海洋磁力测量垂直空间归算中曲面延拓迭代方法的改进

海洋磁力测量中，由于受到海流等因素的影响导致磁力仪传感器（拖鱼）的入水深度起伏变化，测得的海洋磁场数据并不在固定的平面上。为了满足不同用户对海洋磁场数据的应用需求，必须采取合理的“曲化平”，实现整个测区磁场数据垂直空间上的统一。针对位场曲面延拓积分方程的迭代解中高阶垂向导数对高频噪声的放大问题，尝试引入Tikhonov正则化方法对其进行改进，以抑制高频噪声的影响。仿真分析表明，在选择合适的正则化参数后，改进的延拓方法可将延拓精度提高1.6 nT。实测数据分析表明，采用改进曲面延拓迭代方法，将磁测成果数据归算到曲面最低平面时，归算后交叉点磁异常不符值精度可提高2 nT，进一步验证了海洋磁力测量数据垂直空间归算的必要性。

Improved Continuation Iteration Method for Curved Surface on Vertical Space Reduction of Marine Magnetic Survey

The constantly changing of depth of towfish into the water often leads to the magnetic data on a curved surface, which is not taken into account during data processing in marine magnetic survey. For the problem that the high frequency noise in the data is easy to be amplified by vertical derivative in continuation iterative solution of integral equation for curved surface, Tikhonov regularization method is introduced to improve the iterative solution, and the regularization parameter is determined by using the L-curve criterion, which makes the continuation method more anti-noise. Theoretical model and actual examples show that the improved method can effectively suppress the influence of high frequency noise, and the precision of continuation is obviously improved, when the survey data is corrected to the lowest plane of curved surface, the magnetic anomaly discrepancy mean square error of the line network intersection is increased 2 nT than before reduction, which verifies the improved method is feasible for vertical space reduction of marine magnetic survey data.