Tomographic inversion for ALIS noise and resolution

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Abstract
In this report the problems of resolution and noise sensitivity of tomographic reconstructions from ground‐based multistation imaging of aurora with the auroral large imaging system (ALIS) are considered. ALIS is a ground‐based grid of high‐performance CCD‐imaging stations at high latitudes. For evaluation of the resolution and noise sensitivity of current tomographic reconstruction procedures a full model simulation of the ALIS system is presented. The results show that relative errors are typically in the range 0.05 – 0.1 for typical noise levels in measurements of aurora. A general method to estimate resolution in a tomographic imaging system is developed and used to give estimates of the horizontal and vertical resolution. Its current limitations and future perspective are briefly discussed. A method to retrieve feasible tomographic reconstructions from a few image projections with variable noise level are outlined.