blowup problem of ROMS

Dear Staff,

I sincerely apologize that my inquiry is not regarding the installation of COAWST, but rather about model operational issues. The details are as follows:

My objective is to simulate the standalone operation of ROMS and the coupled operation of ROMS+SWAN during a typhoon. The ROMS driving field I employ is derived from FNL reanalysis data. When running ROMS in standalone mode, I observed that during the super typhoon stage, extremely high wind speeds (>50 m/s) caused the flow velocity at the typhoon center to exceed 20 m/s, leading to model blowup (MaxSpeed = 2.0E+01). After investigating potential error causes, I attempted increasing the time step and implementing WET_DRY, but these measures were ineffective. Upon examining the u-velocity component in the rst file at the final time step, the maximum surface flow velocity near the typhoon center reached 17 m/s.

I have attached the grid image (grid_info.png), input file (roms_nep.in.txt), header file (nepartak.h.txt), log file (log.txt) for your reference.

Are there any operational adjustments or techniques for simulating typhoons with ROMS that can mitigate model instability (blowup issue) caused by high wind speeds? Your guidance would be highly appreciated.

Thank you very much!

[roms_nep.in.txt](https://github.com/user-attachments/files/21101315/roms_nep.in.txt)

[nepartak.h.txt](https://github.com/user-attachments/files/21101310/nepartak.h.txt)

[log.txt](https://github.com/user-attachments/files/21101304/log.txt)

Start by reviewing the attached roms_nep.in.txt, nepartak.h.txt, and log.txt files, focusing on the final timestep, the reported MaxSpeed value, and the high-wind typhoon run. Compare the standalone ROMS behavior with the stated WET_DRY and timestep attempts; done would require identifying an operational adjustment that prevents the blowup, though the issue does not define a specific expected change.

Written by the indexing model from the issue text.