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In the context of a High accuracy SBAS-PPP service, we require a different tropospheric delay model than the existing model provided in DO-229F (RTCA, 2020). This will yield more reliable results, but also reduce convergence times with desired accuracy to assist a faster convergence time for the PPP solution, which is imperative for employing the SBAS-PPP corrections for high integrity safety-of-life applications. In this paper we describe a real-time capable global methodology to estimate tropospheric zenith delay and the associated standard deviation values for SBAS applications based on ERA-5 ECMWF forecast weather data. In addition, a new messaging format is developed to disseminate the tropospheric corrections and the associated standard deviation values to the users via the SBAS signal-in-space with least impact on the signal data rate. Validating the proposed methodology against 10 years of more accurate re-analysis ERA-5 ECMWF weather data illustrates the potential of the approach presented in this paper to estimate tropospheric zenith delays in the order of sub-cm level at most locations. This is a significant improvement with respect to the current 0.12 m sigma used in the DO-229F (RTCA, 2020).