Dear all,
I’m running solid Earth tide corrections using gmt earthtide, but I’m a bit confused about the -C flag and the order of the output components. My results appear somewhat different from previous literature, and I suspect this might be due to a mismatch in how I’m handling the output files.
Specifically, if I want to compute the east, north, and vertical components of the Earth tide, should I use:
-Ce,n,v
or
-Cv,e,n
Does the order in the -C flag affect the naming or ordering of the output files, and could this lead to incorrect usage later in processing (e.g., when combining with unit vector rasters using grdmath)?
Here’s the command I’m using:
gmt earthtide -T"$datem1"'T'"$center_time" -G"$epochpath/tmp_tides.%s.nc" -R"$N" -Ce,n,v 2>/dev/null
I think -C is ignored when -L is used and that for grids the order doesn’t real matter, only what components are required
C:\v>earthtide -T2022-07-07T/2022-07-07T01/10m -L-82/9 -Ce,n,v
2022-07-07T00:00:00 -0.0186547577735 -0.0120855709675 0.152718033332
2022-07-07T00:10:00 -0.0191518953079 -0.0142331124781 0.148886469597
2022-07-07T00:20:00 -0.0196071556152 -0.0162922045611 0.144424353961
2022-07-07T00:30:00 -0.0200203538995 -0.0182482500782 0.139360666582
2022-07-07T00:40:00 -0.0203915302281 -0.0200873496634 0.133728709029
2022-07-07T00:50:00 -0.0207209424374 -0.0217964000881 0.127565868473
2022-07-07T01:00:00 -0.0210090576226 -0.0233631869758 0.120913351981
C:\v>earthtide -T2022-07-07T/2022-07-07T01/10m -L-82/9 -Cv,e,n
2022-07-07T00:00:00 -0.0186547577735 -0.0120855709675 0.152718033332
2022-07-07T00:10:00 -0.0191518953079 -0.0142331124781 0.148886469597
2022-07-07T00:20:00 -0.0196071556152 -0.0162922045611 0.144424353961
2022-07-07T00:30:00 -0.0200203538995 -0.0182482500782 0.139360666582
2022-07-07T00:40:00 -0.0203915302281 -0.0200873496634 0.133728709029
2022-07-07T00:50:00 -0.0207209424374 -0.0217964000881 0.127565868473
2022-07-07T01:00:00 -0.0210090576226 -0.0233631869758 0.120913351981
Have also a look at
1 Like
That’s great to know!
I have doubled checked and yes -C doesn’t change the order. it is created as e n v in all different combination.
I also checked the outgrids with -G and then cut with -R flag and drew the component and it was consistent with the point based result;
example of the e file (nc format):
I know that ocean tides are complex - affected by factors other than just the Moon and Sun. That being said, is there any program to compute ocean tides? Just curious.
Well, Mirone ofc. It even has lost somewhere inside its deep guts an implementation of the OSU tide calculator. This is actually something that I have in my loooong TODO list to port to GMT.jl
But you have also Xtide. It probably has now much less coefficients that its (or winxtide?) ancestor that was the source for the Mirone implementation, which still has the original tides coefficients.
