处理了2008-01~2009-03的VLBI观测数据,提取了日长变化信息,并与IVS网站的结果进行了对比;计算了日长变化的月周期长度和半月周期长度;利用近几年VLBI数据中的日长变化信息绘制日长变化曲线,分析了日长的季节性变化及引起日长变化的因素。
We estimate the length of day(LOD) from VLBI observations during 2008-01-2009-03, and analyze its precision. And the estimated results are compared with the results from IVS. Then, the length of the month and half-month periods of the changes of LOD is computed. At the same time, the curve map is made with 2001-2009 VLBI observations to analyze the periods of Earth rotation, with which the seasonal changes is presented and analyzed. At last, the factors that possibly cause the changes of LOD are analyzed.