Using Topex/Poseidon Data to EnhanceERS-1Data

Abstract

This paper presents a relatively straightforward method for efficiently reducing the ERS-1 orbit error using Topex/Postidon data. The method is based on a global minimization of Topex/Poscidon-ERS-1 (TP-E) dual crossover differences. The TP-E crossover differences give an estimate of the ERS-1 radial orbit error almost directly, leading to a geometric estimation of orbit error. Smoothing cubic-spline functions are then used to obtain a continuous estimation of the orbit error over time. The splines can also be adjusted to minimize the ERS-1-ERS-1 (E-E) crossover differences. This allows a better estimation of the orbit error, especially poleward of 66° where no TP-E crossovers are available. The method was successfully applied to the final TP and ERS-1 datasets [i.e., the TP GDRs (geophysical data records) and the ERS-1 OPRs (ocean products)]. The authors used one full 35-day ERS-1 cycle and five TP cycles concurrent with ERS-1 data. Only crossovers with time differences lm than 5 days are used i... Abstract This paper presents a relatively straightforward method for efficiently reducing the ERS-1 orbit error using Topex/Postidon data. The method is based on a global minimization of Topex/Poscidon-ERS-1 (TP-E) dual crossover differences. The TP-E crossover differences give an estimate of the ERS-1 radial orbit error almost directly, leading to a geometric estimation of orbit error. Smoothing cubic-spline functions are then used to obtain a continuous estimation of the orbit error over time. The splines can also be adjusted to minimize the ERS-1-ERS-1 (E-E) crossover differences. This allows a better estimation of the orbit error, especially poleward of 66° where no TP-E crossovers are available. The method was successfully applied to the final TP and ERS-1 datasets [i.e., the TP GDRs (geophysical data records) and the ERS-1 OPRs (ocean products)]. The authors used one full 35-day ERS-1 cycle and five TP cycles concurrent with ERS-1 data. Only crossovers with time differences lm than 5 days are used i...