This paper is focused on improving the quality of nowcasting solar irradiance by enhancing the clear sky component of the model. A simple linear correction for the average atmospheric transmittance is proposed. The correction is based on the most recent measurements recorded prior the forecasting moment. The proposed procedure was tested against data measured on the Solar Platform of the West University of Timisoara. Overall results demonstrates a notable improvement in the clear sky model accuracy.
 Solar Radiation Monitoring Station of the West University of Timisoara, Romania http://solar.physics.uvt.ro/srms
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