Development of a Luminous Efficacy Model Using Ground and Satellite-Based Data from the Tropics

摘要

In this work, a global luminous efficacy model was developed. The formulation of the model was based on global illuminance and global irradiance measured at four tropical sites in Thailand. The model expresses luminous efficacy as an empirical function of aerosol optical depth, precipitable water, satellite-derived cloud index and cosine of solar zenith angle. The aerosol optical depth and precipitable water were obtained from Aerosol Robotic Network (AERONET) of NASA, and cloud index was derived from multifunctional transport satellite (MTSAT)-1R satellite. The model coefficients were calculated using a 4-year period of hourly data (2007-2010), and the model was validated against an independent data set for 2011. The model predicted well the global illuminance with a root mean square difference (RMSD) of 3.6% and a mean bias difference (MBD) of 0.3%. In addition, the model was compared favourably with most existing models when tested against this independent data set.