地磁场S_q的经度效应和UT变化

LONGITUDINAL EFFECTS AND UT VARIATIONS OF THE GEOMAGNETIC S_q FIELD

使用国际地球物理年（ＩＧＹ）和国际地球物理合作年（ＩＧＣ）期间全球地磁台网的资料和中国台站的同期地磁记录，对地磁场太阳日变化Ｓｑ的经度效应和ＵＴ变化进行了分析研究．将适用于瞬时全球磁场的球谐分析法与适用于平均场的双调和分析法相结合，提出了一种分析Ｓｑ磁场的新方案，得到了（θ，Ｔ，ｔ）坐标系中组成Ｓｑ场的三个部分，即仅随地方时ＬＴ变化的部分ＳＬＴ，仅随世界时ＵＴ变化的部分ＳＵＴ以及既随ＬＴ变化又随ＵＴ变化的部分ＳＬＵＴ．从全球来看，在ＩＧＹ／ＩＧＣ期间，这三部分的强度之比分别为：Ｘ分量１．０：０．２：０．３，ｙ分量１．０：０．１：０．６，Ｚ分量１．０：０．４：１．０．Ｓｑ的经度效应和ＵＴ变化虽然表现了同一物理过程，但它们有不同的表达形式，其决定因素是地磁轴对地理轴的倾斜，地磁场的非偶极子成分（即区域性异常）和地球内部电性的横向不均匀性（包括海陆分布、地壳上地幔电导率的区域差异）

The longitudinal effects and UT variations of the geomagnetic Sq field have been analysed on the basis of the magnetic data from the world station network during IGY/C(1957.7-1959.12).The data at 4 observatories in China are included in analysis. A new scheme has been proposed for analysing Sq field which combines the Spheric harmonic analysis and biharmonic analysis. The Sq field has been separated into 3 parts: SLT dependent on local time LT alone, SUT on universal time UT alone, and SLUT on both LT and UT.In globle scale, the ratios of the intensities of the three parts are 1.0:0.2:0.3 for X component, 1.0:0.1:0.6 for Y component,1.0:0.4:1.0 for Z Component. The longitudinal effects of the Sq field and its UT variations have different forms,although they show the same phenomenon.The longitudinal effects and UT variations of the Sq field are attributed to the tilt of the geomagnetic axis,non-diple fields in the earth's magnetic field(regional anomalies),and lateral inhomogeneous conductivities in the crust and the mantle.