Example visual comparison of the predictive performance of our physical model with that of the best competitor model for the dawn ionosphere. First row: ground truth ΔTEC overlaid on noisy draws from the ground truth which are the observations. Second and third rows: posterior mean with uncertainty contours for the physical model and best competitor model respectively. Fourth and fifth rows: residuals between posterior means and ground truth for the physical model and best competitor model respectively. First two columns: results for experimental conditions, (10 directions, 2.5 mTECU noise), for a central antenna (near to reference antenna) and a remote station (far from reference antenna). Last two columns: results for experimental conditions, (30 directions, 1.6 mTECU noise), for a central antenna and a remote station.