我正在写一些必要的方法来计算太阳在特定点上的路径。我已经使用两个不同的来源编写了代码，以进行计算，但都没有产生期望的结果。来源是:http://www.pveducation.org/pvcdrom/properties-of-sunlight/suns-position和
http://www.esrl.noaa.gov/gmd/grad/solcalc/solareqns.PDF
注意:弧分的度数是度* 60分钟。
我选择华盛顿特区作为纬度和经度。 Zenith和Azimuth读数均应为正值，并且对于我现在的区域，分别为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;
}
}
重申一下，本地时间子午线是完全正确的，并且时间和纬度等式是准确的，但不是精确的。
----更新输出----
- - -更新 - - -
使用散点图显示全天太阳的仰角/方位角。我仍然无法确定方位角的输出。长期以来它是正确的，但随后会从增加变为减少(〜270-> 0)。最终确定正确的输出后，我将确保更新代码。
最佳答案
您将经度作为度数传递给localSolarTime()，然后将其除以60，并加上一条注释，声称这是为了转换为弧度分钟。这是错误的；您以后的计算需要度数，即使您需要弧度的分钟数，也要乘以60，而不是除以。
这种错误的划分会导致经度为-1.3°，并且当您发现本地子午线与位置之间的角度时，您会得到一个大角度(大约75°)。它应该是一个小角度，通常为±7.5°。大角度会导致较大的时间校正，并且会丢掉所有内容。
更新:在azimuth()方法的更新版本中，象限选择应基于太阳的时角或等效地基于本地的太阳时间，而不是标准的挂钟时间。并且，在所有计算中使用的小时角不应四舍五入。与其测试四个不同的象限，该方法可能看起来像这样:
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;
}
最后，您将
dcLong作为lat方法的azimuth()参数传入。这应该是dcLat。我建议整个内部都使用弧度，并且仅在输入和输出之间进行度数转换。这将有助于防止错误，并减少舍入错误和不必要的困惑。
关于java - 太阳路径的计算，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/30038320/