THE ASSESSMENT OF FOUR DIFFERENT CORRECTION METHODS APPLIED TO THE DIFFUSE RADIATION MEASURED IN JERUSALEM, ISRAEL

摘要

Four different correction methods were applied to the diffuse radiation measured by a shadow ring at the National Physical Laboratory's meteorological station during the years 2000-2002. The database consisted of global, normal incidence beam, and diffuse radiation. The diffuse radiation was measure by both an occulting disk and a shadow ring instruments. The database was analyzed by two different filtering methods to eliminate spurious measurements. The database was divided into subsets consisting of clear, partially cloudy and cloudy hours based upon the magnitude of the clearness index. The correction models were applied to all the data, viz., irrespective of the magnitude of the hourly clearness index, and the three subsets defined by the magnitude of the hourly clearness index. It was observed that the performance of the correction model was contingent upon both quality control filters applied and the data set analyzed.