Tidal prediction¶

The tidal prediction is calculted for harmonic coefficient for each tidal constituent as :

\( \eta_{tides}(t) = Re\left( \sum^{n=M2, S2...} f_n(t) A_ne^{i\left(\omega_nt + u_n(t) -\phi_n\right)} \right) \)

with \(A\) the amplitude, \(\omega\) the tidal pulsation and \(\phi\) the phase lag. \(f\) are and \(u\) are the amplitude and phase nodal corrections.

Time series from atlas¶

To predict the tidal signal at specific locations from atlases or model harmonic analyses, use the predictor command.

Fist you need a locations.dat file with all the wanted loactions:

number of locations
 lon lat
 lon lat
 lon lat
 ...

For example:

6 
 -45.309906 2.587339
 -45.202062 3.810184
 -44.544542 3.466784
 -44.422247 2.818729
 -44.422247 2.818729
 -46.000000 0.500000

Then, compute the prediction:

fes=/ecola/share/data/tides/FES2022/

predictor -p locations.dat \
          -s "2021/08/01 00:00:00.000" -f "2025/01/01 00:00:00.000" \
          -g $fes/mesh-FES2022.nc \
          -a $fes/DOI/WAVE.FES2022.nc \
          -v Ha Hg \
          -w M2 S2 

TIPS: is doing the interpolation calculation only once for each location so it is better to ask for all the wanted tidal constituent at once.

The predictions will be stored the files “predictions.dat”, an ASCII table with one column for each location:

Time [days since the begining of prediction]
Day [YYYY-MM-DD]
Hour [HH:MM:SS]
Location 1
Location 2
…