MarshallSolarActivityFutureEstimation.java

  1. /* Copyright 2002-2018 CS Systèmes d'Information
  2.  * Licensed to CS Systèmes d'Information (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.forces.drag.atmosphere.data;

  19. import java.io.BufferedReader;
  20. import java.io.IOException;
  21. import java.io.InputStream;
  22. import java.io.InputStreamReader;
  23. import java.io.Serializable;
  24. import java.text.ParseException;
  25. import java.util.Iterator;
  26. import java.util.SortedSet;
  27. import java.util.TreeSet;
  28. import java.util.regex.Matcher;
  29. import java.util.regex.Pattern;

  31. import org.hipparchus.util.FastMath;
  32. import org.orekit.data.DataLoader;
  33. import org.orekit.data.DataProvidersManager;
  34. import org.orekit.errors.OrekitException;
  35. import org.orekit.errors.OrekitMessages;
  36. import org.orekit.forces.drag.atmosphere.DTM2000InputParameters;
  37. import org.orekit.time.AbsoluteDate;
  38. import org.orekit.time.ChronologicalComparator;
  39. import org.orekit.time.DateComponents;
  40. import org.orekit.time.Month;
  41. import org.orekit.time.TimeScale;
  42. import org.orekit.time.TimeScalesFactory;
  43. import org.orekit.time.TimeStamped;

  45. /**
  46.  * This class reads and provides solar activity data needed by
  47.  * atmospheric models: F107 solar flux and Kp indexes.
  48.  * <p>
  49.  * The data are retrieved through the NASA Marshall
  50.  * Solar Activity Future Estimation (MSAFE) as estimates of monthly
  51.  * F10.7 Mean solar flux and Ap geomagnetic parameter.
  52.  * The data can be retrieved at the NASA <a
  53.  * href="http://sail.msfc.nasa.gov/archive_index.htm">
  54.  * Marshall Solar Activity website</a>.
  55.  * Here Kp indices are deduced from Ap indexes, which in turn are tabulated
  56.  * equivalent of retrieved Ap values.
  57.  * </p>
  58.  * <p>
  59.  * If several MSAFE files are available, some dates may appear in several
  60.  * files (for example August 2007 is in all files from the first one
  61.  * published in March 1999 to the February 2008 file). In this case, the
  62.  * data from the most recent file is used and the older ones are discarded.
  63.  * The date of the file is assumed to be 6 months after its first entry
  64.  * (which explains why the file having August 2007 as its first entry is the
  65.  * February 2008 file). This implies that MSAFE files must <em>not</em> be
  66.  * edited to change their time span, otherwise this would break the old
  67.  * entries overriding mechanism.
  68.  * </p>
  69.  * <p>
  70.  * With these data, the {@link #getInstantFlux(AbsoluteDate)} and {@link
  71.  * #getMeanFlux(AbsoluteDate)} methods return the same values and the {@link
  72.  * #get24HoursKp(AbsoluteDate)} and {@link #getThreeHourlyKP(AbsoluteDate)}
  73.  * methods return the same values.
  74.  * </p>
  75.  * <p>
  76.  * Conversion from Ap index values in the MSAFE file to Kp values used by the atmosphere
  77.  * model is done using Jacchia's equation in [1].
  78.  * </p>
  79.  *
  80.  * <h2>References</h2>
  81.  *
  82.  * <ol> <li> Jacchia, L. G. "CIRA 1972, recent atmospheric models, and improvements in
  83.  * progress." COSPAR, 21st Plenary Meeting. Vol. 1. 1978. </li> </ol>
  84.  *
  85.  * @author Bruno Revelin
  86.  * @author Luc Maisonobe
  87.  * @author Evan Ward
  88.  */
  89. public class MarshallSolarActivityFutureEstimation implements DTM2000InputParameters, DataLoader {

  91.     /** Strength level of activity. */
  92.     public enum StrengthLevel {

  94.         /** Strong level of activity. */
  95.         STRONG,

  97.         /** Average level of activity. */
  98.         AVERAGE,

  100.         /** Weak level of activity. */
  101.         WEAK

  103.     }

  105.     /** Serializable UID. */
  106.     private static final long serialVersionUID = -5212198874900835369L;

  108.     /** Pattern for the data fields of MSAFE data. */
  109.     private final Pattern dataPattern;

  111.     /** Data set. */
  112.     private final SortedSet<TimeStamped> data;

  114.     /** Selected strength level of activity. */
  115.     private final StrengthLevel strengthLevel;

  117.     /** First available date. */
  118.     private AbsoluteDate firstDate;

  120.     /** Last available date. */
  121.     private AbsoluteDate lastDate;

  123.     /** Previous set of solar activity parameters. */
  124.     private LineParameters previousParam;

  126.     /** Current set of solar activity parameters. */
  127.     private LineParameters currentParam;

  129.     /** Regular expression for supported files names. */
  130.     private final String supportedNames;

  132.     /** Simple constructor.
  133.      * <p>
  134.      * The original file names used by NASA Marshall space center are of the
  135.      * form: Dec2010F10.txt or Oct1999F10.TXT. So a recommended regular
  136.      * expression for the supported name that work with all published files is:
  137.      * "(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\\p{Digit}\\p{Digit}\\p{Digit}\\p{Digit}F10\\.(?:txt|TXT)"
  138.      * </p>
  139.      * @param supportedNames regular expression for supported files names
  140.      * @param strengthLevel selected strength level of activity
  141.      */
  142.     public MarshallSolarActivityFutureEstimation(final String supportedNames,
  143.                                                  final StrengthLevel strengthLevel) {

  145.         firstDate           = null;
  146.         lastDate            = null;
  147.         data                = new TreeSet<TimeStamped>(new ChronologicalComparator());
  148.         this.supportedNames = supportedNames;
  149.         this.strengthLevel  = strengthLevel;

  151.         // the data lines have the following form:
  152.         // 2010.5003   JUL    83.4      81.3      78.7       6.4       5.9       5.2
  153.         // 2010.5837   AUG    87.3      83.4      78.5       7.0       6.1       4.9
  154.         // 2010.6670   SEP    90.8      85.5      79.4       7.8       6.2       4.7
  155.         // 2010.7503   OCT    94.2      87.6      80.4       9.1       6.4       4.9
  156.         final StringBuilder builder = new StringBuilder("^");

  158.         // first group: year
  159.         builder.append("\\p{Blank}*(\\p{Digit}\\p{Digit}\\p{Digit}\\p{Digit})");

  161.         // month as fraction of year, not stored in a group
  162.         builder.append("\\.\\p{Digit}+");

  164.         // second group: month as a three upper case letters abbreviation
  165.         builder.append("\\p{Blank}+(");
  166.         for (final Month month : Month.values()) {
  167.             builder.append(month.getUpperCaseAbbreviation());
  168.             builder.append('|');
  169.         }
  170.         builder.delete(builder.length() - 1, builder.length());
  171.         builder.append(")");

  173.         // third to eighth group: data fields
  174.         for (int i = 0; i < 6; ++i) {
  175.             builder.append("\\p{Blank}+([-+]?[0-9]+\\.[0-9]+)");
  176.         }

  178.         // end of line
  179.         builder.append("\\p{Blank}*$");

  181.         // compile the pattern
  182.         dataPattern = Pattern.compile(builder.toString());

  184.     }

  186.     /** Get the strength level for activity.
  187.      * @return strength level to set
  188.      */
  189.     public StrengthLevel getStrengthLevel() {
  190.         return strengthLevel;
  191.     }

  193.     /** Find the data bracketing a specified date.
  194.      * @param date date to bracket
  195.      * @throws OrekitException if specified date is out of range
  196.      */
  197.     private void bracketDate(final AbsoluteDate date) throws OrekitException {

  199.         if ((date.durationFrom(firstDate) < 0) || (date.durationFrom(lastDate) > 0)) {
  200.             throw new OrekitException(OrekitMessages.OUT_OF_RANGE_EPHEMERIDES_DATE,
  201.                                       date, firstDate, lastDate);
  202.         }

  204.         // don't search if the cached selection is fine
  205.         if ((previousParam != null) &&
  206.             (date.durationFrom(previousParam.getDate()) > 0) &&
  207.             (date.durationFrom(currentParam.getDate()) <= 0 )) {
  208.             return;
  209.         }

  211.         if (date.equals(firstDate)) {
  212.             currentParam  = (LineParameters) data.tailSet(date.shiftedBy(1)).first();
  213.             previousParam = (LineParameters) data.first();
  214.         } else if (date.equals(lastDate)) {
  215.             currentParam  = (LineParameters) data.last();
  216.             previousParam = (LineParameters) data.headSet(date.shiftedBy(-1)).last();
  217.         } else {
  218.             currentParam  = (LineParameters) data.tailSet(date).first();
  219.             previousParam = (LineParameters) data.headSet(date).last();
  220.         }

  222.     }

  224.     /** Get the supported names for data files.
  225.      * @return regular expression for the supported names for data files
  226.      */
  227.     public String getSupportedNames() {
  228.         return supportedNames;
  229.     }

  231.     /** {@inheritDoc} */
  232.     public AbsoluteDate getMinDate() throws OrekitException {
  233.         if (firstDate == null) {
  234.             DataProvidersManager.getInstance().feed(getSupportedNames(), this);
  235.         }
  236.         return firstDate;
  237.     }

  239.     /** {@inheritDoc} */
  240.     public AbsoluteDate getMaxDate() throws OrekitException {
  241.         if (firstDate == null) {
  242.             DataProvidersManager.getInstance().feed(getSupportedNames(), this);
  243.         }
  244.         return lastDate;
  245.     }

  247.     /** {@inheritDoc} */
  248.     public double getInstantFlux(final AbsoluteDate date) throws OrekitException {
  249.         return getMeanFlux(date);
  250.     }

  252.     /** {@inheritDoc} */
  253.     public double getMeanFlux(final AbsoluteDate date) throws OrekitException {

  255.         // get the neighboring dates
  256.         bracketDate(date);

  258.         // perform a linear interpolation
  259.         final AbsoluteDate previousDate = previousParam.getDate();
  260.         final AbsoluteDate currentDate  = currentParam.getDate();
  261.         final double dt                 = currentDate.durationFrom(previousDate);
  262.         final double previousF107       = previousParam.getF107();
  263.         final double currentF107        = currentParam.getF107();
  264.         final double previousWeight     = currentDate.durationFrom(date)  / dt;
  265.         final double currentWeight      = date.durationFrom(previousDate) / dt;

  267.         return previousF107 * previousWeight + currentF107 * currentWeight;

  269.     }

  271.     /** {@inheritDoc} */
  272.     public double getThreeHourlyKP(final AbsoluteDate date) throws OrekitException {
  273.         return get24HoursKp(date);
  274.     }

  276.     /** Get the date of the file from which data at the specified date comes from.
  277.      * <p>
  278.      * If several MSAFE files are available, some dates may appear in several
  279.      * files (for example August 2007 is in all files from the first one
  280.      * published in March 1999 to the February 2008 file). In this case, the
  281.      * data from the most recent file is used and the older ones are discarded.
  282.      * The date of the file is assumed to be 6 months after its first entry
  283.      * (which explains why the file having August 2007 as its first entry is the
  284.      * February 2008 file). This implies that MSAFE files must <em>not</em> be
  285.      * edited to change their time span, otherwise this would break the old
  286.      * entries overriding mechanism.
  287.      * </p>
  288.      * @param date date of the solar activity data
  289.      * @return date of the file
  290.      * @exception OrekitException if specified date is out of range
  291.      */
  292.     public DateComponents getFileDate(final AbsoluteDate date) throws OrekitException {
  293.         bracketDate(date);
  294.         final double dtP = date.durationFrom(previousParam.getDate());
  295.         final double dtC = currentParam.getDate().durationFrom(date);
  296.         return (dtP < dtC) ? previousParam.getFileDate() : currentParam.getFileDate();
  297.     }

  299.     /** The Kp index is derived from the Ap index.
  300.      * <p>The method used is explained on <a
  301.      * href="http://www.ngdc.noaa.gov/stp/GEOMAG/kp_ap.html">
  302.      * NOAA website.</a> as follows:</p>
  303.      * <p>The scale is 0 to 9 expressed in thirds of a unit, e.g. 5- is 4 2/3,
  304.      * 5 is 5 and 5+ is 5 1/3. The ap (equivalent range) index is derived from
  305.      * the Kp index as follows:</p>
  306.      * <table border="1">
  307.      * <caption>Kp / Ap Conversion Table</caption>
  308.      * <tbody>
  309.      * <tr>
  310.      * <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>
  311.      * </tr>
  312.      * <tr>
  313.      * <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>
  314.      * </tr>
  315.      * <tr>
  316.      * <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>
  317.      * </tr>
  318.      * <tr>
  319.      * <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>
  320.      * </tr>
  321.      * </tbody>
  322.      * </table>
  323.      * @param date date of the Kp data
  324.      * @return the 24H geomagnetic index
  325.      * @exception OrekitException if the date is out of range of available data
  326.      */
  327.     public double get24HoursKp(final AbsoluteDate date) throws OrekitException {

  329.         // get the neighboring dates
  330.         bracketDate(date);

  332.         // perform a linear interpolation
  333.         final AbsoluteDate previousDate = previousParam.getDate();
  334.         final AbsoluteDate currentDate  = currentParam.getDate();
  335.         final double dt                 = currentDate.durationFrom(previousDate);
  336.         final double previousAp         = previousParam.getAp();
  337.         final double currentAp          = currentParam.getAp();
  338.         final double previousWeight     = currentDate.durationFrom(date)  / dt;
  339.         final double currentWeight      = date.durationFrom(previousDate) / dt;
  340.         final double ap                 = previousAp * previousWeight + currentAp * currentWeight;

  342.         // calculating Ap index, then corresponding Kp index
  343.         // equation 4 in [1] for Ap to Kp conversion
  344.         return 1.89 * FastMath.asinh(0.154 * ap);
  345.     }

  347.     /** Container class for Solar activity indexes.  */
  348.     private static class LineParameters implements TimeStamped, Serializable {

  350.         /** Serializable UID. */
  351.         private static final long serialVersionUID = 6607862001953526475L;

  353.         /** File date. */
  354.         private final DateComponents fileDate;

  356.         /** Entry date. */
  357.         private  final AbsoluteDate date;

  359.         /** F10.7 flux at date. */
  360.         private final double f107;

  362.         /** Ap index at date. */
  363.         private final double ap;

  365.         /** Simple constructor.
  366.          * @param fileDate file date
  367.          * @param date entry date
  368.          * @param f107 F10.7 flux at date
  369.          * @param ap Ap index at date
  370.          */
  371.         private LineParameters(final DateComponents fileDate, final AbsoluteDate date, final double f107, final double ap) {
  372.             this.fileDate = fileDate;
  373.             this.date     = date;
  374.             this.f107     = f107;
  375.             this.ap       = ap;
  376.         }

  378.         /** Get the file date.
  379.          * @return file date
  380.          */
  381.         public DateComponents getFileDate() {
  382.             return fileDate;
  383.         }

  385.         /** Get the current date.
  386.          * @return current date
  387.          */
  388.         public AbsoluteDate getDate() {
  389.             return date;
  390.         }

  392.         /** Get the F10.0 flux.
  393.          * @return f10.7 flux
  394.          */
  395.         public double getF107() {
  396.             return f107;
  397.         }

  399.         /** Get the Ap index.
  400.          * @return Ap index
  401.          */
  402.         public double getAp() {
  403.             return ap;
  404.         }

  406.     }

  408.     /** {@inheritDoc} */
  409.     public void loadData(final InputStream input, final String name)
  410.         throws IOException, ParseException, OrekitException {

  412.         // select the groups we want to store
  413.         final int f107Group;
  414.         final int apGroup;
  415.         switch (strengthLevel) {
  416.             case STRONG :
  417.                 f107Group = 3;
  418.                 apGroup   = 6;
  419.                 break;
  420.             case AVERAGE :
  421.                 f107Group = 4;
  422.                 apGroup   = 7;
  423.                 break;
  424.             default :
  425.                 f107Group = 5;
  426.                 apGroup   = 8;
  427.                 break;
  428.         }

  430.         // read the data
  431.         final BufferedReader reader = new BufferedReader(new InputStreamReader(input, "UTF-8"));
  432.         boolean inData = false;
  433.         final TimeScale utc = TimeScalesFactory.getUTC();
  434.         DateComponents fileDate = null;
  435.         for (String line = reader.readLine(); line != null; line = reader.readLine()) {
  436.             line = line.trim();
  437.             if (line.length() > 0) {
  438.                 final Matcher matcher = dataPattern.matcher(line);
  439.                 if (matcher.matches()) {

  441.                     // we are in the data section
  442.                     inData = true;

  444.                     // extract the data from the line
  445.                     final int year = Integer.parseInt(matcher.group(1));
  446.                     final Month month = Month.parseMonth(matcher.group(2));
  447.                     final AbsoluteDate date = new AbsoluteDate(year, month, 1, utc);
  448.                     if (fileDate == null) {
  449.                         // the first entry of each file correspond exactly to 6 months before file publication
  450.                         // so we compute the file date by adding 6 months to its first entry
  451.                         if (month.getNumber() > 6) {
  452.                             fileDate = new DateComponents(year + 1, month.getNumber() - 6, 1);
  453.                         } else {
  454.                             fileDate = new DateComponents(year, month.getNumber() + 6, 1);
  455.                         }
  456.                     }

  458.                     // check if there is already an entry for this date or not
  459.                     boolean addEntry = false;
  460.                     final Iterator<TimeStamped> iterator = data.tailSet(date).iterator();
  461.                     if (iterator.hasNext()) {
  462.                         final LineParameters existingEntry = (LineParameters) iterator.next();
  463.                         if (existingEntry.getDate().equals(date)) {
  464.                             // there is an entry for this date
  465.                             if (existingEntry.getFileDate().compareTo(fileDate) < 0) {
  466.                                 // the entry was read from an earlier file
  467.                                 // we replace it with the new entry as it is fresher
  468.                                 iterator.remove();
  469.                                 addEntry = true;
  470.                             }
  471.                         } else {
  472.                             // it is the first entry we get for this date
  473.                             addEntry = true;
  474.                         }
  475.                     } else {
  476.                         // it is the first entry we get for this date
  477.                         addEntry = true;
  478.                     }
  479.                     if (addEntry) {
  480.                         // we must add the new entry
  481.                         data.add(new LineParameters(fileDate, date,
  482.                                                     Double.parseDouble(matcher.group(f107Group)),
  483.                                                     Double.parseDouble(matcher.group(apGroup))));
  484.                     }

  486.                 } else {
  487.                     if (inData) {
  488.                         // we have already read some data, so we are not in the header anymore
  489.                         // however, we don't recognize this non-empty line,
  490.                         // we consider the file is corrupted
  491.                         throw new OrekitException(OrekitMessages.NOT_A_MARSHALL_SOLAR_ACTIVITY_FUTURE_ESTIMATION_FILE,
  492.                                                   name);
  493.                     }
  494.                 }
  495.             }
  496.         }

  498.         if (data.isEmpty()) {
  499.             throw new OrekitException(OrekitMessages.NOT_A_MARSHALL_SOLAR_ACTIVITY_FUTURE_ESTIMATION_FILE,
  500.                                       name);
  501.         }
  502.         firstDate = data.first().getDate();
  503.         lastDate  = data.last().getDate();

  505.     }

  507.     /** {@inheritDoc} */
  508.     public boolean stillAcceptsData() {
  509.         return true;
  510.     }

  512. }
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