Advances In Aerosol Optical Depth Evaluation From Broadband Direct Normal Irradiance Measurements

摘要

Aerosols are an important part of the phenomena related to the transport of radiation in the atmosphere. These aerosols produce dispersion and absorption of solar radiation at different wavelengths, defining the available solar resource at the earth's surface. Measurements and studies have been made over time to characterize these key parameters involved in Atmospheric Radiative Transfer. This paper presents the advances in the development of a methodology to estimate aerosols from broadband measurements and the use of inverted Radiative Transfer Codes. For this purpose, databases jointly provided by AERONET and BSRN at 16 stations throughout the world are used. The validation of two Radiative Transfer Codes (SMARTS and SOLIS) is first undertaken to estimate the broadband Direct Normal Irradiance (DNI) under clear-sky conditions at each station. Both models achieve good performance, characterized by a relative rRMSE of 3.2% for SMARTS and 3.7% for SOLIS. The Aerosol Optical Depth at 550nm is then derived using these models in reverse mode. This operation is found difficult when only DNI measurements are available. The results improve notably if some key parameters that characterize aerosols can be added as inputs.