The “Seven Stars in the Sky” of Fengyun, what are they “busy” about?

"The main data products of the two Fengyun meteorological 'new stars', Fengyun-3E and Fengyun-4B, will be open to global users for sharing." Recently, at the 75th session of the Executive Council of the World Meteorological Organization (WMO), Zhuang Guotai, Secretary of the Party Leadership Group and Director of the China Meteorological Administration, announced.

What capabilities do these two satellites have to serve the world?

According to reports, Fengyun-3E is the world's first civilian dawn-dusk orbit operational satellite, filling the gap in satellite observation data for the global numerical weather forecast model during the dawn-dusk period; Fengyun-4B is the first operational satellite of my country's new generation of geostationary orbit meteorological satellites, with a minute-level 250-meter resolution regional imaging capability. The two satellites and their ground application systems entered operational trial operation in June this year.

These are just the two newest members of the "Fengyun family". So far, my country has successfully launched 19 Fengyun meteorological satellites, of which 7 are in orbit. As sensitive space outposts, what are they "busy" doing in the vast Milky Way?

People's "cold and warm stars": overlooking the ever-changing situation

In recent days, heavy rain and high temperature have played the leading role. According to the forecast of the Central Meteorological Observatory, from July 11 to 13, a new rain belt will cross from east to west, affecting the eastern part of Northwest my country to the central and southern parts of North China. Faced with complex weather conditions, forecasters have a clear idea: Fengyun meteorological satellites monitor the changes in wind and clouds at all times, providing timely and rich observation data, and the direction of air flow can be seen at a glance.

Ren Suling, chief service officer of the National Satellite Meteorological Center, said that 10 years ago, the Fengyun meteorological satellites only generated a cloud map every half hour or even an hour, with a spatial resolution of several kilometers. Today, the Fengyun-4 meteorological satellite products have a maximum temporal and spatial resolution of 1 minute and 250 meters.

Not long ago, the southern part of the Yangtze River and southern China suffered heavy rainfall, and the Central Meteorological Observatory issued a rainstorm and severe convective weather warning. At the same time, in the vast space, seven Fengyun meteorological satellites closely followed the changes in the wind and clouds, generating a cloud map of China and the surrounding areas every 5 minutes and a cloud map of the designated area every 1 minute.

Whether it is the 90% accuracy rate in heavy rain warnings, the 40-minute advance warning time for severe convective weather, or the first global typhoon forecast... the improvement of my country's weather forecasting level is closely related to the development of observation technology.

"my country has made great progress in typhoon forecasting, and the Fengyun meteorological satellites have made great contributions." Xu Yinglong, chief forecaster of the Typhoon and Marine Meteorological Forecast Center of the Central Meteorological Observatory, introduced that in 2021, the fast imager carried by the Fengyun-4B satellite, which is in the on-orbit test phase, conducted 1 minute of continuous high-frequency observations of Typhoon "Fireworks". The combination of geostationary meteorological satellites and polar-orbiting meteorological satellites provides important support for forecasters to analyze and judge the impact of typhoon wind and rain in real time. On July 2 this year, Typhoon "Siam" landed in Guangdong, and extreme rainfall occurred in many places in South China. The Foshan Meteorological Observatory issued a tornado alert one hour in advance, which bought time for local disaster prevention and personnel evacuation.

Satellite monitoring data can not only accurately reflect changes in weather systems, but can also be integrated into numerical forecasting models through data assimilation technology to further improve forecast accuracy.

It is worth mentioning that my country has achieved the first international assimilation of observation operations of the geostationary infrared hyperspectral atmospheric sounder, the Fengyun-4A atmospheric vertical sounder, which has improved the forecast accuracy of typhoons, rainstorms and other disastrous weather. In the target observation and assimilation of typhoons such as Maria in 2018, the Fengyun-4 meteorological satellite performed well. The numerical forecast and the Fengyun-4 satellite sounder "interacted with the sky and the earth" to carry out target observation and assimilation driven by forecast needs. The 15-minute resolution sounder target observation data were assimilated into the China Meteorological Administration's global four-dimensional variational assimilation system.

The results show that high temporal and high spectral resolution data significantly improve the model's forecast of typhoon paths and the intensity and location of subtropical high pressure. Johannes Schmetz, former chief scientist of the European Organization for the Exploitation of Meteorological Satellites, commented: "This is a milestone in the application of geostationary atmospheric sounding assimilation." From 2018 to 2021, the scientific research team of the China Meteorological Administration carried out 9 target observation assimilation, and the 24-hour and 48-hour typhoon path forecasts increased by an average of 10%.

Grain "Guardian Star": "Wisdom" Knows the Heavens and Acts

As the saying goes, "You depend on the weather for your livelihood." Meteorological conditions have an important impact on agricultural production, and satellites are a pair of "wise eyes" that capture meteorological conditions and agricultural production conditions.

This year's summer harvest is a tough battle. In 2021, northern my country experienced a rare autumn flood, and the sowing period of winter wheat in many places was delayed and the seedling conditions were abnormal, which made it extremely challenging to achieve a bumper summer grain harvest.

"In order to win the battle to protect summer grain, the meteorological department has strengthened its coordination with the agricultural and rural departments and major grain-producing provinces in terms of satellite remote sensing, established a national and provincial agricultural meteorological remote sensing monitoring linkage mechanism, used multi-source satellite remote sensing data to comprehensively assess the growth of winter wheat, and provided timely analysis reports on the growth of crops and the impact of meteorological conditions to relevant departments, providing strong technical support for relevant departments to carry out winter wheat spring management work." Wu Menxin, a senior engineer at the National Meteorological Center, said that the wheat harvest is now nearing its end and the harvest is in good condition. The agricultural meteorological remote sensing service has been well received by all parties.

From "living by the weather" to "working according to the weather", satellite remote sensing has enabled agricultural production to move from the unknown to the known, turning passivity into initiative.

"The essence of agricultural meteorological remote sensing work is to qualitatively or quantitatively evaluate the impact of past and future meteorological conditions on crop growth. Quickly and accurately grasping the spatial distribution of crop planting can improve the temporal and spatial matching accuracy of crop planting distribution and meteorological element distribution, which is of great significance for improving the accuracy of agricultural meteorological disaster monitoring and early warning and crop yield meteorological forecasts." Zhang Mingwei, an associate researcher at the National Satellite Meteorological Center, introduced that in May this year, the China Meteorological Administration's "national-provincial-municipal/county" integrated major crop distribution remote sensing monitoring system was initially established, and the high spatial resolution winter wheat distribution remote sensing products were used for the first time in the China Meteorological Administration's summer grain crop yield meteorological forecast and agricultural meteorological disaster monitoring and early warning business, adding a "weapon" to ensure a bumper grain harvest.

To achieve the goal of “filling our rice bowl mainly with Chinese grain”, we must also strengthen the monitoring and management of our country’s major grain crops.

In recent years, the China Meteorological Administration, the Chinese Academy of Sciences, the Ministry of Agriculture and Rural Affairs, etc. have used Fengyun meteorological satellite data as a data source to carry out meteorological disaster monitoring in important grain-producing areas at home and abroad, and growth monitoring and yield estimation of major grain crops such as wheat, corn, rice and soybeans, providing important and reliable reference for scientific decision-making.

"Agricultural meteorological disasters have a great impact on my country's grain production, among which drought has the most severe impact." In the view of Mao Kebiao, a researcher at the Chinese Academy of Agricultural Sciences, surface temperature and soil moisture are important parameters in drought monitoring. In the past, relevant data were mainly obtained through meteorological stations, but the stations are relatively sparse, the spatial representativeness is insufficient, and the manual method is time-consuming and labor-intensive.

It is understood that with the development of meteorological satellites, the number of bands and radiation resolution have been continuously optimized. Its infrared remote sensing data can invert the surface temperature, and the microwave brightness temperature data can invert the soil moisture, providing strong support for meteorological disaster monitoring and early warning, crop growth monitoring, and yield estimation.

The crop and farmland environmental parameters of remote sensing quantitative inversion products are based on Fengyun meteorological satellite data, providing reliable key crop growth parameters for applications such as crop growth models, data assimilation systems, and crop yield estimation, providing valuable reference for field agricultural management.

With the trial operation of Fengyun-3E, Fengyun-4B and their ground application system services, there will be more possibilities for the development of agricultural satellite remote sensing services in the future.

Ecological "Monitoring Star": Empowering a Beautiful China

"Satellite monitoring images show that blue algae blooms have appeared in the western coastal area and the center of Taihu Lake." Recently, a meteorological satellite monitoring report was sent to the China Meteorological Administration Office and relevant departments such as the Jiangsu Provincial Meteorological Bureau, the Department of Ecology and Environment, and the Department of Water Resources. Subsequently, a blue algae prevention and control action involving inter-departmental linkage and local coordination was quickly launched to achieve early detection, early intervention, and early disposal of blue algae blooms.

This is due to the strong ground monitoring capabilities of the Fengyun meteorological satellites. The geostationary meteorological satellites can provide monitoring of China and its surrounding areas every five minutes, and can generate cloud maps for designated areas every one minute. The three polar-orbiting meteorological satellites can provide high-resolution global monitoring six times a day. It is reported that by taking advantage of multi-satellite networking and coordinated observation, the Fengyun meteorological satellites can also achieve dynamic monitoring and evaluation of the global and key regional ecological and environmental conditions with high temporal and spatial resolutions, helping decision-makers to respond more quickly.

Chahan Nur Lake, located at the junction of Shangdu County, Ulanqab City, Inner Mongolia Autonomous Region and Kangbao County, Zhangjiakou City, Hebei Province, is the largest inland saltwater lake in North China. Due to the lack of systematic protection in the past, its ecology was once severely damaged.

In 2020, a special cooperation mechanism for the protection and restoration of the Chahan Nur wetland was established between Inner Mongolia and Hebei. Two years later, how is the progress of the restoration of the Chahan Nur ecosystem?

"Compared with the same period last year, the vegetation index in Chahan Nur region increased by 8.5% in April, and the water area increased by 0.2 square kilometers." This special report with clear data was produced based on data from the Fengyun-3 meteorological satellite, providing an important basis for evaluating the ecological and environmental governance of Chahan Nur.

Through satellite broadcasting, the Internet, remote sensing application business systems and other means, Fengyun meteorological satellite data and products have now been widely used in ecological monitoring.

The National Satellite Meteorological Center has also established a long-sequence satellite remote sensing data set for vegetation, surface temperature, water bodies, cyanobacteria blooms, dust, snow, etc. since 2000, and has worked with many places to compile more than 10 technical guidelines for vegetation, urban heat islands, water bodies, cyanobacteria blooms, dust, snow, fire conditions, etc. The Satellite Remote Sensing Application System (SMART) 2.0 and 3.0 versions have been developed and used in meteorological departments across the country and promoted to many countries.

In June this year, Fengyun-3E, Fengyun-4B and their ground application systems entered trial operation. Han Xiuzhen, chief service expert of the China Meteorological Administration and senior engineer at the National Satellite Meteorological Center, introduced that the low-light medium-resolution spectral imager carried by Fengyun-3E has the ability to monitor light information in the morning and evening orbit, and can realize dynamic monitoring of urban light images. As the two satellites shine in space, their ecological monitoring capabilities are further enhanced.

At present, my country has provided Fengyun satellite data and products to 124 countries and regions, including ecological environment and natural disaster monitoring and assessment. 30 countries have registered as international users of the emergency guarantee mechanism, and green service channels have been opened to 42 countries. More than 1,200 trainees from more than 100 countries have received special training on Fengyun satellite applications. Our "ecological circle of friends" is expanding day by day. (Reporter Cui Xingyi)

Source: Guangming Daily