Atmospheric Refractive Index Of The Influencing Factors

Refractive index field of atmosphere distributes homogeneously due to the difference of pressure, temperature, relative humidity and carbon dioxide content in the atmospheric optics. Therefore, to reach an accurate decision on ray trace in atmosphere, the variation characteristic of refractive index in atmosphere must be found out.This paper first reviews relative research on the formulas for calculating the refractive index of air. With comparing selected formulas from these sources, this paper presents several suggestions on the choice of formulas.A deep research has been done on the effects dropping some of the terms involved in the BIPM 1981/91 density calculations. And another work has been done is performming a parametric fit on using the extended Rueger formula. The new formula has been made more flexible and applicable in the high temperature environment.Basing on the theory discussed before, I have developed a software which has several practical functions, such as calculating the data between density and refractivity, optimizing the coefficients of the formula automatically, generating a 3D image of the refractivity field and some so on.At last, according to the data provided by National Center of Environment Prediction (NCEP) and National Center for Atmospheric Research (NCAR), this paper has yielded a new set of equations which can calculate the temperature, atmospheric pressure and refractive index of air in different height above sea level. The result matchs the national practice better.