Earth tides

Did you know that it's not only the oceans that have a tide? Yes, the solid Earth has tides as well, and they are not so small as one might imagine.

A global view

This example shows a global view of the vertical component of the Earth tide for a perticular data.

using GMT
G = earthtide(T="2022-07-07T12:00:00");
imshow(G, coast=true, colorbar=true, title="Earth tide at noon 7-July-2022")

The 3 components

Now we show the three components of the Earth tide for a specific location (the Panama Cannal) and time interval (the 7'th July 2022).

First we compute the components that will come out in a GMTdataset with named columns. This is handy because we can refer to them by name instead of by column number.

D = earthtide(range=("2022-07-07T", "2022-07-08T", "1m"), location=(-82,9))
Time East North Vertical
1.65715e9 -0.0186548 -0.0120856 0.152718
1.65715e9 -0.0187063 -0.0123039 0.152364
1.65715e9 -0.0187575 -0.0125214 0.152003
1.65715e9 -0.0188083 -0.0127382 0.151636
1.65715e9 -0.0188586 -0.0129542 0.151263

Now plot the three of them with a legend

using GMT
plot(D[:Time, :Vertical], lc=:red, lw=1, legend=:Vertical,
     title="Earth tide components (m) at Panama Cannal")
plot!(D[:Time, :East],  lc=:green, lw=1, legend=:East)
plot!(D[:Time, :North], lc=:blue,  lw=1, legend=:North, show=true)

One month of tides

And now, let's see a full month of tidal data (vertical component).

using GMT
D = earthtide(range=("2022-07-01T", "2022-07-31T", "1m"), location=(-82,9));
plot(D[:Time, :Vertical], lc=:blue, legend=:Vertical, title="Tides (m), one month", show=true)