【摘要】 由于大气湍流的存在,当光束在大气中传播时会发生相位起伏、光强闪烁等一系列湍流效应现象,严重制约光电系统的性能,是造成天文观测困难的主要原因.大气折射率结构常数C_n~2廓线是评估大气湍流效应的重要参数.本文归纳了几种有代表性的C_n~2廓线模式,提出了修正的CLEAR I夜晚模式;分析了高美古、拉萨、大柴旦、茂名、荣成等5个实验点探空测量数据,给出了5个实验点算术平均拟合的C_n~2廓线公式;计算了各模式和测量数据在波长为0.5μm时的大气相干长度r0、视宁度εFWHM、等晕角θ0、相干时间τ0、等效高度h和等效风速V等大气光学参数以及各大气层C_n~2递减率和不同大气层湍流贡献百分比.重点对H-V(5/7)模式的存疑、 C_n~2廓线模式采用的平均方法、低平流层C_n~2是否具有统一的递减率等问题进行讨论并给出答案.更多还原

【Abstract】 Owing to the existence of atmospheric turbulence, a series of turbulence effects such as phase fluctuation and light intensity scintillation will occur when the electromagnetic waves propagates through the atmosphere,which seriously affects the performance of the electro-optic system, resulting in the difficulty of astronomical observation. The atmospheric refractive index structure constant(evaluate the turbulence effects. This paper summarizes several representative C_n~2 the data using balloon-borne microthermal probes at five sites i.e. Gaomeigu, Lhasa, Dachaidan, Maoming, and Rongcheng. The atmospheirc optical parameters are calculated, such as coherence length, seeing, isoplanatie angle, coherence time, equivalent height, equivalent wind speed, drop-off rate and integrated contribution from each atmosphere layer. The formulas of five sites are developed by fitting the arithmetic average of measurements. Several troubling basic problems such as suspicion the H-V(5/7) model, the model developed by arithmetic average or geometric average, the problem whether there is a uniform lapse rate in the low stratosphere, are discussed and solved. The modified CLEAR I night model is given.更多还原