Package com.kosherjava.zmanim.util

Class NOAACalculator

java.lang.Object
com.kosherjava.zmanim.util.AstronomicalCalculator
com.kosherjava.zmanim.util.NOAACalculator
All Implemented Interfaces:
Cloneable
public class NOAACalculator extends AstronomicalCalculator
Implementation of sunrise and sunset methods to calculate astronomical times based on the NOAA algorithm. This calculator uses the Java algorithm based on the implementation by NOAA - National Oceanic and Atmospheric Administration's Surface Radiation Research Branch. NOAA's implementation is based on equations from Astronomical Algorithms by Jean Meeus. Added to the algorithm is an adjustment of the zenith to account for elevation. The algorithm can be found in the Wikipedia Sunrise Equation article.
Author:
© Eliyahu Hershfeld 2011 - 2023

  • Field Details

  • Constructor Details

  • Method Details

    • getCalculatorName

      public String getCalculatorName()
      Description copied from class: AstronomicalCalculator
      Returns the name of the algorithm.
      Specified by:
      getCalculatorName in class AstronomicalCalculator
      Returns:
      the descriptive name of the algorithm.
      See Also:

    • getUTCSunrise

      public double getUTCSunrise(Calendar calendar, GeoLocation geoLocation, double zenith, boolean adjustForElevation)
      Description copied from class: AstronomicalCalculator
      A method that calculates UTC sunrise as well as any time based on an angle above or below sunrise. This abstract method is implemented by the classes that extend this class.
      Specified by:
      getUTCSunrise in class AstronomicalCalculator
      Parameters:
      calendar - Used to calculate day of year.
      geoLocation - The location information used for astronomical calculating sun times.
      zenith - the azimuth below the vertical zenith of 90 degrees. for sunrise typically the zenith used for the calculation uses geometric zenith of 90° and adjusts this slightly to account for solar refraction and the sun's radius. Another example would be AstronomicalCalendar.getBeginNauticalTwilight() that passes AstronomicalCalendar.NAUTICAL_ZENITH to this method.
      adjustForElevation - Should the time be adjusted for elevation
      Returns:
      The UTC time of sunrise in 24 hour format. 5:45:00 AM will return 5.75.0. If an error was encountered in the calculation (expected behavior for some locations such as near the poles, Double.NaN will be returned.
      See Also:

    • getUTCSunset

      public double getUTCSunset(Calendar calendar, GeoLocation geoLocation, double zenith, boolean adjustForElevation)
      Description copied from class: AstronomicalCalculator
      A method that calculates UTC sunset as well as any time based on an angle above or below sunset. This abstract method is implemented by the classes that extend this class.
      Specified by:
      getUTCSunset in class AstronomicalCalculator
      Parameters:
      calendar - Used to calculate day of year.
      geoLocation - The location information used for astronomical calculating sun times.
      zenith - the azimuth below the vertical zenith of 90°. For sunset typically the zenith used for the calculation uses geometric zenith of 90° and adjusts this slightly to account for solar refraction and the sun's radius. Another example would be AstronomicalCalendar.getEndNauticalTwilight() that passes AstronomicalCalendar.NAUTICAL_ZENITH to this method.
      adjustForElevation - Should the time be adjusted for elevation
      Returns:
      The UTC time of sunset in 24 hour format. 5:45:00 AM will return 5.75.0. If an error was encountered in the calculation (expected behavior for some locations such as near the poles, Double.NaN will be returned.
      See Also:

    • getJulianDay

      private static double getJulianDay(Calendar calendar)
      Return the Julian day from a Java Calendar
      Parameters:
      calendar - The Java Calendar
      Returns:
      the Julian day corresponding to the date Note: Number is returned for start of day. Fractional days should be added later.

    • getJulianCenturiesFromJulianDay

      private static double getJulianCenturiesFromJulianDay(double julianDay)
      Convert Julian day to centuries since J2000.0.
      Parameters:
      julianDay - the Julian Day to convert
      Returns:
      the centuries since 2000 Julian corresponding to the Julian Day

    • getJulianDayFromJulianCenturies

      private static double getJulianDayFromJulianCenturies(double julianCenturies)
      Convert centuries since J2000.0 to Julian day.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the Julian Day corresponding to the Julian centuries passed in

    • getSunGeometricMeanLongitude

      private static double getSunGeometricMeanLongitude(double julianCenturies)
      Returns the Geometric Mean Longitude of the Sun.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the Geometric Mean Longitude of the Sun in degrees

    • getSunGeometricMeanAnomaly

      private static double getSunGeometricMeanAnomaly(double julianCenturies)
      Returns the Geometric Mean Anomaly of the Sun.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the Geometric Mean Anomaly of the Sun in degrees

    • getEarthOrbitEccentricity

      private static double getEarthOrbitEccentricity(double julianCenturies)
      Return the eccentricity of earth's orbit.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the unitless eccentricity

    • getSunEquationOfCenter

      private static double getSunEquationOfCenter(double julianCenturies)
      Returns the equation of center for the sun.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the equation of center for the sun in degrees

    • getSunTrueLongitude

      private static double getSunTrueLongitude(double julianCenturies)
      Return the true longitude of the sun.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the sun's true longitude in degrees

    • getSunApparentLongitude

      private static double getSunApparentLongitude(double julianCenturies)
      Return the apparent longitude of the sun.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      sun's apparent longitude in degrees

    • getMeanObliquityOfEcliptic

      private static double getMeanObliquityOfEcliptic(double julianCenturies)
      Returns the mean obliquity of the ecliptic (Axial tilt).
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the mean obliquity in degrees

    • getObliquityCorrection

      private static double getObliquityCorrection(double julianCenturies)
      Returns the corrected obliquity of the ecliptic (Axial tilt).
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the corrected obliquity in degrees

    • getSunDeclination

      private static double getSunDeclination(double julianCenturies)
      Return the declination of the sun.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      the sun's declination in degrees

    • getEquationOfTime

      private static double getEquationOfTime(double julianCenturies)
      Return the Equation of Time - the difference between true solar time and mean solar time
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      Returns:
      equation of time in minutes of time

    • getSunHourAngleAtSunrise

      private static double getSunHourAngleAtSunrise(double lat, double solarDec, double zenith)
      Return the hour angle of the sun in radians at sunrise for the latitude.
      Parameters:
      lat - the latitude of observer in degrees
      solarDec - the declination angle of sun in degrees
      zenith - the zenith
      Returns:
      hour angle of sunrise in radians

    • getSunHourAngleAtSunset

      private static double getSunHourAngleAtSunset(double lat, double solarDec, double zenith)
      Returns the hour angle of the sun in radiansat sunset for the latitude.
      Parameters:
      lat - the latitude of observer in degrees
      solarDec - the declination angle of sun in degrees
      zenith - the zenith
      Returns:
      the hour angle of sunset in radians
      TODO:
      use - getSunHourAngleAtSunrise(double, double, double) implementation to avoid duplication of code.

    • getSolarElevation

      public static double getSolarElevation(Calendar cal, double lat, double lon)
      Return the Solar Elevation for the horizontal coordinate system at the given location at the given time. Can be negative if the sun is below the horizon. Not corrected for altitude.
      Parameters:
      cal - time of calculation
      lat - latitude of location for calculation
      lon - longitude of location for calculation
      Returns:
      solar elevation in degrees - horizon is 0 degrees, civil twilight is -6 degrees

    • getSolarAzimuth

      public static double getSolarAzimuth(Calendar cal, double lat, double lon)
      Return the Solar Azimuth for the horizontal coordinate system at the given location at the given time. Not corrected for altitude. True south is 0 degrees.
      Parameters:
      cal - time of calculation
      lat - latitude of location for calculation
      lon - longitude of location for calculation
      Returns:
      the solar azimuth

    • getSunriseUTC

      private static double getSunriseUTC(double julianDay, double latitude, double longitude, double zenith)
      Return the Universal Coordinated Time (UTC) of sunrise for the given day at the given location on earth.
      Parameters:
      julianDay - the Julian day
      latitude - the latitude of observer in degrees
      longitude - the longitude of observer in degrees
      zenith - the zenith
      Returns:
      the time in minutes from zero UTC

    • getUTCNoon

      public double getUTCNoon(Calendar calendar, GeoLocation geoLocation)
      Return the Universal Coordinated Time (UTC) of solar noon for the given day at the given location on earth. This implementation returns true solar noon as opposed to the time halfway between sunrise and sunset. Other calculators may return a more simplified calculation of halfway between sunrise and sunset. See The Definition of Chatzos for details on solar noon calculations.
      Specified by:
      getUTCNoon in class AstronomicalCalculator
      Parameters:
      calendar - The Calendar representing the date to calculate solar noon for
      geoLocation - The location information used for astronomical calculating sun times. This class uses only requires the longitude for calculating noon since it is the same time anywhere along the longitude line.
      Returns:
      the time in minutes from zero UTC
      See Also:

    • getSolarNoonUTC

      private static double getSolarNoonUTC(double julianCenturies, double longitude)
      Return the Universal Coordinated Time (UTC) of of solar noon for the given day at the given location on earth.
      Parameters:
      julianCenturies - the number of Julian centuries since J2000.0.
      longitude - the longitude of observer in degrees
      Returns:
      the time in minutes from zero UTC
      See Also:

    • getSunsetUTC

      private static double getSunsetUTC(double julianDay, double latitude, double longitude, double zenith)
      Return the Universal Coordinated Time (UTC) of sunset for the given day at the given location on earth.
      Parameters:
      julianDay - the Julian day
      latitude - the latitude of observer in degrees
      longitude - longitude of observer in degrees
      zenith - zenith
      Returns:
      the time in minutes from zero Universal Coordinated Time (UTC)