News | August 10, 2022

Happy 30th Anniversary to TOPEX/Poseidon!

Image showing a map of how sea levels have changed over the last 30 years — The image shows a map of how sea levels have changed over the last 30 years, with yellow areas rising slowly and red areas rising more quickly. Superimposed over the map is the record of global sea level change, which shows a 10 cm rise over the past 30 years. The natural, yearly cycle of global sea level change is also visible, with sea levels going up and down by about 1 cm each year as water is evaporated from the oceans and rains down over land.

On August 10th, 1992, NASA and the French Space Agency, CNES launched TOPEX/Poseidon, the first highly-accurate mission to measure sea level from space. In the 30 years since, TOPEX was followed by Jason-1, Jason-2, Jason-3 and most recently Sentinel-6 Michael Freilich, all of which flew in the same orbit and overlapped with their predecessor. Together these missions have given us one of the most important records of our changing ocean and climate to date.

TOPEX/Poseidon delivered an astonishing 13+ years of data from orbit. The mission ended in January 2006. In those 13 years, it:

Measured sea levels with unprecedented accuracy to better than 5 cm
Continuously observed global ocean topography
Monitored effects of currents on global climate change and produced the first global views of seasonal changes of currents
Monitored large-scale ocean features like Rossby and Kelvin waves and studied such phenomena as El Niño, La Niña, and the Pacific Decadal Oscillation
Mapped basin-wide current variations and provided global data to validate models of ocean circulation
Mapped year-to-year changes in heat stored in the upper ocean
Produced the most accurate global maps of tides ever
Improved our knowledge of Earth's gravity field

NASA Earth Observatory - Tracking 30 Years of Sea Level Rise

Where were you when TOPEX/Poseidon launched?

A few fond memories from the altimetry community

Download the PDF.

TOPEX/Poseidon Launch.
Image courtesy of Dudley Chelton (photographer unknown)