Hello, where can I find information about creating a nested system 1 and 2. They told me that in a level 1 nested system I should run the model only propagating the tide and then in a level 2 nested system the tide information is received and there I add wind, currents and temperature. But I don't know where to start to do such a thing.
Hello,
There are several ways of setting a nested model system using the MOHID Water engine in OpenFlows FLOOD.
Could you let us know a little more about what type of problem are you trying to solve? Is it coastal flooding? What data do you have available to setup your model?
This would help providing you some guidance.
Kind regards,Luis
Hello, Luis
My work consists of a dynamic downscaling from the output of the MPI-ESM-MR model of CMIP5 (2006-2100) for the surface circulation of the Gulf of California in 2D and also to observe the distribution of plankton. This to evaluate the effects of climate change on the circulation of the Gulf and the distribution of plankton.The circulation in the Gulf is strongly influenced by the tide, the wind and the exchange of heat fluxes with the atmosphere.Create an atmospheric forcing HDF5 file with the variables: air temperature, wind speed (x,y), relative humidity, precipitation, cloud cover and solar radiation.For the initial conditions at the surface I have the variables: sea surface temperature, sea surface salinity, sea level height and current speed (x,y). For the biological variables whose distribution and concentration I want to observe over time, I have chlorophyll concentration data only from diatoms (large cells) and chlorophyll only from cyanobacteria (small cells).
Before adding any other type of forcing, you should validate your tide model. If your "downscaling" of FES2014 to your model domain is not correct, there's no point in making the model 3D and adding more forcing on the boundaries (open boundaries and surface/meteo boundary).
Have you calibrated/validated your tide model comparing the model with observations taken at different locations inside the domain?
You should select and run a period of at least 15 days to compare with observations.
When you have confidence in your results you can then think of adding more forcings.
Keep in mind, that you should use the slow start option in the Hydrodynamic module tide options. Set a value around 1-2 days (i.e 86400/172800 seconds) to ensure the "warm-up" part of the simulation does not generate too much numerical noise that the model may then have difficulty dissipating.
Hola Luis, comparé mis resultados de marea en tres puntos a lo largo del golfo contra datos de un modelo que se llama JTides (https://arachnoid.com/JTides) y los resultados no se parecen, calculé el error y éste anda entre -2 a 3 metros, en ese caso que podría modificar?
I don't know the accuracy of JTides (I can't access the webpage), but for validating the model here's things you should pay attention to:
1) check the time reference you define in the Tide input options. FES2014 is set in UTC so you need to set -6 or -7 if you want to compare to local time data.
2) the open boundary condition of your model should be placed outside the continental shelf, in deeper areas
3) As the gulf is not very wide, make sure the model resolution is fine enough to represent how circulation occurs. Check the real coastline together with the "gridded coastline" and check for inconsistencies.
4) Also when comparing with data make sure the tidal gauge where the observations are taken is well represented in the model. From experience I know that if the model is coarse and you compare with tidal data in La Paz, if the bay is not well represented in the model then the results will not be good, because of the local circulation in the bay.
Can you show some of the results comparison? You can also upload the model (without the FES2014.hdf5 and without results) for us to have a look of what might be wrong.
Thanks and regards,Luis
Hello Luis, I adjusted the local time with -7, I did some tests and the one that showed the most similar results to JTides in three different locations along the gulf was when I assigned the "reference level" in the tides module with 0 m. My first attempt was with 2.4 m because it was read by a tide gauge located in Mazatlán and more or less there I placed my open border condition. Here I attach the configuration of the model.
Thank you!
drive.google.com/.../view
When comparing modelled and observed sea levels you must be aware of what's the bathymetry referential and what's the gauge referential.
Your bathymetry, I assume, is derived from a global database and reference to global mean sea level. But the tidal gauge assumes a different referential. At the scale of your model (0.1 degrees ~10-11 km), the approximations you are assuming in terms of bathymetry are not important in terms of simulating the sea level. Nevertheless you should select a reference level. If you're comparing model results with different gauges it may be that different gauges have different reference levels, so you'll need to post-process your results and add or subtract the difference between the selected reference level and the gauge reference level.
In your case, you had selected 2.4m from Mazatlán, but JTide for La Paz is using zero. You'll need to adjust so that they match.
As I had mentioned, in your model you only have 3-4 cells to describe the bay of La Paz and that may be insufficient to model how tide propagates there. I would suggest increasing your model resolution. It does not mean the model is entirely wrong. Other gauges along the coast may show better results because they don't have the recirculation patterns of La Paz. But to get it right at La Paz you may need a finer grid (or a submodel).
Does the right-hand side graph shows both JTide and MOHID2.4? Do they match? It's not very clear what the graphs represent.
Finally I would suggest that you expand the grid south (~20º N) so that the open boundary is not directly facing and very close to Cabo San Lucas (red square in the image below) and also avoiding possible less accurate data in used tidal harmonics database in the area around the red circle in the image below.
Hi Luis, in a previous post you recommended me to increase the resolution of my grid and also expand it to 20°, I downloaded the global data from CMIP5 and then cut it to approximately 18°.To expand the grid to 20° I also need to have data at that latitude, that is to say that I would have to cut them again and instead of cutting at 18° it would be cutting at 20°? I hope I am explaining myself well. Thank you
Hi Metzli,
Yes, that's it. You need the data from CMIP5 to completely cover the extent of your domain.