Results from the scenario simulation of the radio occultation experiment onboard ALMASat-EO mission

Radio occultation technique performed with GNSS observables acquired by low Earth orbit satellites offer a great amount of data to carry out experiments and measurements in the framework of Earth survey. A dedicated GNSS-based radio occultation experiment has been designed to be installed onboard the microsatellite ALMASat-EO mission, developed at the Microsatellite Laboratory of the II Faculty of Engineering of the University of Bologna. The experiment, named ALASE (ALMASat Atmosphere Sounding Experiment) will offer a large amount of occultation events in order to perform scientific measurements of the atmosphere profile and climatology studies. In order to evaluate the feasibility of the experiment, it has been simulated with a dedicated ALMA GNSS Scenario Simulator Software (ALMAG3S) specifically developed for this purpose. The scenario software includes all GNSS satellites position in a precise post processing and pseudo real time environment. The modeled GNSS observables are perturbed considering the main error sources: satellite clock, receiver clock, instrumental errors, relativistic errors and propagation models. ALMAG3S models the errors and the GNSS satellites position by using the IGS products.