Atmospheric,hydrological and oceanic comprehensive contributions to seasonal polar wobble of Earth Rotation

The geophysical quantitative excitation on seasonal polar wobble of Earth Rotation has not been well achieved so far. The atmospheric, hydrologic and oceanic angular momentum variations are investigated from monthly values simulated by a coupled ocean-atmosphere general circulation model. The simulated equatorial AAM functions agree well with that from the JMA operational analysis in 90°:E direction, but disagree along Greenwich meridian. As for the annual cycle, not only the hydrologic and oceanic excitations partly match the residuals between geodetic functions of polar wobble and JMA AAM functions, but also the combinations with NCEP and JMA analysis AAM functions are better than those estimated from NCAR-CSM1 climate model.     

Is the Chandler Period Stable?

The problem on the Chandler period is an unsolved one. Several authors suggested a hypothesis that the Chandler wobble is only one free period which slightly changes in time and is amplitude-dependent. In this paper, we shall examine the hypothesis more rigorous than that which has been carried yet. A new deconvolution method for Fourier transform is suggested. Using this method, the polar motion data since 1900 are analysed and the varying process of the Chandlerian period and amplitude are given. The analytical results show that the Chandler period is not stable and is indeed amplitude-dependent. The probable explanation for this phenomenon is that it might be caused by non-equilibrium response of the ocean.     

Chandler摆动周期是稳定的吗?

本文提出了一种新的Fourier分析反卷积方法。采用这种方法分析了自1900年以来的极移运动,给出了Chandler摆动周期和振幅的变化过程。分析结果表明,Chandler摆动周期确实是与振幅相关的,振幅变大时,周期变长。对此现象的地球物理机制解释是,它可能是由于非平衡极潮所引起的。     

大气、地表水和海洋对地球自转极移季节变化的综合贡献

极移季节变化的地球物理定量激发迄今未得到圆满的解释. 基于大气海洋耦合数值环流模式, 计算了大气和地表水及海洋角动量变化. 与日本气象局(JMA)客观分析资料计算的大气角动量比较, 模式模拟的大气角动量东经90°分量要优于0°分量. 地表水和海洋激发有效地减少了极移与JMA大气角动量之间季节尺度上的差异, 并且结合JMA和美国环境预测中心(NCEP)的大气角动量对极移周年变化的综合激发都优于NCAR-CSM1气候模式的结果.