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#include <cmath>
#include "calibration.h"
#include <vector>
#include <ctime>
double temperature_to_radiance(double t, double v) { return (1.1910427e-05 * v * v * v) / (pow(e_num, 1.4387752 * v / t) - 1); }
double radiance_to_temperature(double L, double v) { return (1.4387752 * v) / (log(1.1910427e-05 * v * v * v / L + 1)); }
double freq_to_wavenumber(double freq) { return 1e7 / ((299792458.0 / freq) / 10e-10); }
double wavenumber_to_freq(double wavenumber) { return 299792458.0 / ((1e7 / wavenumber) * 10e-10); }
//////////////////////////////////////////////////////////////////////
//// Experimental
//////////////////////////////////////////////////////////////////////
namespace
{
double trapz(std::vector<double> els)
{
double h = 1;
double i = 0;
double sum = 0;
for (; i < els.size(); ++i)
{
if (i == 0 || i == els.size() - 1)
sum += els[i] / 2;
else
sum += els[i];
}
return sum * h;
}
double irrad(double low_wav, double high_wav, double t_bb)
{
// IRRAD calculate radiant flux of the blackbody over some wavelength interval
// double h = 6.63e-34; // J-s, Planck's constant
// double k = 1.38e-23; // J/K, Boltzmann's constant
// double c = 299790000; // m/s, speed of light
double dwav = (high_wav - low_wav) / 50.0;
std::vector<double> E_wav;
double current_wav = low_wav;
for (int i = 0; i < 50; i++)
{
double ewav = temperature_to_radiance(t_bb, freq_to_wavenumber(299792458.0 / current_wav)); // dwav * (2.0 * M_PI * h * pow(c, 2)) / (pow(current_wav, 5) * (exp(h * c / (current_wav * k * t_bb)) - 1.0));
E_wav.push_back(ewav);
current_wav = low_wav + i * dwav;
}
return trapz(E_wav) / (48.0);
}
}
double calculate_sun_irradiance_interval(double low_wav, double high_wav)
{
double E_rad_sun = irrad(low_wav, high_wav, 5772);
double r_eq_sun = 696000000; // m, equatorial radius of sun
double r_AU = 149597870700; // m, exact def of 1 AU
double E_irrad = E_rad_sun * (pow(r_eq_sun, 2) / pow(r_AU, 2));
return E_irrad;
}
namespace
{
int jday(int yr, int month, int day)
{
bool leap;
double j = 0.0;
if (((yr % 4) == 0 && (yr % 100) != 0) || (yr % 400) == 0)
leap = true;
else
leap = false;
if (month == 1)
j = 0.0;
if (month == 2)
j = 31.0;
if (month == 3)
j = 59.0;
if (month == 4)
j = 90.0;
if (month == 5)
j = 120.0;
if (month == 6)
j = 151.0;
if (month == 7)
j = 181.0;
if (month == 8)
j = 212.0;
if (month == 9)
j = 243.0;
if (month == 10)
j = 273.0;
if (month == 11)
j = 304.0;
if (month == 12)
j = 334.0;
if (month > 2 && leap)
j = j + 1.0;
j = j + day;
return j;
}
// From MSG_data_RadiometricProc.cpp
double cos_sol_za(int jday, double hour, double dlat, double dlon)
{
// http://en.wikipedia.org/wiki/Solar_zenith_angle
double coz;
const double sinob = 0.3978;
// Days per year
const double dpy = 365.242;
// Degrees per hour, speed of earth rotation
const double dph = 15.0;
// From degrees to radians
const double rpd = M_PI / 180.0;
// From radians to degrees
const double dpr = 1.0 / rpd;
// Angle in earth orbit in radians, 0 = the beginning of the year
double dang = 2.0 * M_PI * (double)(jday - 1) / dpy;
double homp = 12.0 + 0.123570 * sin(dang) - 0.004289 * cos(dang) +
0.153809 * sin(2.0 * dang) + 0.060783 * cos(2.0 * dang);
// Hour angle in the local solar time (degrees)
double hang = dph * (hour - homp) + dlon;
double ang = 279.9348 * rpd + dang;
double sigma = (ang * dpr + 0.4087 * sin(ang) + 1.8724 * cos(ang) -
0.0182 * sin(2.0 * ang) + 0.0083 * cos(2.0 * ang)) *
rpd;
// Sin of sun declination
double sindlt = sinob * sin(sigma);
// Cos of sun declination
double cosdlt = sqrt(1.0 - sindlt * sindlt);
coz = sindlt * sin(rpd * dlat) + cosdlt * cos(rpd * dlat) * cos(rpd * hang);
return coz;
}
double cos_sol_za(int yr, int month, int day, int hour, int minute, double lat, double lon)
{
double hourz = (double)hour + ((double)minute) / 60.0;
double jd = jday(yr, month, day);
double zenith;
zenith = cos_sol_za(jd, hourz, lat, lon);
return zenith;
}
}
// cos(80deg)
#define cos80 0.173648178
double radiance_to_reflectance(double irradiance, double radiance, time_t ltime, float lat, float lon)
{
// if (chnum != 1 && chnum != 2 && chnum != 3 && chnum != 12)
// return CALIBRATION_INVALID_VALUE;
std::tm t_read = *gmtime(<ime);
int year = t_read.tm_year + 1900;
int month = t_read.tm_mon + 1;
int day = t_read.tm_mday;
int hour = t_read.tm_hour;
int minute = t_read.tm_min;
int jd = jday(year, month, day);
double esd = 1.0 - 0.0167 * cos(2.0 * M_PI * (jd - 3) / 365.0);
double oneoveresdsquare = 1.0 / (esd * esd);
// double torad[4] = {20.76 * oneoveresdsquare, 23.24 * oneoveresdsquare,
// 19.85 * oneoveresdsquare, 25.11 * oneoveresdsquare};
double tr = irradiance * oneoveresdsquare; // (chnum < 4) ? torad[chnum - 1] : torad[3];
double cos_sza = cos_sol_za(year, month, day, hour, minute, lat, lon);
// Use cos(80°) as lower bound, to avoid division by zero
if (cos_sza < cos80)
return -999.99; // CALIBRATION_INVALID_VALUE; // 0.05; // cos80;
return /*100.0 **/ radiance / tr / cos_sza;
}
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