关键词: 海边/
湍流廓线/
参数化/
外尺度
English Abstract
A new model for the profiles of optical turbulence outer scale and Cn2 on the coast
Cai Jun1,2,Li Xue-Bin1,
Zhan Guo-Wei3,
Wu Peng-Fei1,
Xu Chun-Yan1,2,
Qing Chun1,2,
Wu Xiao-Qing1
1.Key Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;
2.Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China;
3.Maoming Meteorological Bureau of Guangdong Province, Maoming 525000, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 41576185) and the Science and Technology Innovation Foundation of the Chinese Academy of Sciences, China (Grant No. CXJJ).Received Date:08 June 2017
Accepted Date:12 October 2017
Published Online:05 January 2018
Abstract:Atmospheric optical turbulence severely restricts the performances of electro-optical systems. The turbulent atmosphere causes the intensity of a light beam to fluctuate or scintillate, leads the light beam to wander and makes the images randomly displace, which directly relates to the refractive index structure parameter Cn2. Therefore the knowledge of Cn2 is essential to evaluate and to predict the effects of optical turbulence on electro-optical imagery systems. During the period from December 13, 2016 to January 2, 2017, 30 sets of sounding data, which include temperatures, humidities, pressures, wind speeds, wind directions and atmospheric refractive index structure parameters, are obtained by using a self-developed meteorological radiosonde for turbulence at Marine Meteorological Science Experiment Base at Bohe of Maoming. On the basis of the HMNSP99 outer scale model, an atmospheric optical turbulence outer scale formula of Maoming is obtained by fitting the sounding data. At the same time, the experimental data of the turbulence profiles are statistically averaged, and then based on the Hufnagel-Valley model, a statistical model is obtained, which is appropriate to the variation of the turbulence profile on the coast. According to Tatarski turbulence parameterization and the Maoming outer scale formula, the new estimated Cn2 values are compared with their experimental observations and the results from other already defined models, respectively. Statistical analysis shows that the overall correlation coefficients of log10(Cn2) between observed values and estimated values by using the new fitting Maoming outer scale formula, the HMNSP99 model, the Dewan model and the Coulman model are 0.924, 0.848, 0.763 and 0.651, respectively. Also, both the trends and magnitudes for these four outer scale models are consistent with each other. The errors of the above four outer scale models are very small:their overall average absolute errors and average relative errors are 0.514 and 2.963%, 0.627 and 3.612%, 0.943 and 5.439%, 0.766 and 4.417%, respectively, and the error of the Maoming outer scale model is smallest. The reliabilities and validities of the new outer scale and Cn2 models are further verified. In addition, it is found that the occurrence of upper air optical turbulence is closely related to wind shear and temperature gradient. The results support the prediction of the atmospheric optical turbulence profile required for electro-optical engineering on the coast.
Keywords: coast/
turbulence profile/
parameterization/
outer scale
