GfsEventHarmonic

From Gerris

EventHarmonic is used to compute the harmonic decomposition of a given variable.

The syntax in parameter files is

[ GfsEvent ] V A B Z (E) P1 P2 P3 ...

where V is a variable name, A, B and Z are the name prefixes of the new variables which will contain the harmonic coefficients and P1, P2, P3 are the periods of each harmonic. The optional parameter E is the name of a new variable used to store the remainder of the decomposition (i.e. the variance of the difference between the complete timeseries and its harmonic decomposition).

Example:

At t=10, starts computing the harmonic decomposition of the pressure field using two harmonics:

P = Z + A0*cos(T0*t) + B0*sin(T0*t) + A1*cos(T1*t) + B1*sin(T1*t)

The corresponding line in the parameter file would be:

EventHarmonic { start = 10 istep = 1 } P A B Z E 1.40563429690 1.45444104333

with T0=1.40563429690 and T1=1.45444104333.

Examples

• Lunar tides in Cook Strait, New Zealand

    EventHarmonic { start = 100000 istep = 10 } P A B Z EP M2F

    EventHarmonic { start = 100000 istep = 10 } U AU BU ZU EU M2F

    EventHarmonic { start = 100000 istep = 10 } V AV BV ZV EV M2F