1 = irradiance (W/sq m/micron) per wavelength (microns)
2 = photon flux (10.0E+16 /sq cm/s/micron) per wavelength (microns)
3 = photon flux density (10.0E+16 /sq cm/s/eV) per energy (eV)
SITE LOCATION:
float latitude -- the latitude of the site, in decimal degrees NORTH. This means
that a site located at 27° 36' 18" S latitude has latitude = -27.605
float longitude -- the longitude of the site, in decimal degrees EAST. This means
that a site located at 102° 54' 36" W longitude has longitude = -102.91
float timezone -- the Standard time zone number of the site, decimal EAST. For example,
Eastern Standard Time in the United States has timezone = -5.0
DATE:
int year -- the 4-digit year. If this is unspecified, the default is year = 2001
int month -- the 2-digit month; e.g., April has month = 4
int day -- the 2-digit day of month; e.g., April 21 has day = 21
TIME (Standard time only; do NOT correct for Daylight Savings Time):
int hour -- the 2-digit hour, ranging from 0 to 23. If this is unspecified,
the default is hour = 12. Example: at 5:44:12 PM, hour = 17
int minute -- the 2-digit minute of the hour. If this is unspecified, the
default is minute = 0. Example: at 5:44:12 PM, minute = 44
int second -- the 2-digit second of the minute. If this is unspecified, the
default is second = 0. Example: at 5:44:12 PM, second = 12
ATMOSPHERIC TEMPERATURE & PRESSURE (optional, used to correct for atmospheric
refraction and to calculate the pressure-corrected airmass):
float temp -- the ambient temperature in °C. If this is unspecified, the
default is temp = 10.0 °C
float press -- the barometric pressure in millibars (mb). If this is unspecified, the
default is press = 1013.0 mb
COLLECTOR ORIENTATION (optional; assumption is a horizontal collector):
float tilt -- the degrees of tilt from the horizontal. If this is unspecified, the
default is tilt = 0.0 (horizontal). tilt > 180.0 means a sun-tracking collector.
float aspect -- the azimuth angle (horizontal orientation), in degrees, that the
surface faces. NORTH = 0°, EAST = 90°, SOUTH = 180°, and WEST = 270°.
If this is unspecified, the default is aspect = 180.0 (South-facing; note that if tilt = 0.0,
the value of aspect is irrelevant). Example: Southwest has aspect = 225.0
GROUND REFLECTIVITY (optional, used to determine the spectral properties of the ground cover):
float spcrfl[6] -- ground reflectivities divided into 6 spectral bands. A reflectivity of 0 is black and a reflectivity of 1 is white. If this is unspecified, all reflectivities are assumed to be 0.2.
float spcwvr[6] -- the 6 spectral bands for which spcrfl[6] applies. If this is unspecified, the
default upper end of each band is { 0.3, 0.7, 0.8, 1.3, 2.5, 4.0 } respectively, in microns.
ATMOSPHERIC PROPERTIES (used to specify the composition of the atmosphere):
float alpha -- the power on Angstrom turbidity (read the documentation). If this is unspecified, alpha is assumed to be 1.14.
float assym] -- the aerosol assymetry factor (read the documentation). If this is unspecified, assym is assumed to be 0.65.
float ozone -- the ozone amount (atmospheric cm). If this is unspecified, the algorithm will assume an (in)appropriate value.
float tau500 -- the aerosol optical depth at 0.5 microns, base e (see
βn in the documentation).
float watvap -- precipitable water vapor (cm).
OUTPUTS:
float specdif[122] -- Diffuse spectrum on panel (see units).
float specdir[122] -- Direct normal spectrum (see units).
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