Flying tandem

Image of the Month - May 2003

Dynamic topography in the Gulf Stream region, on December 11, 2002. Top, as seen by the Jason-1 + Topex/Poseidon tandem; middle, same region by Jason-1 alone (white ground tracks), and, bottom, the (Jason-1 + Topex/Poseidon) - Jason-1 difference. Significant meanders and eddies that are missed by one satellite alone are described by the tandem. (Credits CLS, Gamble project)

Since September 15, 2002, Topex/Poseidon has been on a new orbit, midway between its original ground tracks, now occupied by Jason-1. Paired operation of these two dedicated satellites with the same design, cross-calibrated, yields data every 10 days, acquired from parallel orbits 158 kilometers apart at the equator. The two satellites deliver equivalent performance and their orbits are synchronous, which give us a much better spatial resolution.

This scientific tandem shows the possibilities of a constellation of optimized altimetric satellites.

Comparison with the sea level observed along an ERS-2 track (black track in above maps). The Jason-1 + T/P tandem is able to reproduce most the signals observed by ERS-2, while the Jason-1 map failed to reproduce Gulf Stream meanders (e.g. 39-40°N, with sea level height of about 40 cm). (Credits CLS, Gamble project)