Package org.orekit.models.earth.displacement

Class TidalDisplacement

java.lang.Object

org.orekit.models.earth.displacement.TidalDisplacement

All Implemented Interfaces:

StationDisplacement

public class TidalDisplacement
extends Object
implements StationDisplacement

Modeling of displacement of reference points due to tidal effects.

This class implements displacement of reference point (i.e. ground stations) due to tidal effects, as per IERS conventions.

Displacement can be computed with respect to either conventional tide free or mean tide coordinates. The difference between the two systems is about -12cm at poles and +6cm at equator. Selecting one system or the other depends on how the station coordinates have been computed (i.e. it depends whether the coordinates already include the permanent deformation or not).

Instances of this class are guaranteed to be immutable

Since:

9.1

Author:

Luc Maisonobe

See Also:

• GroundStation

Constructor Summary

Constructors

Constructor	Description
TidalDisplacement(double rEarth, double sunEarthSystemMassRatio, double earthMoonMassRatio, PVCoordinatesProvider sun, PVCoordinatesProvider moon, IERSConventions conventions, boolean removePermanentDeformation)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
Vector3D	displacement(BodiesElements elements, Frame earthFrame, Vector3D referencePoint)	Compute displacement of a ground reference point.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

TidalDisplacement

public TidalDisplacement(double rEarth,
 double sunEarthSystemMassRatio,
 double earthMoonMassRatio,
 PVCoordinatesProvider sun,
 PVCoordinatesProvider moon,
 IERSConventions conventions,
 boolean removePermanentDeformation)

Simple constructor.

Parameters:

rEarth - Earth equatorial radius (from gravity field model)

sunEarthSystemMassRatio - Sun/(Earth + Moon) mass ratio (typically Constants.JPL_SSD_SUN_EARTH_PLUS_MOON_MASS_RATIO)

earthMoonMassRatio - Earth/Moon mass ratio (typically Constants.JPL_SSD_EARTH_MOON_MASS_RATIO)

sun - Sun model

moon - Moon model

conventions - IERS conventions to use

removePermanentDeformation - if true, the station coordinates are considered mean tide and already include the permanent deformation, hence it should be removed from the displacement to avoid considering it twice; if false, the station coordinates are considered conventional tide free so the permanent deformation must be included in the displacement

See Also:

• FramesFactory.getITRF(IERSConventions, boolean)
• FramesFactory.getEOPHistory(IERSConventions, boolean)
• Constants.JPL_SSD_SUN_EARTH_PLUS_MOON_MASS_RATIO
• Constants.JPL_SSD_EARTH_MOON_MASS_RATIO

Method Details

displacement

public Vector3D displacement(BodiesElements elements,
 Frame earthFrame,
 Vector3D referencePoint)

Compute displacement of a ground reference point.

Specified by:

displacement in interface StationDisplacement

Parameters:

elements - elements affecting Earth orientation

earthFrame - Earth frame in which reference point is defined

referencePoint - reference point position in earthFrame

Returns:

displacement vector to be added to referencePoint