## how to prepare the zeta_east data using only two station?

### how to prepare the zeta_east data using only two station?

Hi all,

I am preparing the boundary file, how can I get the free-surface eastern boundary condition using data from only two NOAA stations, which locate on the coast near the each side of the open boundary, respectively?

I am trying to use Matlab to interpolate2D, but it seems not so good.

Any reply will be highly appreciated!

Peter

I am preparing the boundary file, how can I get the free-surface eastern boundary condition using data from only two NOAA stations, which locate on the coast near the each side of the open boundary, respectively?

I am trying to use Matlab to interpolate2D, but it seems not so good.

Any reply will be highly appreciated!

Peter

### Re: how to prepare the zeta_east data using only two station

Depending on the total size of your domain have you consider using TPXO for the free surface boundary condition?

### Re: how to prepare the zeta_east data using only two station

Thank you very much for your kind, ptimko.ptimko wrote:Depending on the total size of your domain have you consider using TPXO for the free surface boundary condition?

The zeta_east equals to tidal data (From TPXO) + non-tidal data (subtidal),right?

When I look into the TPXO data set, there are three files：grid_tpxo7.2.nc, h_tpxo7.2.nc and u_tpxo7.2.nc. The second should be the one, there are three different tidal elevation in it: tidal elevation amplitude at Z-nodes, complex amplitude (real part)and complex amplitude (imag). Which one should I use?

Besides, how can I use the 10 different constituents to make the tidal forcing? are there any matlab scripts?

Any kind will be highly appreciated!

Best!

Peter

### Re: how to prepare the zeta_east data using only two station

You may want to review the documentation section on tidal forcing available on the ROMS website and also the "Packages" section for pre- and post-processing packages. There should be a section on tidal forcing if you follow the "Forcing Package" link.

There is a TMD toolbox that should be available from the TPXO website for reading the TPXO files. For creating the input files there should be a ROMS toolkit around somewhere; not sure where the link to that is. I use "ROMS_tools" from the ROMS-AGRIF website to create my input files. If your familiar with python you may want to check pyroms toolkit.

Patrick

There is a TMD toolbox that should be available from the TPXO website for reading the TPXO files. For creating the input files there should be a ROMS toolkit around somewhere; not sure where the link to that is. I use "ROMS_tools" from the ROMS-AGRIF website to create my input files. If your familiar with python you may want to check pyroms toolkit.

Patrick

### Re: how to prepare the zeta_east data using only two station

Hi, Patrick, Thanks a lot for your kind reminder, it is very helpful.ptimko wrote:You may want to review the documentation section on tidal forcing available on the ROMS website and also the "Packages" section for pre- and post-processing packages. There should be a section on tidal forcing if you follow the "Forcing Package" link.

There is a TMD toolbox that should be available from the TPXO website for reading the TPXO files. For creating the input files there should be a ROMS toolkit around somewhere; not sure where the link to that is. I use "ROMS_tools" from the ROMS-AGRIF website to create my input files. If your familiar with python you may want to check pyroms toolkit.

Patrick

Best!

Peter

### Re: how to prepare the zeta_east data using only two station

Hey, Patrick, For the free surface boundary condition, Is just only using the TPXO data ok, right?ptimko wrote:Depending on the total size of your domain have you consider using TPXO for the free surface boundary condition?

I have looked into the Tidal Forcing documentation and downloaded the TPXO7 and installed the TMD, There is a UI window, where I can choose the constituents that I need. it seems like I can get the tidal constants.

I want to get my domain boundary free surface data monthly from 2006 to 2008, I have the latitude and longitude of the boundary, How do I use the TMD to get what I want? Do you know? or any ideas?

I am looking forward to your help.

Best,

Peter

### Re: how to prepare the zeta_east data using only two station

TMD will extract the tidal elevations and greenwich phase for the tidal constituents you want. It should also be able to make a prediction.

Tidal forcing in ROMS is input in terms of the tidal elevations (amplitude and phase) as well as the tidal ellipses (semi-major axis, semi-minor axis, ellipse inclination, and phase). If you want to create a forcing file to force ROMS for your domain it would be best if you follow this format. The required format can be found by following the packages link, then forcing package link and scrolling down to the section on tidal forcing. It should be possible to force ROMS using elevations only if you choose the reduced physics CPP flag for an eastern boundary the flag should be something like EAST_M2REDUCED.

If you wish to create a time series prediction of the surface elevations for the boundary points based upon TPXO then you should look at the instructions for TMD found here: http://www.esr.org/polar_tide_models/README_TMD.pdf I don't normally use the GUI interfaces so I'm not that familiar with it and do almost all my work using a command line.

If anyone else has any advice please join in or correct me...

Patrick

Tidal forcing in ROMS is input in terms of the tidal elevations (amplitude and phase) as well as the tidal ellipses (semi-major axis, semi-minor axis, ellipse inclination, and phase). If you want to create a forcing file to force ROMS for your domain it would be best if you follow this format. The required format can be found by following the packages link, then forcing package link and scrolling down to the section on tidal forcing. It should be possible to force ROMS using elevations only if you choose the reduced physics CPP flag for an eastern boundary the flag should be something like EAST_M2REDUCED.

If you wish to create a time series prediction of the surface elevations for the boundary points based upon TPXO then you should look at the instructions for TMD found here: http://www.esr.org/polar_tide_models/README_TMD.pdf I don't normally use the GUI interfaces so I'm not that familiar with it and do almost all my work using a command line.

If anyone else has any advice please join in or correct me...

Patrick

### Re: how to prepare the zeta_east data using only two station

Thank you, Patrick. I understand, as long we get the tidal harmonic constants (elevation and phase) of each constituent at the domain boundary, we can calculate the height of each constituent using an equation, right?ptimko wrote:TMD will extract the tidal elevations and greenwich phase for the tidal constituents you want. It should also be able to make a prediction.

Tidal forcing in ROMS is input in terms of the tidal elevations (amplitude and phase) as well as the tidal ellipses (semi-major axis, semi-minor axis, ellipse inclination, and phase). If you want to create a forcing file to force ROMS for your domain it would be best if you follow this format. The required format can be found by following the packages link, then forcing package link and scrolling down to the section on tidal forcing. It should be possible to force ROMS using elevations only if you choose the reduced physics CPP flag for an eastern boundary the flag should be something like EAST_M2REDUCED.

If you wish to create a time series prediction of the surface elevations for the boundary points based upon TPXO then you should look at the instructions for TMD found here: http://www.esr.org/polar_tide_models/README_TMD.pdf I don't normally use the GUI interfaces so I'm not that familiar with it and do almost all my work using a command line.

If anyone else has any advice please join in or correct me...

Patrick

Thanks for your patience!

Best!

Peter

### Re: how to prepare the zeta_east data using only two station

Peter,

Yes, that's the basic idea. If you want to force ROMS then you should use the correct input format for tidal forcing. If all you want is the data then you should be able to use TMD to predict the tidal heights at the boundary.

I'm quite a patient guy (normally), glad I could help...

Patrick

Yes, that's the basic idea. If you want to force ROMS then you should use the correct input format for tidal forcing. If all you want is the data then you should be able to use TMD to predict the tidal heights at the boundary.

I'm quite a patient guy (normally), glad I could help...

Patrick

### Re: how to prepare the zeta_east data using only two station

Right, Patrick, I am very glad to know you. It is so kind of you. Thank you very much for all your replies and help.ptimko wrote:Peter,

Yes, that's the basic idea. If you want to force ROMS then you should use the correct input format for tidal forcing. If all you want is the data then you should be able to use TMD to predict the tidal heights at the boundary.

I'm quite a patient guy (normally), glad I could help...

Patrick

May God bless you!

Peter