farms.farms.farms

farms.farms.farms(tau, cloud_type, cloud_effective_radius, solar_zenith_angle, radius, Tuuclr, Ruuclr, Tddclr, Tduclr, albedo, debug=False)[source]

Fast All-sky Radiation Model for Solar applications (FARMS).

Literature

[1] Yu Xie, Manajit Sengupta, Jimy Dudhia, “A Fast All-sky Radiation Model

for Solar applications (FARMS): Algorithm and performance evaluation”, Solar Energy, Volume 135, 2016, Pages 435-445, ISSN 0038-092X, https://doi.org/10.1016/j.solener.2016.06.003. (http://www.sciencedirect.com/science/article/pii/S0038092X16301827)

Variables

F0

Radiative flux at top of atmosphere

Fd

Direct solar flux in the downwelling direction at the surface (eq 2a from [1])

De

Effective cloud particle size (diameter).

Parameters:

  • tau (np.ndarray) – Cloud optical thickness (cld_opd_dcomp) (unitless).

  • cloud_type (np.ndarray) – Integer values representing different cloud types https://github.nrel.gov/PXS/pxs/wiki/Cloud-Classification

  • cloud_effective_radius (np.ndarray) – Cloud effective particle radius (cld_reff_dcomp) (micron).

  • solar_zenith_angle (np.ndarray) – Solar zenith angle (degrees). Must represent the average value over the integration period (e.g. hourly) under scrutiny.

  • radius (np.ndarray) – Sun-earth radius vector, varies between 1.017 in July and 0.983 in January.

  • Tuuclr (np.ndarray) – Transmittance of the clear-sky atmosphere for diffuse incident and diffuse outgoing fluxes (uu). ***Calculated from multiple REST2 runs at different solar angles. Average of Tddclr w different solar angles (see eq 5 from [1]).

  • Ruuclr (np.ndarray) – Calculated in REST2. Aerosol reflectance for diffuse fluxes.

  • Tddclr (np.ndarray) – Calculated in REST2. Transmittance of the clear-sky atmosphere for direct incident and direct outgoing fluxes (dd). Tddclr = dni / etdirn

  • Tduclr (np.ndarray) – Calculated in REST2. Transmittance of the clear-sky atmosphere for direct incident and diffuse outgoing fluxes (du). Tduclr = dhi / (etdirn * cosz)

  • albedo (np.ndarray) – Ground albedo.

  • debug (bool) – Flag to output additional transmission/reflectance variables.

returns:

  • If debug == True –

    fast_datacollections.namedtuple
    Named tuple with irradiance data with the following attributes:
    ghinp.ndarray

    global horizontal irradiance (W/m2)

    dninp.ndarray

    direct normal irradiance (W/m2)

    dhinp.ndarray

    diffuse horizontal irradiance (W/m2)

    Ruucldnp.ndarray

    Aerosol reflectance for diffuse fluxes for cloudy atmosphere.

    Tddcldnp.ndarray

    Transmittance of the cloudy atmosphere for direct incident and direct outgoing fluxes (dd).

    Tducldnp.ndarray

    Transmittance of the cloudy atmosphere for direct incident and diffuse outgoing fluxes (du).

  • else –

    ghi: np.ndarray

    Global horizontal irradiance (W/m2)

    dni_farmsdni: np.ndarray

    DNI computed by FARMS-DNI (W/m2).

    dni0: np.ndarray

    DNI computed by the Lambert law (W/m2). It only includes the narrow beam in the circumsolar region.