org.orekit.models.earth.troposphere

Class SaastamoinenModel

java.lang.Object

org.orekit.models.earth.troposphere.SaastamoinenModel

All Implemented Interfaces:

DiscreteTroposphericModel, MappingFunction

public class SaastamoinenModel
extends Object
implements DiscreteTroposphericModel

The modified Saastamoinen model. Estimates the path delay imposed to electro-magnetic signals by the troposphere according to the formula:

 δ = 2.277e-3 / cos z * (P + (1255 / T + 0.05) * e - B * tan²
 z) + δR
 

with the following input data provided to the model:

• z: zenith angle
• P: atmospheric pressure
• T: temperature
• e: partial pressure of water vapour
• B, δR: correction terms

The model supports custom δR correction terms to be read from a configuration file (saastamoinen-correction.txt) via the DataProvidersManager.

Author:

Thomas Neidhart

See Also:

"Guochang Xu, GPS - Theory, Algorithms and Applications, Springer, 2007"

Field Summary

Fields

Modifier and Type	Field and Description
static String	DELTA_R_FILE_NAME Default file name for δR correction term table.

Constructor Summary

Constructors

Constructor and Description
SaastamoinenModel(double t0, double p0, double r0, String deltaRFileName) Create a new Saastamoinen model for the troposphere using the given environmental conditions.

Method Summary

Modifier and Type	Method and Description
double[]	computeZenithDelay(double height, double[] parameters, AbsoluteDate date) This method allows the computation of the zenith hydrostatic and zenith wet delay.
<T extends RealFieldElement<T>> T[]	computeZenithDelay(T height, T[] parameters, FieldAbsoluteDate<T> date) This method allows the computation of the zenith hydrostatic and zenith wet delay.
List<ParameterDriver>	getParametersDrivers() Get the drivers for tropospheric model parameters.
static SaastamoinenModel	getStandardModel() Create a new Saastamoinen model using a standard atmosphere model.
double[]	mappingFactors(double elevation, double height, double[] parameters, AbsoluteDate date) This method allows the computation of the hydrostatic and wet mapping functions.
<T extends RealFieldElement<T>> T[]	mappingFactors(T elevation, T height, T[] parameters, FieldAbsoluteDate<T> date) This method allows the computation of the hydrostatic and wet mapping functions.
double	pathDelay(double elevation, double height, double[] parameters, AbsoluteDate date) Calculates the tropospheric path delay for the signal path from a ground station to a satellite.
<T extends RealFieldElement<T>> T	pathDelay(T elevation, T height, T[] parameters, FieldAbsoluteDate<T> date) Calculates the tropospheric path delay for the signal path from a ground station to a satellite.

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.troposphere.MappingFunction

getParameters, getParameters

Field Detail

DELTA_R_FILE_NAME

public static final String DELTA_R_FILE_NAME

Default file name for δR correction term table.

See Also:

Constant Field Values

Constructor Detail

SaastamoinenModel

public SaastamoinenModel(double t0,
                         double p0,
                         double r0,
                         String deltaRFileName)

Create a new Saastamoinen model for the troposphere using the given environmental conditions.

Parameters:

t0 - the temperature at the station [K]

p0 - the atmospheric pressure at the station [mbar]

r0 - the humidity at the station [fraction] (50% -> 0.5)

deltaRFileName - regular expression for filename containing δR correction term table (typically DELTA_R_FILE_NAME), if null default values from the reference book are used

Since:

7.1

Method Detail

getStandardModel

public static SaastamoinenModel getStandardModel()

Create a new Saastamoinen model using a standard atmosphere model.

• temperature: 18 degree Celsius
• pressure: 1013.25 mbar
• humidity: 50%

Returns:

a Saastamoinen model with standard environmental values

pathDelay

public double pathDelay(double elevation,
                        double height,
                        double[] parameters,
                        AbsoluteDate date)

Calculates the tropospheric path delay for the signal path from a ground station to a satellite.

The Saastamoinen model is not defined for altitudes below 0.0. for continuity reasons, we use the value for h = 0 when altitude is negative.

Specified by:

pathDelay in interface DiscreteTroposphericModel

Parameters:

elevation - the elevation of the satellite, in radians

height - the height of the station in m above sea level

parameters - tropospheric model parameters.

date - current date

Returns:

the path delay due to the troposphere in m

pathDelay

public <T extends RealFieldElement<T>> T pathDelay(T elevation,
                                                   T height,
                                                   T[] parameters,
                                                   FieldAbsoluteDate<T> date)

Calculates the tropospheric path delay for the signal path from a ground station to a satellite.

The Saastamoinen model is not defined for altitudes below 0.0. for continuity reasons, we use the value for h = 0 when altitude is negative.

Specified by:

pathDelay in interface DiscreteTroposphericModel

Type Parameters:

T - type of the elements

Parameters:

elevation - the elevation of the satellite, in radians

height - the height of the station in m above sea level

parameters - tropospheric model parameters.

date - current date

Returns:

the path delay due to the troposphere in m

computeZenithDelay

public double[] computeZenithDelay(double height,
                                   double[] parameters,
                                   AbsoluteDate date)

Description copied from interface: DiscreteTroposphericModel

This method allows the computation of the zenith hydrostatic and zenith wet delay. The resulting element is an array having the following form:

• double[0] = D_hz → zenith hydrostatic delay
• double[1] = D_wz → zenith wet delay

Specified by:

computeZenithDelay in interface DiscreteTroposphericModel

Parameters:

height - the height of the station in m above sea level.

parameters - tropospheric model parameters.

date - current date

Returns:

a two components array containing the zenith hydrostatic and wet delays.

computeZenithDelay

public <T extends RealFieldElement<T>> T[] computeZenithDelay(T height,
                                                              T[] parameters,
                                                              FieldAbsoluteDate<T> date)

Description copied from interface: DiscreteTroposphericModel

This method allows the computation of the zenith hydrostatic and zenith wet delay. The resulting element is an array having the following form:

• T[0] = D_hz → zenith hydrostatic delay
• T[1] = D_wz → zenith wet delay

Specified by:

computeZenithDelay in interface DiscreteTroposphericModel

Type Parameters:

T - type of the elements

Parameters:

height - the height of the station in m above sea level.

parameters - tropospheric model parameters.

date - current date

Returns:

a two components array containing the zenith hydrostatic and wet delays.

mappingFactors

public double[] mappingFactors(double elevation,
                               double height,
                               double[] parameters,
                               AbsoluteDate date)

Description copied from interface: MappingFunction

This method allows the computation of the hydrostatic and wet mapping functions. The resulting element is an array having the following form:

• double[0] = m_h(e) → hydrostatic mapping function
• double[1] = m_w(e) → wet mapping function

Specified by:

mappingFactors in interface MappingFunction

Parameters:

elevation - the elevation of the satellite, in radians.

height - the height of the station in m above sea level.

parameters - tropospheric model parameters.

date - current date

Returns:

a two components array containing the hydrostatic and wet mapping functions.

mappingFactors

public <T extends RealFieldElement<T>> T[] mappingFactors(T elevation,
                                                          T height,
                                                          T[] parameters,
                                                          FieldAbsoluteDate<T> date)

Description copied from interface: MappingFunction

This method allows the computation of the hydrostatic and wet mapping functions. The resulting element is an array having the following form:

• T[0] = m_h(e) → hydrostatic mapping function
• T[1] = m_w(e) → wet mapping function

Specified by:

mappingFactors in interface MappingFunction

Type Parameters:

T - type of the elements

Parameters:

elevation - the elevation of the satellite, in radians.

height - the height of the station in m above sea level.

parameters - tropospheric model parameters.

date - current date

Returns:

a two components array containing the hydrostatic and wet mapping functions.

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Description copied from interface: MappingFunction

Get the drivers for tropospheric model parameters.

Specified by:

getParametersDrivers in interface MappingFunction

Returns:

drivers for tropospheric model parameters