1. An adaptive method for estimating an electron content of the ionosphere with an augmentation system to provide corrections for navigation systems using a global navigation satellite system, comprising the following steps performed in succession: collecting a set of measurements carried out by a plurality of fixed receiving beacons on the ground, the plurality of fixed receiving beacons receiving radio frequency signals transmitted by a plurality of transmitting navigation satellites situated in orbit, computing with the augmentation system , for each of the signals of the set of measurements, of spatial coordinates of a point of intersection between a transmission axis of the signal and a surface surrounding the Earth, and a vertical total electron content determined at this point of intersection; a cloud of points, made up of the spatial coordinates of the point of intersection and of a vertical total electron content being thus defined, computing a statistical estimator with the augmentation system, a vertical total electron content, for each of a plurality of nodes of an initial mesh of the surface, performing a statistical dispersion analysis with the augmentation system of the vertical total electron content at each of the plurality of nodes of the initial mesh to select between two predetermined disturbance levels, a weak disturbance or a strong disturbance, of the ionosphere, a step comprising: performing in the case of a weak disturbance, a computation to define a suitable statistical estimator, from the initial statistical estimator with the augmentation system, performing in the case of a strong disturbance, a computation making it possible to generate a new suitable mesh of the surface, from the initial mesh with the augmentation system, performing a statistical error analysis with the augmentation system of the vertical total electron content determined, by the suitable statistical estimator and of the initial mesh in the case of a weak disturbance, or by the initial statistical estimator and the suitable mesh in the case of a strong disturbance; the statistical error analysis to select between two predetermined error levels, a weak error which implies a validation of the adaptation of the method, or a strong error which implies a stopping of the method, and providing correction values based on the vertical total electron content to the navigation systems using the global navigation satellite system.