The invention relates to a method for determining a flow, wherein flow velocities ΔV−LoS in measuring direction mr are measured by means of sensors 2 using at least one measuring position, comprising the following steps: a) Initializing parameters of a flow model representing the flow, b) Calculating simulated flow velocities in the measuring direction at least at one measuring position according to the flow model representing the flow, c) Comparing the measured flow velocities to the simulated flow velocities and adjusting the parameters of the flow model that influences the flow by minimizing a quality function that depends on the comparison result, and d) Repeating of steps b) and c) and determining the flow in dependency of the approximated flow model.