Crossover height differences exceeding 3.5 times the global RMS value of 20.2 cm did not contribute to the statistics. Figure 6 displays the global distribution of the 50,143 crossovers that could be generated from the edited OPR02 data sets for Cycle 9. This Figure also presents the RMS crossover height difference per 20 x 20 cell, based on the operational DUT orbits. In order to eliminate spurious data, editing at a level of 3.5 times the global crossover RMS of 20.2 cm was applied. Some higher crossover differences are influenced by sea level variability caused by strong meandering and variable currents, like the Circumpolar Current, Kuroshio, and Gulf Stream.
Dots indicate the number of crossovers per bin.
This might be due to a remaining local degradation of the radial orbit error, but meandering of currents, and the resulting sea level variability, should not be excluded as a cause. In coastal regions, imperfection in the modelling of tides contribute to a regional increase of the crossover height differences. Low values like in the Eastern Pacific Ocean, where no sizable currents are present, are most indicative of the real radial orbit errors. Dots indicate the number of crossovers per bin. Figure 8 portrays the distribution of the crossover RMS as a function of the time laps between the ascending and descending passes forming the crossover.