时差法水位改正的精度评估方法研究

Research on Precision Assessment of Tidal Time Difference Water Correction

为实现对时差法水位改正结果的精度评估,根据协方差传播律,推导了时差法水位改正的误差方程,讨论了评估潮时差确定精度的方法,并通过数据试验对结果进行了验证。试验结果表明,最小二乘拟合法比相关系数法更能满足时差法水位改正精度评估对潮时差的要求;根据《海道测量规范》要求,试验海域潮时差中误差的限差为6.2min,验潮站网潮时差闭合差中误差的限差为1.0min;水位改正方差反映出了水位改正结果的合理性,可用以评估水位改正精度。

Tidal time difference method is commonly used to determine water level correction value in hydrographic surveying, however, the precision assessment of water correction result has not been realized yet. This paper is to solve this problem. Firstly,the error equation of tidal time difference water correction is educed according to propagation of covariance. Secondly, two methods to determine tidal time difference are compared. At last, experiments are made to check the analysis result. The experiment results show that tidal time difference determined by least square fitting can meet the demand that accuracy assessment of tidal time difference water correction asks for;referenced specifications for hydrographic survey, the root mean square error (RMSE) tolerance of tidal time difference is 6.2 min, and RMSE tolerance of time difference closure of tidal station network is 1.0 min;the effect of water correction result can be reflected by variance which is calculated by RMSE of tidal time difference and difference of water level derivative of controlling stations, which makes it possible to assess the precision of water correction result determined by tidal time difference method.