Hello,
I have a question regarding the lateral boundary conditions for barotropic velocity in ROMS. Specifically, I’m curious about how the 'flather' or 'Shc' conditions are applied to tangential velocity components. For example, in v2dbc.F, these two conditions are available only for the southern and northern boundaries, which are normal to the v velocity component. In the ocean.in file, I typically set the boundary conditions for both the u and v velocity components to either 'flather' or 'Shc' for all four boundaries. Could someone clarify which condition is actually applied to u at the southern and northern boundaries and to v at the western and eastern boundaries in this case?
Many thanks!
Guangyu
lateral boundary conditions for tangential barotropic velocity components
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Re: lateral boundary conditions for tangential barotropic velocity components
As homework, look at routines u2dbc_im.F and v2dbc_im.F, read the papers, and think! We all do that, including professors, scientists, and seasoned ocean model developers. What is the fun of giving you a couple of sentences for an explanation? This is how we all learn in this profession, and it is rewarding when we figure out the answer for ourselves.
Re: lateral boundary conditions for tangential barotropic velocity components
Hello Hernan,
Thanks for your response. I have read Mason et al., (2010) and Marchesiello et al., (2001). My understanding is that to implement the boundary conditions described in Mason et al., (2010), the 'Shc' condition should be used for normal barotropic velocity component, while the 'upstream radiation' condition is needed for tangential velocity components. I have used the 'Shc' conditions for both tangential and normal velocity components in the past, and I now realize that this may be a mistake, although the model results look quite reasonable.
I have also noticed that, in 'u2dbc_im.F' and 'v2dbc_im.F', the 'Shc' condition is not included in the blocks that define lateral boundary conditions for tangential velocity components. My guess is that some other boundary condition is used when 'Shc' is assigned to tangential velocity components in ocean.in. But it is not clear from 'u2dbc_im.F' and 'v2dbc_im.F' which condition it is.
Guangyu
Thanks for your response. I have read Mason et al., (2010) and Marchesiello et al., (2001). My understanding is that to implement the boundary conditions described in Mason et al., (2010), the 'Shc' condition should be used for normal barotropic velocity component, while the 'upstream radiation' condition is needed for tangential velocity components. I have used the 'Shc' conditions for both tangential and normal velocity components in the past, and I now realize that this may be a mistake, although the model results look quite reasonable.
I have also noticed that, in 'u2dbc_im.F' and 'v2dbc_im.F', the 'Shc' condition is not included in the blocks that define lateral boundary conditions for tangential velocity components. My guess is that some other boundary condition is used when 'Shc' is assigned to tangential velocity components in ocean.in. But it is not clear from 'u2dbc_im.F' and 'v2dbc_im.F' which condition it is.
Guangyu