An Illustration of the Contribution of the TOPEX/Poseidon—Jason-1 Tandem Mission to Mesoscale Variability Studies

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Abstract
Almost one year of TOPEX/Poseidon (T/P) and Jason-1 data are processed to analyze the contribution of the tandem mission to mesoscale studies. To merge T/P and Jason-1 sea level anomaly (SLA) data, the main difficulty is to estimate consistent mean profiles for the two missions. An ocean variability correction is thus applied to T/P data before computing the mean profile. As a result, T/P and Jason-1 mean profile crossover differences are reduced from 4.6 cm to 1.5 cm rms only. Results from the tandem mission are then compared with those derived from Jason-1 alone and an external verification is performed with ERS-2 data. We show that, in regions with large mesoscale variability, the sea level and velocity can be mapped respectively with an accuracy of about 6% and 20 to 30% of the signal variance. Compared to Jason-1 or T/P, the tandem mission is also shown to provide a much better description of the Gulf Stream meanders and eddies and of their associated velocity field. These results are very encouraging and demonstrate the potential of an optimised two-satellite constellation for the mesoscale circulation monitoring.