MarshallSolarActivityFutureEstimation.java

  1. /* Copyright 2002-2013 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;

  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.Arrays;
  26. import java.util.Iterator;
  27. import java.util.SortedSet;
  28. import java.util.TreeSet;
  29. import java.util.regex.Matcher;
  30. import java.util.regex.Pattern;

  32. import org.orekit.data.DataLoader;
  33. import org.orekit.errors.OrekitException;
  34. import org.orekit.errors.OrekitMessages;
  35. import org.orekit.time.AbsoluteDate;
  36. import org.orekit.time.ChronologicalComparator;
  37. import org.orekit.time.DateComponents;
  38. import org.orekit.time.Month;
  39. import org.orekit.time.TimeScale;
  40. import org.orekit.time.TimeScalesFactory;
  41. import org.orekit.time.TimeStamped;

  43. /**
  44.  * This class reads and provides solar activity data needed by
  45.  * atmospheric models: F107 solar flux and Kp indexes.
  46.  * <p>
  47.  * The data are retrieved through the NASA Marshall
  48.  * Solar Activity Future Estimation (MSAFE) as estimates of monthly
  49.  * F10.7 Mean solar flux and Ap geomagnetic parameter.
  50.  * The data can be retrieved at the NASA <a
  51.  * href="http://sail.msfc.nasa.gov/archive_index.htm">
  52.  * Marshall Solar Activity website</a>.
  53.  * Here Kp indices are deduced from Ap indexes, which in turn are tabulated
  54.  * equivalent of retrieved Ap values.
  55.  * </p>
  56.  * <p>
  57.  * If several MSAFE files are available, some dates may appear in several
  58.  * files (for example August 2007 is in all files from the first one
  59.  * published in March 1999 to the February 2008 file). In this case, the
  60.  * data from the most recent file is used and the older ones are discarded.
  61.  * The date of the file is assumed to be 6 months after its first entry
  62.  * (which explains why the file having August 2007 as its first entry is the
  63.  * February 2008 file). This implies that MSAFE files must <em>not</em> be
  64.  * edited to change their time span, otherwise this would break the old
  65.  * entries overriding mechanism.
  66.  * </p>
  67.  * <p>
  68.  * With these data, the {@link #getInstantFlux(AbsoluteDate)} and {@link
  69.  * #getMeanFlux(AbsoluteDate)} methods return the same values and the {@link
  70.  * #get24HoursKp(AbsoluteDate)} and {@link #getThreeHourlyKP(AbsoluteDate)}
  71.  * methods return the same values.
  72.  * </p>
  73.  * @author Bruno Revelin
  74.  * @author Luc Maisonobe
  75.  */
  76. public class MarshallSolarActivityFutureEstimation implements DTM2000InputParameters, DataLoader {

  78.     /** Strength level of activity. */
  79.     public static enum StrengthLevel {

  81.         /** Strong level of activity. */
  82.         STRONG,

  84.         /** Average level of activity. */
  85.         AVERAGE,

  87.         /** Weak level of activity. */
  88.         WEAK

  90.     };

  92.     /** Serializable UID. */
  93.     private static final long serialVersionUID = -5212198874900835369L;

  95.     /** 1/3. */
  96.     private static final double ONE_THIRD = 1.0 / 3.0;

  98.     /** 3 hours geomagnetic indices array. */
  99.     private static final double[] KP_ARRAY = new double[] {
  100.         0, 0 + ONE_THIRD, 1 - ONE_THIRD, 1, 1 + ONE_THIRD, 2 - ONE_THIRD,
  101.         2, 2 + ONE_THIRD, 3 - ONE_THIRD, 3, 3 + ONE_THIRD, 4 - ONE_THIRD,
  102.         4, 4 + ONE_THIRD, 5 - ONE_THIRD, 5, 5 + ONE_THIRD, 6 - ONE_THIRD,
  103.         6, 6 + ONE_THIRD, 7 - ONE_THIRD, 7, 7 + ONE_THIRD, 8 - ONE_THIRD,
  104.         8, 8 + ONE_THIRD, 9 - ONE_THIRD, 9
  105.     };

  107.     /** Mean geomagnetic indices array. */
  108.     private static final double[] AP_ARRAY = new double[] {
  109.         0, 2, 3, 4, 5, 6, 7, 9, 12, 15, 18, 22, 27, 32,
  110.         39, 48, 56, 67, 80, 94, 111, 132, 154 , 179, 207, 236, 300, 400
  111.     };

  113.     /** Pattern for the data fields of MSAFE data. */
  114.     private final Pattern dataPattern;

  116.     /** Data set. */
  117.     private final SortedSet<TimeStamped> data;

  119.     /** Selected strength level of activity. */
  120.     private final StrengthLevel strengthLevel;

  122.     /** First available date. */
  123.     private AbsoluteDate firstDate;

  125.     /** Last available date. */
  126.     private AbsoluteDate lastDate;

  128.     /** Previous set of solar activity parameters. */
  129.     private LineParameters previousParam;

  131.     /** Current set of solar activity parameters. */
  132.     private LineParameters currentParam;

  134.     /** Regular expression for supported files names. */
  135.     private final String supportedNames;

  137.     /** Simple constructor.
  138.      * <p>
  139.      * The original file names used by NASA Marshall space center are of the
  140.      * form: Dec2010F10.txt or Oct1999F10.TXT. So a recommended regular
  141.      * expression for the supported name that work with all published files is:
  142.      * "(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\\p{Digit}\\p{Digit}\\p{Digit}\\p{Digit}F10\\.(?:txt|TXT)"
  143.      * </p>
  144.      * @param supportedNames regular expression for supported files names
  145.      * @param strengthLevel selected strength level of activity
  146.      */
  147.     public MarshallSolarActivityFutureEstimation(final String supportedNames,
  148.                                                  final StrengthLevel strengthLevel) {

  150.         firstDate           = null;
  151.         lastDate            = null;
  152.         data                = new TreeSet<TimeStamped>(new ChronologicalComparator());
  153.         this.supportedNames = supportedNames;
  154.         this.strengthLevel  = strengthLevel;

  156.         // the data lines have the following form:
  157.         // 2010.5003   JUL    83.4      81.3      78.7       6.4       5.9       5.2
  158.         // 2010.5837   AUG    87.3      83.4      78.5       7.0       6.1       4.9
  159.         // 2010.6670   SEP    90.8      85.5      79.4       7.8       6.2       4.7
  160.         // 2010.7503   OCT    94.2      87.6      80.4       9.1       6.4       4.9
  161.         final StringBuilder builder = new StringBuilder("^");

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

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

  169.         // second group: month as a three upper case letters abbreviation
  170.         builder.append("\\p{Blank}+(");
  171.         for (final Month month : Month.values()) {
  172.             builder.append(month.getUpperCaseAbbreviation());
  173.             builder.append('|');
  174.         }
  175.         builder.delete(builder.length() - 1, builder.length());
  176.         builder.append(")");

  178.         // third to eighth group: data fields
  179.         for (int i = 0; i < 6; ++i) {
  180.             builder.append("\\p{Blank}+([-+]?[0-9]+\\.[0-9]+)");
  181.         }

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

  186.         // compile the pattern
  187.         dataPattern = Pattern.compile(builder.toString());

  189.     }

  191.     /** Get the strength level for activity.
  192.      * @return strength level to set
  193.      */
  194.     public StrengthLevel getStrengthLevel() {
  195.         return strengthLevel;
  196.     }

  198.     /** Find the data bracketing a specified date.
  199.      * @param date date to bracket
  200.      * @throws OrekitException if specified date is out of range
  201.      */
  202.     private void bracketDate(final AbsoluteDate date) throws OrekitException {

  204.         if ((date.durationFrom(firstDate) < 0) || (date.durationFrom(lastDate) > 0)) {
  205.             throw new OrekitException(OrekitMessages.OUT_OF_RANGE_EPHEMERIDES_DATE,
  206.                                       date, firstDate, lastDate);
  207.         }

  209.         // don't search if the cached selection is fine
  210.         if ((previousParam != null) &&
  211.             (date.durationFrom(previousParam.getDate()) > 0) &&
  212.             (date.durationFrom(currentParam.getDate()) <= 0 )) {
  213.             return;
  214.         }

  216.         if (date.equals(firstDate)) {
  217.             currentParam  = (LineParameters) data.tailSet(date.shiftedBy(1)).first();
  218.             previousParam = (LineParameters) data.first();
  219.         } else if (date.equals(lastDate)) {
  220.             currentParam  = (LineParameters) data.last();
  221.             previousParam = (LineParameters) data.headSet(date.shiftedBy(-1)).last();
  222.         } else {
  223.             currentParam  = (LineParameters) data.tailSet(date).first();
  224.             previousParam = (LineParameters) data.headSet(date).last();
  225.         }

  227.     }

  229.     /** Get the supported names for data files.
  230.      * @return regular expression for the supported names for data files
  231.      */
  232.     public String getSupportedNames() {
  233.         return supportedNames;
  234.     }

  236.     /** {@inheritDoc} */
  237.     public AbsoluteDate getMinDate() {
  238.         return firstDate;
  239.     }

  241.     /** {@inheritDoc} */
  242.     public AbsoluteDate getMaxDate() {
  243.         return lastDate;
  244.     }

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

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

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

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

  266.         return previousF107 * previousWeight + currentF107 * currentWeight;

  268.     }

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

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

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

  327.         // get the neighboring dates
  328.         bracketDate(date);

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

  340.         // calculating Ap index, then corresponding Kp index
  341.         final int i = Arrays.binarySearch(AP_ARRAY, ap);
  342.         if (i >= 0) {
  343.             // the exact value for ap has been found, return the corresponding Kp
  344.             return KP_ARRAY[i];
  345.         } else {
  346.             // the exact value has not been found, we have an insertion point
  347.             final int jSup = -(i + 1);
  348.             final int jInf = jSup - 1;
  349.             if ((ap - AP_ARRAY[jInf]) < (AP_ARRAY[jSup] - ap)) {
  350.                 return KP_ARRAY[jInf];
  351.             } else {
  352.                 return KP_ARRAY[jSup];
  353.             }
  354.         }

  356.     }

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

  361.         /** Serializable UID. */
  362.         private static final long serialVersionUID = 6607862001953526475L;

  364.         /** File date. */
  365.         private final DateComponents fileDate;

  367.         /** Entry date. */
  368.         private  final AbsoluteDate date;

  370.         /** F10.7 flux at date. */
  371.         private final double f107;

  373.         /** Ap index at date. */
  374.         private final double ap;

  376.         /** Simple constructor.
  377.          * @param fileDate file date
  378.          * @param date entry date
  379.          * @param f107 F10.7 flux at date
  380.          * @param ap Ap index at date
  381.          */
  382.         private LineParameters(final DateComponents fileDate, final AbsoluteDate date, final double f107, final double ap) {
  383.             this.fileDate = fileDate;
  384.             this.date     = date;
  385.             this.f107     = f107;
  386.             this.ap       = ap;
  387.         }

  389.         /** Get the file date.
  390.          * @return file date
  391.          */
  392.         public DateComponents getFileDate() {
  393.             return fileDate;
  394.         }

  396.         /** Get the current date.
  397.          * @return current date
  398.          */
  399.         public AbsoluteDate getDate() {
  400.             return date;
  401.         }

  403.         /** Get the F10.0 flux.
  404.          * @return f10.7 flux
  405.          */
  406.         public double getF107() {
  407.             return f107;
  408.         }

  410.         /** Get the Ap index.
  411.          * @return Ap index
  412.          */
  413.         public double getAp() {
  414.             return ap;
  415.         }

  417.     }

  419.     /** {@inheritDoc} */
  420.     public void loadData(final InputStream input, final String name)
  421.         throws IOException, ParseException, OrekitException {

  423.         // select the groups we want to store
  424.         final int f107Group;
  425.         final int apGroup;
  426.         switch (strengthLevel) {
  427.         case STRONG :
  428.             f107Group = 3;
  429.             apGroup   = 6;
  430.             break;
  431.         case AVERAGE :
  432.             f107Group = 4;
  433.             apGroup   = 7;
  434.             break;
  435.         default :
  436.             f107Group = 5;
  437.             apGroup   = 8;
  438.             break;
  439.         }

  441.         // read the data
  442.         final BufferedReader reader = new BufferedReader(new InputStreamReader(input, "UTF-8"));
  443.         boolean inData = false;
  444.         final TimeScale utc = TimeScalesFactory.getUTC();
  445.         DateComponents fileDate = null;
  446.         for (String line = reader.readLine(); line != null; line = reader.readLine()) {
  447.             line = line.trim();
  448.             if (line.length() > 0) {
  449.                 final Matcher matcher = dataPattern.matcher(line);
  450.                 if (matcher.matches()) {

  452.                     // we are in the data section
  453.                     inData = true;

  455.                     // extract the data from the line
  456.                     final int year = Integer.parseInt(matcher.group(1));
  457.                     final Month month = Month.parseMonth(matcher.group(2));
  458.                     final AbsoluteDate date = new AbsoluteDate(year, month, 1, utc);
  459.                     if (fileDate == null) {
  460.                         // the first entry of each file correspond exactly to 6 months before file publication
  461.                         // so we compute the file date by adding 6 months to its first entry
  462.                         if (month.getNumber() > 6) {
  463.                             fileDate = new DateComponents(year + 1, month.getNumber() - 6, 1);
  464.                         } else {
  465.                             fileDate = new DateComponents(year, month.getNumber() + 6, 1);
  466.                         }
  467.                     }

  469.                     // check if there is already an entry for this date or not
  470.                     boolean addEntry = false;
  471.                     final Iterator<TimeStamped> iterator = data.tailSet(date).iterator();
  472.                     if (iterator.hasNext()) {
  473.                         final LineParameters existingEntry = (LineParameters) iterator.next();
  474.                         if (existingEntry.getDate().equals(date)) {
  475.                             // there is an entry for this date
  476.                             if (existingEntry.getFileDate().compareTo(fileDate) < 0) {
  477.                                 // the entry was read from an earlier file
  478.                                 // we replace it with the new entry as it is fresher
  479.                                 iterator.remove();
  480.                                 addEntry = true;
  481.                             }
  482.                         } else {
  483.                             // it is the first entry we get for this date
  484.                             addEntry = true;
  485.                         }
  486.                     } else {
  487.                         // it is the first entry we get for this date
  488.                         addEntry = true;
  489.                     }
  490.                     if (addEntry) {
  491.                         // we must add the new entry
  492.                         data.add(new LineParameters(fileDate, date,
  493.                                                     Double.parseDouble(matcher.group(f107Group)),
  494.                                                     Double.parseDouble(matcher.group(apGroup))));
  495.                     }

  497.                 } else {
  498.                     if (inData) {
  499.                         // we have already read some data, so we are not in the header anymore
  500.                         // however, we don't recognize this non-empty line,
  501.                         // we consider the file is corrupted
  502.                         throw new OrekitException(OrekitMessages.NOT_A_MARSHALL_SOLAR_ACTIVITY_FUTURE_ESTIMATION_FILE,
  503.                                                   name);
  504.                     }
  505.                 }
  506.             }
  507.         }

  509.         if (data.isEmpty()) {
  510.             throw new OrekitException(OrekitMessages.NOT_A_MARSHALL_SOLAR_ACTIVITY_FUTURE_ESTIMATION_FILE,
  511.                                       name);
  512.         }
  513.         firstDate = data.first().getDate();
  514.         lastDate  = data.last().getDate();

  516.     }

  518.     /** {@inheritDoc} */
  519.     public boolean stillAcceptsData() {
  520.         return true;
  521.     }

  523. }
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