The ztd estimated values from three models named Site-wise, Grid-wise, and GPT3 and the ztd reference values provided by IGS between 2016 and 2020.

<p>The data includes the zenith total delay (ztd) values computed by three models provided by the VMF data server, namely <strong>Site-wise, Grid-wise, and GPT3</strong>, for target stations during the period from 2016 to 2020, along with the corresponding ztd values extracted from <strong>IGS-ztd</strong> for the respective sites and epochs.</p> <p>These data are utilized for specific accuracy analysis and model evaluation.</p>