France and China's space agencies unveiled their first joint satellite in Beijing Friday, which will be used to improve forecasting of ocean storms and cyclones.

The satellite, named CFOSAT (China-France Oceanography Satellite), is due to be launched next year by China and will primarily be used to study wind and ocean wave patterns.

"In practical terms, it will be used to improve forecasts of strong storms, cyclones or waves for all coastal activities", Daniele Hauser, a French scientist working on the project, told AFP.

Understanding the interaction between the oceans and the atmosphere will also help to model and tackle climate change, scientists said.

The satellite will include two radars: a French system designed to measure direction and wavelength of ocean waves, and a Chinese version focusing on wind strength and direction.

The satellite is the first to be jointly constructed by France and China.

The project was originally envisaged as a joint programme for the French and European space agencies.

But an increasingly close working relationship between France and China on space technology over the past ten years prompted the switch to the unprecedented collaboration on CFOSAT, said Hauser, who acknowledged there was also a "political component".

Wang Lili, China's project manager on the satellite, said: "We partnered with France because we were certain of the support of both states, but also because of France's expertise in wave analysis."

The satellite will be placed into Earth's orbit in the second half of 2018 by a rocket from China's "Long March" programme. The project is scheduled to last three years.