Study of High Accuracy Adjust Method of Atmospheric Refraction of Low Elevation

According to the atmospheric refraction affect to the optic angle error,a mathematic model of the relationship between the rate of atmospheric refraction and examination error is built,and two effective methods are put forward to correct the atmospheric refraction errors.The comparisons are carried on through real data test,and the results have shown that in low angle of elevation(5°) there aren't angle of pitch,and the calculating value is small,the precision is high.