湿度起伏对可见光波段折射率结构常数的影响

大气折射率起伏主要是由温度和湿度起伏引起的。提出一种研究湿度起伏对折射率结构常数影响的新方法，即从超声风速计测量的虚温信号中提取出湿度起伏的信息，可计算出湿度起伏、温湿相关项的结构常数。采用自行研制的温度脉动仪和超声风速计分别在湿度差异较大的干燥的戈壁滩和潮湿的海边进行实验，并用实验时的气象参量对湿度起伏进行了模式计算。测量和模式计算都表明：湿度起伏本身对Cn^2的贡献很小，可忽略不计，湿度起伏对Cn^2的影响主要是通过与温度起伏相结合来实现的，在一般情况下，这种贡献不到10％。但在湿度较大，特别是日落前Cn^2处于最小值附近，温湿相关项的贡献可超过10％。

Effects of Humidity Fluctuation on the Structure Parameter of the Refractive Index for Visible Radiation

The refractive index fluctuation of atmosphere are mainly caused by variations in temperature and humidity. A new method of studying effects of humidity fluctuation on the structure parameter of the refractive index is proposed. Humidity fluctuations is obtained from fluctuations of 'sonic temperature', very closely equivalent to virtual temperature ,using a three component sonic anemometer. The structure parameters CQ2 , CTQ, can be calculated. Cn2 and temperature fluctuation, humidity fluctuation are measured by a sonic anemometer and microthermal probe both in dry desert and in damp sea shore. Meanwhile, the humidity fluctuation can be estimated by a mode using field experiment meteorologic condition as input parementers. Both measurement and mode show that humidity directly influencing Cn2 can be ignored. Humidity effects is mainly achiered associating with tempera time fluctuation. Generally, the contribution to Cn2 is less than 10% except near a marine surface or saturated soil especially during occurrence minimal CH2 before sunset.