Package org.orekit.models.earth.ionosphere

Class GlobalIonosphereMapModel

java.lang.Object

org.orekit.models.earth.ionosphere.AbstractIonosphericModel

org.orekit.models.earth.ionosphere.GlobalIonosphereMapModel

All Implemented Interfaces:

IonosphericModel, ParameterDriversProvider

public class GlobalIonosphereMapModel
extends AbstractIonosphericModel

Global Ionosphere Map (GIM) model. The ionospheric delay is computed according to the formulas:

           40.3
    δ =  --------  *  STEC      with, STEC = VTEC * F(elevation)
            f²
 

With:

• f: The frequency of the signal in Hz.
• STEC: The Slant Total Electron Content in TECUnits.
• VTEC: The Vertical Total Electron Content in TECUnits.
• F(elevation): A mapping function which depends on satellite elevation.

The VTEC is read from a IONEX file. A file contains, for a given day, VTEC maps corresponding to snapshots at some sampling hours within the day. VTEC maps are TEC Values on regular latitude, longitude grids (typically global 2.5° x 5.0° grids).

A bilinear interpolation is performed the case of the user initialize the latitude and the longitude with values that are not contained in the stream.

A temporal interpolation is also performed to compute the VTEC at the desired date.

IONEX files are obtained from Crustal Dynamics Data Information System.

The files have to be extracted to UTF-8 text files before being read by this loader.

Example of file:

      1.0            IONOSPHERE MAPS     GPS                 IONEX VERSION / TYPE
 BIMINX V5.3         AIUB                16-JAN-19 07:26     PGM / RUN BY / DATE
 BROADCAST IONOSPHERE MODEL FOR DAY 015, 2019                COMMENT
   2019     1    15     0     0     0                        EPOCH OF FIRST MAP
   2019     1    16     0     0     0                        EPOCH OF LAST MAP
   3600                                                      INTERVAL
     25                                                      # OF MAPS IN FILE
   NONE                                                      MAPPING FUNCTION
      0.0                                                    ELEVATION CUTOFF
                                                             OBSERVABLES USED
   6371.0                                                    BASE RADIUS
      2                                                      MAP DIMENSION
    350.0 350.0   0.0                                        HGT1 / HGT2 / DHGT
     87.5 -87.5  -2.5                                        LAT1 / LAT2 / DLAT
   -180.0 180.0   5.0                                        LON1 / LON2 / DLON
     -1                                                      EXPONENT
 TEC/RMS values in 0.1 TECU; 9999, if no value available     COMMENT
                                                             END OF HEADER
      1                                                      START OF TEC MAP
   2019     1    15     0     0     0                        EPOCH OF CURRENT MAP
     87.5-180.0 180.0   5.0 350.0                            LAT/LON1/LON2/DLON/H
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92
    ...
 

Note that this model pathDelay methods requires the topocentric frame to lie on a OneAxisEllipsoid body shape, because the single layer on which pierce point is computed must be an ellipsoidal shape at some altitude.

Author:

Bryan Cazabonne

See Also:

• "Schaer, S., W. Gurtner, and J. Feltens, 1998, IONEX: The IONosphere Map EXchange Format Version 1, February 25, 1998, Proceedings of the IGS AC Workshop Darmstadt, Germany, February 9–11, 1998"

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	GlobalIonosphereMapModel.TimeInterpolator	Interpolation model for TEC maps.

Nested classes/interfaces inherited from interface org.orekit.models.earth.ionosphere.IonosphericModel

IonosphericModel.DelayCalculator, IonosphericModel.FieldDelayCalculator<T extends CalculusFieldElement<T>>

Constructor Summary

Constructors

Constructor	Description
GlobalIonosphereMapModel(OneAxisEllipsoid earth, String supportedNames)	Constructor with supported names given by user.
GlobalIonosphereMapModel(OneAxisEllipsoid earth, String supportedNames, DataProvidersManager dataProvidersManager, TimeScale utc)	Deprecated. as of 13.1.1, replaced by GlobalIonosphereMapModel(OneAxisEllipsoid, String, DataProvidersManager, TimeScale, TimeInterpolator)
GlobalIonosphereMapModel(OneAxisEllipsoid earth, String supportedNames, DataProvidersManager dataProvidersManager, TimeScale utc, GlobalIonosphereMapModel.TimeInterpolator interpolator)	Constructor that uses user defined supported names and data context.
GlobalIonosphereMapModel(OneAxisEllipsoid earth, TimeScale utc, DataSource... ionex)	Deprecated. as of 13.1.1, replaced by GlobalIonosphereMapModel(OneAxisEllipsoid, TimeScale, TimeInterpolator, DataSource...)
GlobalIonosphereMapModel(OneAxisEllipsoid earth, TimeScale utc, GlobalIonosphereMapModel.TimeInterpolator interpolator, DataSource... ionex)	Constructor that uses user defined data sources.

Method Summary

Modifier and Type	Method	Description
GlobalIonosphereMapModel.TimeInterpolator	getInterpolator()	Get the time interpolator used.
List<ParameterDriver>	getParametersDrivers()	Get the drivers for parameters.
<T extends CalculusFieldElement<T>> T	pathDelay(FieldVector3D<T> localP1, FieldVector3D<T> localP2, TopocentricFrame baseFrame, FieldAbsoluteDate<T> receptionDate, double frequency, T[] parameters)	Calculates the ionospheric path delay for the signal path from a ground station to an observing object (ground station or satellite).
double	pathDelay(Vector3D localP1, Vector3D localP2, TopocentricFrame baseFrame, AbsoluteDate receptionDate, double frequency, double[] parameters)	Calculates the ionospheric path delay for the signal path from a ground station to an observing object (ground station or satellite).

Methods inherited from class org.orekit.models.earth.ionosphere.AbstractIonosphericModel

checkIfPathIsValid, checkIfPathIsValid, getEarth

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.models.earth.ionosphere.IonosphericModel

pathDelay, pathDelay

Methods inherited from interface org.orekit.utils.ParameterDriversProvider

getNbParametersDriversValue, getParameterDriver, getParameters, getParameters, getParameters, getParameters, getParametersAllValues, getParametersAllValues, isSupported

Constructor Details

GlobalIonosphereMapModel

@DefaultDataContext
public GlobalIonosphereMapModel(OneAxisEllipsoid earth,
 String supportedNames)

Constructor with supported names given by user. This constructor uses the default data context.

Parameters:

earth - earth body shape

supportedNames - regular expression that matches the names of the IONEX files to be loaded. See DataProvidersManager.feed(String, DataLoader).

Since:

14.0

See Also:

• GlobalIonosphereMapModel(OneAxisEllipsoid, String, DataProvidersManager, TimeScale, TimeInterpolator)

GlobalIonosphereMapModel

@Deprecated
public GlobalIonosphereMapModel(OneAxisEllipsoid earth,
 String supportedNames,
 DataProvidersManager dataProvidersManager,
 TimeScale utc)

Deprecated.

as of 13.1.1, replaced by GlobalIonosphereMapModel(OneAxisEllipsoid, String, DataProvidersManager, TimeScale, TimeInterpolator)

Constructor that uses user defined supported names and data context.

Parameters:

earth - earth body shape

supportedNames - regular expression that matches the names of the IONEX files to be loaded. See DataProvidersManager.feed(String, DataLoader).

dataProvidersManager - provides access to auxiliary data files.

utc - UTC time scale.

Since:

14.0

GlobalIonosphereMapModel

public GlobalIonosphereMapModel(OneAxisEllipsoid earth,
 String supportedNames,
 DataProvidersManager dataProvidersManager,
 TimeScale utc,
 GlobalIonosphereMapModel.TimeInterpolator interpolator)

Constructor that uses user defined supported names and data context.

Parameters:

earth - earth body shape

supportedNames - regular expression that matches the names of the IONEX files to be loaded. See DataProvidersManager.feed(String, DataLoader).

dataProvidersManager - provides access to auxiliary data files.

utc - UTC time scale.

interpolator - interpolator to use

Since:

14.0

GlobalIonosphereMapModel

@Deprecated
public GlobalIonosphereMapModel(OneAxisEllipsoid earth,
 TimeScale utc,
 DataSource... ionex)

Deprecated.

as of 13.1.1, replaced by GlobalIonosphereMapModel(OneAxisEllipsoid, TimeScale, TimeInterpolator, DataSource...)

Constructor that uses user defined data sources.

Parameters:

earth - earth body shape

utc - UTC time scale.

ionex - sources for the IONEX files

Since:

14.0

GlobalIonosphereMapModel

public GlobalIonosphereMapModel(OneAxisEllipsoid earth,
 TimeScale utc,
 GlobalIonosphereMapModel.TimeInterpolator interpolator,
 DataSource... ionex)

Constructor that uses user defined data sources.

Parameters:

earth - earth body shape

utc - UTC time scale.

interpolator - interpolator to use

ionex - sources for the IONEX files

Since:

14.0

Method Details

getInterpolator

public GlobalIonosphereMapModel.TimeInterpolator getInterpolator()

Get the time interpolator used.

Returns:

time interpolator used

Since:

13.1.1

pathDelay

public double pathDelay(Vector3D localP1,
 Vector3D localP2,
 TopocentricFrame baseFrame,
 AbsoluteDate receptionDate,
 double frequency,
 double[] parameters)

Description copied from interface: IonosphericModel

Calculates the ionospheric path delay for the signal path from a ground station to an observing object (ground station or satellite).

This method is intended to be used for orbit determination issues. In that respect, if the elevation is below 0° the path delay will be equal to zero.

For individual use of the ionospheric model (i.e. not for orbit determination), another method signature can be implemented to compute the path delay for any elevation angle.

Parameters:

localP1 - position of path start point in baseFrame

localP2 - position of path end point in baseFrame

baseFrame - topocentric frame of point with lowest altitude between p1 and p2

receptionDate - date at signal reception

frequency - frequency of the signal in Hz

parameters - ionospheric model parameters at state date

Returns:

the path delay due to the ionosphere in m

pathDelay

public <T extends CalculusFieldElement<T>> T pathDelay(FieldVector3D<T> localP1,
 FieldVector3D<T> localP2,
 TopocentricFrame baseFrame,
 FieldAbsoluteDate<T> receptionDate,
 double frequency,
 T[] parameters)

Description copied from interface: IonosphericModel

Calculates the ionospheric path delay for the signal path from a ground station to an observing object (ground station or satellite).

This method is intended to be used for orbit determination issues. In that respect, if the elevation is below 0° the path delay will be equal to zero.

For individual use of the ionospheric model (i.e. not for orbit determination), another method signature can be implemented to compute the path delay for any elevation angle.

Type Parameters:

T - type of the elements

Parameters:

localP1 - position of path start point in baseFrame

localP2 - position of path end point in baseFrame

baseFrame - topocentric frame of point with lowest altitude between p1 and p2

receptionDate - date at signal reception

frequency - frequency of the signal in Hz

parameters - ionospheric model parameters at state date

Returns:

the path delay due to the ionosphere in m

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Description copied from interface: ParameterDriversProvider

Get the drivers for parameters.

Returns:

drivers for parameters