地磁台站连续观测分钟值连接阈值选择

Selection of connection threshold of continuous observation minute data of geomagnetic stations

对流动地磁矢量观测数据进行日变通化时,需借助周边地磁台站长时段连续观测分钟值数据,以计算测点处观测时刻至通化日零时H、D和Z三分量变化量,而台站实际相对记录数据多存在相邻两日非正常台阶差值,需予以消除,以保证数据的连续性。选取满洲里、德都、蒙城、泰安、静海、隆尧、锡林浩特和长春8个固定地磁台站2020年5月相对记录数据,讨论H、D和Z分量的连接阈值。为筛选得到更多的台阶值,首选较小值进行连接尝试,分析台阶值在相邻两台站的同步性,并统计台阶值出现前后连续分钟值的正常波动幅度,讨论台阶值的合理性,进而对阈值进行调整,得到3个分量的合理阈值分别为1.0 nT、0.35 nT和0.4 nT。在实际应用中,由于不同台站的地磁观测数据质量存在差异,根据需要可适当提高阈值,尤其是Z分量阈值。

When performing diurnal generation of the mobile geomagnetic vector observation data,it is necessary to use the long-term continuous observation minute date of surrounding geomagnetic stations to calculate the variation of H,D and Z components from the observation time to the origin time of correction.However,there are many unreasonable step values between adjacent days in actual recorded data,which need to be eliminated to ensure the continuity of data.In this paper,the relative geomagnetic data of eight fixed stations,i.e.,Manzhouli,Dedu,Mengcheng,Taian,Jinghai,Longyao,Xilinhaote and Changchun in May 2020 are taken as an example to discuss the connection threshold of H,D and Z components.Smaller values are preferred for connection attempt to screen more step values.Then,by analyzing whether these step values appear synchronously in two adjacent stations,and counting the normal fluctuation range of continuous minute date before and after step values,the rationality of these step values is discussed,and the threshold is adjusted to obtain the reasonable connection thresholds of three components,which are 1.0 nT,0.35 nT and 0.4 nT respectively.In practice,due to the differences in the quality of geomagnetic observation data at different stations,the threshold,especially the Z component threshold,can be appropriately raised as needed.