This paper introduces a new method for determining the meridional wind velocity during an ionospheric storm based on a sequence of Doppler ionograms. By this new method, the height- and time-dependent meridional wind velocity in the F2 layer was obtained during the magnetic substorm on April 17, 2002. The peak velocity of meridional wind at 300 km altitude is about 300 m/s, the deduced propagation velocity of traveling atmospheric disturbances (TADs) is about 520 m/s. Furthermore, not only the amplitude but also the onset time and phase velocity of the TAD-associated wind perturbation can be explained by the present theories and observations of meridional winds. This work offers a new method to investigate the propagation and morphology of meridional wind during a magnetic substorm by using Digisonde routine observations.