双重约束条件下的连续重力观测非线性漂移改正方法分析

Nonlinear Drift Correction Method for Continuous Gravity Observation under Dual Constraints

连续重力观测去除固体潮后所得重力残差结果,除了受仪器故障、自然因素、人为因素以及供电系统干扰外,弹簧重力仪的长期漂移也成为重力变化的重要影响因素,故漂移改正不可忽略。本文以高台地震台近5年的连续重力观测资料为数据基础,采用多阶多项式拟合法,并以驰豫分析结果和流动重力场结果为约束,研究弹簧重力仪的非线性漂移特征及其漂移改正的合理性。研究结果表明:高台重力仪的线性和非线性漂移特征明显,严重影响了其他微弱重力信号的提取,而驰豫分析处理结果和流动重力场成为有效地辅助约束手段,在其双重制约下进行非线性漂移改正,使所得重力非潮汐结果更为准确可靠,为地震预测预报提供较为准确的参考依据。

Drift correction is important since gravity residuals,aside from interference due to instrument and power failure and natural and human factors,are strongly influenced by longterm drift.In this study,continuously observed gravity data from a recent fiveyear period at Gaotai seismic station were analyzed.Nonlinear drift characteristics of the spring gravimeter,and the rationality of corresponding drift correction using the multinomial polynomial fitting method,are discussed.Results of the relaxation analysis and the mobile gravity observation showed that the linear and nonlinear drift characteristics of the PET gravimeter at Gaotai seismic station were clear.This seriously influenced the extraction of other weak gravity signals.Nonlinear drift correction was carried out under the double constraints of relaxation analysis and mobile gravity observation.The obtained residual gravity was more accurate and reliable.This study can provide a more accurate reference for future earthquake prediction.