Longitude correction method for the field magnetic surveyed diurnal-variation correction

Solar quiet daily variation(Sq)are dependent on local time.Herein,we applied the moving superposition method to separate the Sq component of correction observatory data and performed a time diff erence correction on the Sq component according to the longitudinal diff erence between the correction observatory and the field station while maintaining the time of other data components.The data were then reconstructed and used for diurnal-variation correction to improve the accuracy of the daily variations correction resu;lts The moving superposition method employs data of“nonmagnetic disturbance days”obtained 15 d before and after to perform the superposing average calculation on a daily basis,aiming to obtain the Sq of continuous morphological changes.The effect of longitude correction was tested using the observatory record and field survey data.The average correction distance of the test observatories was 2114 km,and the correction accuracies of the H(horizontal component of geomagnetic field),D(geomagnetic declination),and Z(vertical component of geomagnetic field)were improved by 28.4%,45.0%,and 21.7%,respectively;the average correction distance of the field stations was 2130 km,and the correction accuracies of the F(geomagnetic total intensity),D,I(geomagnetic inclination)components were improved by 35.2%,26.7%,and 13.9%,respectively.The test results also demonstrated that the longitude correction eff ect was greater with an increased correction distance.

野外地震地磁测量的主磁场长期变化改正方法研究

本文应用野外测点的重复测量数据,通过加权最小二乘方法,对测量数据进行了长期变改正,并与现行方法的结果进行了对比。统计数据表明:①新方法显著改善了原方法存在的长期变空间畸变问题,产出的主磁场长期变化结果与IGRF_SV模型的线性相关程度更高。“F、D、I”3要素与IGRF_SV模型“差值的均方差”,分别为原方法结果的“10.7%、47.0%、14.5%”;②应用新的长期变化改正方法,可获得更加稳定、合理的地壳磁场变化结果。“F、D、I”3要素地壳磁场变化的“平均幅度”分别为原结果的“28.5%、55.4%、34.4”,“均方差”分别为原结果的“59.1%、56.5%、40.3%”,“平均梯度”分别为原结果的“93.6%、91.9%、97.0%”;③在新方法的处理结果中,震磁信息得到明显的优化,震中位置与地壳磁场变化“0”值线的吻合程度明显更好。新方法的处理结果明显优于原方法,具备较高的应用价值。

张家口—渤海地震带岩石圈磁场时空变化特征

利用2016—2018年3期华北地区流动地磁矢量原始测量资料,经数据计算获得2期华北地区和张家口—渤海地震活动带及邻区岩石圈磁场时空变化模型。研究结果显示:张家口—渤海地震带岩石圈磁场变化空间分布不均匀,具有明显的分区特征,在张家口段(西段)与北京段(中西段)分界处和北京段(中西段)与唐山段(中东段)分界处岩石圈磁场各要素具有明显的异常变化,如水平矢量存在转向和幅值变化,磁偏角与磁倾角具有正负异常高梯度带的特征,这与张家口—渤海地震带构造分段性特征密切相关。张家口—渤海地震带位于燕山块体与华北平原块体之间,两者运动的平动速率之差是张家口—渤海地震带左旋走滑的直接动力来源,而各断裂带左旋走滑速率之差很可能是岩石圈磁场空间变化分段性分布的主要原因。