Xue Xianghui, a professor in the School of Earth and Space Sciences at the University of Science and Technology of China (USTC), has made a major breakthrough in the development of a coherent wind measurement lidar system, achieving the first wind field detection with a spatial resolution of 3 meters and a temporal resolution of 0.1 seconds. It is reported that this is the most accurate continuous wind field detection in the world reported so far. The related results were published in the internationally renowned optics journal Optics Express.
The wind measurement lidar package prototype. Photo by the research team
Atmospheric wind field detection with the meter-subsecond resolution is of great significance in aerospace safety, high-value target assurance, and numerical weather prediction, but continuous wind field observation with the high spatial and temporal resolution is still a challenge for lidar. For example, in order to obtain 3-meter and 0.1-second spatial and temporal resolution wind field observation results, the existing LIDAR signal detection sensitivity needs to be improved by more than two orders of magnitude.
In order to achieve a high spatial and temporal resolution wind measurement lidar that can “see far, see fine, measure fast and measure accurately”, the team optimized the lidar in terms of laser light source, optical transceiver system, high-speed data acquisition circuit and data processing algorithm, and proposed a new inversion algorithm based on time-frequency analysis and pulse coding. The team proposed a new inversion algorithm based on time-frequency analysis and pulse coding, which greatly improved the accuracy and robustness of wind field inversion, and finally realized a set of fully localized “product-level” test prototype.
According to the introduction, the radar prototype works at 1550.1 nm, which has the characteristics of human eye safety, light equipment (40 kg for the whole equipment), stable work, and strong environmental adaptability.
Through the field comparison test, the radar prototype wind field observation results and the calibration equipment comparison error is less than 0.5 meters per second.
To further test the radar observation performance and environmental adaptability, the team measured the wind field structure in the wake stream of high-speed trains in the field at the high-speed railway station in Suzhou, Anhui Province. The radar worked continuously and stably for more than 100 hours unattended and obtained continuous observations of the high-speed train wake flow at 350 km/h at the high temporal resolution of 3 m and 0.1 s. For the first time, the lidar was used to capture the wind field structure in the high-speed train wake flow similar to the von Kammen vortex street, which was highly consistent with the results of computational fluid dynamics simulations.
The reviewers concluded that “the observations are striking and impressive” and “the first high-resolution results of continuous observations to date.”