To reduce natural disasters, how can meteorological technology “outrun” natural disasters?

On October 8 this year, the Ministry of Emergency Management, together with the Ministry of Natural Resources, the China Meteorological Administration and other relevant departments and units, held a consultation and analysis of the national natural disaster situation in the first three quarters of 2023.

In the first three quarters, my country's natural disaster situation was complex and severe, with floods, droughts, typhoons, wind and hail, and geological disasters as the main disasters, and low temperatures, freezing and snow disasters, earthquakes, sandstorms, forest and grassland fires, etc. also occurring to varying degrees. Various natural disasters caused 89.118 million people to be affected to varying degrees and caused huge economic losses.

Image source: Copyright Library

01

The first line of defense for disaster prevention and mitigation

Among all types of disasters, floods are one of the natural disasters that pose the greatest threat to human life and property safety and have the widest impact on the stability of economic and social development. [1] Heavy precipitation, as a meteorological disaster, is the direct cause of floods and can trigger secondary disasters such as mountain torrents, landslides, and mudslides. Therefore, timely and effective issuance of early warning signals for meteorological disasters such as heavy rain and severe convection is the key to the success of disaster prevention and mitigation work. Meteorological science and technology is the source of strength to build a solid first line of defense for disaster prevention and mitigation.

02

"Clairvoyance" and "Clairaudience"

In order to make good forecasts and warnings for disastrous weather such as heavy rain and severe convection, we first need to "keep an eye on all directions, listen carefully in all directions, observe everything clearly, and know ourselves and the enemy". Meteorological satellites and meteorological radars are the weather forecaster's most important "eyes and ears".

Since my country successfully launched its first Fengyun satellite in 1988, the Fengyun-3G satellite was successfully launched on the Long March 4B Y51 carrier rocket on April 16, 2023. At present, my country has launched 21 meteorological satellites, of which 9 are in orbit, realizing the commercial operation of polar-orbiting satellites and geostationary satellites. The detection data of Fengyun meteorological satellites provide strong support for the monitoring of disastrous weather such as typhoons, heavy rains, hail, tornadoes, etc., especially in the monitoring of small and medium-scale weather systems such as heavy rains, hail, tornadoes, etc. The high-frequency and high-resolution observation cloud image animation of geostationary satellites can "detect" the origin, movement and development process of small and medium-scale weather, and provide real-time forecasts for small and medium-scale weather systems. At the same time, based on the scale, duration and shape of mesoscale clouds monitored by satellite remote sensing, the classification and identification of rainstorm clouds, as well as the identification of convective clouds and tracking of cold areas can be carried out, which will help to make weather monitoring and forecasting more accurate and timely. [2]

Typhoon Dusurui Cloud System

Image source: Fengyun-4B National Satellite Meteorological Center

Meteorological radar also plays an indispensable role in the detection of disastrous weather processes. Weather radar is the main means of physical detection of the atmosphere, clouds and precipitation. At present, the new generation of Doppler weather radars built in my country are mainly S and C electromagnetic wave bands suitable for observing raindrops. The rainy eastern region mainly uses S-band weather radars, while the western region mainly uses C-band weather radars. The main purpose of weather radar waveform design is to obtain deep convective information from clear sky atmosphere to precipitation and severe convective weather based on factors such as different structural characteristics, horizontal scales and vertical scales of weather systems. [3] Meteorologists analyzed radar echo maps in combination with circulation conditions and disaster mechanisms, and summarized features such as "bounded weak echo area", "bow echo" and "hook echo" to identify severe convective weather systems such as supercells and squall lines, and then make more accurate forecasts of disastrous weather such as heavy rain, hail, thunderstorms, gale and tornadoes. [4] Nowadays, with the gradual improvement of dual-polarization detection technology and phased array detection technology, the high temporal and spatial resolution and particle morphology detection capabilities are becoming increasingly stronger. Dual-polarization active phased array weather radar that can reveal the microphysical structure characteristics inside the storm will become a new development direction.

03

Weather forecast and warning: the “starting gun” for disaster prevention and mitigation

When forecasters have collected rich weather data through various means and have a preliminary foresight on major disastrous weather, the scientific and technological achievements in the formation mechanism and forecasting methods of disastrous weather such as heavy rain and severe convection will help us fire the "starting gun" for disaster prevention and mitigation.

Heavy rain research plays an important role in my country's atmospheric science research. Important weather systems that affect China's heavy rain include low-level jets, subtropical high pressure, fronts, tropical cyclones, southwest low vortices, and the northeast cold vortex, which has attracted more and more attention recently. Meteorologists have conducted in-depth research on the circulation background, dynamic and thermal structure, triggering conditions, and spatiotemporal variation characteristics of the heavy rain in South China during the pre-flood season, which are closely related to the East Asian summer monsoon circulation, the Jianghuai plum rain maintained by the plum rain front, the short-term severe convection and heavy precipitation in North China under the coupling of multi-scale systems, the northeast heavy rain under the background of the northeast cold vortex, the southwest heavy rain caused by the southwest low vortex, and the extreme heavy rain disasters caused by the landing of typhoons/tropical cyclones. The heavy rain theory summarized has laid a solid scientific research foundation for heavy rain forecasting and warning services. [5]

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my country started numerical weather forecasting early, and the business development of numerical weather forecasting has also progressed rapidly. Older scientists such as Ye Duzheng and Zeng Qingcun guided and promoted the development of numerical weather forecasting in China, and made important contributions to the mathematical and physical foundations of numerical weather forecasting models. [6] Today, in order to quantitatively estimate the uncertainty of atmospheric forecasts, a new type of heavy rain numerical forecasting method, ensemble forecasting, has flourished. With the continuous optimization of algorithms, heavy rain forecasting services have developed from "subjective weather process forecasting" to "subjective and objective fusion quantitative precipitation forecasting", and to quantitative precipitation probability forecasting containing forecast uncertainty information. The forecast and warning timeliness of some heavy rain events has been significantly improved. In the future, the improvement of the 100-meter meteorological numerical model requires more precise and complete observation data as well as corresponding data assimilation technology and physical parameterization schemes. [7] The road ahead is long and arduous, but it will soon be achieved.

Even today, although the public still has the stereotype that "weather forecasts are inaccurate", the development of meteorological technology has greatly improved the accuracy and timeliness of disastrous weather forecast information and meteorological disaster warning signals, and has enabled them to be transformed into disaster prevention and mitigation actions for governments at all levels and the public. "Fighting natural disasters is an eternal topic for human survival and development." We still need to improve the early warning system, increase the speed of disaster emergency response, strengthen disaster risk management, and use technology and wisdom to continuously improve our own and society's disaster prevention and mitigation capabilities.

References:

【1】The Ministry of Emergency Management released the national natural disaster situation in the first three quarters of 2023 - Ministry of Emergency Management of the People's Republic of China (mem.gov.cn)

【2】Gao Hao, Tang Shihao, Han Xiuzhen. Development and application of Fengyun meteorological satellites[J]. Science and Technology Review, 2021, 39(15): 9-22.

【3】Li Bai. Development of China's meteorological radar technology and the challenges it faces[J]. Progress in Meteorological Science and Technology, 2022, 12(05): 37-46.

【4】 Yu Xiaoding, Zheng Yongguang. Research and operational progress of severe convective weather in contemporary China[J]. Acta Meteorologica Sinica, 2020, 78(03): 391-418.

【5】Luo Yali, Sun Jisong, Li Ying, et al. Science and forecast of heavy rain in China: research results of 40 years of reform and opening up[J]. Acta Meteorologica Sinica, 2020, 78(03): 419-450.

【6】Chen Zhenghong. General History of Meteorological Science and Technology (Volume 2)[M]. Beijing: Meteorological Press, 2020:697-700.

【7】 Ma Xiaojiao, Chen Min, Huang Xiangyu, et al. Research progress and prospects of centimeter-level meteorological numerical simulation[J]. Chinese Journal of Geophysics, 2023, 66(05): 1911-1930.

Author: Yan Jun, Engineer of Liaoning Meteorological Disaster Monitoring and Early Warning Center

Chen Zhenghong, Senior Engineer, China Meteorological Administration Meteorological Cadre Training Institute