1. A method for determining a flow, wherein flow velocities ΔV−LoS in a measuring direction are measured by one or more sensors using at least one measuring position, comprising the following steps: a) initializing parameters of a flow model representing a flow, b) calculating one or more simulated flow velocities in the measuring direction at least at one measuring position according to the flow model representing the flow, c) comparing one or more measured flow velocities (ΔV−LoS) to the one or more simulated flow velocities and adjusting the parameters of the flow model representing the flow by minimizing a quality function that depends on at least one comparison result to obtain an approximated flow model, and d) repeating of steps b) and c) and determining the flow in dependency of the approximated flow model.