Issues with Maintaining Ocean Stratification Using Climatology and Nudging in Idealized Model

[hyc006]

Hello ROMS Community,

I am encountering an issue with maintaining ocean stratification over time in my idealized model. Despite using climatology data and applying nudging, the ocean becomes unstratified after approximately 30 days (My total model time is about 120 days). I am confident that the model is correctly reading the climatology data, so I suspect the issue might lie within the nudging settings.
My model domain is for a circle island in shallow ocean, the bathymetry of the domain look like this: (x and y axis are longitude and latitude)

Below are the relevant settings from my .h and .in files:

From .h file:

Code: Select all

/* Add nudging to climate data*/
#define ANA_TCLIMA  
#define ANA_NUDGCOEF 

for using analytical climatology setting
or

Code: Select all

/* Add nudging to climate data*/
#define ANA_NUDGCOEF

for using climatology file

From .in file:

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! Nudging/relaxation time scales, inverse scales will be computed
! internally, [1:Ngrids].

       TNUDG == 365.0d0                    ! days
       ZNUDG == 5*365.0d0                      ! days
      M2NUDG == 5*365.0d0                      ! days
      M3NUDG == 5*365.0d0                      ! days

! Factor between passive (outflow) and active (inflow) open boundary
! conditions, [1:Ngrids]. If OBCFAC > 1, nudging on inflow is stronger
! than on outflow (recommended).

      OBCFAC == 4*365.0d0                      ! nondimensional 

&

Code: Select all

! Logical switches (TRUE/FALSE) to read and process climatology fields.
! See glossary below for details.

     LsshCLM == F                          ! sea-surface height
      Lm2CLM == F                          ! 2D momentum
      Lm3CLM == F                          ! 3D momentum

  LtracerCLM == T T                        ! temperature, salinity, inert

! Logical switches (TRUE/FALSE) to nudge the desired climatology field(s).
! If not analytical climatology fields, users need to turn ON the logical
! switches above to process the fields from the climatology NetCDF file
! that are needed for nudging. See glossary below for details.

 LnudgeM2CLM == F                          ! 2D momentum
 LnudgeM3CLM == F                          ! 3D momentum

  LnudgeTCLM == T T                        ! temperature, salinity, inert

Nudging is enabled for temperature and salinity (LnudgeTCLM = TRUE TRUE).

Despite these settings, the ocean still becomes unstratified within around 30 days of simulation. I would greatly appreciate any insights or suggestions on what might be going wrong or how I can improve the nudging settings to maintain stratification. Is there's anything I forgot to do for using the climatology data?

Thank you for your help!

Best regards,
Hsin-Yi

[wilkin]

Your nudging time scale is 365 days, so it won't do much on the 30-day time frame you are concerned about. Try making that time scale smaller, like 30 days.

You are nudging to an analytical climatology, so be sure that is correct.