farms.disc.disc

farms.disc.disc(ghi, sza, doy, pressure=1013.25, sza_lim=87)[source]

Estimate DNI from GHI using the DISC model.

*Warning: should only be used for cloudy FARMS data.

The DISC algorithm converts global horizontal irradiance to direct normal irradiance through empirical relationships between the global and direct clearness indices.

Parameters:

  • ghi (np.ndarray) – Global horizontal irradiance in W/m2.

  • sza (np.ndarray) – Solar zenith angle in degrees.

  • doy (np.ndarray) – Day of year (array of integers).

  • pressure (np.ndarray) – Pressure in mbar (same as hPa).

  • sza_lim (float | int) – Upper limit for solar zenith angle in degrees. SZA values greater than this will be truncated at this value. 87 deg chosen to simulate the FORTRAN code in use by SRRL (from Perez).

Returns:

DNI (np.ndarray) – Estimated direct normal irradiance in W/m2.