[Editor’s Note: the Beijing 2022 Winter Olympics was officially opened on February 4. In addition to the crystal white world of ice and snow, the Beijing 2022 is featured by another bright color—green, the symbol of environmental protection. The Games embodies the concept of “greenness” in every dimension, such as ecology, buildings and transportation. This is Part II of a two-part story, showcasing how ZJU scientists have contributed to a “green and clean” Winter Olympics.]
A new lidar: help to fight air pollution
The blue sky and the white snow play a unique duet. The science team led by Prof. LIU Dong and Prof. LIU Chong from the College of Optical Science and Engineering actively participates in the meteorological services of the Beijing 2022 with their independently developed high-spectral-resolution lidar (HSRL).
They are mainly responsible for characterizing the meteorological features of Beijing, studying the causality of the winter haze in Beijing, monitoring the transported dust storms from Northwest China, and investigating aerosol-cloud-precipitation interactions.
To guarantee the quality of the meteorological services for Beijing 2022, the team conducted several field campaigns in Beijing a year ahead of schedule, and have in collaboration with several universities and institutes, including Peking University, Beijing Normal University, the National Meteorological Administration, the CAS Institute of Atmospheric Physics, and Beijing Yanqing Meteorological Bureau.
The HRSL system developed by the ZJU team employs the ultra-narrowband spectral discrimination technology to separate Mie scattering and Rayleigh scattering of the atmospheric lidar signals. It overcomes the difficulty of “one equation and two unknowns” for the atmospheric lidars, and enables us to retrieve atmospheric properties accurately.
“Using HSRL to observe the properties of aerosols and clouds is not only crucial for teasing out the causality of air pollution, but also significantly improves our understandings of climate in a more in-depth way. Compared to the atomic vapor spectral filter for a single wavelength in classical HSRL techniques, the field-widened Michaelson interferometer (FWMI) developed by our team is suitable for any wavelength in theory (e.g., from infrared to ultraviolet band). It also remarkably expands the receiving filed-of-view and enhances the signal-to-noise ratio, compared with the conventional Michaelson interferometer. The high-resolution and high-precision observations of atmospheric optical properties with multiple wavelengths provides the solid basis for the further retrievals of atmospheric microphysical properties,” Prof. Liu said.
Photo provided by the research teams