太陽的路徑計算

Question

我正在寫幾種必要的方法來計算太陽在特定點的路徑。我已經使用兩種不同的來源編寫了代碼用於計算，並且都沒有產生期望的結果。來源是：http://www.pveducation.org/pvcdrom/properties-of-sunlight/suns-position和 http://www.esrl.noaa.gov/gmd/grad/solcalc/solareqns.PDF

注意：度到弧分是Deg * 60分。

1. localSolartime：我已轉換的經度以「分鐘」，從localStandardTimeMeridian方法得到的當地標準時間子午線（LSTM）返回一個值，該值是在「分鐘」，並且這也是在返回的equationOfTime '分鐘'。使用pveducation的公式，我計算了時間校正，它說明了給定時間範圍內的小時間變化。當我將這個結果和localTime分別應用到當地的太陽時間（lst）方程時，結果爲676.515（此刻），這對我來說沒有任何意義。據我瞭解，當地的太陽時間表示相對於太陽的時間，當它處於天空的最高點時，在當地被認爲是太陽中午。 676.515沒有意義。有沒有人瞭解可能導致這種情況的原因。

2. HourAngle：我希望一旦我修復localSolarTime方法，這將不需要更正。

我選擇了華盛頓哥倫比亞特區的經緯度。 Zenith和Azimuth的讀數都應該是正值，現在我的區域分別是66和201。

public class PathOfSun { 
static LocalTime localTime = LocalTime.now(); 
static double dcLat = 38.83; 
static double dcLong = -77.02; 
static DecimalFormat df = new DecimalFormat("#.0"); 

public static void main(String [] args) { 
    int day = dayOfYear(); 
    double equationOfTime = equationOfTime(day); 
    double lstm = localTimeMeridian(); 
    double lst = localSolarTime(equationOfTime, dcLong, lstm); 
    double declination = declination(day); 
    double hourAngle = hourAngle(lst); 

    double zenith = zenith(dcLat, declination, hourAngle); 
    double azimuth = azimuth(dcLong, declination, zenith, hourAngle); 

} 

//Longitude of timezone meridian 
public static double localTimeMeridian() { 
    TimeZone gmt = TimeZone.getTimeZone("GMT"); 
    TimeZone est = TimeZone.getTimeZone("EST"); 
    int td = gmt.getRawOffset() - est.getRawOffset(); 
    double localStandardTimeMeridian = 15 * (td/(1000*60*60)); //convert td to hours 
    //System.out.println("Local Time Meridian: " + localStandardTimeMeridian); 
    return localStandardTimeMeridian; 
} 

//Get the number of days since Jan. 1 
public static int dayOfYear() { 
    Calendar localCalendar = Calendar.getInstance(TimeZone.getDefault()); 
    int dayOfYear = localCalendar.get(Calendar.DAY_OF_YEAR); 
    //System.out.println("Day: " + dayOfYear); 
    return dayOfYear; 
} 

//Emperical equation to correct the eccentricity of Earth's orbit and axial tilt 
public static double equationOfTime (double day) { 
    double d =(360.0/365.0)*(day - 81); 
    d = Math.toRadians(d); 
    double equationTime = 9.87*sin(2*d)-7.53*cos(d)-1.54*sin(d); 
    //System.out.println("Equation Of Time: " + equationTime); 
    return equationTime; 
} 
//The angle between the equator and a line drawn from the center of the Sun(degrees) 
public static double declination(int dayOfYear) { 
    double declination = 23.5*sin((Math.toRadians(360.0/365.0))*(dayOfYear - 81)); 
    //System.out.println("Declination: " + df.format(declination)); 
    return declination; 
} 

//Add the number of minutes past midnight localtime// 
public static double hourAngle(double localSolarTime) { 
    double hourAngle = 15 * (localSolarTime - 13); 
    System.out.println("Hour Angle: " + df.format(hourAngle)); //(degrees) 
    return hourAngle; 
} 

//Account for the variation within timezone - increases accuracy 
public static double localSolarTime(double equationOfTime, double longitude, double lstm) { 
    //LocalSolarTime = 4min * (longitude + localStandardTimeMeridian) + equationOfTime 
    //Time Correction is time variation within given time zone (minutes) 
    //longitude = longitude/60; //convert degrees to arcminutes 
    double localStandardTimeMeridian = lstm; 
    double timeCorrection = (4 * (longitude + localStandardTimeMeridian) + equationOfTime); 
    System.out.println("Time Correction: " + timeCorrection); //(in minutes) 
    //localSolarTime represents solar time where noon represents sun's is highest position 
    // in sky and the hour angle is 0 -- hour angle is negative in morning, and positive after solar noon. 
    double localSolarTime = (localTime.toSecondOfDay() + (timeCorrection*60)); //(seconds) 
    localSolarTime = localSolarTime/(60*60); //convert from seconds to hours 
    //Convert double to Time (HH:mm:ss) for console output 
    int hours = (int) Math.floor(localSolarTime); 
    int minutes = (int) ((localSolarTime - hours) * 60); 
    //-1 for the daylight savings 
    Time solarTime = new Time((hours-1), minutes, 0); 
    System.out.println("Local Solar Time: " + solarTime); //hours 

    return localSolarTime; 
} 

public static double azimuth(double lat, double declination, double zenith, double hourAngle) { 
    double azimuthDegree = 0; 
    double elevation = 90 - zenith; 
    elevation = Math.toRadians(elevation); 
    zenith = Math.toRadians(zenith); 
    lat = Math.toRadians(lat); 
    declination = Math.toRadians(declination); 
    hourAngle = Math.round(hourAngle); 
    hourAngle = Math.toRadians(hourAngle); 

    //double azimuthRadian = -sin(hourAngle)*cos(declination)/cos(elevation); 
    double azimuthRadian = ((sin(declination)*cos(lat)) - (cos(hourAngle)*cos(declination)* 
      sin(lat)))/cos(elevation); 

    //Account for time quadrants 
    Calendar cal = Calendar.getInstance(); 
    int hour = cal.get(Calendar.HOUR_OF_DAY); 
    if(hour > 0 && hour < 6) { 
    azimuthDegree = Math.toDegrees(acos(azimuthRadian)); 
    } 
    else if(hour >= 6 && hour < 12) { 
     azimuthDegree = Math.toDegrees(acos(azimuthRadian)); 
     azimuthDegree = 180 - azimuthDegree; 
    } else if (hour >= 12 && hour < 18) { 
     azimuthDegree = Math.toDegrees(acos(azimuthRadian)); 
     azimuthDegree = azimuthDegree - 180; 
    } else if (hour >= 18 && hour < 24) { 
     azimuthDegree = Math.toDegrees(acos(azimuthRadian)); 
     azimuthDegree = 360 - azimuthDegree; 
    } 

    System.out.println("Azimuth: " + df.format(azimuthDegree)); 
    return azimuthDegree; 
} 

public static double zenith(double lat, double declination, double hourAngle) { 
    lat = Math.toRadians(lat); 
    declination = Math.toRadians(declination); 
    hourAngle = Math.round(hourAngle); 
    hourAngle = Math.toRadians(hourAngle); 
    //Solar Zenith Angle 
    double zenith = Math.toDegrees(acos(sin(lat)*sin(declination) + (cos(lat)*cos(declination)*cos(hourAngle)))); 
    //Solar Elevation Angle 
    double elevation = Math.toDegrees(asin(sin(lat)*sin(declination) + (cos(lat)*cos(declination)*cos(hourAngle)))); 
    System.out.println("Elevation: " + df.format(elevation)); 
    System.out.println("Zenith: " + df.format(zenith)); 
    return zenith; 
} 

}

只是重申一下，這一天，當地時間經絡是完全正確的，時間和赤緯公式是準確的，但並不確切。 ----輸出更新----

----- ----- UPDATE用於 的scatterchart顯示整個白天太陽的仰角/方位角。我仍然無法找出方位輸出。這是正確的很長一段時間，但它會從增加和開始減少（〜270 - > 0）。一旦我最終獲得輸出權限，我一定會更新代碼。

Answer 1

您將經度作爲度數傳遞給localSolarTime()，然後將其除以60，並聲明這是爲了將其轉換爲弧的分鐘數。這是錯誤的;你以後的計算需要度數，即使你需要幾分鐘的弧度，你也會乘以60，而不是分割。

這個錯誤的劃分結果是-1.3 °的經度，並且當你找到當地時間子午線和你的位置之間的角度時，你會得到一個很大的角度（大約75 °）。它應該是一個小角度，一般爲±7.5 °。大角度會導致大量的時間校正，並拋出所有的東西。

---

更新：在azimuth()方法的更新版本，象限選擇應基於太陽，或者，等同的時角，對本地太陽時，而不是標準的牆上時鐘時間。而且，在所有計算中使用的小時角度不應該四捨五入。而不是測試的四個不同象限，該方法看起來是這樣的：

public static double azimuth(double lat, double declination, double zenith, double hourAngle) 
{ 
    double elevation = Math.toRadians(90 - zenith); 
    lat = Math.toRadians(lat); 
    declination = Math.toRadians(declination); 
    hourAngle = Math.toRadians(hourAngle); 
    double azimuthRadian = acos(((sin(declination) * cos(lat)) - (cos(hourAngle) * cos(declination) * sin(lat)))/cos(elevation)); 
    double azimuthDegree = Math.toDegrees(azimuthRadian); 
    if (hourAngle > 0) 
    azimuthDegree = 360 - azimuthDegree; 
    System.out.println("Azimuth: " + df.format(azimuthDegree)); 
    return azimuthDegree; 
} 

最後，你是在爲azimuth()方法的lat參數傳遞dcLong;這應該是dcLat。

我建議在整個內部使用弧度，並且只對輸入和輸出進行轉換和轉換。這將有助於防止錯誤，並減少舍入誤差和不必要的混亂。