act.retrievals.calculate_longwave_radiation(ds, temperature_var=None, vapor_pressure_var=None, met_ds=None, emiss_a=0.61, emiss_b=0.06)[source]

Function to calculate longwave radiation during clear and cloudy sky conditions using equations from Monteith and Unsworth 2013, Prata 1996, as reported in Splitt and Bahrmann 1999.

  • ds (xarray.Dataset) – Xarray dataset where variables for these calculations are stored

  • temperature_var (str) – Name of the temperature variable to use

  • vapor_pressure_var (str) – Name of the vapor pressure variable to use

  • met_ds (xarray.Dataset) – Xarray dataset where surface meteorological variables for these calculations are stored if not given, will assume they are in the main dataset passed in

  • emiss_a (float) – a coefficient for the emissivity calculation of e = a + bT

  • emiss_b (float) – a coefficient for the emissivity calculation of e = a + bT


ds (xarray.Dataset) – Xarray dataset with 3 new variables; monteith_clear, monteith_cloudy, prata_clear


Monteith, John L., and Mike H. Unsworth. 2013. Principles of Environmental Physics.

Edited by John L. Monteith and Mike H. Unsworth. Boston: Academic Press.

Prata, A. J. 1996. “A New Long-Wave Formula for Estimating Downward Clear-Sky Radiation at

the Surface.” Quarterly Journal of the Royal Meteorological Society 122 (533): 1127–51.

Splitt, M. E., and C. P. Bahrmann. 1999. Improvement in the Assessment of SIRS Broadband

Longwave Radiation Data Quality. Ninth ARM Science Team Meeting Proceedings, San Antonio, Texas, March 22-26