Ocean Modeling Discussion

A paper describing larval transport results using ROMSpath in a nested grid configuration is here: Garwood, J.C., Fuchs, H.L., Gerbi, G.P., Hunter, E.J., Chant, R.J. and Wilkin, J.L., 2022. Estuarine retention of larvae: Contrasting effects of behavioral responses to turbulence and waves. Limnology...

Thanks for pointing out in this direction, we are considering it as well. However, the major concern, for which I have not found an answer yet, is that tracking particles in 3D with turbulence would require me to output u,v,w,akt,salt,temp (the last two for computing density; if I tweak the code and...

Here must be something wrong with my interpolation... But I've adopted another approach now; I just added two more fields to the track array in DRIFTER to store the bed stress, interpolated using interp_float subroutine that comes with the ROMS code. Preliminarily, the results seem to make sense to ...

i think 0 is at the lower left psi point. maybe Hernan is better to answer. if so,then int(track(ixgrd)) would give the left side of the box at a u-point, and int(track(ixgrd))+1 would be the right side u-point. but you have i1 = MIN(INT (track(ixgrd,nfp1,1)+0.5_r8) ,Lm(ng)+1) i2 = MAX(i1 + 1,0) so...

Hi, I'm currently modifying ROMS code for the floats time stepping. We want to allow particles to resuspend (rather than either rebound or be permanently stuck), according to a critical shear stress criterion. I know that I may use the interp_floats subroutine that comes with ROMS, but it may requir...

It might have something to do with bathymetry. You may want to have a look at http://www.coastalwiki.org/wiki/Tidal_asymmetry_and_tidal_basin_morphodynamics (especially the section "Tidal wave deformation in the presence of friction and intertidal areas", which applies to friction-dominate...

An update: 1. Now we are happy with our model results. The reason it didn't work was due to some (silly) mistake on my part. We were using a synthesised initial field based on some VERY OLD references (1986ish) and three or four transects measured over the past few years. They provided a good starti...

Aha, I can find ssflux in globaldefs.h but not in the Functionals folder. Not being able to see it in the Functionals folder is why I always missed it when preparing the header file. Thanks for pointing this out! So the code has not really compiled anything involving 4dvar etc. Then it really leaves...

I was a bit surprised by ROMS looking for swflux as well, yet just pretended that nothing wrong was going on, that the E-P stuff is "different" from surface tracer flux (e.g. stflux is the flux of the tracer per se, E-P takes dilution into account, etc.). 1. As for the MPDATA flag in .h fi...

I was taking a brief break and now I'm back at the model. I was running into a weird problem with adding passive tracers to the model; although I have found a work-around, yet I have no idea why things were going that way. The log file (unfortunately, the version storing the error message has been o...

Kia ora John, Thanks for the suggestions and sharing your experiences with the Delaware Bay model. I am not very familiar with setting up long time-span models yet, so this might be a dumb question to ask, yet I wonder if we now aim for using some more extreme initial conditions (such that we can es...

I have calculated the tidal prism volume, at the maximum of the Spring tide (it is also when the underestimate of zeta is the most severe), it is 159 million versus 177 million as reported elsewhere, so a 10% underestimate as suggested by zeta. This could be partly due to some underestimate of the s...

Thanks for the advice. My reasoning is that the zeta at CB and SB suggests here could be a 5 to 10% underestimate of the tidal volume (assuming the bathymetry is correct) ; however, the bathymetry has always been a headache; for example, the nautical chart is not up-to-date for the upstream regions ...

Hi John, Thanks for your questions regarding the model. Below are my answers to them. -how long did you run this for? looks like the salt is getting better as time goes on. The model was run for 50 days in total. The validation shown here covers the period of Day 34 to 39, 6 days in total. The CTD w...

We are trying to model a system characterized by tides of medium strength (range of spring tide ~ 3.2m over water depth around 10 to 20 meters) and intermittent freshwater runoff. The freshwater runoff over the modelled period was low, only about 1 to 10 m3/s, yet in-situ observations show that such...

Thanks to Dr. Wilkin's suggestions, I have solved this issue. It was indeed due to some errors in my initial salinity field. After interpolation, I forgot to set the land point values to _FillValue, which later on caused troubles at some land points.... Case closed :D I will now investigate how to a...

1. I am doing this; and I have just further smoothed the grid and opted for VStretching = 4 (originally was 3) and see how it goes... 2. Aha, the story is like this. I decided to use the initial salinity field (representative of the April Waitematā) derived from some old reference and our regular mo...

Also here, a snapshot of the bathymetry, without being masked: Bathy_NoMask.JPG The region-of-interest is in the black circle, and the very negative numbers are in the red circle, the two are very far-apart. The bathymetry in the black circle is based on nautical chart(s) and some LiDAR dataset, and...

Hi Wilkin, Thanks for the prompt reply! 1. I totally forgot about this. Yet, from the very initial salinity field, NaN values have populated the land points. Below is what I mean, the snapshot of the initial salinity field, as it is, without any mask being applied (so the NaNs have been there from t...

A belated update: It is indeed a weird case. I did nothing to my cpp options or input file (at least, not in any significant way I would keep in my lab record). I simply upgraded to the SVN revision 1098 (used to be 1053 or something near that), then the problem with restarting was gone. I don't qui...

Hi, I have run into a situation not similar to any posted problems on this forum (as far as I can see). The model blows up after about 2,000 steps, with the reason being PEchar = NAN; the potential energy, hence the tracers, or the depth, have gone crazy (while KEchar is a valid number; please see t...

Hi, It seems like we have addressed this problem, in a weird way.... Neither wet-and-dry nor GLS-mixing was the culprit; switching off either of them did not help. However, my colleague is using a more recent version of the model (1089 or 1096?) versus mine (1053); when we were running the same rest...

A few things ... You have #define TS_FIXED so your tracer fields temp and salt are not going to evolve in time. I can see this might be a valid approach for your initial testing, especially if you have set them to constants so you are effectively solving a homogenous ocean problem with z-dependence...

The C-preprocessing option is CHECKSUM . It is there because I code it: ... ASSUMED_SHAPE Using assumed-shape arrays CHECKSUM Report order-invariant checksum (hash) when processing I/O BOUNDARY_ALLREDUCE Using mpi_allreduce in mp_boundary routine ... INITIAL: Configuring and initializing forward no...

Yes, using checksum is a good idea. ROMS also has checksum for I/O processing. You need to activate the CPP option CHECKSUM . Hi Arango, Thanks for the suggestion. However, I have tried to find CHECKSUMS flag in both my own directory and also in the most up-to-date trunk directory, it is not in eit...

The first thing to do is to track down the restart issue. You can run the model for two steps, restart it for two more, then compare that solution to a run that's four steps long. You have to restart after an even number of steps because the model doesn't save nstp, which alternates between 1 and 2...

Hi everyone, We are currently working on a 3D tidal model. My colleague tried to use my restart file (with perfect_restart variables) stored in it to continue the model run, yet bizarre things have occurred. The restarted model crashes after about 600 steps since restarting (about 40 minutes in term...

Hi, Charles, I uploaded a quick fix to the problem (at least working for the refinement-subclass, telescoped grid), https://www.myroms.org/forum/viewtopic.php?f=23&t=5525. Hopefully other subclasses could be addressed in the future, probably we could add a dropdown list for creating subgrid: if ...

Hi, all, Attached is a script for cleaning up coastline data extracted from GIS datasets. In this type of data I ran into some trouble with the ordering of the points. The data can jump from point A on the mainland to point B on a small island --- than circle around the island in a clockwise/counter...

Hi, all, I wonder if anyone here is also struggling with creating nested grids with GridBuilder. As mentioned in this post https://www.myroms.org/forum/viewtopic.php?t=5018 (Floor #22), Charles, the developer of GridBuilder mentioned that the psi points of the outputted subgrids do not align exactly...