近地层气温梯度逆转时刻的预报

Prediction of the Moment the Air Temperature Gradient of the Lowest Tropsphere Reverses

近地层气温梯度逆转时刻是光电测距的最佳观测时刻,本文介绍了两个预报全国各地任何日期近地层气温梯度逆转时刻的计算公式,验算结果表明,预报中误差在±14~m 以内以推算出的逆转时刻为时间中心,在前后半小时内进行对称的距离观测,能使大气折射率误差对测距结果的影响在0.5ppm.D 以下,从而使光电测距精度达到所用仪器的最高水平.

The moment at which the air temperature gradient of che lowest troposphere reverses is the optimum time for electro-optical distance measurement.This paper introduces two calculation formulas to forecast the reverse moment of any date and any place in China.The checking computations indicate that the mean square error of prediction is within±14~m.Taking the reverse moment calculated as the center of time and measuring the distance symmetrically in half an hour,the distance error caused by the air index error is less than 0.5ppmD,and the attainable accuracy of electro-optical distance measurement indicates the fullest use of the instrument.