August 5, 2021

China launches Fengyun weather satellite into polar orbit


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A Chinese Long March 4C rocket takes off carrying the Fengyun 3E weather satellite. Credit: Xinhua

A new Chinese Fengyun weather satellite launched Sunday and flew into an early morning polar orbit to feed data into global computer models, adding inputs that international weather officials said will improve medium and long-range forecasts.

The Fengyun 3E satellite rocketed into orbit on top of a Long March 4C rocket at 7:28 p.m. EDT Sunday (2328 GMT; 7:28 a.m. Monday in Beijing), according to the China Aerospace Science and Technology Corp., or CASC, the top state-run contractor for China’s space program.

The three-stage Long March 4C rocket lifted off from the Jiuquan spaceport in the Inner Mongolia region of northwestern China. The liquid-fueled launcher flew south from Jiuquan before releasing the Fengyun 3E weather satellite into a polar orbit about 500 miles (800 kilometers) above Earth.

China launched the roughly 2.5-ton Fengyun 3E satellite into an orbit that flies along the terminator, or the line between the day and night sides of Earth. Fengyun 3E crosses the equator in the early morning, local time, making it the first civilian weather satellite to launch directly into an early morning orbital plane.

The China Meteorological Administration said Fengyun 3E, designed for a service life of at least eight years, will fill a gap in the early morning orbit. There are aging U.S. military DMSP weather satellites in a similar orbit, but they are well beyond their design lives, and no more DMSP satellites are scheduled for launch.

Chinese officials said the Fengyun 3E satellite joins two other Chinese polar-orbiting weather observatories, Fengyun 3C and Fenygun 3D, flying in mid-morning and afternoon orbits. Together, the satellites provide global weather measurements to feed into numerical weather prediction models at six-hour intervals.

The United States, China, and Europe operate the majority of the world’s weather satellites.

Polar-orbiting satellites provide measurements to improve medium and long-range forecasts, while weather observatories in geosynchronous orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator make time-critical measurements and imagery to track severe storms and tropical cyclones.

Phil Evans, director general of Europe’s weather satellite agency, agreed that Fengyun 3E’s presence in an early morning orbit fills an “important orbital gap at the international level.”

“Thanks to its modern payload, which includes advanced instruments, such as the atmospheric vertical sounder, FY-3E will bring benefits to the entire global user community,” Evans said in a statement. “Considering its unique orbit, FY-3E would have a direct and positive impact on global numerical weather prediction, as has been demonstrated by many studies, performed by partner agencies in the context of the Coordination Group for Meteorological Satellites, CGMS.”

Eumetsat, the European weather satellite agency, is responsible for flying weather satellites in the mid-morning polar orbit. NOAA operates U.S. satellites in the afternoon orbit. Adding a Chinese satellite to the early morning orbit gives forecasters around the world a snapshot of critical weather data three times per day.

“Now, with the advent of FY-3E, CMA will become the third pillar in the global meteorological polar orbiting constellation,” said Petteri Taalas, secretary general of the World Meteorological Organization. “I am looking forward to seeing the data from this new satellite and a continued commitment from CMA for the long-term for the provision of follow-on missions for this orbit.”

Weather data collected during early morning satellite passes will help meteorologists monitor tropical cyclones, fog, fires, air quality, and provide measurements for more thorough climate data records. The early morning orbit also gives a boost to rainfall monitoring, according to Taalas.

Test team members pose with the Fengyun 3E weather satellite before launch. Credit: SITP/Chinese Academy of Sciences

Fengyun 3E hosts 11 payloads, including three brand new weather monitoring instruments, according to CMA.

The satellite’s payload includes microwave and infrared sounders to measure temperature and moisture profiles in the atmosphere, an instrument to derive atmospheric conditions and ocean winds using reflected navigation satellite signals, and a spectral imager to observe clouds and measure sea surface temperatures, a driver of tropical cyclone development.

There is also a suite of five space weather instruments, including monitors to measure the sun’s energy output and photometers to measure how solar activity affects the environment around Earth.

One of the new instruments debuting on Fengyun 3E is WindRad, a radar to measure the direction and speed of winds near the ocean surface.

“We therefore anticipate a significant contribution from observations collected by FY-3E to global weather forecast skill,” said Florence Rabier, director general of the European Center for Medium-Range Weather Forecasts, which runs one of the world’s leading global forecast models.

Rabier said the European and Chinese agencies have a cooperation agreement to jointly evaluate the value of Fengyun 3E’s new instruments, and its early morning orbit.

‘This includes assessing together the quality of the new observations and their impact on the accuracy of numerical weather forecasts,” she said.

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Follow Stephen Clark on Twitter: @StephenClark1.


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