In October 2020, the Lanzhou University 'Belt and Road' lidar network-Ruoqiang Station, jointly built by Lanzhou University, Xinjiang Meteorological Bureau and other units, was officially inaugurated. So far, all 7 stations in the domestic section of the radar observation network have been completed, while in the foreign section, 4 stations in countries along the 'Belt and Road' will soon be constructed.
From hardware technology improvement to new algorithm inversion, and to atmospheric remote sensing and environmental monitoring applications... In recent years, the radar intelligent manufacturing team led by professors Huang Jianping and Huang Zhongwei from the College of Atmospheric Sciences of Lanzhou University has continuously overcome difficulties and independently developed multi-band Raman, which not only covers high-precision, high-resolution weather disaster forecasting and early warning systems for countries and regions along the 'Belt and Road', serves railways and logistics transportation, but also plays an active role in global climate change research and other fields.
'Follow the light', which is originated from the dialogue under Cuiying Mountain
'Do you know lidar?'
'Do you have the confidence to make it in the future?'
In the autumn of 2006, Huang Zhongwei, an undergraduate student at the School of Physics and Technology of Lanzhou University in 2003, passed the cross-professional graduate assessment of the College of Atmospheric Sciences due to his interest in radar research. At the scene, Professor Huang Jianping of the College of Atmospheric Sciences directly said to Huang Zhongwei: 'You go to the top of Cuiying Mountain!'
On the top of Cuiying Mountain is the semi-arid climate and environment observation station of Lanzhou University that has just been completed. At that time, the lidar of the observatory was a meter scattering lidar imported from abroad, and it had been a ground-based instrument until then. 'Imported lidar is expensive with limited functions and few signal analyses sources, and it cannot accurately measure the concentration and composition of solid particles, and it is difficult to adapt to the arid and semi-arid climate conditions in the northwest region such as large temperature differences and high particle concentrations.' Huang Jianping said, we must build radars by ourselves and conduct meteorological research.
In the fall of 2009, Huang Zhongwei went to Tohoku University in Japan for joint training. In Japan, he not only learned lidar technology, but also mastered a 'super ability'-fluorescence multi-band measurement. In 2011, Huang Zhongwei returned to China to build a lidar laboratory and a radar intelligent manufacturing team. In January 2014, in this 'radar processing workshop' with a total area of less than 40 square meters, China's first multi-band Raman-fluorescence lidar was born, and it became the reference standard for the production of other radars.
'It is not easy to manufacture a lidar. From the beginning of drawing and designing with SolidWorks software, to the assembly and debugging of the purchased parts, there are more than 100 optical parts for a lidar, and each part needs to prepare 2-3 plans.' Huang Zhongwei said that compared with other radars, multi-band Raman-fluorescence lidar can achieve fine detection of the full fluorescence spectrum of atmospheric aerosols.
'It's like taking a multi-dimensional panoramic photo, you can see different sides of atmospheric particles, and the measured atmospheric data is more comprehensive, three-dimensional, and accurate.' Huang Zhongwei added that the multi-band Raman-fluorescence lidar can measure atmospheric particulate matter within 38 bands and 20 kilometers, which not only improves the inversion accuracy of signal data, but also determines the material composition based on the frequency of scattering changes.
'Luminous' to fill the gap in the research and development of lidar
If hardware technology is compared to the torso of radar, the inversion algorithm is the brain of radar. Good hardware provides high-quality signals, and good algorithms calculate accurate data, and the two complement each other. The high-precision inversion algorithm based on lidar is another core achievement of the radar intelligent manufacturing team.
Huang Jianping introduced that using the principle of Raman-fluorescence scattering, the signals collected by lidars are converted into atmospheric data that can be adopted by professionals, that is, 'products', such as atmospheric water vapor, particulate matter and other attributes and concentrations.Based on this, we learned the important properties of atmospheric pollutants, and highlighted the analysis of the composition and concentration of atmospheric particulate matter, which filled the gap in China's research and development in the field of multi-band Raman-fluorescence lidar.
In 2010, the team proposed an effective inversion algorithm for lidar aerosol optical properties. On this basis, through the development of hardware technology and new inversion algorithms, A new algorithm based on LIDAR data is developed to reverse aerosol volume concentration and particle effective radius. At present, based on the inversion algorithm, the mass concentration of PM2.5 and PM10, the microphysical characteristics of aerosols, the profile of aerosol absorption coefficient, etc., and the types of aerosols and clouds can be accurately measured.
They have developed a multi-band Raman-fluorescence lidar system, a laser device for online monitoring of atmospheric bioaerosols, a three-dimensional scanning multi-parameter lidar system for environmental monitoring, and a lidar system with multi-channel echo signal conversion connection devices, and gas samplers and systems for measuring aerosol concentrations. These invention patents range from radar hardware system design to data inversion algorithms, from multi-band Raman polarization lidar data acquisition control software V1.0 to V2.0, and also include three-dimensional scanning environment monitoring lidar data acquisition control software V1.0, and lidar control and data display system V1.0.
In the past 14 years, the radar intelligent manufacturing team of Lanzhou University has developed 6 international and domestic invention patents and 4 computer software copyrights in data acquisition control software, radar control system, data display system, etc., which not only meets the team’s scientific research needs, but also the transformation of scientific and technological achievements has been realized.
'Gathering Light ', Layout' Belt and Road 'Radar Observation Network
'Do you dare to build the Belt and Road lidar network?'
In 2017, this is another conversation between Huang Zhongwei and Huang Jianping ,10 years after the last examination.
'Lidar is a sophisticated optical instrument that requires high stability of power, network and ambient temperature.' When team members were worried about lidar 'going' out of the laboratory, Huang Zhongwei argued that only by 'distributing' lidar can we find and solve problems.
In the winter of 2017, on the roof of the Urumqi Environmental Protection Bureau at minus 20 degrees Celsius, Huang Zhongwei’s team 'guarded' the first deployed radar for more than 20 days. We have accumulated experience in heat preservation performance, the installation of battery life, the installation of a power failure alarm system, and the improvement of its adaptability to the external environment. There is no problem with the radar going out.
On the wall of Huang Zhongwei's office, a panoramic map of the 'Belt and Road' lidar observation network is pasted, starting from Lanzhou in the east to Algeria in the west, with 14 stations spanning more than 8,000 kilometers in a straight line. According to the observation requirements, each radar station is equipped with a single-band, multi-band, with or without fluorescence and other functional combinations of lidars. It is also equipped with a multi-channel microwave radiometer, a sun-sky-moon photometer, and an online particulate matter monitor, and also equipped with other meteorological observation instruments, and remote sensing observations by satellites such as CLOUDsat and Fengyun-4.
'The construction of the'Belt and Road' lidar observation network has the value of scientific research, talent training and international cooperation.' Huang Zhongwei said that the deployment of lidar observation network can track the source of dust in the atmosphere along the 'Belt and Road' and analyze the trend of dust in the air, which is conducive to a better understanding of the causes of dust weather in China.
In the recent period, there are a few white tin boxes emitting green light near the student dormitory 12 on the Chengguan campus of Lanzhou University, with the words 'Raman Polarized Lidar' written on them, which is particularly eye-catching. Soon, these white iron boxes will take the China-Europe Express train to countries along the “Belt and Road” such as Tajikistan and Pakistan. They will be connected in tandem with little green lights, and they will be woven into a lidar observation network spanning tens of thousands of kilometers. (China Education News-China Education News Reporter Yin Xiaojun Correspondent Xu Wenyan Li Hui)
Author: Yin Xiaojun Xu Wenyan Li Hui
