EstimatedModel.java
/* Copyright 2002-2024 CS GROUP
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* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.models.earth.troposphere;
import java.util.Collections;
import java.util.List;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.util.FastMath;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.bodies.FieldGeodeticPoint;
import org.orekit.bodies.GeodeticPoint;
import org.orekit.models.earth.weather.ConstantPressureTemperatureHumidityProvider;
import org.orekit.models.earth.weather.FieldPressureTemperatureHumidity;
import org.orekit.models.earth.weather.PressureTemperatureHumidity;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.FieldTrackingCoordinates;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.TrackingCoordinates;
/** An estimated tropospheric model. The tropospheric delay is computed according to the formula:
* <p>
* δ = δ<sub>h</sub> * m<sub>h</sub> + (δ<sub>t</sub> - δ<sub>h</sub>) * m<sub>w</sub>
* <p>
* With:
* <ul>
* <li>δ<sub>h</sub>: Tropospheric zenith hydro-static delay.</li>
* <li>δ<sub>t</sub>: Tropospheric total zenith delay.</li>
* <li>m<sub>h</sub>: Hydro-static mapping function.</li>
* <li>m<sub>w</sub>: Wet mapping function.</li>
* </ul>
* <p>
* The mapping functions m<sub>h</sub>(e) and m<sub>w</sub>(e) are
* computed thanks to a {@link #model} initialized by the user.
* The user has the possibility to use several mapping function models for the computations:
* the {@link GlobalMappingFunctionModel Global Mapping Function}, or
* the {@link NiellMappingFunctionModel Niell Mapping Function}
* </p> <p>
* The tropospheric zenith delay δ<sub>h</sub> is computed empirically with a
* {@link DiscreteTroposphericModel tropospheric model}
* while the tropospheric total zenith delay δ<sub>t</sub> is estimated as a {@link ParameterDriver},
* hence the wet part is the difference between the two.
* @since 12.1
*/
public class EstimatedModel implements TroposphericModel {
/** Name of the parameter of this model: the total zenith delay. */
public static final String TOTAL_ZENITH_DELAY = "total zenith delay";
/** Mapping Function model. */
private final TroposphereMappingFunction model;
/** Driver for the tropospheric zenith total delay.*/
private final ParameterDriver totalZenithDelay;
/** Model for hydrostatic component. */
private final TroposphericModel hydrostatic;
/** Build a new instance using the given environmental conditions.
* <p>
* This constructor uses a {@link ModifiedSaastamoinenModel} for the hydrostatic contribution.
* </p>
* @param h0 altitude of the station [m]
* @param t0 the temperature at the station [K]
* @param p0 the atmospheric pressure at the station [mbar]
* @param model mapping function model.
* @param totalDelay initial value for the tropospheric zenith total delay [m]
*/
@DefaultDataContext
public EstimatedModel(final double h0, final double t0, final double p0,
final TroposphereMappingFunction model, final double totalDelay) {
this(new ModifiedSaastamoinenModel(new ConstantPressureTemperatureHumidityProvider(new PressureTemperatureHumidity(h0,
TroposphericModelUtils.HECTO_PASCAL.toSI(p0),
t0,
0.0,
Double.NaN,
Double.NaN))),
model, totalDelay);
}
/** Build a new instance using the given environmental conditions.
* @param hydrostatic model for hydrostatic component
* @param model mapping function model.
* @param totalDelay initial value for the tropospheric zenith total delay [m]
* @since 12.1
*/
public EstimatedModel(final TroposphericModel hydrostatic,
final TroposphereMappingFunction model,
final double totalDelay) {
totalZenithDelay = new ParameterDriver(EstimatedModel.TOTAL_ZENITH_DELAY,
totalDelay, FastMath.scalb(1.0, 0), 0.0, Double.POSITIVE_INFINITY);
this.hydrostatic = hydrostatic;
this.model = model;
}
/** Build a new instance using a standard atmosphere model.
* <ul>
* <li>altitude: 0m
* <li>temperature: 18 degree Celsius
* <li>pressure: 1013.25 mbar
* </ul>
* @param model mapping function model.
* @param totalDelay initial value for the tropospheric zenith total delay [m]
*/
@DefaultDataContext
public EstimatedModel(final TroposphereMappingFunction model, final double totalDelay) {
this(0.0, 273.15 + 18.0, 1013.25, model, totalDelay);
}
/** {@inheritDoc} */
@Override
public List<ParameterDriver> getParametersDrivers() {
return Collections.singletonList(totalZenithDelay);
}
/** {@inheritDoc} */
@Override
public TroposphericDelay pathDelay(final TrackingCoordinates trackingCoordinates,
final GeodeticPoint point,
final PressureTemperatureHumidity weather,
final double[] parameters, final AbsoluteDate date) {
// zenith hydrostatic delay
final double zd = hydrostatic.pathDelay(trackingCoordinates, point, weather, parameters, date).getZh();
// zenith wet delay
final double wd = parameters[0] - zd;
// mapping functions
final double[] mf = model.mappingFactors(trackingCoordinates, point, weather, date);
// composite delay
return new TroposphericDelay(zd, wd, mf[0] * zd, mf[1] * wd);
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldTroposphericDelay<T> pathDelay(final FieldTrackingCoordinates<T> trackingCoordinates,
final FieldGeodeticPoint<T> point,
final FieldPressureTemperatureHumidity<T> weather,
final T[] parameters, final FieldAbsoluteDate<T> date) {
// zenith hydrostatic delay
final T zd = hydrostatic.pathDelay(trackingCoordinates, point, weather, parameters, date).getZh();
// zenith wet delay
final T wd = parameters[0].subtract(zd);
// mapping functions
final T[] mf = model.mappingFactors(trackingCoordinates, point, weather, date);
// composite delay
return new FieldTroposphericDelay<>(zd, wd, mf[0].multiply(zd), mf[1].multiply(wd));
}
}