海洋重力不规则测线网平差模型对比分析

Adjustment Model Comparison of Irregular Surveying Network of Marine Gravity

基于国际共享MW9006航次船载实测资料,针对目前已经被广泛运用的最小二乘和半系统差调整两种平差模型进行讨论,提出了一种适用于不规则复杂测网下重力测线数据的平差方法。规则测线网下,随着半系统差调整平差次数的增加,其结果趋近于最小二乘平差。然而,在实际应用于不规则测线网平差中时,由于存在斜交主测线和联络线的补充测线,最小二乘平差只能损失部分交点数据不参与平差而降低精度,而半系统差调整可通过遍历测线的方式计算全部交点并参与平差,但存在交点差重复参与计算的问题。所以两种平差方法又均有局限,亟待提出一种新的方法来处理解决上述问题。基于补充测线与主测线、联络线交点的分布及大小等因素,将不规则测线网分为6种类型开展最小二乘平差和半系统差调整平差工作。在对6种结果进行评价时,选取了测线精度、交点差均方根及平差结果整体均一性等三个要素进行分析评估,并最终确定不规则测线网下的平差方式及结果,最终航次内114个交点均方根降为(±1.84×10^(-5))m/s^(2)。

Based on the survey line data of the NGDC MW9006,this study compared two widely used adjustment models(semi-system adjustment and least squares),and presented an adjustment procedure for irregular and complicated gravity survey lines.Under the regular survey network,they are almost the same.However,under the irregular survey network adjustment in the actual application,both of them have limitations.Due to the crossover between the supplementary line with the main and tie line,the least-square adjustment can only lose part of crossover errors,while the semi-system adjustment can accomplish by traversing all the lines with some crossover errors resulting from repeated calculation.In the present study,the measured data is reasonably classified into 6 types.Three factors,including data precision of survey lines,the root-mean-square of the crossover errors and the data uniformity after adjustment,are used as reference index to establish a comprehensive adjustment procedure,while in all 114 crossovers the root mean square of differences is decreased to be(±1.84×10^(-5))m/s^(2).