天测与测地VLBI资料处理中的剩余钟行为建模

On the Modeling of the Residual Clock Behavior in the Analysis of the Astrometric and Geodetic VLBIObservations

利用实测资料和模拟数据,分析了在天测与测地VLBI数据处理软件CALC/SOLVE中,剩余钟行为连续分段线性拟合的局限性和周期函数拟合的可行性.对CALC/SOLVE系统增配了周期函数拟合模块,并选取了1990年至2001年的1567次天测与测地VLBI实验,进行了剩余钟行为两种拟合模型情况下的实测资料综合解算.结果表明,在获得同等水平的时延拟合残差加权均方根(wrms)的情况下,对剩余钟行为采用周期函数拟合,使得解算参数的个数相比于连续分段线性拟合有显著减少,提高了解算的自由度.虽然在两种模型情况下的台站和射电源坐标以及地球定向参数等的解算精度无显著差异,但周期函数拟合存在可以识别的优势,85％以上的台站坐标和74％以上的源坐标以及51％以上的EOP精度均有所提高,均值分别为0.02 mm、0.3μas和1.5μas.

Based on the observations and the simulated data, the modeling of the residual clock behavior in the CALC/SOLVE system of the astrometry and geodetic VLBI data reduction was discussed. The limitations of the continuous piecewise linear modeling and the feasibility of the periodic function modeling were demonstrated. A module block of the periodic function modeling was realized in the CALC/SOLVE system. Two global solutions of 1,567 astrometric and geodetic VLBI sessions from 1990 to 2001 were performed corresponding to the two types modeling of the resicual clock behavior. It is shown that, compared with the continuous piecewise linear modeling of the residual clock behavior, the number of unknowns in the solution could be evidentry decreased and so the degree of freedom increased when the periodic function modeling was used. Though the calculated errors of the coordinates of stations and sources as well as the Earth Orientation Parameter are on the same level, it is slightly better to model the residual clock behavior by the periodic functions than the continuous piecewise linear methoe . The calculated errors of coordinates could be decreased for more than 85% of stations and 74% of sources and 51%EOP, and the mean values of the decreased formal errors are 0.02 mm , 0.3 μas and 1.5 μas respectively.