Yang Jun, director of the National Satellite Meteorological Center, accepted an exclusive interview with the Beijing News reporter: According to continuous satellite monitoring, the water level of the Jiujiang section of the Yangtze River will continue to exceed the alarm

  Fengyun 3 patrols major rivers and lakes 6 times a day

The layout map of my country's meteorological satellites in orbit. Photo courtesy of National Satellite Meteorological Center

  There are 7 Fengyun meteorological satellites in China that monitor the weather 24 hours a day. At present, China’s most advanced meteorological satellite, Fengyun-4 A, monitors the weather including our country every 15 minutes. If necessary, it can be monitored locally every five minutes. The Fengyun-3 polar-orbit satellite combination patrols major river basins and lakes in China 6 times a day.

  How can satellite monitoring help weather forecasting and early warning and flood control and flood relief? Yesterday, a reporter from the Beijing News interviewed Yang Jun, director of the National Satellite Meteorological Center, to reveal the secrets of meteorological satellite monitoring.

  According to Yang Jun, the latest Fengyun-3 satellite and Fengyun-4 starting business star in orbit at dawn and dusk are about to enter the launch schedule. In the future, my country will continue to improve the accuracy and maneuverability of meteorological satellite monitoring and achieve linkage between satellites.

On flood control

  Poyang Lake related dikes still face greater pressure

  Beijing News: What is the significance of satellite monitoring of Poyang Lake and other waters for flood control?

  Yang Jun: We used the comprehensive monitoring of Fengyun satellites, high scores, sentinels and other multi-source satellites, and the results of satellite remote sensing monitoring since 2010, combined with the meteorological observation data of the past 60 years, to carry out changes in the main body of Poyang Lake and the surrounding waters in Jiangxi Province. According to scientific analysis and evaluation, the latest results show that the main body of Poyang Lake and the surrounding water area reach 4403 square kilometers, the largest in ten years.

  Taking floods as an example, satellite monitoring first looks at the growth and decline of lake areas. my country's Fengyun Satellite has been developing for 50 years. Through years of comparative analysis of satellite monitoring data, it provides quantitative scientific data and provides a scientific and reliable basis for decision-making departments to rescue and disaster relief.

  Meteorological satellite monitoring is intuitive. First of all, it supports weather forecasting, improves the accuracy of forecasting, and can accurately forecast the precipitation process during the flood season. It is important that it also monitors and evaluates various meteorological disasters that may be triggered after precipitation, and uses long-term serial satellite remote sensing monitoring data to provide a comprehensive basis for government departments to make decisions.

  Beijing News: According to the satellite monitoring data of Poyang Lake, do you have any suggestions for the next flood control?

  Yang Jun: According to continuous satellite monitoring, the recent heavy precipitation in the Poyang Lake area has gradually weakened, and the water level is gradually decreasing. However, in the future, there will still be heavy precipitation in the upper reaches of the Yangtze River. The water level of the Jiujiang section of the Yangtze River will continue to exceed the alarm level, which will have a supporting effect on the water level of Poyang Lake and delay the rate of water withdrawal. The relevant dikes are still facing great pressure. We recommend that we maintain patrol inspections of polders around Poyang Lake, strengthen levee removal and resettlement.

 Talking about monitoring

  Fengyun Satellite is on par with international meteorological satellites

  Beijing News: In addition to Poyang Lake, which water bodies do you focus on?

  Yang Jun: At present, my country's Fengyun satellites are comparable to the international meteorological satellites. China's most advanced meteorological satellite Fengyun-4 satellite A monitors the weather including our country every 15 minutes, if necessary, local area monitoring every 5 minutes (such as typhoon monitoring, etc.), Fengyun-3 polar orbit satellite combination 6 major rivers and lakes in China are inspected 6 times a day. At the same time, the Taihu Lake and the Dongting Lake are closely monitored, as well as the Miyun Reservoir, Guanting Reservoir, and Danjiangkou Reservoir.

  Beijing News: To understand in layman terms, how does satellite monitoring work?

  Yang Jun: Satellites fly in the sky, like a big camera, taking pictures of the earth. From the meteorological point of view, the first concern is the atmosphere, because the precipitation process is caused by the movement of clouds to bring a lot of water vapor. Water vapor encounters suitable meteorological conditions, especially during the flood season. Heavy precipitation will continue to affect my country. Through monitoring, some quantitative physical parameters in the atmosphere, such as the condition of the cloud, temperature, humidity, pressure, etc., are handed over to the computer and the numerical prediction model to let it predict the future weather situation.

  Secondly, heavy rainfall will cause many secondary disasters, such as floods, landslides, debris flows, etc. At this time, satellites are required to enter the ground from the atmosphere. At present, my country uses a large number of satellite remote sensing methods for the monitoring of meteorological disasters. After years of development, my country's Fengyun Satellite has formed an omnidirectional stereoscopic observation system. There are both low-orbit satellites (polar orbit satellites) relatively close to the ground and geostationary satellites over 36,000 kilometers of geostationary orbit, which form a three-dimensional meteorological satellite monitoring network.

  In addition, radar satellites can see the ground through clouds. In this flood monitoring of Poyang Lake, we comprehensively used radar satellite data such as my country's Gaofen-3 and European sentinels to see the entire flood situation and provide a basis for local governments and national flood control departments.

Talking about planning

  The latest satellites of Fengyun 3 and 4 enter the launch plan

  Beijing News: Is there any plan to launch my country's Fengyun Meteorological Satellite recently?

  Yang Jun: It is expected that more advanced follow-up satellites will be launched this year or next year. Currently preparing for the launch of the latest Fengyun-3 satellite in orbit at dawn and dusk, Fengyun-4's first service star is about to enter the launch plan.

  Beijing News: In what ways is the upcoming Fengyun Satellite more advanced?

  Yang Jun: The advanced nature of meteorological satellites generally has several factors. Just like when we take a telescope, how far can you see, how big can you see, can you see clearly, meteorological satellites also require the same. In addition, how many factors can be observed is also a manifestation of advanced nature. For example, whether cloud, aerosol, temperature, humidity, wind, pressure and other parameters in the atmosphere, as well as data from terrestrial and oceanic earth systems, can be reversed through satellite observations is an aspect of measuring the advanced nature of satellites.

  The second is the level of technology, how accurate is the observation, for example, how large is the error in monitoring the surface temperature with satellite remote sensing? On the whole, my country's Fengyun meteorological satellites have entered the international advanced ranks.

  Beijing News: Which satellites are composed of my country's satellite stereo observation network?

  Yang Jun: There are many kinds of satellites, including communication satellites, navigation satellites, and remote sensing satellites. Remote sensing satellites are divided into meteorological satellites, ocean satellites, and land satellites according to different observation points. In this way, we can observe the earth in all directions. Human beings can never control natural disasters and can only cope with them. Therefore, the first thing we need to do is to understand the causes and the entire process of the disaster. At present, if we want to see this process clearly, satellites are the most effective and need the highest priority. One of the means of development.

  Meteorological satellites are divided into two categories. The first category is low-orbit satellites, which completes the observation of the earth's band every time it orbits the earth, which is equivalent to a "sweep". It can travel around the earth to see the world every day; , Equivalent to staring at the earth. Meteorological satellites will carry various observation instruments, such as Fengyun-3, usually with more than ten kinds of remote sensing instruments to provide comprehensive and comprehensive observations.

  For meteorological observation, satellites alone are not enough. Meteorological radar and a network of meteorological observation stations all over the country are also needed. All of the above constitute the entire integrated meteorological observation system.

 Talk about the future

  Will improve satellite monitoring accuracy and maneuverability

  Beijing News: While the observation methods are very advanced, what are the main reasons for the error of the weather forecast?

  Yang Jun: The accuracy of weather forecast depends on the understanding of atmospheric dynamic process. It is difficult to find out the laws of atmospheric motion and accurately describe the atmospheric motion itself. Atmospheric science itself is an approximate science. For example, I suddenly dusted you with a handful of dust. Can you tell that this dust is thrown at you, but can you tell how every dust inside moves? This is very difficult.

  Secondly, on the basis of observation, it is necessary to establish a mathematical physics model to describe this complex process, and then solve this process, which is difficult. The computer needs a lot of observation data, it is impossible to observe every corner of the earth, every time point, there are always leaks in time and space.

  In terms of meteorology, improving the accuracy of forecasting is our eternal pursuit. We have a saying that the weather forecast cannot be 100% accurate, but we will do our best.

  Beijing News: What other breakthroughs are needed for meteorological satellite monitoring capabilities?

  Yang Jun: The first is to improve the accuracy of observation, that is, the precision of observation, especially stereoscopic observation. Some observation elements are relatively lacking. For example, the observation of wind requires a breakthrough in the next step.

  Secondly, we are also very concerned about whether we can monitor the greenhouse gas elements that cause climate change and observe the reverse performance through satellites.

  Third, from the perspective of the performance of the satellite itself, the next step is to break through mobility, that is, to see if you can add some smart functions. Now sometimes I feel that it is not enough when it is really needed.

  Finally, we must strive to achieve linkage between different types of satellites.

  Fengyun No. 2 series of meteorological satellites: China's first generation of geostationary orbit meteorological satellites, carrying visible light infrared spin-scanning radiometers on the stars, acquiring a set of earth's full disc maps every hour or half an hour, with 6-minute interval regional observation capability Geostationary weather satellite. At present, there are still three on-orbit businesses in operation, including FY-2F, FY-2G, and FY-2H (mainly used for “Belt and Road” services).

  Fengyun-3 series of meteorological satellites: my country's second-generation polar orbit meteorological satellites, polar orbit meteorological satellites with global, all-weather, multi-spectral, three-dimensional, quantitative ground observation capabilities. There are currently three on-orbit operations, including FY-3B, FY-3C, and FY-3D.

  Fengyun No. 4 series of meteorological satellites: my country's second-generation geostationary orbit meteorological satellites, which improves the spatial and temporal resolution of earth observations, is a meteorological satellite with high-spectral three-dimensional detection and high-frequency imaging capabilities, and many indicators have reached the world's leading level. There is currently one on-orbit business, namely FY-4A.

  Beijing News reporter Deng Qi