地球自转长期变化非潮汐机制之一

A Mechanism for the Non tidal Variation of the Earth Rotation

地球自转的长期减慢一般归为日月潮汐摩擦，根据古代日月食的记载及珊瑚类生物生长线的研究，可估算地球自转变慢为每世纪２．４ｍｓ左右的日长变化．但是，潮汐摩擦并不是减速的唯一机制，还要考虑其它非潮汐因素．本文试图考虑太阳风和磁层的相互作用，分析地球磁层中的磁力线在背阳面，由于地球自转引起磁力线压缩与稀疏，产生附加磁压力而引起的力矩对地球自转长期变化的影响．结果表明：这一非潮汐变化机制引起的角加速度约为ω＝－１．６１×１０－２２ｒａｄ／ｓ．

The secular variation in the Earth's rotation is generally explained by tidal friction. From historical records of solar and lunar eclipses as well as the study of growth lines of coral, a rate of 2.4 ms/cy in LOD has been estimated. In this paper we consider another possible factor: the solar wind distorts the field lines in the magnetosphere and so will introduce a magnetic pressure and a torque on the rotation. It is shown that this mechanism can produce an angular deceleration of the Earth rotation of the order of = -1.61×10 -22 /s 2. variation further.