Seasonal and inter-annual variations of length of day and polar motion observed by SLR in 1993-2006
Seasonal and inter-annual variations of length of day and polar motion observed by SLR in 1993-2006
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1993-2006年单反观测日长和极移的季节和年际变化
DOI：
10.1007/s11434-008-0504-1
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发表时间：
2009-01-01
影响因子：
--
通讯作者：
Han YanBen
中科院分区：
文献类型：
--
作者：
Guo JinYun;Han YanBen
利用1993 - 2006年LAGEOS 1/2卫星激光测距技术（SLR）的测距数据，估算了日长（LOD）和极移（PM）时间序列。与国际地球自转和参考系服务（IERS）发布的EOPC 04相比，PM的LOD、X和Y的均方根误差分别为0.0067毫秒（ms）、0.18毫弧秒（mas）和0.20 mas。利用小波变换和最小二乘法对时间序列进行分析。小波分析表明，LOD和PM具有明显的季节和年际变化，但由于两者的频率非常接近，无法将其年际变化与钱德勒变化区分开来。在最小二乘意义下给出了LOD和PM的趋势和周期变化。LOD随年度和半年周期变化。1993-2006年的LOD变化趋势率为-0.18ms/a，与1.7ms/世纪的百年变化趋势率相差很大，说明不同时期的LOD变化趋势率可能存在差异。PM在X和Y方向的趋势率分别为2.25和1.67 mas/a，北极相对于地壳向36.5 E方向移动，与格陵兰方向不同。
A time series of length of the day (LOD) and polar motion (PM) were estimated from the range data measured by the satellite laser ranging technique (SLR) to LAGEOS 1/2 through 1993 to 2006. Compared with EOPC04 released by the International Earth Rotation and Reference Systems Service (IERS), the root mean squares errors for LOD, X and Y of PM are 0.0067 milliseconds (ms), 0.18 milli-arc-seconds (mas) and 0.20 mas, respectively. Then the time series are analyzed with the wavelet transformation and least squares method. Wavelet analysis shows that there are the obvious seasonal and inter-annual variations of LOD and PM, but the annual variation cannot be distinguished from the Chandler variation because these two frequencies are very close. The trends and periodic variations of LOD and PM are given in the least squares sense. LOD changes with the annual and semiannual periods. The annual and Chandler variations for PM are also detected, but the semiannual motion for PM is not found. The trend rate of the LOD change in 1993-2006 is -0.18 ms per year, and the difference from the well-known 1.7 ms per century showed that the trend rate is diverse in different periods possibly. The trend rates of PM in the X and Y directions are 2.25 and 1.67 mas per year respectively, and the North Pole moves to 36.5 E relative to the crust, which is different from the direction of Greenland.