Tides

This class computes functionals of the time depending tide potential, e.g potential, acceleration or gravity gradients.

If several instances of the class are given the results are summed up. Before summation every single result is multiplicated by a factor. To get the difference between two ocean tide models you must choose one factor by 1 and the other by -1. To get the mean of two models just set each factor to 0.5.

AstronomicalTide

This class computes the tide generating potential (TGP) of sun, moon and planets (Mercury, Venus, Mars, Jupiter, Saturn). It takes into account the flattening of the Earth (At the moment only at the acceleration level).

The computed result is multiplied with factor.

Name	Type	Annotation
useMoon	boolean	TGP of moon
useSun	boolean	TGP of sun
usePlanets	boolean	TGP of planets
useEarth	boolean	TGP of Earth
c20Earth	double	J2 flattening of the Earth
factor	double	the result is multiplied by this factor, set -1 to subtract the field

EarthTide

This class computes the earth tide according to the IERS2003 conventions. The values of solid Earth tide external potential Love numbers and the frequency dependent corrections of these values are given in the file inputfileEarthtide. The effect of the permanent tide is removed if includePermanentTide is set to false.

The computed result is multiplied with factor.

Name	Type	Annotation
inputfileEarthtide	filename
includePermanentTide	boolean	results in FALSE: zero tide, TRUE: tide free gravity field
factor	double	the result is multiplied by this factor, set -1 to subtract the field

PoleTide

The potential coefficients of the solid Earth pole tide according to the IERS2003 conventions are given by \[ \begin{split} \Delta c_{21} &= s\cdot(m_1 + o\cdot m_2), \\ \Delta s_{21} &= s\cdot(m_2 - o\cdot m_1), \end{split} \]with $s$ is the scale, $o$ is the outPhase and $(m_1,m_2)$ are the wobble variables in seconds of arc. They are related to the polar motion variables $(x_p,y_p)$ according to \[ \begin{split} m_1 &= (x_p - \bar{x}_p), \\ m_2 &= -(y_p - \bar{y}_p), \end{split} \]The mean pole $(\bar{x}_p, \bar{y}_p)$ is approximated by a polynomial read from inputfileMeanPole.

The displacment is calculated with \[ \begin{split} S_r &= -v\sin2\vartheta(m_1\cos\lambda+m_2\sin\lambda),\\ S_\vartheta &= -h\cos2\vartheta(m_1\cos\lambda+m_2\sin\lambda),\\ S_\lambda &= h\cos\vartheta(m_1\sin\lambda-m_2\cos\lambda), \end{split} \]where $h$ is the horizontalDisplacement and $v$ is the verticalDisplacement.

The computed result is multiplied with factor.

Name	Type	Annotation
scale	double
outPhase	double
inputfileMeanPole	filename
horizontalDisplacement	double	[m]
verticalDisplacement	double	[m]
factor	double	the result is multiplied by this factor, set -1 to subtract the field

OceanPoleTide

The ocean pole tide is generated by the centrifugal effect of polar motion on the oceans. The potential coefficients of this effect is given by IERS2003 conventions are given by \[ \begin{Bmatrix} \Delta c_{nm} \\ \Delta s_{nm} \end{Bmatrix}= \begin{Bmatrix} c_{nm}^R \\ s_{nm}^R \end{Bmatrix} (m_1\gamma^R+m_2\gamma^I)+ \begin{Bmatrix} c_{nm}^I \\ s_{nm}^I \end{Bmatrix} (m_2\gamma^R-m_1\gamma^I) \]where the coefficients are read from file inputfileOceanPole, $\gamma=\gamma^R+i\gamma^I$ is given by gammaReal and gammaImaginary and $(m_1,m_2)$ are the wobble variables in radians. They are related to the polar motion variables $(x_p,y_p)$ according to \[ \begin{split} m_1 &= (x_p - \bar{x}_p), \\ m_2 &= -(y_p - \bar{y}_p), \end{split} \]The mean pole $(\bar{x}_p, \bar{y}_p)$ is approximated by a polynomial read from inputfileMeanPole.

The computed result is multiplied with factor.

Name	Type	Annotation
inputfileOceanPole	filename
minDegree	uint
maxDegree	uint
gammaReal	double
gammaImaginary	double
inputfileMeanPole	filename
factor	double	the result is multiplied by this factor, set -1 to subtract the field

DoodsonHarmonicTide

The time variable potential of ocean tides is given by a fourier expansion \[ V(\M x,t) = \sum_{f} V_f^c(\M x)\cos(\Theta_f(t)) + V_f^s(\M x)\sin(\Theta_f(t)), \]where $V_f^c(\M x)$ and $V_f^s(\M x)$ are spherical harmonics expansions and are read from the file inputfileDoodsonHarmonic. If set the expansion is limited in the range between minDegree and maxDegree inclusivly. $\Theta_f(t)$ are the arguments of the tide constituents $f$: \[ \Theta_f(t) = \sum_{i=1}^6 n_f^i\beta_i(t), \]where $\beta_i(t)$ are the Doodson's fundamental arguments ($\tau,s,h,p,N',p_s$) and $n_f^i$ are the Doodson multipliers for the term at frequency $f$.

The major constituents given by inputfileDoodsonHarmonic can be used to interpolate minor tidal constituents using the file inputfileAdmittance. This file can be created with DoodsonHarmonicsCalculateAdmittance.

After the interpolation step a selection of the computed constituents can be choosen by selectDoodson. Only these constiuents are considered for the results. If no selectDoodson is set all constituents will be used. The constituents can be coded as Doodson number (e.g. 255.555) or as names intoduced by Darwin (e.g. M2).

The computed result is multiplied with factor.

Name	Type	Annotation
inputfileTides	filename
inputfileAdmittance	filename	interpolation of minor constituents
selectDoodson	doodson	consider only these constituents, code number (e.g. 255.555) or darwin name (e.g. M2)
minDegree	uint
maxDegree	uint
nodeCorr	uint	nodal corrections: 0-no corr, 1-IHO, 2-Schureman
factor	double	the result is multiplied by this factor, set -1 to subtract the field

Centrifugal

Computes the centrifugal potential in a rotating system \[ V(\M r, t) = \frac{1}{2} (\M\omega(t)\times\M r)^2. \]The current rotation vector $\M\omega(t)$ is computed from the earthRotation provided by the calling program. The computed result is multiplied with factor.

Be careful, the centrifugal potential is not harmonic. Convolution with a harmonic kernel (e.g. to compute gravity anomalies) is not meaningful.

Name	Type	Annotation
factor	double	the result is multiplied by this factor, set -1 to subtract the field

SolidMoonTide

This class computes the solid moon tide according to the IERS2010 conventions. The values of solid Moon tide external potential Love numbers are given and there are no frequency dependent corrections of these values. The computed result is multiplied with factor.

Name	Type	Annotation
k20	double
k30	double
factor	double	the result is multiplied by this factor, set -1 to subtract the field

Group

Groups a set of tides and has no further effect itself.

Name	Type	Annotation
tides	tides
factor	double	the result is multiplied by this factor