[MITgcm-support] issues with SST/SSS restoring and OBCS in EXF package

[Martin Losch]

Hi Andreas,

when you uncomment
# useExfCheckRange  = .TRUE.,
does the model complain about weird forcing values?

Wild guess: you use
>  exf_iprec         = 32,
>  exf_iprec_obcs    = 32,
are your input fields really 32 bit (and you used readBinaryPrec=32 in data&PARM01)?

Then, if you use the same files, readStressOnAgrid should be false, shouldn’t it? without exf the model expects the forcing to be on the appropriate grid points, ie. U and V points for stress.

Not important but I think you don’t  need to set ustressRepCycle etc to the same value if you set  repeatPeriod=31104000.

Martin

> On 22. Jan 2021, at 08:02, Andreas Klocker <aklocker42 at gmail.com> wrote:
> 
> Hi all,
> 
> I'm having some issues with the EXF package which I just can't understand. Maybe one of you can help.
> 
> I am running a regional model configuration using the OBCS package. In my first experiment I set
> 
> periodicExternalForcing=.TRUE.,
> externForcingPeriod=2592000.,
> externForcingCycle=31104000.,
> tauThetaClimRelax = 864000.,
> tauSaltClimRelax = 2592000.,
> 
> in the data file, i.e. I restore surface T/S with above restoring time scale/forcing period/forcing cycle. This works fine. 
> 
> Then I wanted to add sea ice to my open boundary conditions which, if I understand correctly, means that I have to use the EXF package to set the restoring time scale/forcing period/forcing cycle. To move forward in baby steps, I didn't use sea ice yet, but just tried to let the EXF package do exactly the same as the restoring and obcs did before I switched to the EXF package. See below for my data.exf file. But when I try and run this, the solver immediately writes NaNs, despite me using the same initial conditions, obcs files,  and restoring files as before. I would have thought that both ways of using OBCS and restoring should give the same results, but one runs fine while the other one crashes immediately without me being able to find the issue.
> 
> Please let me know if anyone is seeing something I'm doing wrong here.
> 
> Thanks in advance!
> 
> Andreas Klocker
> 
> 
> #
> # *********************
> # External Forcing Data
> # *********************
>  &EXF_NML_01
> #
> # useExfCheckRange  = .TRUE.,
> # repeatPeriod      = 2592000.0,
>  exf_iprec         = 32,
>  exf_iprec_obcs    = 32,
>  useAtmWind=.FALSE.,
>  readStressOnAgrid=.TRUE.,
> #
>  &
> 
> # *********************
>  &EXF_NML_02
> #
>  ustressstartdate1 = 19790101,
>  ustressstartdate2 = 000000,
>  ustressperiod     = 2592000.0,
>  ustressRepCycle   = 31104000.,
> #
>  vstressstartdate1 = 19790101,
>  vstressstartdate2 = 000000,
>  vstressperiod     = 2592000.0,
>  vstressRepCycle   = 31104000.,
> #
>  climsststartdate1  = 19790101,
>  climsststartdate2  = 000000,
>  climsstperiod      = 2592000.0,
>  climsstTauRelax    = 2592000.0,
>  climsstRepCycle    = 31104000.,
> #
>  climsssstartdate1  = 19790101,
>  climsssstartdate2  = 00000,
>  climsssperiod      = 2592000.0,
>  climsssTauRelax    = 864000.0,
>  climsssRepCycle    = 31104000.,
> #
>  ustressfile       = 'TauX_BSOSE ',
>  vstressfile       = 'TauY_BSOSE ',
>  climsstfile       = 'SST_BSOSE.res ',
>  climsssfile       = 'SSS_BSOSE.res',
> #
>  &
> 
> # *********************
>  &EXF_NML_03
>  &
> 
> # *********************
> # old open64 compiler (4.2.1) cannot skip this namelist to read in the next one;
> # comment out this namelist (not read).
> #&EXF_NML_04
> #&
> 
> # *********************
>  &EXF_NML_OBCS
> 
> # useOBCSYearlyFields = .TRUE.,
> 
>  obcsSstartdate1   = 19790101,
>  obcsSstartdate2   = 000000,
>  obcsSperiod       = 2592000.0,
>  obcsSRepCycle     = 31104000.,
> #
>  obcsNstartdate1   = 19790101,
>  obcsNstartdate2   = 000000,
>  obcsNperiod       = 2592000.0,
>  obcsNRepCycle     = 31104000.,
> #
>  obcsWstartdate1   = 19790101,
>  obcsWstartdate2   = 000000,
>  obcsWperiod       = 2592000.0,
>  obcsWRepCycle     = 31104000.,
> #
>  obcsEstartdate1   = 19790101,
>  obcsEstartdate2   = 000000,
>  obcsEperiod       = 2592000.0,
>  obcsERepCycle     = 31104000.,
> #
>  &
> 
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