Ocean Modeling Discussion

sonaljit.m

Hi. I need to use a 3D visualization software for ROMS outputs. Most visualization tools use a Cartesian coordinate system. But since the ROMS outputs are in terrain following sigma coordinates, I have to interpolate the sigma grid to a Cartesian grid, which is time consuming. Is there a good visual...

sonaljit.m

Hi, Thanks for the help. I am attaching a csv file, containing AMSEAS 2019 water level outputs from 3 different buoy locations: San Juan, St Thomas and St Croix. The data is 3-hourly, and the starting time is 01/01/2019 00:00:00 . There are some nan values near the end of the arrays. I need to find ...

sonaljit.m

Hi all, This is not a ROMS related problem, but I am looking for some help. I need to find out the tidal components (M2, S2 etc) and their corresponding amplitudes and phase from an hourly water-level data. The data contains date/time, and the corresponding water levels for 1 year duration. Is there...

sonaljit.m

Hi John, thanks for the suggestion. There seems to be mismatch. I calculated tidal phases from the NOAA gauge and TPXO outputs at the same location (south of St Thomas) and compared them. For the M2 tide, the phases are 24.5 (NOAA) and 17.427 (TPXO) (in degrees). For the S2 - 8.13 (NOAA) vs 21.91 (T...

sonaljit.m

The region between red and blue - is that the transition layer? The red area seems to be a mixed layer. At day 15 your plot shows minute undulations in the transition layer, which indicates that there is some activity happening. I'd suggest look into the vertical profiles of N^2 and shear^2 to get a...

sonaljit.m

Hi all, My ROMS setup uses tidal inputs from TPXO9 global tidal atlas, climatology from HYCOM and wind forcing from NAVGEM. All data are being used from 2015, and interpolated from their respective grids to my ROMS regional grid. When comparing the velocity outputs with ADCP measurements, I see a mi...

sonaljit.m

Hi, If anyone is using the AGRIF/CROCO model, I had a small question. It is probably very simple, but I couldn't figure out. How do I set the values of imin, imax, jmin and jmax? I have a parent grid with 2 km resolution with 224(lat)*299(lon) rho points. Within that, I am using a nested child grid ...

sonaljit.m

Hi Kate, I am trying offline nesting. I have a confusion about the bathymetry in the nested grid - My parent grid's bathymetry is smoothed so that my Haidvogel and Haney numbers are: rx0 = 0.17, rx1 = 2.11 . My confusion is about determining the nested grid's bathymetry. - Should I directly interpol...

sonaljit.m

Hi all, This is probably a simple issue, but I need some help. I am trying to build a nested grid for my ROMS configuration. I have built a parent grid setup at 2 km resolution, with climatology/initialization/forcing files (using pyroms). My nested grid needs to be within the parent grid, will have...

sonaljit.m

hi all, This is not directly related to ROMS, but I was hoping if someone could provide me some specific information that I am looking for. (or please guide me to the literature where this info is available) I am working on a ROMS based coastal ocean circulation setup that uses 3D data from an opera...

sonaljit.m

This is another timelapse video of a simulation with different initial condition: https://youtu.be/sFFqxAKvUHY

sonaljit.m

Hello, Attached, is a timelapse video of a temperature longitudinal transect from my simulation. https://youtu.be/wELpEsKAvqc This is the first 2000 timesteps in my simulation, with open boundary condition in the north and south walls (left and right walls in the video). The temperature data supplie...

sonaljit.m

The variables I am providing in the forcing file, are the following: Temperature fluxes -> swrad(srf_time), lwrad(lrf_time), latent(lhf_time), sensible(shf_time), shflux(shf_time) (all units in W/m^2) For Precipitation -> swflux(swf_time,eta_rho,xi_rho) (cm/day) For bottom temperature and salinity -...

sonaljit.m

Hello, I am running a simulation with HYCOM fields reconfigured for my ROMS grid. Momentum fluxes are taken from MERRA, and net heat flux is taken as an hourly time series with a diurnally varying shortwave radiation, obtained from a mooring station. Plot of the net heat flux is given below. shflux....

sonaljit.m

Thanks Kate. My objective is to simulate particle transport in the coastal areas, and for that I need the model to evolve the surrounding oceanic circulation by taking climatological inputs (from HYCOM). However, my concern is that the sharp bathymetry features give rise to spurious pressure gradien...

sonaljit.m

You can also use basic python/matlab routines for interpolation. For my grids, I do interpolation from HYCOM/NCODA to the ROMS grid using scipy.griddata and scipy.interp1d . griddata is for 2D interpolation: I use it for transforming the fields from HYCOM meshgrid to the ROMS meshgrid. And for the 1...

sonaljit.m

Hello, I am trying to apply nudging to the sea surface height and the scalar fields (temp/salinity), in a domain with 1 km grid size. The objective is to relax the SSH and temp/salinity fields to the climatology input, and allow the velocities to evolve accordingly. My question is - How do I pick an...

sonaljit.m

Thanks very much for all the feedback. Based on your suggestions, I did the following changes which resulted in better performance of the simulation. - As Kate suggested, I am now using DJ_GRADPS for pressure gradient. - Deepak, thanks for the feedback. I am currently using biharmonic friction with ...

sonaljit.m

Hello, My ROMS setup is showing unrealistic velocities near the surface at the locations right next to the masked areas. The diagnostic output shows that the viscous fluxes (u_hvisc, v_hvisc) are shooting up to very high levels, messing up the velocity profiles only at the sigma points near the surf...

sonaljit.m

There should be an input file with a .in extension, which provides all the ROMS parameters for running the model, including the file paths for the river input file. The compilation command should be something like this: ./oceanG < ocean.in Check your ocean.in file. The river runoff input is given as...

sonaljit.m

Hello, I am running an idealized simulation in ROMS using an uneven terrain grid that represents the VI-Puerto Rico bathymetry. I smoothed the bathymetry from the original ETOPO 1km version, such that rx0 = 0.16 and rx1 (Haney number) = 3.92. The bathymetry plot is shown below. (This simulation does...

sonaljit.m

I tried that, but doesn't seem to make a difference. Still the same patterns forming along bathymetry.

sonaljit.m

#define UV_ADV #define UV_COR #define UV_LOGDRAG #define PJ_GRADP #define SPLINES_VDIFF #define SPLINES_VVISC #ifdef TS_U3ADV_SPLIT # define TS_DIF2 # define DIFF_GRID # define MIX_GEO_TS #endif #ifdef UV_U3ADV_SPLIT # define UV_VIS2 # define VISC_GRID # define MIX_GEO_UV #endif #define NONLIN_EOS ...

sonaljit.m

density and velocity fields - Obtained from HYCOM/NCODA analysis 1/12. Interpolation - Yes, all fields are interpolated to the ROMS grid. After running for a while, the problem still persists. The unrealistic velocities build up and the model crashes. I tried using smaller time step, in which case ...

sonaljit.m

Hello, Previously, I posted a couple of discussion threads on 'unrealistic' velocities forming along the bathymetry on my domain. As a follow-up - I did some more analysis, and found out that the unrealistic velocities are forming due to spurious patterns in the pressure gradient, evolving along the...

sonaljit.m

DT 30 seconds.
NDTFAST 60.
horizontal resolution is 1000 m.

This is a plot of the u velocity along the longitude, at the bottom.

These zig-zag patterns are forming next to the boundary.

With shorter time steps, the simulation is running a bit further, but eventually blowing up again.

sonaljit.m

Hello. In the previous thread, I discussed about my runs blowing up due to unrealistic velocities forming along the bathymetry. Following this, I tried to make my runs more simpler by removing any variability in the bathymetry, and initializing with constant quantities everywhere in the domain. This...

sonaljit.m

Here are the steps I'm taking for building the ROMS climat fields. HYCOM/NCODA: I first design the ROMS grid, then interpolate the fields from the HYCOM/NCODA grid to the ROMS grid. During interpolation, I am first doing the horizontal 2D interpolation and then the vertical interpolation on the sigm...

sonaljit.m

Okay, I made a few more changes based on your points. Advection is now 4th order central for all parameters. #define UV_C4ADVECTION #define TS_C4HADVECTION #define TS_C4VADVECTION Regarding bottom smooting, here's what I did: Obtained the bathy data h from ETOPO1, then lowpassed it with 10 km cutoff...

sonaljit.m

Thanks for the reply. Yes, turns out that the barotropic timestep was not small enough. So, I increased NDTFAST, allowing more number of barotropic timesteps between DT, and those anomalies along the north topography disappeared. The simulation continues for a little while, and then again blows up o...

sonaljit.m

Hello, I am facing an issue with my simulation using ROMS, and need some suggestions. I am initializing my domain with HYCOM and NCODA analyzed fields from 2015 March, forced with atmospheric fluxes from MERRA 2. The bathymetry is obtained from ETOPO1. https://www.dropbox.com/s/00jxl0wj8q67sg3/veloc...

sonaljit.m

Hello. I'm facing a small problem; its probably a simple one but I couldn't get it sorted out. My initialization netCDF file looks like this: dimensions(sizes): s_rho(32), xi_rho(424), eta_rho(324), xi_u(423), eta_u(324), xi_v(424), eta_v(323), init_time(1), ocean_time(3) variables(dimensions): floa...

sonaljit.m

Thanks very much. This seems to be what I needed.

sonaljit.m

Hi everyone, Is there any example setup of a 'clamped (Dirichlet) boundary condition' in ROMS? I am trying to impose a Dirichlet condition for temperature, salinity and velocities on the 4 vertical walls of my domain. I have the vertical transects for the properties, but I need to understand in what...

sonaljit.m

Hi everyone, I built a 3D grid using Pyroms, and initialized it with temperature, salinity and velocity data. The compilation worked smoothly, however when I run the code it BLOWS UP showing exit_flag 1 . The error output is shown below: STEP Day HH:MM:SS KINETIC_ENRG POTEN_ENRG TOTAL_ENRG NET_VOLUM...

sonaljit.m

I am new to ROMS, but from what I understand, you can define or undef the Coriolis parameter in the header .h file ( #define UV_COR ) for your case. If you want to use a different Coriolis parameter, that is a bit tricky because for that you have to change the latitude/longitude which is embedded in...

sonaljit.m

Hi all, I'm new to modeling in ROMS. I am trying to setup the vertical grid for my simulations based on Shchepetkin 2005, using the function pyroms.vgrid.s_coordinate_4 (pyroms). Here's the code: theta_b = 0.1 theta_s = 7 Tcline = 1000 N = 16 vgrd = pyroms.vgrid.s_coordinate_4(h, theta_b, theta_s, T...

sonaljit.m

I tried using Mercator; didn't work. Still the same offset. pm shows ~1/2000 whereas pn ~1/500.

sonaljit.m

Hi all, I'm trying to setup a ROMS grid for the Puerto Rico and Virgin Islands region using pyroms, and I'm facing an issue with setting the horizontal grid resolution. My objective is to set up a 1km resolution along both zonal and meridional directions, but for some reasons I'm not getting it righ...

sonaljit.m

Hello, After a few modifications, the pyroms code got installed in my system. I was having problems with the module scrip , and with the compilers gfortran and f2py for linking with netcdf. I will explain the solutions below (in case anyone faces these problems during installation). netcdf : For ins...

sonaljit.m

Hello, The netcdf issue got solved; I re-installed netcdf and provided the correct path to -lnetcdf in the makefile. The command make -f makefile2 (in the makefile) is working. Thank you Kate. Following that - I'm facing another error while compiling pyscrip.f90 (the command make -f makefile2 f2py )...

sonaljit.m

Thanks Kate. The error seems to have gone; the Gridgen code is compiling. I'm facing another problem. Even though this is not interfering with Gridgen, but it says 'scrip.so missing. Remapping function will not be available' Looks like I could not get the scrip.so file installed. I tried running the...

sonaljit.m

Hi all, I recently joined the ROMS community and started working with the ROMS model as part of my postdoctoral work. Currently I am trying to setup the grid for my simulations using pyroms, bathy_smoother and pyroms_toolbox. I'm running python2.7 with anaconda2 on Ubuntu 16.04. I have installed the...

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