地磁日变化记录准确度标定的目的，是为了定量考察地磁记录仪器记录到的地磁日变化的准确度，以利于确定台站绝对观测的合适时间段及数据的研究应用。 受探头轴向正交度、格值线性度、安装定向准确度和稳定性、温度稳定性和温度变化等因素的影响，地磁相对记录仪器记录到的地磁日变化与真空的日变化之间有一定的误差，并且每个台站和每套仪器的误差均不相同^[1]。2011年10月12日，通海台用Mingeo-DIM磁力仪对台站的M15和GM4的日变化记录准确度进行了标定。从标定结果上来看，M15和GM4两套仪器的基线值均受到地磁日变化的影响。

 The purpose of calibrate the accuracy of geomagnetic diurnal variation records is to Quantitatively inspect the accuracy of geomagnetic diurnal variation records, which is produced by geomagnetic recording instruments , then it will be conducive to arrange the Schedule of absolute magnetic measurement , also advantageous to do Research and application of these data. It is affected by a variety of elements, such as orthogonality of probe axial, linearity of scale value, accuracy and stability of installation orientation, stability and variation of indoor temperature etc. The geomagnetic diurnal variation recorded by relative observation instrument is different from the variation measured in vacuum, it also associated with different instruments and stations. We did calibration on M15 and GM4 by Mingeo-DIM magnetometer on October 12, 2011, and the result appeared that the baselines of each instrument are affected by geomagnetic variation.