Ionospheric disturbance mitigation methods and systems

System comprising at least one of a navigation satellite system receiver, hereinafter abbreviated as “NSS receiver”, and a processing entity capable of receiving data from the NSS receiver, the system being for estimating parameters useful to determine a position, the NSS receiver observing NSS signals from NSS satellites, and the system being configured for:

• operating at least one estimation process, each estimation process being hereinafter referred to as “NSS estimator” and the at least one NSS estimator being hereinafter referred to as “NSS estimator set”, wherein each NSS estimator uses state variables and computes values of its state variables based on at least one of:
• NSS signals observed by the NSS receiver, and information derived from the NSS signals;
• obtaining ionospheric disturbance information comprising at least one of:
• ionospheric scintillation information and ionospheric gradient information;
• determining that the ionospheric disturbance information indicates an ionospheric disturbance level exceeding a threshold;
• and,
• for at least one NSS estimator of the NSS estimator set, performing at least one of a first operation and a second operation, wherein the first operation comprises:
• adapting an ionospheric noise model of the NSS estimator based on the ionospheric disturbance information;
• or
• switching the NSS estimator to ionospheric free observations;
• and
• the second operation comprises:
• adapting an observation noise model of the NSS estimator based on the ionospheric disturbance information.