Coastline file for the ROMS Plotting Package

[lcbernardo]

Hi everyone,

I only recently got to compile the ROMS Plotting Package on my system and have enjoyed using its plotting features. However, as my domain is quite small, it doesn't seem to appear in any of the coastline selections. If I want to create a custom coastline file, are there any available guides?

By inspecting some of the files (for example, philip_high.cst), each polygon seems to be separated by a header consisting of 999.0000000 and 1.000000 on a single line, and then the polygons are defined by a two-column lat lon list. I notice some negative values however, so how should I interpret this? Does it have to do with rotation direction? Or perhaps the location of a lake? Would appreciate any help. Thanks!

Lawrence

[arango]

Yes, that's correct. There are several coastline files at various resolutions including global datasets: global_low.cst, global_crude.cst, and global_inter.cst. Western longitudes and southern latitudes are negative with ranges -180 to 180 and -90 to 90, respectively.

[lcbernardo]

Thank you for the explanation Prof. Arango. I will initially attempt to make simplified coastline files for my study domains.

In one of my modeling runs however, parts of Taiwan make up some of the land areas. I assumed that perhaps the global_inter.cst would represent Taiwan even coarsely. But I don't see it when I activate the coast. I could run the example for DAMEE4 with coastlines drawn, so I'm wondering if it' a problem with my netcdf file. In any case, I'll give it a try.

Lawrence

[arango]

I pretty much doubt that you will be able to do this. These coastlines files are very special and extremely difficult to reproduce. We need closed polygons and the order of values matters to distinguish between continents, islands, and lakes. The filling algorithm in the plotting package requires that the discritized coastline points have water to the left (continent, island) or right (lakes) when looking from one coast point to the next. This order is NOT trivial.

However, the only thing that you need to do is install ROMS matlab repository and use the script coastlines/get_coast.m to extract your data from the Global Self-consistent, Hierarchical, High-resolution Shoreline (GSHHS) dataset. I use Version 1.2. You need to get this dataset from elsewhere. Use Google.

Or you can use the provided global files and the plotting package will use only the values within the specified drawing box.

[lcbernardo]

I see! Thank you for clarifying, and for directing me to the get_coast.m script. Creating the file manually does not seem trivial indeed. I have worked with the GSHHS shoreline dataset before using a different application, and my sites do appear when using the full resolution global dataset. If I still cannot view the coastline after doing as you suggest, then at least I know it really may have to do with the netcdf file.