MarshallSolarActivityFutureEstimation.java
/* Copyright 2002-2024 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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package org.orekit.models.earth.atmosphere.data;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import org.hipparchus.analysis.UnivariateFunction;
import org.hipparchus.analysis.interpolation.LinearInterpolator;
import org.hipparchus.util.FastMath;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.data.DataContext;
import org.orekit.data.DataProvidersManager;
import org.orekit.data.DataSource;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitInternalError;
import org.orekit.models.earth.atmosphere.data.MarshallSolarActivityFutureEstimationLoader.LineParameters;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.DateComponents;
import org.orekit.time.DateTimeComponents;
import org.orekit.time.TimeComponents;
import org.orekit.time.TimeScale;
import org.orekit.time.TimeStampedDouble;
import org.orekit.utils.Constants;
import org.orekit.utils.GenericTimeStampedCache;
import org.orekit.utils.OrekitConfiguration;
import org.orekit.utils.TimeStampedGenerator;
/**
* This class provides solar activity data needed by atmospheric models: F107 solar flux, Ap and Kp indexes.
* <p>
* Data comes from the NASA Marshall Solar Activity Future Estimation (MSAFE) as estimates of monthly F10.7
* Mean solar flux and Ap geomagnetic parameter
* (see <a href="https://www.nasa.gov/solar-cycle-progression-and-forecast"> Marshall Solar Activity website</a>).
*
* <p>Data can be retrieved at the NASA
* <a href="https://www.nasa.gov/solar-cycle-progression-and-forecast/archived-forecast/"> Marshall Solar Activity archived forecast</a>.
* Here Kp indices are deduced from Ap indexes, which in turn are tabulated equivalent of retrieved Ap values.
*
* <p> If several MSAFE files are available, some dates may appear in several files (for example August 2007 is in all files from
* the first one published in March 1999 to the February 2008 file). In this case, the data from the most recent file is used
* and the older ones are discarded. The date of the file is assumed to be 6 months after its first entry (which explains why
* the file having August 2007 as its first entry is the February 2008 file). This implies that MSAFE files must <em>not</em>
* be edited to change their time span, otherwise this would break the old entries overriding mechanism.
*
* <p>With these data, the {@link #getInstantFlux(AbsoluteDate)} and {@link #getMeanFlux(AbsoluteDate)} methods return the same
* values and the {@link #get24HoursKp(AbsoluteDate)} and {@link #getThreeHourlyKP(AbsoluteDate)} methods return the same
* values.
*
* <p>Conversion from Ap index values in the MSAFE file to Kp values used by atmosphere models is done using Jacchia's equation
* in [1].
*
* <p>With these data, the {@link #getAp(AbsoluteDate date)} method returns an array of seven times the same daily Ap value,
* i.e. it is suited to be used only with the {@link org.orekit.models.earth.atmosphere.NRLMSISE00 NRLMSISE00} atmospheric
* model where the switch #9 is set to 1.
*
* <h2>References</h2>
*
* <ol> <li> Jacchia, L. G. "CIRA 1972, recent atmospheric models, and improvements in
* progress." COSPAR, 21st Plenary Meeting. Vol. 1. 1978. </li> </ol>
*
* @author Bruno Revelin
* @author Luc Maisonobe
* @author Evan Ward
* @author Pascal Parraud
* @author Vincent Cucchietti
*/
public class MarshallSolarActivityFutureEstimation
extends AbstractSolarActivityData<LineParameters, MarshallSolarActivityFutureEstimationLoader> {
/**
* Default regular expression for the supported name that work with all officially published files.
*
* @since 10.0
*/
public static final String DEFAULT_SUPPORTED_NAMES =
"\\p{Alpha}\\p{Lower}\\p{Lower}\\p{Digit}\\p{Digit}\\p{Digit}\\p{Digit}(?:f|F)10(?:[-_]prd)?\\.(?:txt|TXT)";
/** Serializable UID. */
private static final long serialVersionUID = -5212198874900835369L;
/** Selected strength level of activity. */
private final StrengthLevel strengthLevel;
/** Cache dedicated to average flux. */
private final transient GenericTimeStampedCache<TimeStampedDouble> averageFluxCache;
/**
* Simple constructor. This constructor uses the {@link DataContext#getDefault() default data context}.
* <p>
* The original file names used by NASA Marshall space center are of the form: may2019f10_prd.txt or Oct1999F10.TXT. So a
* recommended regular expression for the supported name that work with all published files is:
* {@link #DEFAULT_SUPPORTED_NAMES}.
* <p>
* It provides a default configuration for the thread safe cache :
* <ul>
* <li>Number of slots : {@code OrekitConfiguration.getCacheSlotsNumber()}</li>
* <li>Max span : {@code Constants.JULIAN_YEAR}</li>
* <li>Max span interval : {@code 0}</li>
* </ul>
*
* @param supportedNames regular expression for supported files names
* @param strengthLevel selected strength level of activity
*
* @see #MarshallSolarActivityFutureEstimation(String, StrengthLevel, DataProvidersManager, TimeScale)
*/
@DefaultDataContext
public MarshallSolarActivityFutureEstimation(final String supportedNames,
final StrengthLevel strengthLevel) {
this(supportedNames, strengthLevel,
DataContext.getDefault().getDataProvidersManager(),
DataContext.getDefault().getTimeScales().getUTC());
}
/**
* Constructor that allows specifying the source of the MSAFE auxiliary data files.
* <p>
* It provides a default configuration for the thread safe cache :
* <ul>
* <li>Number of slots : {@code OrekitConfiguration.getCacheSlotsNumber()}</li>
* <li>Max span : {@code 31 * Constants.JULIAN_DAY}</li>
* <li>Max interval : {@code 0}</li>
* <li>Minimum step: {@code 27 * Constants.JULIAN_DAY}</li>
* </ul>
*
* @param supportedNames regular expression for supported files names
* @param strengthLevel selected strength level of activity
* @param dataProvidersManager provides access to auxiliary data files.
* @param utc UTC time scale.
*
* @since 10.1
*/
public MarshallSolarActivityFutureEstimation(final String supportedNames,
final StrengthLevel strengthLevel,
final DataProvidersManager dataProvidersManager,
final TimeScale utc) {
this(supportedNames, strengthLevel, dataProvidersManager, utc, OrekitConfiguration.getCacheSlotsNumber(),
Constants.JULIAN_DAY * 31, 0, Constants.JULIAN_DAY * 27);
}
/**
* Constructor that allows specifying the source of the MSAFE auxiliary data files and customizable thread safe cache
* configuration.
*
* @param supportedNames regular expression for supported files names
* @param strengthLevel selected strength level of activity
* @param dataProvidersManager provides access to auxiliary data files.
* @param utc UTC time scale.
* @param maxSlots maximum number of independent cached time slots in the
* {@link GenericTimeStampedCache time-stamped cache}
* @param maxSpan maximum duration span in seconds of one slot in the {@link GenericTimeStampedCache time-stamped cache}
* @param maxInterval time interval above which a new slot is created in the
* {@link GenericTimeStampedCache time-stamped cache}
* @param minimumStep overriding minimum step designed for non-homogeneous tabulated values. To be used for example when
* caching monthly tabulated values. May be null.
*
* @since 10.1
*/
public MarshallSolarActivityFutureEstimation(final String supportedNames,
final StrengthLevel strengthLevel,
final DataProvidersManager dataProvidersManager,
final TimeScale utc,
final int maxSlots,
final double maxSpan,
final double maxInterval,
final double minimumStep) {
super(supportedNames, new MarshallSolarActivityFutureEstimationLoader(strengthLevel, utc),
dataProvidersManager, utc, maxSlots, maxSpan, maxInterval, minimumStep);
// Initialise fields
this.strengthLevel = strengthLevel;
this.averageFluxCache = new GenericTimeStampedCache<>(N_NEIGHBORS, OrekitConfiguration.getCacheSlotsNumber(),
Constants.JULIAN_DAY, 0, new AverageFluxGenerator());
}
/**
* Simple constructor which use the {@link DataContext#getDefault() default data context}.
* <p>
* It provides a default configuration for the thread safe cache :
* <ul>
* <li>Number of slots : {@code OrekitConfiguration.getCacheSlotsNumber()}</li>
* <li>Max span : {@code 31 * Constants.JULIAN_DAY}</li>
* <li>Max interval : {@code 0}</li>
* <li>Minimum step: {@code 27 * Constants.JULIAN_DAY}</li>
* </ul>
*
* @param source source for the data
* @param strengthLevel selected strength level of activity
*
* @since 12.0
*/
@DefaultDataContext
public MarshallSolarActivityFutureEstimation(final DataSource source,
final StrengthLevel strengthLevel) {
this(source, strengthLevel, DataContext.getDefault().getTimeScales().getUTC());
}
/**
* Simple constructor.
* <p>
* It provides a default configuration for the thread safe cache :
* <ul>
* <li>Number of slots : {@code OrekitConfiguration.getCacheSlotsNumber()}</li>
* <li>Max span : {@code 31 * Constants.JULIAN_DAY}</li>
* <li>Max interval : {@code 0}</li>
* <li>Minimum step: {@code 27 * Constants.JULIAN_DAY}</li>
* </ul>
*
* @param source source for the data
* @param strengthLevel selected strength level of activity
* @param utc UTC time scale
*
* @since 12.0
*/
public MarshallSolarActivityFutureEstimation(final DataSource source,
final StrengthLevel strengthLevel,
final TimeScale utc) {
this(source, strengthLevel, utc, OrekitConfiguration.getCacheSlotsNumber(),
Constants.JULIAN_DAY * 31, 0, Constants.JULIAN_DAY * 27);
}
/**
* Constructor with customizable thread safe cache configuration.
*
* @param source source for the data
* @param strengthLevel selected strength level of activity
* @param utc UTC time scale
* @param maxSlots maximum number of independent cached time slots in the
* {@link GenericTimeStampedCache time-stamped cache}
* @param maxSpan maximum duration span in seconds of one slot in the {@link GenericTimeStampedCache time-stamped cache}
* @param maxInterval time interval above which a new slot is created in the
* {@link GenericTimeStampedCache time-stamped cache}
* @param minimumStep overriding minimum step designed for non-homogeneous tabulated values. To be used for example when
* caching monthly tabulated values. Use {@code Double.NaN} otherwise.
*
* @since 12.0
*/
public MarshallSolarActivityFutureEstimation(final DataSource source,
final StrengthLevel strengthLevel,
final TimeScale utc,
final int maxSlots,
final double maxSpan,
final double maxInterval,
final double minimumStep) {
super(source, new MarshallSolarActivityFutureEstimationLoader(strengthLevel, utc), utc,
maxSlots, maxSpan, maxInterval, minimumStep);
this.strengthLevel = strengthLevel;
this.averageFluxCache = new GenericTimeStampedCache<>(N_NEIGHBORS, OrekitConfiguration.getCacheSlotsNumber(),
Constants.JULIAN_DAY, 0, new AverageFluxGenerator());
}
/** {@inheritDoc} */
public double getInstantFlux(final AbsoluteDate date) {
return getMeanFlux(date);
}
/** {@inheritDoc} */
public double getMeanFlux(final AbsoluteDate date) {
return getLinearInterpolation(date, LineParameters::getF107);
}
/** {@inheritDoc} */
public double getThreeHourlyKP(final AbsoluteDate date) {
return get24HoursKp(date);
}
/**
* Get the date of the file from which data at the specified date comes from.
* <p>
* If several MSAFE files are available, some dates may appear in several files (for example August 2007 is in all files
* from the first one published in March 1999 to the February 2008 file). In this case, the data from the most recent
* file is used and the older ones are discarded. The date of the file is assumed to be 6 months after its first entry
* (which explains why the file having August 2007 as its first entry is the February 2008 file). This implies that MSAFE
* files must <em>not</em> be edited to change their time span, otherwise this would break the old entries overriding
* mechanism.
* </p>
*
* @param date date of the solar activity data
*
* @return date of the file
*/
public DateComponents getFileDate(final AbsoluteDate date) {
// Get the neighboring solar activity
final LocalSolarActivity localSolarActivity = new LocalSolarActivity(date);
final LineParameters previousParam = localSolarActivity.getPreviousParam();
final LineParameters currentParam = localSolarActivity.getNextParam();
// Choose which file date to return
final double dtP = date.durationFrom(previousParam.getDate());
final double dtC = currentParam.getDate().durationFrom(date);
return (dtP < dtC) ? previousParam.getFileDate() : currentParam.getFileDate();
}
/**
* The Kp index is derived from the Ap index.
* <p>The method used is explained on <a
* href="http://www.ngdc.noaa.gov/stp/GEOMAG/kp_ap.html"> NOAA website.</a> as follows:</p>
* <p>The scale is 0 to 9 expressed in thirds of a unit, e.g. 5- is 4 2/3,
* 5 is 5 and 5+ is 5 1/3. The ap (equivalent range) index is derived from the Kp index as follows:</p>
* <table border="1">
* <caption>Kp / Ap Conversion Table</caption>
* <tbody>
* <tr>
* <td>Kp</td><td>0o</td><td>0+</td><td>1-</td><td>1o</td><td>1+</td><td>2-</td><td>2o</td><td>2+</td><td>3-</td><td>3o</td><td>3+</td><td>4-</td><td>4o</td><td>4+</td>
* </tr>
* <tr>
* <td>ap</td><td>0</td><td>2</td><td>3</td><td>4</td><td>5</td><td>6</td><td>7</td><td>9</td><td>12</td><td>15</td><td>18</td><td>22</td><td>27</td><td>32</td>
* </tr>
* <tr>
* <td>Kp</td><td>5-</td><td>5o</td><td>5+</td><td>6-</td><td>6o</td><td>6+</td><td>7-</td><td>7o</td><td>7+</td><td>8-</td><td>8o</td><td>8+</td><td>9-</td><td>9o</td>
* </tr>
* <tr>
* <td>ap</td><td>39</td><td>48</td><td>56</td><td>67</td><td>80</td><td>94</td><td>111</td><td>132</td><td>154</td><td>179</td><td>207</td><td>236</td><td>300</td><td>400</td>
* </tr>
* </tbody>
* </table>
*
* @param date date of the Kp data
*
* @return the 24H geomagnetic index
*/
public double get24HoursKp(final AbsoluteDate date) {
// get the daily Ap
final double ap = getDailyAp(date);
// get the corresponding Kp index from
// equation 4 in [1] for Ap to Kp conversion
return 1.89 * FastMath.asinh(0.154 * ap);
}
/** {@inheritDoc} */
public double getDailyFlux(final AbsoluteDate date) {
return getMeanFlux(date.shiftedBy(-Constants.JULIAN_DAY));
}
public double getAverageFlux(final AbsoluteDate date) {
// Extract closest neighbours average
final List<TimeStampedDouble> neighbors = averageFluxCache.getNeighbors(date).collect(Collectors.toList());
// Create linear interpolating function
final double[] x = new double[] { 0, 1 };
final double[] y = neighbors.stream().map(TimeStampedDouble::getValue).mapToDouble(Double::doubleValue).toArray();
final LinearInterpolator interpolator = new LinearInterpolator();
final UnivariateFunction interpolatingFunction = interpolator.interpolate(x, y);
// Interpolate
final AbsoluteDate previousDate = neighbors.get(0).getDate();
final AbsoluteDate nextDate = neighbors.get(1).getDate();
return interpolatingFunction.value(date.durationFrom(previousDate) / nextDate.durationFrom(previousDate));
}
/** {@inheritDoc} */
public double[] getAp(final AbsoluteDate date) {
// Gets the AP for the current date
final double ap = getDailyAp(date);
// Retuns an array of Ap filled in with the daily Ap only
return new double[] { ap, ap, ap, ap, ap, ap, ap };
}
/**
* Gets the daily Ap index.
*
* @param date the current date
*
* @return the daily Ap index
*/
private double getDailyAp(final AbsoluteDate date) {
return getLinearInterpolation(date, LineParameters::getAp);
}
/**
* Replace the instance with a data transfer object for serialization.
*
* @return data transfer object that will be serialized
*/
@DefaultDataContext
private Object writeReplace() {
return new DataTransferObject(getSupportedNames(), strengthLevel);
}
/**
* Get the strength level for activity.
*
* @return strength level to set
*/
public StrengthLevel getStrengthLevel() {
return strengthLevel;
}
/** Strength level of activity. */
public enum StrengthLevel {
/** Strong level of activity. */
STRONG,
/** Average level of activity. */
AVERAGE,
/** Weak level of activity. */
WEAK
}
/** Generator generating average flux data between given dates. */
private class AverageFluxGenerator implements TimeStampedGenerator<TimeStampedDouble> {
/** {@inheritDoc} */
@Override
public List<TimeStampedDouble> generate(final AbsoluteDate existingDate, final AbsoluteDate date) {
// No prior data in the cache
if (existingDate == null) {
return generateDataFromEarliestToLatestDates(getCurrentDay(date), getNextDay(date));
}
// Prior data in the cache, fill with data between date and existing date
if (date.isBefore(existingDate)) {
return generateDataFromEarliestToLatestDates(date, existingDate);
}
return generateDataFromEarliestToLatestDates(existingDate, date);
}
/**
* Generate data from earliest to latest date.
*
* @param earliest earliest date
* @param latest latest date
*
* @return data generated from earliest to latest date
*/
private List<TimeStampedDouble> generateDataFromEarliestToLatestDates(final AbsoluteDate earliest,
final AbsoluteDate latest) {
final List<TimeStampedDouble> generated = new ArrayList<>();
// Add next computed average until it brackets the latest date
AbsoluteDate latestNeighbourDate = getCurrentDay(earliest);
while (latestNeighbourDate.isBeforeOrEqualTo(latest)) {
generated.add(computeAverageFlux(latestNeighbourDate));
latestNeighbourDate = getNextDay(latestNeighbourDate);
}
return generated;
}
/**
* Get the current day at midnight.
*
* @param date date
*
* @return current day at midnight.
*/
private AbsoluteDate getCurrentDay(final AbsoluteDate date) {
// Find previous day date time components
final TimeScale utc = getUTC();
final DateComponents dateComponents = date.getComponents(utc).getDate();
// Create absolute date for previous day
return new AbsoluteDate(new DateTimeComponents(dateComponents, TimeComponents.H00), utc);
}
/**
* Get the next day at midnight.
*
* @param date date
*
* @return next day at midnight.
*/
private AbsoluteDate getNextDay(final AbsoluteDate date) {
// Find previous day date time components
final TimeScale utc = getUTC();
final DateComponents dateComponents = date.getComponents(utc).getDate();
final DateComponents shiftedComponents = new DateComponents(dateComponents, 1);
// Create absolute date for previous day
return new AbsoluteDate(new DateTimeComponents(shiftedComponents, TimeComponents.H00), utc);
}
/**
* Compute the average flux for given absolute date.
*
* @param date date at which the average flux is desired
*
* @return average flux
*/
private TimeStampedDouble computeAverageFlux(final AbsoluteDate date) {
// Extract list of neighbors to compute average
final TimeStampedGenerator<LineParameters> generator = getCache().getGenerator();
final AbsoluteDate initialDate = date.shiftedBy(-40 * Constants.JULIAN_DAY);
final AbsoluteDate finalDate = date.shiftedBy(40 * Constants.JULIAN_DAY);
final List<LineParameters> monthlyData = generator.generate(initialDate, finalDate);
// Create interpolator for given data
final LinearInterpolator interpolator = new LinearInterpolator();
final double[] x = monthlyData.stream().map(param -> param.getDate().durationFrom(initialDate))
.mapToDouble(Double::doubleValue).toArray();
final double[] y = monthlyData.stream().map(LineParameters::getF107).mapToDouble(Double::doubleValue).toArray();
final UnivariateFunction interpolatingFunction = interpolator.interpolate(x, y);
// Loops over the 81 days centered on the given date
double average = 0;
for (int i = -40; i < 41; i++) {
average += interpolatingFunction.value(date.shiftedBy(i * Constants.JULIAN_DAY).durationFrom(initialDate));
}
// Returns the 81 day average flux
return new TimeStampedDouble(average / 81, date);
}
}
/** Internal class used only for serialization. */
@DefaultDataContext
private static class DataTransferObject implements Serializable {
/** Serializable UID. */
private static final long serialVersionUID = -5212198874900835369L;
/** Regular expression that matches the names of the IONEX files. */
private final String supportedNames;
/** Selected strength level of activity. */
private final StrengthLevel strengthLevel;
/**
* Simple constructor.
*
* @param supportedNames regular expression for supported files names
* @param strengthLevel selected strength level of activity
*/
DataTransferObject(final String supportedNames,
final StrengthLevel strengthLevel) {
this.supportedNames = supportedNames;
this.strengthLevel = strengthLevel;
}
/**
* Replace the deserialized data transfer object with a {@link MarshallSolarActivityFutureEstimation}.
*
* @return replacement {@link MarshallSolarActivityFutureEstimation}
*/
private Object readResolve() {
try {
return new MarshallSolarActivityFutureEstimation(supportedNames, strengthLevel);
}
catch (OrekitException oe) {
throw new OrekitInternalError(oe);
}
}
}
}