Ocean Modeling Discussion

drews

Here is what I did to reduce the size of the SWAN coupling/output files to keep them smaller than 2 Gigabytes: 1. Increase the coupling interval from 1 to 6 minutes. I can't remember exactly where I changed this run parameter. 2. The block output from SWAN has to be changed, too. That command in ...

drews

I just encountered the same problem again, this time on the volcanic island of Nakanoshima at lat-lon coordinates (29.875° North, 129.875° East). Nakanoshima is between Japan and Taiwan, and the summit of Mt. Ontake rises to 979 meters above sea level. With a grid resolution of 4 km, the grid has a h ...

drews

You never want to have any of your h values be zero. Period. h is the bathymetry at rho-points (positive downward). For my model domain the Shuttle Radar Topography Mission at 3 arc-seconds reports an elevation of 0 meters at several portions of the shoreline. Am I supposed to increase those values ...

drews

Since storm surge and wind setdown develop over many hours, I took John's suggestion and made the lowering of the water level at the upwind/northern boundary dependent on time: #if defined INLET_TEST IF (NORTHERN_EDGE) THEN cff=-1.0_r8*sin(2.0_r8*pi*time(ng)/(12.0_r8*3600.0_r8)) cff = cff - 0.10_r8 ...

drews

How would you modify the Inlet test to add onshore wind forcing? The Inlet test uses the northern domain boundary to generate tidal oscillations that propagate south through a narrow strait and into an inlet. Here is the tidal forcing in ana_fsobc.h within the Coupled sub-directory: #if defined ...

drews

I just debugged a blowup situation involving very shallow water and drying on the coast. From the color scale I cannot tell if your bathymetry rises above sea level, but if it does: Try increasing the critical depth DCRIT. This is a simple revision to make, and it might tell you something about the ...

drews

I'm working in the Nile delta, which is really flat. I have strong winds but no tide, and consequently there is a lot of wetting and drying going on. I have set my permanent land-sea mask at a height of 30 meters above sea level (absurdly high). I have a river point source at 5 meters above sea ...

drews

I am using the ROMS Quadratic bottom friction formulation (UV_QDRAG) and have tried Cd=0.003-0.010 (constant) values.

Cd=RDRG2=0.003 is the ROMS default. Can you tell me what RDRG2=0.010 means physically? A lot of rocks on the bottom? A lot of seaweed? What would be a reasonable maximum value?

drews

I am using ROMS-SWAN to study storm surge and wind setdown on Lake Erie. Wave radiation stress does not appear to make much difference. Is there a formulation for wave-dependent surface drag?

drews

I tried running the Lake Erie model with DCRIT = 0.5 meters and time step DT = 0.5 seconds. The maximum Courant value Cw reported in the ROMS log file is 0.939, which removes the possibility of a CFL violation. The model terminated at 01:53:56 hours with a blowup error in cell (399,192). That cell ...

drews

Converting SWAN to use the Nautical convention for wind was not easy. I am forcing SWAN from a file of wind components (all constant for now). The wind is blowing from the West-Southwest along the axis of the lake (20 degrees north of due east), from Toledo to Buffalo. This wind direction at 20 m/s ...

drews

It looks like my combined model has a direction problem. I had set up SWAN for Cartesian coordinates, but ROMS requires the Nautical convention for wave direction, as John pointed out in this recent thread: https://www.myroms.org/forum/viewtopic.php?f=14&t=2301 For SWAN use: SET INRHOG 1 NAUTICAL ...

drews

I am applying wind stress at 20 m/s to Lake Erie at an angle of 20° north of due east (from the WSW, aligned with the axis of the lake). I get a blowup error at time 01:34:45 (hours), and upon further investigation I see unrealistic instabilities arising along the north shore, where the waves impact ...

drews

I was getting the same error messages shown in red above. The problem went away (and Inlet Test ran correctly) when I switched from /usr/local/mpich2-1.3.1-pgf90/bin/mpirun to /usr/pgi/linux86/8.0/mpi/mpich/bin/mpirun I suspect the problem came from a mismatch between the compilers used for building ...

drews

MHHW is Mean Higher High Water: http://tidesandcurrents.noaa.gov/mhhw.html I use ROMS to study storm surge (wetting) and wind setdown (drying) in Egypt's Nile delta. I #define WET_DRY like John says, and use the default critical depth of 0.10 meters. I set my land/sea masking to 30 meters above sea ...

drews

More information: My model domain has one analytical point source of river inflow. ana_psource.h has three !$OMP BARRRIER directives in it (svn $Id: ana_psource.h 429 2009-12-20 17:30:26Z). One of those directives makes it into Build/analytical.f90, near line 174, just before the Qbar values are ...

drews

I believe that I am using shared memory alone and not distributed memory. Here is the entire USE_ section of build.bash: #export USE_MPI=on #export USE_MPIF90=on export FORT=xlf export USE_OpenMP=on #export USE_DEBUG=on export USE_LARGE=on #export USE_NETCDF4=on I am not using any customized ...

drews

I get the following run-time errors on NCAR's bluefire supercomputer: 1587-114 Incorrect nesting of OpenMP directives. 1587-114 Incorrect nesting of OpenMP directives. SVN Revision: 442M. ROMS/TOMS version 3.4. The last entry in the ROMS log file is: Initial basin volumes: TotVolume = 5.0360477799E ...

drews

Here is a picture of the staggered grid from the ROMS wiki:

https://www.myroms.org/wiki/index.php/Grid_Generation

(I guess my initial 16 m/s current is _not_ "reasonable", but at least it doesn't blowup!

)

drews

Here is the ubar current in my upstream grid cell (no masking): http://acd.ucar.edu/~drews/inflow.jpg Those points are at 1-second intervals. This appears to be the same numerical problem, judging from your plot. If you can get your 4 masks to accurately represent the ROMS concept of "upstream cell ...

drews

I had a problem similar to this one a few weeks ago with SVN revision 436. I got extreme velocities in the cell directly upstream of my river point source. Some differences: 1. I am using the 2-D barotropic mode (1 vertical level). 2. My grid resolution is 86m, 10x finer than yours. 3. I have wetdry ...

drews

This problem sounds like one I had last year: Water temperature from -492 to 602 degrees Celsius? https://www.myroms.org/forum/viewtopic.php?f=17&t=995 As Kate noted, the model involves 3D flow in shallow water. My fix was to #define MY25_MIXING in myModel.h, which turns on Mellor-Yamada vertical ...

drews

I have seen spuriously large currents along a domain boundary when the Coriolis force pushes the current against the wall. My solution was to set the domain boundaries to no-slip: GAMMA2 == -1.0d0 This change makes the walls less greasy. I am modeling wave radiation stress with NEARSHORE_MELLOR as ...

drews

This error message: 0: ALLOCATE: 16721214976 bytes requested; not enough memory probably means that the ROMS executable has run out of memory, based on the grid size that you are using. 16 Gigabytes is a lot of space; I found a similar problem on my Linux workstation, when ROMS could not allocate ...

drews

I just finished setting up a one-way forcing from WRF to ROMS (my Master's thesis project). I moved a 12-km grid of hurricane Katrina 2005 to the Philippines and sent it over Manila to see what storm surge would result. It works. The ROMS developers have set up a very nice scheme for time ...

drews

I'm using the 2-D ROMS configuration to model typhoon-driven storm surge. My model is forced with winds and atmospheric pressure. The code edits provided by rongzr produce a 1.5-meter rise in sea level for 850 mb, which is what I expect (after some sloshing). Thanks! Here are the headers for my ...

drews

What is the proper way for handling sea cliffs? In the Philippines, at about 121.283 degrees East and 13.6 degrees North, there is a sea cliff that rises from the deep ocean. At 900-meter horizontal resolution (SRTM30 data) the north-south cross section of bathymetry/topography is plotted below. The ...

drews

wjlee - The September 2008 issue of Physics Today had an article by Donald Resio and Joannes Westerink, "Modeling the physics of storm surges", that may be useful. On page 34 they state formula (1): height of surge eta is proportional to: (tau/gh)W This formula indicates that wind-driven storm surge ...

drews

Kate - Thanks for the suggestions. (Sorry, I was looking at your Joined date, not the Bristol Bay Posted date.) I'm using a horizontal resolution of 100 meters, with a strong wind stress of 2.73 N/m2 blowing toward shore. Steep gradients in the bathymetry (1:20) blow up sooner than shallow gradients ...

drews

I'm modeling wind stress toward a sloping shoreline. I get a blowup error at the same time and place that the water temperature spikes to hundreds of degrees Celsius, negative and positive. This problem sounds somewhat like the "Trouble in shallow water" discussion of Bristol Bay back in 2003, but ...

drews

Try the SHOREFACE example; that one defines WET_DRY and has h values of < 0 up on the beach.

Carl

drews

Okay, here's what fixes the READ_PHYPAR problem for me. Comment out the definition of NPZD_POWELL on line 114 of build.bash, like this: #export MY_CPP_FLAGS="-DNPZD_POWELL" Now the initial conditions are all analytical, like Kate said they should be. Curiously enough, NPZD_POWELL is not defined in ...

drews

I'm still puzzling over this. When I run the windbasin example I get:

READ_PHYPAR - could not find input file: ocean_ini.nc

Kate, are you saying that the build.bash script for my windbasin has to specify Functionals/ana_initial.h?

Carl

drews

Jamie - Thanks for the information about mixing and convection. Your comments will be useful to me, since my research involves shallow water. That Python code is a quick-and-dirty script that I put together to produce a plot. I posted it in case someone needs to review my processing to answer my ...

drews

I have plotted the flow vectors in a cross section of the upwelling example. Everything looks fine except for the left (south) side of the channel. Recall that the wind here is into the page and the Coriolis force is to the left (southern hemisphere). Here is the entire section: https://www.myroms ...

Ocean Modeling Discussion

Search found 35 matches

Re: Instabilities with SWAN_COUPLING and WET_DRY together

Re: Sea cliffs

Re: ROMS blows up

Re: Wind AND tidal forcing in the Inlet test

Wind AND tidal forcing in the Inlet test

Re: What to correct to keep ROMS from blowing up?

Re: River locations when there is wetting/drying

Re: Dependence of water levels on sigma parameters

Re: ROMS-SWAN Coupled System Users

Re: Instabilities with SWAN_COUPLING and WET_DRY together

Re: Instabilities with SWAN_COUPLING and WET_DRY together

Re: Instabilities with SWAN_COUPLING and WET_DRY together

Instabilities with SWAN_COUPLING and WET_DRY together

Re: problem when coupling roms and swan

Re: ROMS wetting/drying inundation/storm-surge simulations

Re: Incorrect nesting of OpenMP directives

Re: Incorrect nesting of OpenMP directives

Incorrect nesting of OpenMP directives

Re: Velocities in land grid cells

Re: Velocities in land grid cells

Re: Velocities in land grid cells

Re: model blow-up due to abnormal temperatures

Re: Coupled ROMS-SWAN experiment

Re: what's the error?

Re: Coupling ROMS and WRF

Re: apply the atmosphere pressure in Storm simulation

Sea cliffs

Re: storm surge problem

Re: Water temperature from -492 to 602 degrees Celsius?

Water temperature from -492 to 602 degrees Celsius?

That Python code

Left side of the upwelling example