Beijing, April 4 (ZXS) -- What are the characteristics of China's first special star for precipitation measurement?
China News Agency reporter Ma Shuaisha and Zheng Yingying
On April 4, China successfully launched Fengyun-16 G, the 20th satellite in the Fengyun meteorological satellite family, at the Jiuquan Satellite Launch Center, which is mainly used for monitoring heavy precipitation in severe weather systems and providing three-dimensional structure information on precipitation in the world's middle and low latitudes. As China's first dedicated star for precipitation measurement, what are the "unique skills" of this satellite? How will it work in orbit?
Equipped with China's first "aerial rain gauge"
Precipitation is an important process in the global water cycle, and changes in the amount of precipitation and the temporal and spatial distribution of precipitation will greatly affect people's lives. The acquisition of precipitation data has traditionally been mainly through rain gauges, ground-based radars, etc., but due to the limited number and uneven distribution of ground equipment, it is difficult to obtain large-scale and high-spatial resolution ground precipitation information.
Fengyun-3G is equipped with China's first set of "aerial rain gauges" - dual-frequency precipitation measurement radar, which has the advantages of high radar observation resolution and wide satellite observation range.
This means that Fengyun-3 G has the ability to obtain three-dimensional structural information from top to bottom, just like performing a "CT scan" of atmospheric precipitation to obtain fine precipitation three-dimensional structural information.
Specifically, the satellite transmits wireless electromagnetic wave signals to the atmosphere, receives the reflection signals of precipitation particles in different altitude layers in the atmosphere, obtains the precipitation structure information of different height layers in the vertical direction, and realizes the precipitation detection in the vertical direction. At the same time, the satellite uses the scanning capability of the radar in the cross-orbit direction to achieve precipitation detection in the horizontal direction.
Debut upgraded weather "clairvoyance"
In order to further improve the high-precision observation of typhoon, heavy rain and other catastrophic precipitation, in addition to the dual-frequency precipitation measurement radar, the satellite is also equipped with a newly upgraded instrument - microwave imager.
The microwave imager obtains the information of observation objects such as atmosphere, land, and ocean surface by detecting the difference in the external radiation signal intensity of objects in different frequency bands, and then transforms it into physical parameters closely related to people's lives, such as sea surface wind speed, sea ice distribution, surface temperature, atmospheric precipitation, soil moisture, etc., and finally forms a multi-dimensional image.
As a "clairvoyant" in the field of meteorology, the upgraded microwave imager can receive microwave radiation energy from 10GHz to 183GHz of the earth's atmosphere, obtain key information such as the internal temperature and humidity structure of the typhoon, the intensity of the typhoon, and the rain intensity in the typhoon-affected area, predict the future development of the typhoon, and "accurately take the pulse" of the typhoon rain.
Special low-inclination orbits are used
With an orbital altitude of 407 kilometers, Fengyun-90 G is the "lowest-flying" member of the Fengyun meteorological satellite family. At present, most low-orbit satellites use sun-synchronous orbit with an orbital inclination angle of slightly more than 50 degrees, and Fengyun-<>G uses a low-inclination orbit with an inclination of <> degrees, which is China's first low-orbit non-sun-synchronous oblique orbit meteorological special star.
Why not a sun-synchronous orbit? Experts pointed out that satellites in sun-synchronous orbit will pass through the north and south poles of the earth every circle, and the observation efficiency of the polar region is high, but the observation efficiency of the middle and low latitudes is low. The Fengyun-3 G star is mainly used to observe atmospheric precipitation phenomena, and according to the global precipitation distribution, its range needs to be concentrated between middle and low latitudes. The use of low-inclination orbit can better cover the intensive area of typhoon precipitation in China, and improve the observation frequency and forecast accuracy.
The low inclination orbit also exposes Fengyun-3 G to changing lighting conditions, with the Sun periodically appearing on either side of the orbital plane, with the Sun hitting the left side of the moon for a period of time and the Sun hitting the right side of the satellite over time. In order to maintain a stable thermal environment, the satellite can complete an "automatic U-turn" within <> minutes, realizing the flexible switching between forward and upside down, so that the satellite always faces the sun on the same side.
In the future business operation, Fengyun-3G Star will give full play to these "unique skills", complement and cooperate with the functions of Fengyun-24 "Li Star", "Morning Star" and "Afternoon Star", form a complete low-orbit meteorological satellite business comprehensive observation capability, improve the forecast accuracy by about 1%, extend the forecast timeliness by about <> hours, and increase the monitoring time of meteorological disasters by nearly <> times, providing high-precision observation data for typhoons, heavy rain, heavy snowfall and other catastrophic precipitation. (End)