对流层模型对精密单点定位估计ZPD、钟差及定位精度的影响研究

t present, in the error sources of GPS positioning the troposphere correction is still immature and is improving permanently. In this paper, the parameter estimation method of wet component and the effect of the horizontal gradient to the PPP precision are studied; including estimating ZPD according to PPP, coordinate calculation and clock bias estimation. The study shows that in general adding the horizontal gradient some improvement to the PPP precision can be made, and it has a great relation with the meteorology on observation; The precision of estimating ZPD with piece wise linear method is a little higher than the piece wise constant method, but the improvement is little. Estimating ZPD with the piece wise linear method and considering the horizontal gradient, the zenith troposphere delay calculated by static PPP can have a precision within 5mm, the level of the positioning precision of the horizontal direction is mm, the altitude direction is about 1cm, and the precision of clock bias estimation is at the level of 0.1ns.The precision of positioning by dynamic PPP is a little lower, the horizontal is about 1cm and the altitude direction is about 2cm.