_dyn3d to apply boundary
> !! conditions
> !!----------------------------------------------------------------------
> USE oce ! ocean dynamics and tracers 
> USE dom_oce ! ocean space and time domain
> USE bdy_oce ! ocean open boundary conditions
> USE bdydyn2d ! open boundary conditions for barotropic solution
> USE bdydyn3d ! open boundary conditions for baroclinic velocities
> USE lbclnk ! ocean lateral boundary conditions (or mpp link)
> USE in_out_manager !
> USE domvvl ! variable volume
> USE trd_oce ! trends: ocean variables
> USE trddyn ! trend manager: dynamics
> 
> IMPLICIT NONE
> PRIVATE
> 
> PUBLIC bdy_dyn ! routine called in dyn_nxt
> 
> !! * Substitutions
> # include "domzgr_substitute.h90"
> !!----------------------------------------------------------------------
> !! NEMO/OCE 4.0 , NEMO Consortium (2018)
> !! $Id: bdydyn.F90 13237 2020-07-03 09:12:53Z smasson $ 
> !! Software governed by the CeCILL license (see ./LICENSE)
> !!----------------------------------------------------------------------
> CONTAINS
> 
> SUBROUTINE bdy_dyn( kt, Kbb, puu, pvv, Kaa, dyn3d_only )
> !!----------------------------------------------------------------------
> !! ***SUBROUTINE bdy_dyn***
> !!
> !! ** Purpose : - Wrapper routine for bdy_dyn2d and bdy_dyn3d.
> !!
> !!----------------------------------------------------------------------
> INTEGER , INTENT(in) :: kt ! Main time step counter
> INTEGER , INTENT(in) :: Kbb, Kaa ! Ocean time level indices
> REAL(dp), DIMENSION(jpi,jpj,jpk,jpt), INTENT(inout) :: puu, pvv ! Ocean velocities (to be updated at open boundaries)
> LOGICAL, OPTIONAL , INTENT(in) :: dyn3d_only ! T => only update baroclinic velocities
> !
> INTEGER :: jk, ii, ij, ib_bdy, ib, igrd ! Loop counter
> LOGICAL :: ll_dyn2d, ll_dyn3d, ll_orlanski
> REAL(wp), ALLOCATABLE, DIMENSION(:,:,:) :: ua_tmp, va_tmp ! RDP: temporary save of 2d momentum
> REAL(wp), DIMENSION(jpi,jpj) :: zua2d, zva2d ! after barotropic velocities
> REAL(wp), ALLOCATABLE, DIMENSION(:,:,:) :: zbdytrdu, zbdytrdv ! bdy trends
> !!----------------------------------------------------------------------
> !
> ll_dyn2d = .true.
> ll_dyn3d = .true.
> !
> IF( PRESENT(dyn3d_only) ) THEN
> IF( dyn3d_only ) ll_dyn2d = .false.
> ENDIF
> !
> IF ( l_trddyn ) THEN
> IF ( ll_dyn3d ) THEN
> ! ALLOCATE( zbdytrdu(jpi,jpj,jpk), zbdytrdv(jpi,jpj,jpk) )
> IF (.NOT. ALLOCATED ( zbdytrdu) ) THEN 
> ALLOCATE( zbdytrdu(jpi,jpj,jpk) )
> zbdytrdu(:,:,:) = 0._wp
> ENDIF     
> IF (.NOT. ALLOCATED ( zbdytrdv) ) THEN
> ALLOCATE( zbdytrdv(jpi,jpj,jpk) )
> zbdytrdv(:,:,:) = 0._wp
> ENDIF  
> ENDIF
> ENDIF
> 
> ll_orlanski = .false.
> DO ib_bdy = 1, nb_bdy
> IF ( cn_dyn2d(ib_bdy) == 'orlanski' .OR. cn_dyn2d(ib_bdy) == 'orlanski_npo' &
> & .OR. cn_dyn3d(ib_bdy) == 'orlanski' .OR. cn_dyn3d(ib_bdy) == 'orlanski_npo') ll_orlanski = .true.
> END DO
> 
> IF ( l_trddyn ) THEN
> IF (.NOT. ALLOCATED ( zbdytrdu) ) THEN 
> ALLOCATE( zbdytrdu(jpi,jpj,jpk) )
> zbdytrdu(:,:,:) = puu(:,:,:,Kaa)
> ENDIF    
> IF (.NOT. ALLOCATED ( zbdytrdv) ) THEN 
> ALLOCATE( zbdytrdv(jpi,jpj,jpk) )
> zbdytrdv(:,:,:) = pvv(:,:,:,Kaa)
> ENDIF           
> ENDIF
> 
> !-------------------------------------------------------
> ! Split velocities into barotropic and baroclinic parts
> !-------------------------------------------------------
> 
> ! ! "After" velocities: 
> zua2d(:,:) = 0._wp
> zva2d(:,:) = 0._wp     
> DO jk = 1, jpkm1
> zua2d(:,:) = zua2d(:,:) + e3u(:,:,jk,Kaa) * puu(:,:,jk,Kaa) * umask(:,:,jk)
> zva2d(:,:) = zva2d(:,:) + e3v(:,:,jk,Kaa) * pvv(:,:,jk,Kaa) * vmask(:,:,jk)
> END DO
> zua2d(:,:) = zua2d(:,:) * r1_hu(:,:,Kaa)
> zva2d(:,:) = zva2d(:,:) * r1_hv(:,:,Kaa)
> 
> DO jk = 1 , jpkm1
> puu(:,:,jk,Kaa) = ( puu(:,:,jk,Kaa) - zua2d(:,:) ) * umask(:,:,jk)
> pvv(:,:,jk,Kaa) = ( pvv(:,:,jk,Kaa) - zva2d(:,:) ) * vmask(:,:,jk)
> END DO
> 
> IF( ll_orlanski ) THEN ! "Before" velocities (Orlanski condition only) 
> DO jk = 1 , jpkm1
> puu(:,:,jk,Kbb) = ( puu(:,:,jk,Kbb) - uu_b(:,:,Kbb) ) * umask(:,:,jk)
> pvv(:,:,jk,Kbb) = ( pvv(:,:,jk,Kbb) - vv_b(:,:,Kbb) ) * vmask(:,:,jk)
> END DO
> ENDIF
> 
> !-------------------------------------------------------
> ! Apply boundary conditions to barotropic and baroclinic
> ! parts separately
> !-------------------------------------------------------
> 
> IF( ll_dyn2d ) CALL bdy_dyn2d( kt, zua2d, zva2d, uu_b(:,:,Kbb), vv_b(:,:,Kbb), r1_hu(:,:,Kaa), r1_hv(:,:,Kaa), ssh(:,:,Kaa) )
> 
> IF( ll_dyn3d ) CALL bdy_dyn3d( kt, Kbb, puu, pvv, Kaa )
> 
> !-------------------------------------------------------
> ! Recombine velocities
> !-------------------------------------------------------
> !
> DO jk = 1 , jpkm1
> puu(:,:,jk,Kaa) = ( puu(:,:,jk,Kaa) + zua2d(:,:) ) * umask(:,:,jk)
> pvv(:,:,jk,Kaa) = ( pvv(:,:,jk,Kaa) + zva2d(:,:) ) * vmask(:,:,jk)
> END DO
> !
> IF ( ll_orlanski ) THEN
> DO jk = 1 , jpkm1
> puu(:,:,jk,Kbb) = ( puu(:,:,jk,Kbb) + uu_b(:,:,Kbb) ) * umask(:,:,jk)
> pvv(:,:,jk,Kbb) = ( pvv(:,:,jk,Kbb) + vv_b(:,:,Kbb) ) * vmask(:,:,jk)
> END DO
> END IF
> !
> IF ( l_trddyn ) THEN
> zbdytrdu(:,:,:) = ( puu(:,:,:,Kaa) - zbdytrdu(:,:,:) ) * r1_Dt
> zbdytrdv(:,:,:) = ( pvv(:,:,:,Kaa) - zbdytrdv(:,:,:) ) * r1_Dt
> CALL trd_dyn( zbdytrdu, zbdytrdv, jpdyn_bdy, kt )
> DEALLOCATE( zbdytrdu, zbdytrdv )
> ENDIF
> 
> END SUBROUTINE bdy_dyn
> 
> !!======================================================================
> END MODULE bdydyn
> 
> ```

> **additions to field\_def\_nemo-oce.xml**
>
> ```auto
> 
> <!-- next variables available with key_diahth -->
> <field id="mlddzt" long_name="Thermocline Depth (depth of max dT/dz)" standard_name="depth_at_maximum_upward_derivative_of_sea_water_potential_temperature" unit="m" />
> <field id="maxdzT" long_name="Maximum of dT/dz)" standard_name="maximum_upward_derivative_of_sea_water_potential_temperature" unit="degC/m" />
> <field id="mldr10_3" long_name="Mixed Layer Depth (dsigma = 0.03 wrt 10m)" standard_name="ocean_mixed_layer_thickness_defined_by_sigma_theta" unit="m" />
> 
> <field_group id="trendU" grid_ref="grid_U_3D">
> <!-- variables available with ln_dyn_trd -->
> <field id="hu" long_name="total time-varying depth at U-points" unit="m" grid_ref="grid_U_2D" />
> <field id="utrd_hpg" long_name="i-trend: hydrostatic pressure gradient" unit="m/s^2" />
> <field id="utrd_spg2d" long_name="i-trend: surface pressure gradient: true trend" unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_keg" long_name="i-trend: KE gradient or hor. adv." unit="m/s^2" />
> <field id="utrd_rvo" long_name="i-trend: relative vorticity or metric term" unit="m/s^2" />
> <field id="utrd_pvo" long_name="i-trend: planetary vorticity: 3D component" unit="m/s^2" />
> <field id="utrd_pvo2d" long_name="i-trend: planetary vorticity: 2D component" unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_zad" long_name="i-trend: vertical advection" unit="m/s^2" />
> <field id="utrd_udx" long_name="i-trend: U.dx[U]" unit="m/s^2" />
> <field id="utrd_ldf" long_name="i-trend: lateral diffusion" unit="m/s^2" />
> <field id="utrd_zdf" long_name="i-trend: vertical diffusion" unit="m/s^2" />
> <field id="utrd_frc2d" long_name="i-trend: barotropic constant forcing " unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_tau" long_name="i-trend: wind stress in top layer " unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_tau2d" long_name="i-trend: wind stress: 2D component " unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_bfr" long_name="i-trend: bottom friction (3D) in bottom layer" unit="m/s^2" />
> <field id="utrd_bfr2d" long_name="i-trend: bottom friction: 2D component" unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_tfr" long_name="i-trend: top friction (3D) in top layer" unit="m/s^2" />
> <field id="utrd_tfr2d" long_name="i-trend: top friction: 2D component" unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_tot" long_name="i-trend: total momentum trend before atf" unit="m/s^2" />
> <field id="utrd_tot2d" long_name="i-trend: total momentum trend before atf: 2D component" unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_atf" long_name="i-trend: asselin time filter trend" unit="m/s^2" />
> <field id="utrd_atm2d" long_name="i-trend: atmospheric pressure: 2D component " unit="m/s^2" grid_ref="grid_U_2D" />
> <field id="utrd_bdy" long_name="i-trend: lateral boundary forcing" unit="m/s^2" />
> <field id="utrd_bdy2d" long_name="i-trend: lateral boundary forcing: 2D component " unit="m/s^2" grid_ref="grid_U_2D" />
> <!-- thickness weighted versions -->
> <field id="utrd_hpg_e3u" unit="m2/s^2" > utrd_hpg * e3u </field>
> <field id="utrd_keg_e3u" unit="m2/s^2" > utrd_keg * e3u </field>
> <field id="utrd_rvo_e3u" unit="m2/s^2" > utrd_rvo * e3u </field>
> <field id="utrd_pvo_e3u" unit="m2/s^2" > utrd_pvo * e3u </field>
> <field id="utrd_zad_e3u" unit="m2/s^2" > utrd_zad * e3u </field>
> <field id="utrd_ldf_e3u" unit="m2/s^2" > utrd_ldf * e3u </field>
> <field id="utrd_zdf_e3u" unit="m2/s^2" > utrd_zdf * e3u </field>
> <field id="utrd_tot_e3u" unit="m2/s^2" > utrd_tot * e3u </field>
> <field id="utrd_atf_e3u" unit="m2/s^2" > utrd_atf * e3u </field>
> <field id="utrd_bfr_e3u" unit="m2/s^2" > utrd_bfr * e3u </field>
> <field id="utrd_tfr_e3u" unit="m2/s^2" > utrd_tfr * e3u </field>
> <field id="utrd_bdy_e3u" unit="m2/s^2" > utrd_bdy * e3u </field>
> <field id="utrd_spg2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_spg2d * hu </field>
> <field id="utrd_pvo2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_pvo2d * hu </field>
> <field id="utrd_frc2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_frc2d * hu </field>
> <field id="utrd_tau2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_tau2d * hu </field>
> <field id="utrd_tfr2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_tfr2d * hu </field>
> <field id="utrd_bfr2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_bfr2d * hu </field>
> <field id="utrd_tot2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_tot2d * hu </field>
> <field id="utrd_atm2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_atm2d * hu </field>
> <field id="utrd_bdy2d_hu" unit="m2/s^2" grid_ref="grid_U_2D" > utrd_bdy2d * hu </field>
> </field_group>
> 
> <field_group id="trendV" grid_ref="grid_V_3D">
> <!-- variables available with ln_dyn_trd -->
> <field id="hv" long_name="total time-varying depth at V-points" unit="m" grid_ref="grid_V_2D" />
> <field id="vtrd_hpg" long_name="j-trend: hydrostatic pressure gradient" unit="m/s^2" />
> <field id="vtrd_spg2d" long_name="j-trend: surface pressure gradient: true trend" unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_keg" long_name="j-trend: KE gradient or hor. adv." unit="m/s^2" />
> <field id="vtrd_rvo" long_name="j-trend: relative vorticity or metric term" unit="m/s^2" />
> <field id="vtrd_pvo" long_name="j-trend: planetary vorticity: 3D component" unit="m/s^2" />
> <field id="vtrd_pvo2d" long_name="j-trend: planetary vorticity: 2D component" unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_zad" long_name="j-trend: vertical advection" unit="m/s^2" />
> <field id="vtrd_vdy" long_name="j-trend: V.dx[V]" unit="m/s^2" />
> <field id="vtrd_ldf" long_name="j-trend: lateral diffusion" unit="m/s^2" />
> <field id="vtrd_zdf" long_name="j-trend: vertical diffusion" unit="m/s^2" />
> <field id="vtrd_frc2d" long_name="j-trend: barotropic constant forcing " unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_tau" long_name="j-trend: wind stress in top layer " unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_tau2d" long_name="j-trend: wind stress: 2D component " unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_bfr" long_name="j-trend: bottom friction (3D) in bottom layer" unit="m/s^2" />
> <field id="vtrd_bfr2d" long_name="j-trend: bottom friction: 2D component" unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_tfr" long_name="j-trend: top friction (3D) in top layer" unit="m/s^2" />
> <field id="vtrd_tfr2d" long_name="j-trend: top friction: 2D component" unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_tot" long_name="j-trend: total momentum trend before atf" unit="m/s^2" />
> <field id="vtrd_tot2d" long_name="j-trend: total momentum trend before atf: 2D component" unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_atf" long_name="j-trend: asselin time filter trend" unit="m/s^2" />
> <field id="vtrd_atm2d" long_name="j-trend: atmospheric pressure: 2D component " unit="m/s^2" grid_ref="grid_V_2D" />
> <field id="vtrd_bdy" long_name="j-trend: lateral boundary forcing" unit="m/s^2" />
> <field id="vtrd_bdy2d" long_name="j-trend: lateral boundary forcing: 2D component " unit="m/s^2" grid_ref="grid_V_2D" />
> <!-- thickness weighted versions -->
> <field id="vtrd_hpg_e3v" unit="m2/s^2" > vtrd_hpg * e3v </field>
> <field id="vtrd_keg_e3v" unit="m2/s^2" > vtrd_keg * e3v </field>
> <field id="vtrd_rvo_e3v" unit="m2/s^2" > vtrd_rvo * e3v </field>
> <field id="vtrd_pvo_e3v" unit="m2/s^2" > vtrd_pvo * e3v </field>
> <field id="vtrd_zad_e3v" unit="m2/s^2" > vtrd_zad * e3v </field>
> <field id="vtrd_ldf_e3v" unit="m2/s^2" > vtrd_ldf * e3v </field>
> <field id="vtrd_zdf_e3v" unit="m2/s^2" > vtrd_zdf * e3v </field>
> <field id="vtrd_tot_e3v" unit="m2/s^2" > vtrd_tot * e3v </field>
> <field id="vtrd_atf_e3v" unit="m2/s^2" > vtrd_atf * e3v </field>
> <field id="vtrd_bfr_e3v" unit="m2/s^2" > vtrd_bfr * e3v </field>
> <field id="vtrd_tfr_e3v" unit="m2/s^2" > vtrd_tfr * e3v </field>
> <field id="vtrd_bdy_e3v" unit="m2/s^2" > vtrd_bdy * e3v </field>
> <field id="vtrd_spg2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_spg2d * hv </field>
> <field id="vtrd_pvo2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_pvo2d * hv </field>
> <field id="vtrd_frc2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_frc2d * hv </field>
> <field id="vtrd_tau2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_tau2d * hv </field>
> <field id="vtrd_tfr2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_tfr2d * hv </field>
> <field id="vtrd_bfr2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_bfr2d * hv </field>
> <field id="vtrd_tot2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_tot2d * hv </field>
> <field id="vtrd_atm2d_hv" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_atm2d * hv </field>
> <field id="vtrd_bdy2d_hu" unit="m2/s^2" grid_ref="grid_V_2D" > vtrd_bdy2d * hv </field>
> </field_group>
> 
> ```