China's new satellite to enhance global weather forecasting

Fengyun 3E, the world's first early morning orbit weather satellite that China launched for civil use on Monday, will improve global weather forecast by filling in the data gap in a certain time of a day and assist in achieving 100 percent global data coverage every six hours, experts said.

Zhang Peng, deputy director of the National Satellite Meteorological Center, also the chief commander of the Fengyun 3 series ground system, said Fengyun 3E with a designed lifetime of eight years belongs to the polar-orbiting satellite group whose combination monitors weather, climate and environment of the whole world.

Polar orbits that pass over the north and south poles in a north-south ellipse are synchronous with the Sun. Satellites on the orbits pass places on the Earth at the same local time.

"Polar-orbiting satellites can be divided by orbits whose passes are at different local times. Before Fengyun 3E, polar-orbiting weather satellites operated only in AM and PM orbits above the Earth. The newly launched one will complement the two previous orbits in time period and spatial coverage to increase mid- and long-term weather forecast's accuracy," he said.

In an early morning orbit, a satellite usually passes downward over the equator between 5 and 6 am while on its symmetrical side of the planet it passes upward over the equator between 5 and 6 pm, the center said.

The AM orbital pass over the equator downward occurs at around 10 with the PM at about 1:40, the center said.

Satellites in polar orbits can cover the entire globe regularly when they circle the Earth which rotates beneath them.

"The Fengyun 3E together with other polar-orbiting ones helps achieve collect the entire globe's data every six hours that the numerical forecast commonly requires to ensure the effectiveness. Previously, there was always around one-fourth of the planet missing in the global image," Zhang said.

He added that back in 2009, experts from the World Meteorological Organization pointed out the problem and suggested developing the third kind of orbit. In 2014, China started to research on the new polar-orbiting satellite.

Tang Shihao, chief designer of the Fengyun satellites' engineering application system, said that Fengyun 3E will also fill the data gap by monitoring atmospheric conditions in early morning and at dusk — time periods that AM and PM ones can't cover.

One advanced technology carried by the early morning-orbit satellite solved the problem of night imaging, Tang said.

"Sunlight conditions during sunrise and sunset are not favorable for imaging during a day. We added night camera functions to take clear pictures.

"The atmospheric conditions at the time remain the most stable of a day and analysis on them can represent climatic characteristics the most.

"Certain weather events including fogs always occur in early morning and the satellite can detect and forecast them to aid transportation," he said.

It can also assist researches on urban economic activities, fire detection and air pollution monitoring, he added.

Other new remote-sensing product on Fengyun 3E involve imaging facilities for solar activities and wind fields, the center said.

All the data can be transmitted to ground systems, five of which are in China and two in north and south poles, in two hours, the center said.

The data will be shared globally as the current data have served 118 countries, the center said.

"The successful launch of the early-morning-orbit satellite enabled China to have its unique feature in the global weather satellite industry and offered a complementary advantage for the international community," Zhang Peng said.

Presently, the country has nine weather satellites in orbits, of which five are geostationary that travel above the equator and synchronous with the Earth and four are polar-orbiting.

Currently, only the United States, the European Union and China have both the geostationary and polar-orbiting weather satellites, the center said.