Studies On Wind Field Measurement And Data Inversion Method Of The Coherent LIDAR

The atmospheric wind plays an important role in climatological and meteorological studies, such as numerical weather predictions, atmospheric dynamics studies, environmental monitoring, wind power generation, military and aerial safety. The characteristics of coherent Doppler LIDAR measurement are high temporal and spatial resolution, especially high precision and sensitivity in wind speed, and it is not sensitive to background light. The coherent Doppler LIDAR is very suitable for wind measurement in clear sky. It is an important development direction in recent years and has an extensive application range. The wind field inversion method was studied in this paper. Using the coherent Doppler LIDAR, which was devised by SIOM (Shanghai Institute of Optics and Fine Mechanics, the Chinese Academy of Sciences), to do the wind measurement test. And the wind field detection results were analyzed in this paper.This article describes the related theoretical knowledge in coherent detection. The method of extracting the light-of-sight wind speed and the wind profile inversion method of multi-directional scanning were studied. According to the LIDAR measured results, correlation algorithms were optimized.The introduction of the structure of coherent LIDAR system, which was developed by the project team of SIOM, is described in this paper. We carried out the appropriate calibration experiment including the intermediate frequency, system zeros and blind zone. Also, we carried out a series of comparative observations and field experiments.(1) Comparisons of detection results from the coherent Doppler LIDAR and the sounding balloon are conducted. The results show that the correlation coefficient of the different wind speed measurements is 0.93 and their discrepancy 0.64m/s, and the correlation coefficient for wind direction values is 0.92 and their discrepancy 5.8deg, which verified the reliability of the observational data of the coherent Doppler LIDAR.(2) Comparisons of detection results from the coherent Doppler LIDAR and the commercial wind LIDAR are also performed. The results show that the correlation coefficients of 10min mean wind direction and wind speed measurements at 70m are 0.99 and 0.98 respectively, and the correlation coefficients are the same at 100m, which verified the detection performance of the coherent Doppler LIDAR.(3) According to different atmospheric conditions, we described the measurement results of wind field, the horizontal wind field of sea surface and land surface observed by coherent LIDAR. Under condition of clear sky, the atmospheric wind shows obvious diurnal variation. The clouds move and develop with wind, the three-dimensional wind at the different height of cloud layer appears greater change during the short time. When it rains, the atmospheric wind is changing more complicated. At the beginning of haze formation, the atmospheric stratification starts and gradually develops a very significant shear of wind speed and direction in space, as the same time the convection is weak, which is more favorable to the further development of haze.