Measurement Of Optical Turbulence In The Surface Layer Of Gansu Area

In view of the effect of light in the atmosphere transmission of atmospheric optical turbulence theory and atmospheric physical characteristics, according to the requirement of the actual measurement, we researched the methods and apparatus for measure the atmospheric optical turbulence parameters, refractive index structure constant, and statistically analyzed the refractive index structure constant characteristics and rules.According to the measurement requirements, we need a long time observation of the optical turbulence near the surface layer in Wuwei, Zhangye, Jiayuguan Gansu Province simultaneously, therefore we designed and set up a set of an automatic observation system for optical turbulence in the near surface layer. The system includes three sub measuring and a control center, the system can simultaneously measure meteorological parameters and atmospheric refractive index structure constant Cn2, through wireless transmission and solar power to achieve unmanned automatic observation, greatly saves the manpower and material resources.After the preliminary test and a long period observation in the Gansu area, mainly including the following contents:(1) The automatic observation system of optical turbulence in the near surface laye can meet the requirements of the observation, its working performance is stable, and it can adapt to the harsh environment. According to the characteristics of the system, a reliable algorithm for calculating the refractive index structure constant is determined.(2) The calculated results from the automatic observation system are in good agreement with the micro-thermal meter, it has a high degree of accuracy and reliability. We calibrate the consistency of the results of the three sets of the automatic observation systems.(3) The three dimensional sonic anemometer measures the ultrasonic virtual temperature, and the ultrasonic virtual temperature contains humidity information, so the refractive index structure constant Cn2 calculated by using ultrasound virtual temperature is on the high side, by comparing the differences before and after the humidity correction, the humidity correction is necessary.(4) We analyzed the regular meteorological parameters and the variation of atmospheric refractive index structure constant of the four observation points in Gansu area. We analyzed the diurnal and seasonal variations of air pressure, relative humidity, temperature, absolute humidity, wind speed and direction of the three places of Wuwei, Zhangye and Jiayuguan, and emphatically analyzed the refraction index structure constant of diurnal variation and seasonal variations. The three locations have obvious diurnal variation law, the Cn2 is bigger at daytime, while it is smaller at night, and it has the obvious transition time. The difference of monthly average of the refractive index structure constant of the three locations different weather conditions and different underlying surfaces was compared and analyzed. We counted the frequency of log(Cn2) of the three places, and the probability distribution curve used Gaussian fitting, which is consistent with the log normal distribution.