预报对流层大气折射误差的新公式

A new formulae for predicting tropospheric refractive error

基于理论,把计算折射误差中的转换函数描述为通用归一化仰角函数和地面折射率(N0)常数或总折射率(NT)常数,从而给出了以N0为先验值或以NT为先验值的预报公式,(11)式或(12)式。实例证明,N0法的预报误差不大于2%,有时可小于1%,NT法的预报误差小于10-3量级。引入通用归一化仰角函数是改善预报误差的主要原因。NT预报公式可作为计算距离误差的简便而精确的公式,应用于GPS和星载SAR等测量系统。

On the basis of theoretical analysis, the mapping function for calculating refractive error is described as general normalized elevation angle function and surface refractivity （N0） constant or total refractivity （NT） constant, and the formulae for predicting tropospheric refractive error with prior value of N0 or of NT are obtained as shown in expressions （11）and （12） in this paper. The prediction error of N0-method is no more than 2%, even then can be less than 1%, and that of NT-method is less than minus 3 orders of magnitude. The improvement of predicting error is mainly due to introduction of general normalized elevation angle function. The expression （12） can be considered as a simplified method for calculating range error and applied to measuring systems, such as GPS and satellite borne SAR.