【摘要】 VLBI (very long baseline interferometry)相位参考在高频波段(约大于10 GHz)的主要误差源是对流层延迟模型误差,减小该项误差的有效途径是采用实测资料对其精确拟合。常用的修正方法有两种:一种是在相位参考观测中穿插测地观测,用以拟合剩余大气延迟;另一种是使用GPS并置站的对流层产品改正。两种改正方法的精度约为2 cm。从残余相位中提取出了残余大气信息,提出了传统方法与残余相位拟合大气参数相结合的改正方法,并通过实测数据对该方法进行了验证。更多还原

【Abstract】 Among the various error sources in VLBI phase referencing, uncompensated tropospheric delays typically dominate systemic errors at observing frequencies(～> 10 GHz). Generally, the tropospheric delays can be calibrated by geodetic-like VLBI observing blocks or by using co-located GPS observations. However, the derived tropospheric delay offsets from these two methods are sometimes greater than 2 cm, this implies that there are still residual tropospheric delays, which limit the quality of phase-referenced image and the astrometry accuracy. In this paper, we propose a two-step method of tropospheric delay calibration, which combines the VLBI geodetic-block(or GPS) calibration with an image-optimization calibration. We analyze archived VLBI data using this method, both image quality and astrometry accuracy are improved.更多还原