Atmospheric-weighted-mean temperature (Tm
) is a key parameter in precipitable water vapour (PWV) remote sensing using GPS technique. This paper develops a new voxel-based empirical Tm
model, which takes into consideration the lapse rate and diurnal variations of Tm
. The theoretical RMS error of PWV resulting from the new model is generally less than 0.8 m over the globe. Therefore, it can be used as an alternative Tm
determination method in the real-time GPS-based water vapour detection systems.