Analysis on GPS satellite clock error linear prediction from IGS ultra-rapid products

Based on the analysis on IGS ultra-rapid satellite clock error,we compare the predictions predicted by linear model and quadratic polynomial model to the predictions from IGS ultra-rapid product,and then,predict the succeeding day and the next two-days with linear model fitted by observed satellite clock error from IGS ultra-rapid product,at the same time,predict the third day's satellite clock error with linear model fitted by the front continuous two-days observed ones from IGS ultra-rapid product,at last,we get some helpful conclusions to discuss with relative scholar.