Error analysis of empirical ocean tide models estimated from TOPEX/POSEIDON altimetry

An error budget is proposed for the TOFEX/POSEIDON (T/P) empirical ocean tide models estimated during the primary mission. The error budget evaluates the individual contribution of errors in each of the altimetric range corrections, orbit errors caused by errors in the background ocean tide potential, and errors caused by the general circulation of the oceans, to errors in the ocean tide models of the eight principal diurnal and semidiurnal tidal components, and the two principal long-period tidal components. The effect of continually updating the T/P empirical ocean tide models during the primary T/P mission is illustrated through tide gauge comparisons and then used to predict the impact of further updates during the extended mission. Both the tide gauge comparisons and the error analysis predict errors in the tide models for the eight principal diurnal and semidiurnal constituents to be of the order of 2-3 cm root-sum-square. The dominant source of errors in the T/P ocean tide models appears to be caused by the general circulation of the oceans observed by the T/P altimeter. Further updates of the T/P empirical ocean tide models during the extended mission should not provide significant improvements in the diurnal and semidiurnal ocean tide models but should provide significant improvements in the long-period ocean tide models, particularly in the monthly (Mm) tidal component.