A priori zenith wet delays in the analysis of VLBI CONT sessions

Tropospheric delay is one of the major sources error in VLBI (Very Long Baseline Interferometry) analysis. The principal component this can be accurately computed through reliable surface pressure data —hydrostatic delay— yet there also a small but volatile —wet which difficult to modelled priori. In analysis, troposphere typically theoretical delays using Zenith Hydrostatic Delays (ZHD) and dry mapping function. Wet Delay (ZWD) not estimated analysis process. This work studies inter alia impact including external GNSS estimates model priori ZWD as well other models ZWD. first stage, two different products are compared period 5 years. solution with best agreement results injected value options dataset used for empirical consists six CONT campaigns. It has been found that modelling no significant either on baseline length coordinates repeatabilities. Nevertheless, change magnitude few millimeters up respect non-modelling approach. addition, influence Earth Orientation Parameters (EOP) —Zenith Total (ZTD) gradients—has analysed, resulting both geodetic products.