Simulating Atmospheric Phase Errors, Phase Correction and the Impact on ALMA Science

We present a framework for modelling atmospheric phase errors and their correction by both the fast-switching and water vapour radiometeric techniques. Notable features are simulating three dimensional turbulent volumes instead of flat phase screens, considering three representative configurations of ALMA and parametrisation in terms of phase fluctuations on a 300m baseline, allowing referencing to the site-testing interferometer data. We use this framework to simulate relative point source sensitivity and effective resolution for a range of atmospheric conditions, with and without phase correction. We also consider the effect of phase fluctuation on short ‘snapshot’ observations, where the variance and correlation of atmospheric phase fluctuations between the antennas becomes important.