中文摘要：

目前海洋对极移季节变化的激发尚未得到合理的定量结果．许多研究已经表明大气运动是极移季节变化最大的激发源，海洋运动是剩余部分最主要的激发源之一．利用新一代SODA海洋同化资料（SODA_1．4．2和SODA_1．4．3）以及ECCO海洋同化资料，深入研究了1992-2004年全球海洋对极移周年变化的激发以及激发随纬度的分布．结果表明，SODA海洋激发的季节变化与从测地激发函数中扣除大气、陆地水作用剩余部分的季节变化在所研究的大部分时段非常接近，二者的周年振幅和位相结果基本相当．此外，与早期SODA_Beta7的结果比较，新一代的SODA海洋激发有了明显改善．SODA和ECCO海洋对极移周年激发的纬度分布，在格林威治方向上比较一致；在东经90°方向上有明显的差别．

英文摘要：

The variation in the orientation of Earth＇s rotational axis with respect to Earth＇s figure axis is called polar wobble, which results from internal excitation processes, such as wind, current, pressure fluctuations in atmosphere, ocean and land-water, etc. The seasonal polar wobble has been confirmed to be largely caused by changes in atmospheric planetary angular momentum, due to atmospheric mass redistribution for periods between intra-seasonal time scale and a few years. However, the cause of the observed seasonal polar wobble is not fully understood. A growing body of evidence points to the oceans as one of the sources of much of the remaining excitation. In recent years, significant progresses have also been made in demonstrating the importance of ocean angular momentum （OAM） variability in explaining non-atmospheric polar wobble at periods of one year and shorter, with improvements in non-data assimilative and data assimilative ocean general circulation models （OGCM）, as well as satellite radar altimeter observations. But compared with atmospheric angular momentum （AAM） determinations, OAM estimates remain relatively more problematic mainly due to scarce observations of the global oceans and large uncertainties in predictions of the ocean general circulation models. This paper contributes to this body of evidence by comparing effective OAM functions estimated from two improved assimilated models SODA_1.4.2 and SODA_1.4.3 to the non-atmospheric-hydrologic residual, which is the observed geodetic excitation function with atmospheric and hydrologic effects being removed. The Simple Ocean Data Assimilation （SODA） is recently developed at University of Maryland. For the seasonal fluctuation, the SODA assimilated effective OAM functions agree better with the non-atmospheric- hydrologic residual, than those estimated from the previous assimilated model SODA_Beta7, also for the annual variations. It has also been found that annual effective OAM vectors for SODA and ECCO in each latitude band