Climatology as open boundary

[hpftcb]

Hi all,

I'd like to know how to use only climatology file as open boundary (not nudging, as boundary conditions). Do I have to create a bry file too? If I have a bry and a clm file, which one is used as open boundary?
My BC are:

LBC(isFsur) == Clo Che Che Che ! free-surface
LBC(isUbar) == Clo Shc Shc Shc ! 2D U-momentum
LBC(isVbar) == Clo Shc Shc Shc ! 2D V-momentum
LBC(isUvel) == Clo RadNud RadNud RadNud ! 3D U-momentum
LBC(isVvel) == Clo RadNud RadNud RadNud ! 3D V-momentum
LBC(isMtke) == Clo Gra Gra Gra ! mixing TKE

LBC(isTvar) == Clo RadNud RadNud RadNud ! temperature
Clo RadNud RadNud RadNud ! salinity
Clo RadNud RadNud RadNud ! dye_01

And I set the following parameters:

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

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

LtracerCLM == T T F ! temperature, salinity, inert

Thank you in advance.

Fernando

[kate]

Yes, you have to have a boundary file as well as a climatology file for the options you have picked. The LBC choices demand boundary values from a boundary file or from ana_xxx.h files. For the same number of records, the boundary files should be much smaller than the climatology file, but in general, we use higher frequency boundary files (5-daily to daily) and monthly climatology files.

[wilkin]

If you use Rad instead of RadNud you will not require a boundary conditions file.

If the climatology nudging is effective, it hardly matters there's no nudging at the perimeter.

I'd be cautious with the climatology nudging for both 2-D and 3-D velocity. You'll want to be very sure they are consistent (i.e. that 2-D is an accurate vertical average of the 3-D data on your model grid), and since the 2-D velocity links intimately with the continuity equation it may be important that it conserves volume in a horizontal spatial sense. I recommend you run some tests with 3-D and 2-D velocity nudging independently on and off and in combination.

[hpftcb]

Thank you for the replies.

I tried to put Rad instead of RadNud in order to use clm as boundary conditions, but it still asked for bry file. In there a way to use only clm file as boundary condition.

Thank you

[wilkin]

Code: Select all

LBC(isUbar) == Clo Shc Shc Shc ! 2D U-momentum

The Shchepetkin condition for 2-D velocity requires boundary data.

[corvianawatie]

Yes, you have to have a boundary file as well as a climatology file for the options you have picked. The LBC choices demand boundary values from a boundary file or from ana_xxx.h files. For the same number of records, the boundary files should be much smaller than the climatology file, but in general, we use higher frequency boundary files (5-daily to daily) and monthly climatology files.

Dear Kate, I want to ask. Do ROMS make a temporal interpolation for climatology or boundary data?
I mean, if I have monthly climatology, then how the nudging works?
1. will ROMS read those data only one time a month?
2. or it will be interpolated for every time step?
3. or it will read the same value for each month and change to the new value at next month?
Same question for the boundary file.

Please kindly reply to this question. Thank you

[kate]

You can look through the ROMS output to stdout to watch it reading files. Yes, it reads files once per record, be that daily or monthly. It stores two records in memory and linearly interpolates between them every timestep. The reading happens in get_data.F and the interpolation calls are made from set_data.F.